# Review of / Measurement on Charger module with TP4056 controller



## HKJ (Oct 8, 2012)

[size=+3]Charger module with TP4056 controller[/size]




Click for larger picture

This charger is a very small module for DIY people, it uses the TP4056 controller and standard configuration is with 1A charge current. It does not include any power supply or tray. It did not include any documentation either, just a couple of boards.
The review is about a specific charger module, but any module with the TP4056 will have identical performance.










I got it in an envelope with 5 circuits on 2 boards and nothing else. The boards is precut and very easy to break apart.
There is some documentation on the sellers ebay page.






A close study showed that there was a small difference between the size of the boards.






The board needs a 5 volt power supply, this can either be from a mini usb connector or soldered directly to the board.
The "current resistor" can be replaced for other (lower) charge currents, because it is a 0603 size smd resistor (i.e. very small) it can be difficult to replace it.
On my boards I have a blue led for charging and a red led for done.

The charge led will be on when charging and it will be flashing when no battery is connected.
The done led will be on when charging is done or no battery is connected.






The backside of the board has some internal connections and the connections points are also accessible here.






The board is small, the battery is a AAA battery.











With the mounted resistor the charger can handle larger batteries, but changing the resistor makes it to possible to charge smaller batteries.




[size=+2]Measurements[/size]

Below 2.85 volt the charger will charge with about 80mA in 1A configuration (blue led is on).
Above 2.85 volt the charger is applying regular charge current (See curve below).
When charger is disconnected from power, but with a battery in, it will draw below 1uA from the battery.
When the charge current goes below the termination current the charging is stopped and it will charge with around 4 uA.
The charger will restart charging when the cell drops to 4.0 volt.
The charger will not restart after a power loss or battery insertion, except if the battery voltage is below 4.0 volt.








First test is with a 3400mAh battery, the charger does a good CC/CV, except the change from CC to CV is a bit soft, this increase charge time but has no bad effect on the battery. The charger is also a bit below the 1A current, it only charges with 0.85A.
The CV voltage is slightly below 4.2 volt, that is not surprising, because the datasheet for the TP4056 specify that it can be between 4.137 and 4.263 volt. This chip uses 1/10 of the charge current as termination current.
I added a temperature measurement to the test this time, as can be seen the chip heats up fast and then slowly drops in temperature when the battery voltage increases.






Reducing the supply voltage to 4.5 volt, increases the charge time and reduces the temperature, but the final voltage is slightly lower.






Increasing the voltage does increase the temperature, but also reduces the current. When the chip gets to hot, it reduces the current.






Here I have added a heatsink to keep the temperature down (Remember electric isolation between PCB and heatsink). It works very well, the temperature is lower than with 5.0 volt supply.






The heatsink was just a piece of aluminium under the board with some isolation between.






My old 16340 IMR cell is also charged without any problems.


[size=+2]Modified resistor[/size]

Replacing the standard 1.2 kohm resistor with a 2.157 kohm reduces the charge current to 470mA.
The resistor is a 0603 SMD resistor, i.e. it is 1.6 x 0.8 mm.






Here a 0603 resistor is placed next to an old style quarter watt resistor.







Again the charger does a CC/CV charging, because the charge current is lower, the termination current is also lower.






A 16340 battery is a more reasonable size to charge with 0.5A.

Replacing the standard 1.2 kohm resistor with a 4.726 kohm reduces the charge current to 210mA.






Again I tested with a16340 battery and get a CC/CV curve.



[size=+2]The last and fatal test[/size]

Somebody asked what happen if the battery was connected backwards.
After a fast test I can conclude that it gives smoke and a dead charger module.








[size=+2]Conclusion[/size]

The charger has a good CC/CV profile and can be adapted for many different charge configurations, for multichannel operation it is easy to use multiple board, for smaller batteries the resistor can be replaced. When used at 1A it might be a good idea to mount it on a small heatsink (Remember isolation), to avoid any slowdown in charging and keep the temperature down.
I do not like that it is using a mini usb connector, a micro usb connector would have been better (That is the same as used on phones).
I will call it a good charger for DIY projects.



[size=+3]Notes[/size]

I bought the module on ebay from "1984yht888" where it is called "5pcs Mini 5V USB Interface 1A Charging Board Module Charger For Lithium Battery"

The temperature measurements is not the chip temperature and probably not even the surface temperature of the chip (I believe that the probe is affecting the measurement).

Here is an explanation on how I did the above charge curves: How do I test a charger


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## tobrien (Oct 8, 2012)

thanks for reviewing this unique board!

so this is, for lack of a better phrase, a cottonpickers style charger but without the displays and switches?


