AAA/AA NiMh battery capacity meter - has anyone seen such a thing?

[Dave Plowman (News)]

I have the Lidl one which takes all sizes. And sometimes it won't start charging a cell. Just leave it 'on charge' for a while then remove and replace that cell - it usually starts then.

[whisky-dave]

How did you manage to get Rod Speed turning a dynamo in AUS to charge up your batteries.

After all DIY is cheaper than any professonal way of going about things ;-)

[PeterC]

I found that removing a cell that is fully charged and putting it back on charge after a few seconds results in about 10 - 15 min. more charging. I don't know if this is good, bad or useless.

[pamela]

I do the same but I let the cell rest for a couple of hours in case it has got a temporarily higher voltage which might then fool Delta-V sensing.

The last thing a partially failing cell needs is to get overcharged.

[pamela]

Is this Uniross on Amazon the same charger as the La Cross BC 700? It has the same sort of look but is promoted as a "one hour" charger.

The back of the packet says it charges at 200, 500, 700, 1000 mA.

[cl]

I've just got mine (Uniross that is) from 7dayshop. Yes, it does charge at those currents and (in spite of the writing on the outside) does charge all four cells independently.

I'm just running the first batch of cells through it, seems to do what it's supposed to do. :-)

[T i m]

I think that is because if you set it to 1000mA (or possibly more if you are only charging 2 cells) and have 1000mA cells it should charge them in one hour. However, set the charge rate at 200 and it will charge them in 5 hours (all 'ish' etc).

I don't think it's 'the same' as the BC 700 only goes to 700mA but it could well be the same technically (apart from that ).

This suggests that some of the variants are as thought:

For me 'the point' for such chargers is the slow charge / cycling / testing and I feel that is best done at less than 'maximum' charge rate. That's not to say that that isn't a test / use in itself, just not one I need (or have other chargers for).

Cheers, T i m

[pamela]

I particularly like the capacity measurement with that charger. It helps eliminate failing cells.

[T i m]

And that was one of the main reasons for buying one for me as there are plenty of basic chargers out there. ;-)

Cheers, T i m

[pamela]

When a man who has 20-odd chargers thinks a particular charger is useful then I'm persuaded. I placed an order.

Watch out now, I might blame you loudly for ever more for any and every difficulty with the charger no matter how trivial. Heh!

[T i m]

This is true. ;-)

LCD's ya know.

It really depends on the spec of the cells themselves. That said, most NiCd / MiMh cells are vented these days so *should* be able to tolerate a fairly quick charge. Does it not say on them what the max charge rate is?

Or more if it's doing the capacity test, rather than just a charge.

I would suggest it was and not just because they are Eneloops. The best things in life are worth waiting for. ;-)

Cheers, T i m

[cl]

So far I'm not all that keen on the user interface of my UniRoss version. I tried a random collection of two AAs and two AAAs in it on 'test' and it said one was dead (which I think is probably correct), two had zero capacity (unlikely) and one was 2Ah (possibly). However the display when it had finished was very confusing.

I've currently got a set of four similar AAs in it and the result seems totally confusing. Running 'charge test' again on them just tells me they're FULL and have 0mAH capacity.

[T i m]

Hmmm. ;-(

Then I wonder just how 'alike' the UniRoss unit is to the BC-700 as I've only seen reasonable information from mine.

The setup does require you do make some changes within 10 seconds of turning it on or some such but apart from that, the displays, controls and functions are logical, to me anyway.

One minor niggle is that it doesn't display the terminal voltage on each cell for very long (if you wanted to note them etc) but that's only a minor issue.

Cheers, T i m

[pamela]

I hope I don't have to learn this charger's quirks by trial and error because some of those operations can take a day or two.

[T i m]

You shouldn't, however, you do need to have an understanding of what you are looking at and how it works to get the best (information and results) from it.

If it's anything like my BC-700 then the only thing (IMHO) that isn't completely intuitive is setting of the charging within 10s of power on.

Loads of overviews of them in use on Youtube showing you the range of things they can do and how typically you could use them (if you were interested etc).

Cheers, T i m

[pamela]

Interesting video although I wish he made his points faster.

There's also a lot of discussion forums. I can understand people wanting to discuss charging secondary cells but I never knew people would discuss a particular charger (La Crosse, Maha, whatever) in such detail. By buying the charger I feel I've nearly joined an enthusiast community!

I have a question for you, if you don't mind.

For the sake of argument, let's say a AA cell is rated at 2,000 mAh and is used regularly. Also let's say the "Test" feature on my BC-700 lookalike shows it holds 1,850 mAh.

What amount of capacity increase might you get by using "Refresh"?

I'm asking because I don't want to run the charger for several days, only to get a measly 80 mAh increase.

[T i m]

Hey, we (humans) can pretty well discuss anything to any level, if it interests us enough. ;-)

Welcome.

Of course not.

Ok.

Ok.

Assuming it's a NiMh and given that you already stated that the cell is 'used regularly' then you are likely to see little to no increase in capacity, *depending* on how you normally charge the cell.

No, and I wouldn't suggest you do in that case as I wouldn't say that's what that charger is meant to do (or any, under the said circumstances).

If however you had a quantity of mixed (age, make, capacity, charge / usage status) cells and you wanted to 'sort them out' (into good / bad, equal capacity etc) then that's when the likes of the BC-700 would come into it's own.

I'd grab four of the same (make, chemistry, capacity), bung them in the BC-700 and put them on 'Refresh' and see what comes out. Any around the marked capacity I would keep, any well below I'd either refresh again or recycle (battery recycling box at Sainsbury's) and I'd mark the tested capacity on the cell itself (with a Sharpie) so I could then use them in matched groups (making them last longer and run better).

My new charger arrived this morning and I was just playing with it cycling a 3000mA NiMh model RC car pack.

A cool feature is that when you are on the discharge cycle it can dump the discharging current back into the source / supply battery (I'm currently running it from a smallish 12V lead acid / gel battery).

I bought it primarily to check / balance a(n expensive) 10A x 10 cell Li-Ion pack but knowing it could do so much more. ;-)

Cheers, T i m

[pamela]

I guess you also write the date so you know when the capacity was measures. I have been getting some very low values on AAA Eneloops:

540 mAh instead of the rated 750 to 800 mAh.

That BC-700 charger is a bit unpredictable. I was using Refresh on a single low capacity Eneloop cell and after a day or so I wanted to Test another cell.

I put the new cell in another position and to check the charge current was set correctly I pressed the Current button. The first press increased the current (to 500 mA) and did it for all positions includign the one that was running a Refresh! Not only that but it reset the Refresh programme back to the beginning. Oh my! I thought each channel was entirely independent of the others. I'm learning.

On your chart current seems to increase as time progresses. After the initial 5 minutes, current increases in a strictly linear way. That's not right, is it?

That's interesting I suppose but how is it useful?

What cheapish digital multimeter do you use to test a cell by the meter putting a load across it? The AideTek VC97 meter was discussed here in positive terms a few months ago and it seems to do everything except open the door. However it doesn't load test cells.

[Chris J Dixon]

If you want to work with a selected cell, press and hold the button for that cell until it is flashing, then continue with what you want to do.

Chris

[pamela]

That's what I was missing. Thank you. So that bumpy looking design isn't actually a bumpy looking design, it's really a row of bumpy looking switches. :-)