Advanced Battery Charger With Analyzer?

Looking at getting a battery charger with battery/cell capacity (discharge) analysis.

Requirements are -

* mains powered

* charges NiMH cells primarily, but preferably charges Li-Ion batteries/cells as well, including LiFePO4​ and, if possible, 3.0V regulated/protected RCR123 at 4.5V(?)

* discharges, cycles, and analyzes cells (and displays cell discharge capacity in mAh)

* charge current should be adjustable down to 100 mA (or even lower if possible)

* should have at least two independent charging slots

* takes batteries from AAA size up to around 18650 size

The two chargers that seem to meet most requirements I've found so far are -

SkyRC MC3000

ISDT C4


Any other suitable chargers, please?

You can check this list: https://lygte-info.dk/info/roundCellChargerIndex Analyzer UK.html

Thanks for that! But I have already gone through that list.

With reference to that list -

the Opus BM100 in that list shows 0.1 A as the minimum charge current, but the BM100 minimum charging current is actually 200 mA or 0.2 A.

likewise, the FT2000 minimum charge current in that list should also be 200 mA or 0.2 A.

So both the BM100 and FT2000 chargers are not suitable.

Miboxer C2-4000 - seems to have some problems charging LiFePO4​ cells and with slow charging NiMH cells. So this charger is not really an attractive option.

Miboxer C4-12 - this also seems to have some problem slow charging NiMH cells. Plus it doesn't show cell discharge capacity(?) This charger is not really suitable.


So, are there any other possible/suitable chargers?

Thanks, I have fixed the currents.

Is there a reason why you need such low charge current (100mA), if this is intended primarily for NiMH? Even a AAA NiMH cell should be able to take at least 400mA without getting very warm, especially if they're in good shape. I have some really old crappy AA NiMH cells with internal resistance over 3000 milliohms, and they can take the 300mA charge from the Liitokala Li-500, and still get a full charge (compared to a slow charger that just forces 150mA into them for 16 hours).

Hi,

The Opus BTC3400 charges at different charge rates, and will lower the charge automatically if the cell internal resistance is too high for a normal charge.
I think the min set point is 200ma but it will go down lower i think if the cell cant take it.

WalkIntoTheLight said:

Is there a reason why you need such low charge current (100mA), if this is intended primarily for NiMH? Even a AAA NiMH cell should be able to take at least 400mA without getting very warm, especially if they're in good shape. I have some really old crappy AA NiMH cells with internal resistance over 3000 milliohms, and they can take the 300mA charge from the Liitokala Li-500, and still get a full charge (compared to a slow charger that just forces 150mA into them for 16 hours).

Click to expand...

I want to have the option of charging low capacity cells at a low current when needed, especially if the cells are old. Some cells in the future that need to be charged may be smaller than AAA size.

MrAl said:

Hi,

The Opus BTC3400 charges at different charge rates, and will lower the charge automatically if the cell internal resistance is too high for a normal charge.
I think the min set point is 200ma but it will go down lower i think if the cell cant take it.

Click to expand...

Thanks. I have the Opus BT-C3100 V2.2 charger which is essentially the same as the BT-C3400 I understand(?) Anyway, I have not observed (as yet) any reduction in charge current from the 200 mA setting when using the BT-C3100, although the (old) cells being charged had/have not so high internal resistance maybe?

So, apart from the SkyRC MC3000, the iSDT C4, and hobby chargers (which are getting to be too expensive), there are apparently no other suitable chargers with a charging current down to 100 mA?

meeshu said:

[...] So, apart from the SkyRC MC3000, the iSDT C4, and hobby chargers (which are getting to be too expensive), there are apparently no other suitable chargers with a charging current down to 100 mA?

Click to expand...

