# Series charging a Dyson DC16 li-ion pack



## Aquanaut (May 15, 2012)

Instead of buying a new original Dyson DC16 li-ion battery pack at $75 for my hand held vacuum, I decided to rebuild the 6 cell series pack. Looking at the four contacts to the pack, I could not understand how they were recharging the pack untill I opened up the pack. It turns out that the cells were charged in series without any balancing whatsoever! This goes against all my instincts garnered from CPF.

Two of the pack leads were used to series charge, and the other two were leading to a thermistor in the middle of the pack to measure pack temperature. The pack was listed at 1,000 mAh capacity, so I could easily double or triple the running time. The charger is listed at 28V and 400 ma.

Question: is it worth rebuilding the pack? Could it be that the cells are closely matched in capacity or have some other characteristics for the series charging to work? Can anyone enlighten  me? Comments appreciated.


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## BringerOfLight (May 16, 2012)

You should look at the battery protection board. It may very well have balancing built in, e.g. by doing something like this:
http://www.analogzone.com/pwrt0207.pdf

I would expect the board to use some standard battery management IC. If it does, you can check the datasheet...


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## Aquanaut (May 16, 2012)

Thank you BringerOfLight. That was very interesting reading.

In order to balance the cells, there must be "extra" leads to the intermediate conjunctions of the series connected cells. There were none of these extra leads. There also were no electronic circuits within the battery pack, except for a thermistor.

I have a theory how these cells are monitored during charging and discharging. I believe that the thermistor plays a significant roll inside the battery pack. Could it be that charging/discharging uses heat sensing? I will report back after making a small experiment.


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## AnAppleSnail (May 16, 2012)

Broadly speaking, cells tend to use charge energy to change chemicals until fully charged, then that energy goes to heat. So a thermistor can give a crude, rude idea of cell state. But it will only average all the cells (Or the two next to the thermistor!) and do no balancing. This could help to limit overcharging, but I don't know at what voltage Li-Ion cells heat up on trickle charge.


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## infinus (May 17, 2012)

Ugh..... I have one of those..... is it really 6 non-protected cells in series with no load balancing? I might have to figure out a way to start charging them out of the pack! Was it hard to take apart? Is it something you could do regularly to charge the cells outside the pack? If you put 3100mah cells in there it may not be too bad.


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## infinus (May 17, 2012)

Hmmm, that has me thinking about wiring up a 6 cell 18650 holder to power the vacuum.........


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## Aquanaut (May 17, 2012)

AnAppleSnail said:


> Broadly speaking, cells tend to use charge energy to change chemicals until fully charged, then that energy goes to heat. So a thermistor can give a crude, rude idea of cell state. But it will only average all the cells (Or the two next to the thermistor!) and do no balancing. This could help to limit overcharging, but I don't know at what voltage Li-Ion cells heat up on trickle charge.



I opened up the pack and removed the thermistor away from the pack. When charging, I heated up the thermistor with a heat gun. Charging stopped and the status lights blinked. The manual said for the blinking lights: "Battery outside of temperature range". So, the thermistor is a safety cutoff. The thermistor was positioned in the middle of the pack and an insulating layer was installed over the thermistor and pack.

It might be crude, but I have used the vacuum 2 or 3 times a week for more than 4 years. With only 6 minutes of run time, the pack must be charged after every use. Dyson must be doing something right.



infinus said:


> Ugh..... I have one of those..... is it really 6 non-protected cells in series with no load balancing? I might have to figure out a way to start charging them out of the pack! Was it hard to take apart? Is it something you could do regularly to charge the cells outside the pack? If you put 3100mah cells in there it may not be too bad.



The battery pack is definitely 6 series charged cells with no balancing. There were 2 wires leading to the battery pack for charging. Another 2 wires were for a thermistor. I have charged the pack with my hobby charger attached to the two outside + and - contacts.

The pack is easy to take apart. Just lift up what looks like a cap on the contact end. The cap is not glued on. There are small hooks on the cap and recesses in the body on all four sides to keep the cap on. Carefully pry the cap up off the main body.



infinus said:


> Hmmm, that has me thinking about wiring up a 6 cell 18650 holder to power the vacuum.........



That is a good idea. I am now considering a new rebuild with balancing leads installed inside the pack. I believe this can be done in the old original enclosure. My old pack died after more than 4 years of use. Just keep in mind that a 1,000 mAh pack took 6 to 8 minutes to discharge. That's a lot of amps.


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## Shadowww (May 17, 2012)

Aquanaut said:


> Just keep in mind that a 1,000 mAh pack took 6 to 8 minutes to discharge. That's a lot of amps.