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## HKJ (Oct 8, 2012)

tobrien said:


> thanks for reviewing this unique board!
> 
> so this is, for lack of a better phrase, a cottonpickers style charger but without the displays and switches?



It is just about the same as the cheapest charger from cottonpickers, but his is definitely a better size (usb stick) and you get it ready to use, without needing to do any soldering.


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## march.brown (Oct 8, 2012)

HKJ said:


> It is just about the same as the cheapest charger from cottonpickers, but his is definitely a better size (usb stick) and you get it ready to use, without needing to do any soldering.


Thank you HKJ for your test of this charger board ... I have been using my four charger boards very successfully , powered by my 5V 4A switch-mode PSU ... I have set the PSU voltage to a few mV below 5V and am very happy with the performance ... My PSU has four USB sockets attatched and I have 50cm interconnect cables (USB to mini-USB) ... I personally have no problem in using mini-USB connectors ... For me it was just a simple matter of buying the right 50cm cables which are now kept in a box along with the charger boards , the PSU and the magnets.

Will you be testing these boards in parallel to give a higher charge current ? ... Some users might prefer a higher charge current when charging 3100mAh Li-Ions ... On the other hand , two boards in parallel with each set to a lower charging current than one amp would also reduce the temperature of the chip ... That would only increase the charger cost by another £1 or so.

Can you suggest a better method of attatching a heatsink to the module or indeed to the chip itself ? ... ... I did try cooling with a small fan , but although it did cool the chip it didn't seem to reduce the charging time significantly ... I understand that these chips will tolerate a fairly high temperature so perhaps just a simple heatsink would be the way to go ... My boards are used in a near vertical position with the USB at the top , so maybe there is a slightly better cooling airflow.

Thanks again for your charger board test.
.


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## HKJ (Oct 8, 2012)

march.brown said:


> Thank you HKJ for your test of this charger board ... I have been using my four charger boards very successfully , powered by my 5V 4A switch-mode PSU ... I have set the PSU voltage to a few mV below 5V and am very happy with the performance ... My PSU has four USB sockets attatched and I have 50cm interconnect cables (USB to mini-USB) ... I personally have no problem in using mini-USB connectors ... For me it was just a simple matter of buying the right 50cm cables which are now kept in a box along with the charger boards , the PSU and the magnets.



For four charger boards it would be easier to just solder a cable between them.
Micro usb connectors are much stronger than mini usb connectors and with many phones using them also much more common.



march.brown said:


> Will you be testing these boards in parallel to give a higher charge current ? ... Some users might prefer a higher charge current when charging 3100mAh Li-Ions ... On the other hand , two boards in parallel with each set to a lower charging current than one amp would also reduce the temperature of the chip ... That would only increase the charger cost by another £1 or so..



I do not plan on testing any more on them.



march.brown said:


> Can you suggest a better method of attatching a heatsink to the module or indeed to the chip itself ? ... ... I did try cooling with a small fan , but although it did cool the chip it didn't seem to reduce the charging time significantly ... I understand that these chips will tolerate a fairly high temperature so perhaps just a simple heatsink would be the way to go ... My boards are used in a near vertical position with the USB at the top , so maybe there is a slightly better cooling airflow.



As you can see on my curves, there is no reduction in current at 5 volt input, but electronic always last longer at lower temperature. The easiest heatsink is just a piece of aluminium, where you place the board against (Remember some isolation between), as you can see on the temperature curve, the temperature was reduced significantly.


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## Norm (Oct 8, 2012)

There has been an ongoing discussion on this type of board here.

Thanks HKJ, it's very helpful to have some definitive data on these boards.

Norm


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## candle lamp (Oct 10, 2012)

Excellent review as always. HKJ!

Thanks a lot for your effort & time you put in all of this. :thumbsup:

By the way, after battery reverse connetion, the charger module is broken? 

Do you have any idea to prevent failure from reverse connection?


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## HKJ (Oct 10, 2012)

candle lamp said:


> By the way, after battery reverse connetion, the charger module is broken?



Definitely, smoke is a very bad sign, especially when there also is some light (The chip did shortly light up).




candle lamp said:


> Do you have any idea to prevent failure from reverse connection?



It would require some extra components, a p-channel fet transistor could probably solve it.


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## nginx (Oct 12, 2012)

I was browsing ebay yesterday to see if there was anything I could hook up directly to my 4x18650 battery pack (4P config) and charge it without having to take apart the battery pack everytime. This module was the first thing that came up on search. A little search for a review on Google landed me here. Thank you HKJ for doing such a in-depth review.