Note that you can obtain fractions of the (min) current I by charging cells in parallel, e.g. I/2 for a 2P, and I/3 for a 3P, etc. (assuming they have reasonably close IR). I do this occasionally when I don't have access to a charger with sufficiently low current capability. If you do it a lot you may want to build a harness to make it convenient, Note that you may need to bring them close in voltage before paralleling them so to avoid too high (self) balancing currents (which may not be an issue if they were married in a device)

meeshu said:

I want to have the option of charging low capacity cells at a low current when needed, especially if the cells are old. Some cells in the future that need to be charged may be smaller than AAA size.




Thanks. I have the Opus BT-C3100 V2.2 charger which is essentially the same as the BT-C3400 I understand(?) Anyway, I have not observed (as yet) any reduction in charge current from the 200 mA setting when using the BT-C3100, although the (old) cells being charged had/have not so high internal resistance maybe?

So, apart from the SkyRC MC3000, the iSDT C4, and hobby chargers (which are getting to be too expensive), there are apparently no other suitable chargers with a charging current down to 100 mA?

Click to expand...

Hello again,

Well yes it is actually easy to understand that the current does not go lower than 200ma and that is because the power 0.2*1.6 is only 0.36 watts and since the temperature rise is dependent on both the power and the surface area, that 0.36 watts easily dissipates into the surrounding air without raising the case temperature much at all. So in other words, 200ma is VERY safe when the charge time and/or voltage is monitored. This begs the question: Why do you want to charge at only 100ma? 100ma is old school, which is how cheap chargers do it. It also takes at least 24 hours to charge a 2000mAHr cell so i cant see hwy anyone would want to do this when they have a good charger already.
Recall that a 1/2 watt resistor (0.5 watts) is very small compared to a AA or AAA cells, and yet they are rated for a power level higher than that of which we see here at 200ma.

So the question is, do you have a good reason for wanting to charge at 100ma rather than 200ma?
Note that the charge acceptance is better at 200ma and also at 100ma it is harder to detect the end of charge.

100ma chargers are easy to build. Just use a DC wall wart and a resistor or two to drop current and a battery holder. That's your average cheapo charger.

What smaller type of cells do you want to charge? N size maybe, or AAAA size?

Charging of several batteries in parallel to effectively reduce charging current is noted. Thanks.

100 mA charging current may be the better option for very low capacity cells and/or for cells with high(er) internal resistance. Gentle charging of cells is usually preferred to maximize cell lifetime.

So, again, there are no other suitable chargers it seems?

meeshu said:

100 mA charging current may be the better option for very low capacity cells and/or for cells with high(er) internal resistance. Gentle charging of cells is usually preferred to maximize cell lifetime.

So, again, there are no other suitable chargers it seems?

Click to expand...

I don't think you'll find a charger like that, because there simply isn't any reason for it. A NiMH cell can be charged at 0.5C without any stress. Up to 1C for a good cell (like an Eneloop). 0.25C is 200mA for a AAA cell. Even old worn-out cells can take that.

Unless you're planning to charge lithium-ion button cells or something small like that, you won't need a current less than 200mA. Chances are anything that requires a battery that small will have its own dedicated charger anyway.

meeshu said:

Charging of several batteries in parallel to effectively reduce charging current is noted. Thanks.

100 mA charging current may be the better option for very low capacity cells and/or for cells with high(er) internal resistance. Gentle charging of cells is usually preferred to maximize cell lifetime.

So, again, there are no other suitable chargers it seems?

Click to expand...

Hi again,

I just want to reiterate the idea that you can easily build your own charger from a wall wart, resistor, and battery holder.
100ma is easy to achieve and you can even go lower like 50ma if you really feel the need to do that.
The resistor and wall wart is sized to fit the number of batteries you connect in series. Four batteries in series is typical. Look forward to very long charge times however like 24 hours for 2000mAHr cells at 100ma.

I dont recommend charging in parallel however especially with a store bought charger. It's too hard or impossible to get the current shared equally.

MrAl said:

I dont recommend charging in parallel however especially with a store bought charger. It's too hard or impossible to get the current shared equally.