1000mAh @ 6-8 minutes = 7.5A - 10A, Panasonic CGR18650CH cells can do that for example (they are 2250mAh)


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## infinus (May 18, 2012)

Or you could double it up to a 12 pack of li-ion! 2 parallel banks of 6 in series! Talk about run time!!!!! You could then use some redilast or aw protected 3100's! An hour of run time! 

That'd be a big investment.........


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## CKOD (May 18, 2012)

Aquanaut said:


> I opened up the pack and removed the thermistor away from the pack. When charging, I heated up the thermistor with a heat gun. Charging stopped and the status lights blinked. The manual said for the blinking lights: "Battery outside of temperature range". So, the thermistor is a safety cutoff. The thermistor was positioned in the middle of the pack and an insulating layer was installed over the thermistor and pack.
> 
> It might be crude, but I have used the vacuum 2 or 3 times a week for more than 4 years. With only 6 minutes of run time, the pack must be charged after every use. Dyson must be doing something right.
> 
> ...


6 minutes of run time, or a 10C draw, and 1000mAh would make me think its a Li-Mn pack similar to most power tools. While balancing wouldnt hurt, not balancing isnt as huge of a risk as if you had rebuilt it with Li-Co cells. Also, at 10A a holder may become questionable unless it has good positive contact pressure on the cells.


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## Aquanaut (May 18, 2012)

CKOD said:


> 6 minutes of run time, or a 10C draw, and 1000mAh would make me think its a Li-Mn pack similar to most power tools. While balancing wouldnt hurt, not balancing isnt as huge of a risk as if you had rebuilt it with Li-Co cells. Also, at 10A a holder may become questionable unless it has good positive contact pressure on the cells.



You are right on. I removed one of the cells and it turns out to be a Sony SE US18650VT, rated at 1,100mAh and 15A discharge current. Another version is rated at 1,500mAh. The cell is a hybrid Lithium-Manganese Oxide (Li-Mn) and Lithium-Nickle Oxide (Li-Ni). The cell I removed was from a spent battery pack. When I discharged it at 5A (as high as my hobby charger could discharge), it got pretty hot. That is why my Dyson vacuum would cut out via the thermistor.

It it used in power tools such as Makita. Here is some info I swiped off a DeWalt web page:


A123 APR18650M1 cell have nominal voltage of 3.3 volt and 1000ma this give a 3.3 w/h, output 30amp discharg
sony se us18650vt cell have nominal voltage of 3.7 volt and 1100ma this give a 4.07 w/h, output 15Amp discharge
sony se us18650vt cell have nominal voltage of 3.7 volt and 1500ma this give a 5.55 w/h, output 15Amp discharge
sanyo UR18650SAX cell have nominal voltage of 3.7 volt and 1250ma this give a 4.63 w/h, output 20Amp discharge
Samsung INR18650 13q cell have nominal voltage of 3.6 volt and 1300ma this give a 4.68, w/h output 18Amp discharge
Samsung INR18650 13p cell have nominal voltage of 3.6 volt and 1300ma this give a 4.68, w/h output 10Amp discharge
E-Moli IMR-18650E cell have nominal voltage of 3.8 volt and 1400ma this give a 5.32w/h, output 20Amp discharge
Discharge rate give you the torque possibility of battery, but the real workhorse is the watts/hour it give you the real capacity of the cell, the power output in the time
I could not find a USA source for the SE US18650VT cell. However, I found a German supplier who said: "The cell does not need any Balancer. It has near the weight/energy ratio as LiPo cells but it is safe. Short circuit will make a "ploop" and the cell is destroyed but is does not catch fire."

Mystery solved. Thanks for all the comments. :twothumbs


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## Geogecko (Oct 12, 2012)

Dang it. Thought I'd find a complete rebuild at the end of this thread. We've had this DC16 for probably 5 years total now, and we now have a second battery pack that has failed. $83 shipped, for a replacement battery is out of the question. I took apart the original, and did similar research on the cell, and also found it strange that there was no cell balancing inside, however, I could also not locate a source for the strange cells.

So, what did you end up doing? I'd really like to rebuild for about half the price, but am guessing it's probably not possible. This is the only option I have been able to find, and would cost $41.40 for a new pack, fully assembled (cells spot welded). I may have to give it a go, because it seems like the cheaper B&D hand vac has been getting bad reviews after the redesign.

So for $6.90 a cell (free shipping), this guy will even spot weld the cells for you, just have to tell him the configuration of the cells.
http://www.ebay.com/itm/1pcs-3-7V-3...US_Rechargeable_Batteries&hash=item3379df112f


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## Aquanaut (Oct 12, 2012)

Geogecko said:


> So, what did you end up doing? I'd really like to rebuild for about half the price, but am guessing it's probably not possible.