I only have one question. Will it work if I parallel 3 of these modules and connect them to the battery pack to achieve faster charging or will it all go up in smoke? One module will take forever to charge a pack of 9000mah. I know the best solution would be to obviously get one module capable of 3A or more but I can't find one unfortunately


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## Shadowww (Oct 12, 2012)

You can find dual-TP4056 boards that are configured for 1.5A, e.g. eBay lot ID 270980008241.
If you re-configure them for 1A each (instead of 750mA each), and add some decent heatsinking, you'll get 2A which will give you ~acceptable charging rate for 9000mAh pack.


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## Lightfoot98 (Oct 14, 2012)

you can parallel the boards with no problem.


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## Fallingwater (Mar 4, 2013)

I ordered three boards exactly like these, and three that look different but are based on the same chip:

http://smartrobots.pl/additional_images/TP4056.jpg (not my picture)

I'm unsure what's the current resistor I need to change on these to get a lower-current charge. Any idea?


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## HKJ (Mar 4, 2013)

Fallingwater said:


> I ordered three boards exactly like these, and three that look different but are based on the same chip:
> 
> http://smartrobots.pl/additional_images/TP4056.jpg (not my picture)
> 
> I'm unsure what's the current resistor I need to change on these to get a lower-current charge. Any idea?



Look like it is R4, but I would prefer better pictures and from both sides of the pcb to be sure.


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## zsnopek (Mar 31, 2013)

What will happen to 14500 battery (900mAh) if I charge it without any modifications to the board?

I don't understand exactly how this chip works. USB provides only 500mA and by default TP4056 is set to charging current of 1000mA.
Does it amplify 500mA to 1000mA to charge the battery?

Soldering SMD resistor is unfortunately out of question for me. I hope I can keep using 14500 (don't mind if it diminishes their lifecycle a little).

Thanks!


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## HKJ (Mar 31, 2013)

zsnopek said:


> What will happen to 14500 battery (900mAh) if I charge it without any modifications to the board?
> 
> I don't understand exactly how this chip works. USB provides only 500mA and by default TP4056 is set to charging current of 1000mA.
> Does it amplify 500mA to 1000mA to charge the battery?
> ...



You will be charging with a to high current and this will reduce the lifetime of the battery.

USB might be rated at 0.5A, but on PC's it is usual possible to draw more. The TP4056 is a linear regulator, i.e. input and output current is the same, except for a small consumption by the chip.


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## zsnopek (Mar 31, 2013)

HKJ said:


> You will be charging with a to high current and this will reduce the lifetime of the battery.
> 
> USB might be rated at 0.5A, but on PC's it is usual possible to draw more. The TP4056 is a linear regulator, i.e. input and output current is the same, except for a small consumption by the chip.



Great news...
The good thing is that I don't plan to charge it using PC. I plan to use it as bicycle battery charger.. Luckily, dynamo is constructed to limit the current at ~500mA. I know it's still a little bit high, but better that than 1A.

Thanks for the info


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## Masure (Apr 19, 2013)

Hi guys,

Sorry for my electronic's noob question but what's the component between BAT- and BAT+ ? What's its purpose ?

Thanks

edit : I read the TP4056 specs and the component is a capacitor. But I still don't know its function.


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## HKJ (Apr 19, 2013)

Masure said:


> Sorry for my electronic's noob question but what's the component between BAT- and BAT+ ? What's its purpose ?



It is a capacitor, the purpose is to decouple the output.

They word "decouple" does probably not tell you much, here it is used because the chip is fast in regulating the current and if you have long wires the current will not be stable, but change up and down at a fast rate (Oscillate). To prevent this a capacitor is added to the output, it will prevent any funny businesses due to long wires (Long wires might be as short as 10cm or 4 inches).

This kind of components are often used, because the data sheet for the chip recommends it, not because calculations or experiments shows that it is necessary.


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## Masure (Apr 19, 2013)

Thanks HKJ

Could I safely remove this capacitor with <4cm wires to my battery ? I'm using this board in a very tight box and I wish to cut it down. If I do so, I remove this capacitor. I'd like to know if it's safe.

Regards


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## HKJ (Apr 19, 2013)

Masure said:


> Could I safely remove this capacitor with <4cm wires to my battery ? I'm using this board in a very tight box and I wish to cut it down. If I do so, I remove this capacitor. I'd like to know if it's safe.



The datasheet I could find does not specify if it can work without the capacitor.


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## eatkabab (Sep 17, 2013)

I recently received one of these chips (micro USB variation) and hooked it up to a single 2000mah LiPo cell and two of the leads on the IC started to spark, sizzle, and a small flame occurred....
I mean this is pretty simple stuff and I'm sure I attached the battery leads to the correct terminals as seen in the picture. Could it be that the +/- as printed on the board is flipped?

(I made this picture for the china seller of the board so please don't be offended by my arrowing)






Any help is HUGELY appreciated.