Click to expand...

It works fine as long as their IR is close.

Comments noted, thanks.

In the end, I've just bought the iSDT C4 charger. It was the best choice I believe.

The charging and discharging currents can be set independently of each other, and all four slots are independent. Charging current can be set as low as 100 mA when needed. And the detailed display of cell charging/discharging status is brilliant! This avoids having to push buttons to see other cell status parameters (most other chargers require additional button presses in order to see all cell status parameters).

Presently using the iSDT C4 to cycle a couple of cells. So far so good!

The C4 will now be my primary charger. And it is likely I'll pick up another C4 charger as a backup in the near future.

Gauss163 said:

It works fine as long as their IR is close.

Click to expand...

Hello,

And i guess you have a good way to determine that?
There are so many other points that need to be addressed here though that even if they are the same it doesnt matter.
For a quick example, the two voltages. For another quick example, the two SOC's.
To make sure the current is the same isnt the only criterion either, but then again it takes a bit of work to be able to measure this when you are doing four cels at a time so we have the measurement issue too.

meeshu said:

Comments noted, thanks.

In the end, I've just bought the iSDT C4 charger. It was the best choice I believe.

The charging and discharging currents can be set independently of each other, and all four slots are independent. Charging current can be set as low as 100 mA when needed. And the detailed display of cell charging/discharging status is brilliant! This avoids having to push buttons to see other cell status parameters (most other chargers require additional button presses in order to see all cell status parameters).

Presently using the iSDT C4 to cycle a couple of cells. So far so good!

The C4 will now be my primary charger. And it is likely I'll pick up another C4 charger as a backup in the near future.

Click to expand...

Hi,

Nice to hear you have found one you like. I hope it fits your needs.

MrAl said:

And i guess you have a good way to determine that {IR is close)?

Click to expand...

You could use your charger's IR function or, lacking that, do a simple (pulse) load test, or measure in-parallel current, etc. You don't need to do this often since typically IR increases very slowly during normal usage.

MrAl said:

There are so many other points that need to be addressed here though that even if they are the same it doesnt matter. For a quick example, the two voltages. For another quick example, the two SOC's.

Click to expand...

That's the only "other point" and it was already addressed in the final sentence of my original post mentioning this method.

If you know what you are doing, i.e. have basic knowledge of batteries and electronics (Ohm's law), then this method works fine.

Gauss163 said:

You could use your charger's IR function or, lacking that, do a simple (pulse) load test, or measure in-parallel current, etc. You don't need to do this often since typically IR increases very slowly during normal usage.



That's the only "other point" and it was already addressed in the final sentence of my original post mentioning this method.

If you know what you are doing, i.e. have basic knowledge of batteries and electronics (Ohm's law), then this method works fine.

Click to expand...

Hello again,

Well i dont think people want to get into measuring their own internal resistance unless they already have an instrument that does that.
But i was also thinking SOC, and the only way i think we can see equal SOC's is if they are both run down all the way.

Then there is the question of how a given store bought charger handles two cells in parallel when the termination methods are different. For example, minus delta V. It's not reasonable to assume that both cells will come up to termination at the same point in time, so one cell reaches it's termination minus delta V point while the other cell voltage is just climbing a little. It seems like that would make it harder to detect. The only method left then might be just pure timing, where the cells are kept on charge for a certain time and that's it.
How do you do your parallel charging? What setup do you use and what store bought charger?

MrAl said:

Well i dont think people want to get into measuring their own internal resistance unless they already have an instrument that does that.

Click to expand...

Many chargers measure IR, and as I mentioned there are other methods too, e.g. measuring actual current.

MrAl said:

Then there is the question of how a given store bought charger handles two cells in parallel when the termination methods are different. For example, minus delta V [...]

Click to expand...

Oh, you're considering NiMH too (I was assuming Li-ion above). Then you may need different techniques depending on the charge algorithm. I rarely use NiMh so I never had the motivation to research such.