I bought six Samsung INR18650 15Q cells for $45.50 from Redilast, including tabs and shipping. Samsung rates if for a maximum discharge current of 18A, and 1500mAh capacity with a 300mA, 2.5V discharge.

I tested one cell, only one time: charged to 4.2V @ 0.7A, discharged using 300mA to 2.5V and measured 1339 mAh on my hobby charger.

I have not built the Dyson pack yet, since while researching what to do, I purchased a VDQ battery pack for $45.81 via Amazon. The pack seems to be doing its job, but I have only been using it since the end of May, 2012. It has a waranty of 14 months and I will definitely make use of the waranty if the battery pack fails during this time.


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## Geogecko (Oct 12, 2012)

Ah, the ones I saw had horrible reviews. Looks like two are getting consistent reviews now, and saw your review of the VDQ one.

The PWR+ one has the most reviews, almost all 5 star, but $39.90: http://amzn.com/B004TNDR0Y

The VDQ one is now $32.90: http://amzn.com/B004QVM48K

Seems like it may be worth a try to get one of these first. I'd be curious to see what kind of cells they used, since we know they aren't standard Li-Ion in the Dyson's pack. That would be my only concern.


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## Geogecko (Oct 13, 2012)

I ordered the PWR+ one off Amazon, so we will see how it goes. If the case is similar to the Dyson ones, and not glued together, I'll pop it open and see what's inside. I just hope they used the original cells, and not some Li-Ion cells, since there is no cell balancing...would think that could be a fire hazard if so.


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## Geogecko (Oct 17, 2012)

Ok, detectives, need a little help here. Google comes up blank on this cell. This is what was in the PWR+ battery pack. Looks to be constructed exactly the same as the Dyson, except for the sensor placement. The cells are labeled with the following numbers, as shown in the pictures.

LGDAHB11865
K090C315A1 <---Could be 'O' instead of '0', not sure.

https://dl.dropbox.com/u/22358885/Forums/cpf/dysonbattery01.jpg

https://dl.dropbox.com/u/22358885/Forums/cpf/dysonbattery02.jpg

https://dl.dropbox.com/u/22358885/Forums/cpf/dysonbattery03.jpg


Your images are too large and have been replaced with links Please resize and repost.
See Rule #3 If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels. - Thanks Norm


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## Aquanaut (Oct 17, 2012)

Those are LG batteries which are made in South Korea. LG has a good reputation. I found similar batteries at megabatteries.com. Search for lithium ion batteries on the site. I found the following on megabatteries which has similar numbers to the ones you showed. 

LGABB41865
K048B176A3

I googled: "lg 11865 18650 battery" to find the link.


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## Aquanaut (Oct 17, 2012)

I just looked up some Dell laptop batteries that I recycled when the pack itself died. Some of the 18650s were OK to use in my 18650 powered lights. They were LGDB118650.

Hopefully, your PWR+ cells are new, and not recycled. The only way to tell is to measure the capacity of the cells. I am guessing that my old laptop batteries were rated at 2600 mAh.


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## Geogecko (Oct 17, 2012)

They look new, and of course the box says new, but who knows. It powered up just fine, and the vacuum gave three green lights, which it hasn't done in a long time.

My concern is if these are Li-Mn cells, instead of Li-Po's. They could be a fire hazard of the cells actually need balancing...

I guess time will tell now. I will save my review for after the year mark, to see if it makes it past the warranty or not. Technically, to be a better buy, it needs to last longer than a year and a half, because the Dyson battery lasted 3 years, and was about twice the cost. Hopefully I can get 2+ years out of it. If you ever open the case on yours, report the findings.


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## fogfrank (Aug 2, 2014)

Hang the batteries. Can't we just wire for 110 current and screw these expensive batts.

fogfrank


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## snakebite (Aug 2, 2014)

look in vape shops for the sony vtc5.
double your runtime.
common laptop lico cells are NOT up to this task!


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## Dr. Mario (Aug 2, 2014)

Curiously, I am wondering what type of Lithium-ion cells are in there. If there's no balancing circuit, it sounds more and more like Lithium : Iron Phosphate batteries. Yank one cell and charge it to maybe 70% on the single bay charger (whatever you have but not Boomfire model), at normal 4.2 V Li-ion model and leave it out for an hour (3.2 Volts Li : FePO4 cell will bled off excess charge and settle at 3.2 - 3.6 Volt), then check with DMM. But if it's 4.2 Volts even after a day's rest after charging, it's IMR Lithium : Nickel - Manganese Oxide cells specifically for power tool. Buy the most tough protection board possible (the motor will draw 30 Amps or more when starting).

Sent from my XT907 using Candlepowerforums mobile app


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