Also, if you leave the battery connected to this circuit, does it draw any current? I assume it does given that it's a circuit...any idea how much? Will a 2000mah cell last for weeks, months if just left from a full charge?

Also, OP, thank you so much. This is exactly what I was looking for.


Edit: Upon inspection, I note that the "Batt +, Batt -" are printed on the same sides as the OP pictures, although reversed running towards the USB connector instead of away. Dunno if that means anything.

Update: I just reversed the batt polarity (just tapped the leads) and the same two leads on the IC started sizzling/sparking. :shrug:


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## billy_gr (Sep 18, 2013)

A bit to late... but you polarity according to the first post of HKJ was ok...

It looks like pins 5 and 6 of the TP4056 are soldered together, you can verify it with an ohm meter while disconnecting the battery and the USB, it would be close to zero ohm.

On the other hand if it is burned allready... you will not be 100% sure for the result


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## eatkabab (Sep 18, 2013)

billy_gr said:


> It looks like pins 5 and 6 of the TP4056 are soldered together, you can verify it with an ohm meter while disconnecting the battery and the USB, it would be close to zero ohm.



Thanks very much for your reply but I just checked and they're not connected. The flash of light in the picture is misleading. It's coming from under the very corner pin. It still sparkles and sizzles if I leave the batt connected for more than a few seconds...


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## malow (Sep 18, 2013)

DX has this charging boards in 2 flavors for $2.30

http://dx.com/p/tp4056-1a-li-ion-battery-charging-module-blue-4v-8v-215797
http://dx.com/p/1a-lithium-battery-charging-module-blue-205188

also a MP1405 based with a li-ion protection circuit on it:

http://dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454

i got a few of them, and as mentioned, they get quite hot at 1A charging. glued a small heatsink over the ic with thermal glue. works great 

i use them together with a small switching regulator, so i get a 6v~28v input charger:
http://dx.com/p/mini-3a-4-5-28v-input-0-8-20v-output-step-down-voltage-regulator-green-238815


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## eatkabab (Sep 20, 2013)

So the ebay seller replied about my faulty chip and said i'm supposed to have the usb power plugged in before soldering the batt leads. That seems really counter intuitive... do I just have a faulty fried chip?


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## puchu (Oct 2, 2013)

eatkabab said:


> So the ebay seller replied about my faulty chip and said i'm supposed to have the usb power plugged in before soldering the batt leads.



That seems to be an excuse, you could contact ebay, if its under ebay protection for Paypal
--------------------------------------
Please have a look at the following circuit based on the same IC most likely.

I am going to buy this for 1.11$
http://www.ebay.com/itm/400353508118#payCntId
same item is on DX.com I think the circuit is capable of output also but; is it 5 volts or just battery O/P.
http://dx.com/p/tp4056-1a-li-ion-battery-charging-module-blue-4v-8v-215797

- Model: TP4056 
- Quantity: 1
- Color: Blue
- Material: PCB + plastic + iron
- Board TP4056 lithium charge management chip
- Mini USB head can link directly to the computer USB port charging
- The charging board can also power supply from (IN + and IN-) pin
- Setting aside the the TEMP pin interface can be used as lithium battery temperature detection
- Input voltage: 4V~8V 
- Maximum output charging current: 1000mA
- D1 indicator lights on when in charging, D2 lights on when charging completed 
- English Manual/Spec: Yes
- Great for DIY project
- Packing list: 
- 1 x Lithium battery charging module 

Has anyone used this ?


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## eatkabab (Oct 3, 2013)

puchu said:


> That seems to be an excuse, you could contact ebay, if its under ebay protection for Paypal
> --------------------------------------
> Please have a look at the following circuit based on the same IC most likely.
> 
> ...



They refunded me. There only seems to be two different circuits in the micro usb form so I ordered the other one. Hoping the one I had was just faulty. 

As for the one you ordered, it seems they just moved the IN pins to thr back of the board next to the OUT pins. That doesnt exactly make sense but its china... the board can only be powered by those pins, it probably wont feed power out the usb plug.


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## puchu (Oct 3, 2013)

eatkabab said:


> They refunded me. There only seems to be two different circuits in the micro usb form so I ordered the other one. Hoping the one I had was just faulty.
> 
> As for the one you ordered, it seems they just moved the IN pins to thr back of the board next to the OUT pins. That doesnt exactly make sense but its china... the board can only be powered by those pins, it probably wont feed power out the usb plug.



May be its for people who won't use the USB port instead they would put a solar panel through a 7805


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## eatkabab (Oct 10, 2013)

So I got my new module, hooked up the battery and it works great. The last one was probably defective.

It charges great but around when the battery is almost full it does this funny thing where the red and green lights flicker together really fast. Sometimes it goes straight to green and stays there, other times it does that funny behavior. Is it just phasing between charging and full? Does this mean it's just about almost full? Is this bad?

Just a note, I actually got the version with a built in protective circuit. I'm not sure that makes a difference or even matters if the battery is already protected though. It appears to be much higher quality than the previous one which is the same as the OP's.
http://www.ebay.com/itm/151115248051?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
It's $4.49 now but I got it for $3.35 just two weeks ago...


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## bob_ninja (Oct 31, 2013)

I found the flickering red/blue to be caused by poor contact and other times almost full cell.
Seems to be normal, no issues.


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## Lightfoot98 (Nov 2, 2013)

malow said:


> also a MP1405 based with a li-ion protection circuit on it:
> 
> http://dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454




What chip does this use?

Can't find anything on "MP1405"


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## eatkabab (Nov 3, 2013)

*HUGE NOTE!! * I figured out why my first board burnt up!!!
I almost always use solder solution. When it boils under soldering it splatters around...onto the MP1405...which I now know will de-solder/fry it's connection under the battery's typical idle current/voltage.

DO NOT USE SOLDER SOLUTION/REDUCING AGENT ANYWHERE NEAR THESE BOARDS!!!

Maybe add this to the OP? I mean we don't want people burning up their $2 investments. I had to do it twice before figuring it out


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## HKJ (Nov 3, 2013)

eatkabab said:


> *HUGE NOTE!! * I figured out why my first board burnt up!!!
> I almost always use solder solution. When it boils under soldering it splatters around...onto the MP1405...which I now know will de-solder/fry it's connection under the battery's typical idle current/voltage.
> 
> DO NOT USE SOLDER SOLUTION/REDUCING AGENT ANYWHERE NEAR THESE BOARDS!!!
> ...



You do never use that when working with electronic, you always uses flux.


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## eatkabab (Nov 3, 2013)

Also, here's what I've made with it. I'll be making about 10 of these. That black thing is a 3.5mm headphone port used for basically a tiny very focused flashlight on a wire that uses an XRE LED. I ended up just buying 3.5mm extension cables for use because those damn 3.5mm female components cost 5x the cost of the entire wire. It gets affixed better with the case on so no movement stress on any electronics.









The one in a case uses a custom circuit board I developed based on a cell phone camera light driver. The one without a case is just an AMC7135. I tried using the cell chip because it gives me buck/boost functionality which is theoretically more efficient. The cell chip at 318ma runs for 9.5hrs on the 3400ma Panasonic 18650. The AMC7135 goes at 350ma so right off the bat I would expect to cut at least an hour off...we'll see.


This is the 'cell phone' driver used in the one within a case:


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## eatkabab (Nov 3, 2013)

HKJ said:


> You do never use that when working with electronic, you always uses flux.



So I've now learned...  Interesting since I never had a problem for many years. I do always try to be very neat about it though.
The basic concept is just a reducing agent so whatever it is it still sizzles off. Does the flux pen not spatter and rather just smoke away?

Oh you're the one that does the battery tests! EXCELLENT WORK! That test is hugely valuable and should be published in books and updated regularly. I commend your very scientific methods. It's more determinant, informative and efficient than the mountains of conflicting medical research at least. I chose my battery based off your test. Then realized Tesla also uses a variation of this cell for their cars which is reassuring.


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## HKJ (Nov 3, 2013)

eatkabab said:


> So I've now learned...  Interesting since I never had a problem for many years. I do always try to be very neat about it though.
> The basic concept is just a reducing agent so whatever it is it still sizzles off. Does the flux pen not spatter and rather just smoke away?



A flux pen works more like a regular pen, there is no splatter. 
And flux is not dangerous for electronic parts (Depends a bit on type, some flux has to be washed away).

For most electronic soldering work you uses solder with build in flux and seldom has to apply flux.


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## eatkabab (Nov 3, 2013)

HKJ said:


> A flux pen is works more like a regular pen, there is no splatter.
> And flux is not dangerous for electronic parts (Depends a bit on type, some flux has to be washed away).
> 
> For most electronic soldering work you uses solder with build in flux and seldom has to apply flux.



I'm embarrassed to show the soldering iron I'm using. It's worse than those radioshack things. I'm basically soldering with an 8mm tip that I even modified to get that small. It can barely keep itself heated so It needs all the help it can get.
Thank you for all the information. I'll grab some flux pen for the remainder.


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## psychbeat (Nov 3, 2013)

eatkabab said:


> Also, here's what I've made with it. I'll be making about 10 of these. That black thing is a 3.5mm headphone port used for basically a tiny very focused flashlight on a wire that uses an XRE LED. I ended up just buying 3.5mm extension cables for use because those damn 3.5mm female components cost 5x the cost of the entire wire. It gets affixed better with the case on so no movement stress on any electronics.
> 
> 
> 
> ...



^^Those look cool!


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## maly (Dec 23, 2013)

Hi guys. 

I am new in this DIY charging batteries and I wanted to make my own battery pack from 2 18650 batteries 5300mAh to have a total of 7.4v with 5300mAh. Now I already bought the USB charging circuit TP4056. However, I don't have an idea on how exactly i should connect the batteries to this circuit in order to be able to charge and use the batteries at the same time without removing the batteries from my project enclosure. Also, does the TP4056 needs a PCM board in order to work or it has built in protection. 

I have used the diagram here http://scriptasylum.com/rc_speed/lipo.html for wiring but it didn't give me any information about the protection circuit, I am little bit confused here. :shakehead

Thanks for your help.


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## dlong (Feb 11, 2014)

Has anyone compared (or reviewed) the MP1405 to the TP4056 to see what the charging profile is? Can't find anything (datasheet) on the MP1405. Are we sure it's an actual part number of the chip and not just some made up model for the module?

-d


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## eatkabab (Mar 18, 2014)

maly said:


> Hi guys.
> 
> I am new in this DIY charging batteries and I wanted to make my own battery pack from 2 18650 batteries 5300mAh to have a total of 7.4v with 5300mAh. Now I already bought the USB charging circuit TP4056. However, I don't have an idea on how exactly i should connect the batteries to this circuit in order to be able to charge and use the batteries at the same time without removing the batteries from my project enclosure. Also, does the TP4056 needs a PCM board in order to work or it has built in protection.
> 
> ...



Sorry for the delayed response. First off, a 5300mah 7.4v two cell pack is not possible. I assume you're trying to use 2x2650mah cells in series to get the 7.4v but the capacity isn't additive. You either get 3.7v at double the capacity or 7.4v at the same capacity. Anything else would not conserve energy. 5300 x 7.4 = ~39Wh but if you have a 2650 cell at 3.7v, 2650 x 3.7 = ~10Wh. Two cells cannot produce more than 20Wh combined in any parallel/series configuration. If this isn't clear, look up the difference between series and parallel. You're also probably at a very very basic level and I would not advise you to be messing with custom lipo cells.

As for the charger and pack you want to produce, what you're trying to do is again, not advised. You cannot charge two lipo cells off a charger designed to charge a single cell. You want 7.4v but the charger you've chosen is only designed to charge up to 4.2v on a single cell.

Some really basic info about lipo charging:
- The charger generates 4.2v constant
- current is applied to the cell and the cells voltage is constantly monitored
- as the cell approaches the maximum charged voltage of 4.2v, the current is slowly reduced
- at 4.2v charging is turned OFF. No trickle charging
(I may not be 100% right about the 4.2v constant voltage but I'm pretty sure)


What you need is a charger designed for TWO cells. This means that EACH cell has a +/- lead attached to the charging board. This is absolutely required for balancing of cells. You cannot have one cell that has more capacity than another. If that were the case, one cell would drain while the other is still chugging away...the drained cell will fall below the critical ~3.0v and will be damaged or potentially burst into flames/heat up a lot.

The other issue is cell protection. The protection circuit is designed to avoid the cell being overcharged or over discharged (bursting into flames, or, thermal runaway). You can buy cells that have built in protection circuits (advised), or you can use a power management board which both charges/balances the cells while also protecting EACH cell from over/under voltage. In the latter scenario your +/- terminal to whatever application you're using it with would come off the POWER MANAGEMENT BOARD and NOT from the cells themselves. The board must be specifically designed to take 2, 3, 4, 5, 6 whatever number cells and provide you with 3.7, 7.4, 11.1, 22.2v whatever voltage...basically must be designed to operate with parallel/series designed circuitry.

Due to this very custom design necessity, there aren't very many readily available power management boards that are cheap. Even fewer offer a simple charging solution in addition to power management. They'll often need some specific voltage and minimum current to be applied to the charging leads. Not to mention it would be very inefficient trying to charge more than a single cell off a very convenient cell phone charger. Instead, the typical model is to have a separate cell charger that charges single protected cells then drop those cells into a flashlight, plane, robot, laser, whatever you're using them for. Take them out when they're drained and recharge. Or the modern R/C model of having cells linked in simple 1S, 3S, 4S...with a balance wire which just has + leads from each cell and a common ground so the charger can balance the cells.

There is one semi trick you could do however. You could hook up two protected cells to a single TP4056 in parallel but operate them in series. I'm not 100% sure how this would work, but I imagine during charging, the charger would just keep going for a longer period since the charge current is being split (you'll want a higher charge current but mind the charging chip heat). One charging issue however would be if the cells eventually become unbalanced, one would charge to max first and the charger would just cut out and not charge the other cell. During discharge they should operate normally until again over time they become unbalanced; one cell will drop to the 3.0v minimum and cut out. So this method is not really advised (at least not for several charge/discharge cycles).

If you really want embedded cells, your best bet is probably just using two TP4056 boards and two cell phone chargers. Wire your cells in series to get your 7.4v but have separate circuits for charging also hooked up to the cells. Don't ever use soldering solution on electronic boards, but it's highly advised to use some sort of soldering agent when soldering lipo cells to avoid overheating them with the solder/iron.

Hope that helps, good luck.


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## Squashie (May 29, 2014)

Do u know if this board can be used to charge the battery and power a devise simultaneously? 

For example i want to power an led while charging the battery.


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## WingLoader (Jul 31, 2014)

eatkabab said:


> If you really want embedded cells, your best bet is probably just using two TP4056 boards and two cell phone chargers. Wire your cells in series to get your 7.4v but have separate circuits for charging also hooked up to the cells. Don't ever use soldering solution on electronic boards, but it's highly advised to use some sort of soldering agent when soldering lipo cells to avoid overheating them with the solder/iron.
> 
> Hope that helps, good luck.



I made a 3 cell "pack" in series. I put taps on each cell. On each charging board I put a volt meter module so I can see the voltage of each cell. If I plug a USB charger into each board (3 chargers) I can charge each cell independently and track the voltage with the little meters.

I thought it would be neat to power all three boards with a common power supply. I used an old ATX power supply and used the 5v supply wire and used it as a common +5 on each board. Well, don't do that. When I plugged in the first cell tap...3.86 volts and charging. When I plugged in the second cell to the second board, smoke and two fried boards.

It seems like there is a reverse flow of current from the two cells going back through the boards because the negative side of one cell is connected to the positive side of the other cell. Would putting diodes somewhere in there isolate the cells? I read something about using an isolated ground charging method. 

I have an AR Drone and there is a balanced charger. It uses the "taps" to charge each cell independently to make sure they are balanced. I am effectively trying to do the same thing by using these 1 dollar units. Any advice on how to use a common power supply to three boards so that I can charge three cells independently even though they are soldered in series?

Thanks!
Joe


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## InHisName (Aug 2, 2014)

Three independent 5v supplies would work for sure.
Possibly one 15v supply with 5v & 10v 'taps', now you have 3x5v but they are connected to each other. As long as nothing is grounded, it 'might' work.


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## BringerOfLight (Aug 4, 2014)

WingLoader said:


> I made a 3 cell "pack" in series. I put taps on each cell. On each charging board I put a volt meter module so I can see the voltage of each cell. If I plug a USB charger into each board (3 chargers) I can charge each cell independently and track the voltage with the little meters.
> 
> I thought it would be neat to power all three boards with a common power supply.


The input ground goes directly to the battery '-' output. So if you use the same power supply with multiple boards, you get a short. You need separate power supplies with separate grounds (a single supply with multiple outputs will likely have a shared ground for those outputs).


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## WingLoader (Aug 4, 2014)

BringerOfLight said:


> The input ground goes directly to the battery '-' output. So if you use the same power supply with multiple boards, you get a short. You need separate power supplies with separate grounds (a single supply with multiple outputs will likely have a shared ground for those outputs).



Yup. That is what happened. The chargers for 3 cell packs that use the balanced "taps" to charge individual cells must have special circuitry to prevent what is occurring to me. 

I came up with a Rube Goldberg way to do it. I am going to put a double pole switch that disconnects the connections between the batteries when I am charging.


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## kosPap (Sep 7, 2014)

hi all! i have two questions on the board.

1. I intend on recreating the cottonpickers charger but i will be addign a voltage display of 3-12Volt.
I want to be able to measure 12V SLA batetries with it (as well as my 18650s) but hooking the leads on a 12V battery it will also backfeeding 12V to the board.
Do you think it will take it? Should I add a diode and on what pole?

2. What would the board output if the power in is less than a USB 1A supply?


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## HKJ (Sep 7, 2014)

kosPap said:


> hi all! i have a question on the board.
> 
> I intend on recreating the cottonpickers charger but i will be addign a voltage display of 3-12Volt.
> I want to be able to measure 12V SLA batetries with it (as well as my 18650s) but hooking the leads on a 12V battery it will also backfeeding 12V to the board.
> Do you think it will take it? Should I add a diode and on what pole?



I doubt it will take it and adding a diode would be a bad idea, because it would interfere with the charging.


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## kosPap (Sep 7, 2014)

indeed, it did not think of this...
thanks....


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## BringerOfLight (Sep 7, 2014)

kosPap said:


> 1. I intend on recreating the cottonpickers charger but i will be addign a voltage display of 3-12Volt.


IMO, it's not a good design. The display is powered from the battery side, so when power is disconnected or the charger is finished charging, the battery will be drained (you expect those displays to draw <15mA). There are 3/4 lead voltage displays that have a power input (you would connect that to 5V) and a measurement input, so you won't drain the battery. Make sure sure you get one with enough accuracy/resolution in the 3 - 4.3V range.


> I want to be able to measure 12V SLA batetries with it (as well as my 18650s) but hooking the leads on a 12V battery it will also backfeeding 12V to the board.


I would just get another display, they are extremely cheap in China (eBay). I don't think there is a simple solution protecting the TP4056 from the 12V (and you will most certainly fry it with that).


> 2. What would the board output if the power in is less than a USB 1A supply?


If the TP4056 is configured for 1A (there is a resistor that is used to set the charge current), you will likely fry the power supply (unless it has good current limiting). The TP is a linear regulator, meaning input current is equal to output/charge current.


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## kosPap (Sep 8, 2014)

and not the other way around...thanks!


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## thegreatfixer (Dec 25, 2014)

thank you for the review it was very in depth 
i have a few questions 
do you know if this or the new boards (w/reverse polarity protection) with Micro USB can work as a regulated ~4.2v CONSTANT power supply 

if i wanted to take an led light and run it all the time AND have 1 or 2 18650 as a backup power source can the TP4056 do both power the light and charge the batteries and in case of power failure run of the now fully charged batteries
???

thank you 
thegreatfixer


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## HKJ (Dec 25, 2014)

thegreatfixer said:


> do you know if this or the new boards (w/reverse polarity protection) with Micro USB can work as a regulated ~4.2v CONSTANT power supply



I have not tried it, but it might work in some cases. Remember that the chip turns off current when output load is below a specific current.




thegreatfixer said:


> if i wanted to take an led light and run it all the time AND have 1 or 2 18650 as a backup power source can the TP4056 do both power the light and charge the batteries and in case of power failure run of the now fully charged batteries



The chip will charge the batteries, if they are never filled up (due to current drain) I believe that the chip will continue to charge. If they get filled up the chip will turn off, but turn on again when the voltage drops below 4 volt.
Keeping you batteries at full voltage permanently will reduce the lifetime of them.


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## sandalian (Jan 13, 2015)

Thanks for your review HKJ, this is the thing I'm looking for.

If I'm about to build a sub 100mAh charger (just like for battery 10180) what size is the replacement resistor? Please advise.

Thanks!


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## HKJ (Jan 13, 2015)

sandalian said:


> If I'm about to build a sub 100mAh charger (just like for battery 10180) what size is the replacement resistor? Please advise.



Check the datasheet, it has a table and the formula.
I am not sure that the manufacturer recommends using the chip with current below about 100mA, but you can always try.


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## sandalian (Jan 13, 2015)

excelent, thanks!


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## thegreatfixer (Feb 4, 2015)

HKJ said:


> I have not tried it, but it might work in some cases. Remember that the chip turns off current when output load is below a specific current.
> 
> The chip will charge the batteries, if they are never filled up (due to current drain) I believe that the chip will continue to charge. If they get filled up the chip will turn off, but turn on again when the voltage drops below 4 volt.
> Keeping you batteries at full voltage permanently will reduce the lifetime of them.



thanks i am looking for a way to use 18650 in emergency lights and even always on lights

BTW with the NEW MICRO USB boards with 2 pin outs for +&- i would like to get screw terminals for them do you know if they are 5mm or 3.8mm or 2.5mm


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## samgab (Sep 23, 2015)

Just got a few of these TP4056 charging boards and a few 18650 holders, all for chump change. Really good little charger. Amazing to think the price 18650 CC/CV chargers used to go for.
I've done a bit of my own testing on the ones I received, checked the max V level, and the current levels etc, and it's all perfectly safe. I'm very impressed.


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## cloudbuster (Dec 11, 2015)

Hi, I would like to know if by combining the board with a solar panel I would get a safe charger or if I am missing something.
solar panel 2.5W 5V 500mA
http://www.amazon.com/gp/product/B00CBT8A14/?tag=cpf0b6-20 do all solar panel keep the LED off during the day while they charge?
also would I need a one way diode? 

Boards
http://www.amazon.com/dp/B00AUDQWXQ/?tag=cpf0b6-20
or
http://www.amazon.com/dp/B00QGVP944/?tag=cpf0b6-20

is to replace a patio solar panel LED that does not charge the 3.7 li bat fully

thanks.


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## kosPap (Dec 12, 2015)

I had bad luck with a 2.5W panel and a 400mA Cottonpickers charger.
but it may be just me


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