LiDL batteries

[Andy Burns]

I've had several batches of AA/AAA batteries from LiDL and found them OK, some of my oldest ones not holding so much charge now, so noticed them on the shelves today and picked up so AAs, got them home and they felt suspiciously light ...

So I've weighed pairs of various AAs I'd had over the years, in roughly chronological order, some are well past-it and only used in last resort.

Ansmann 2200mAh NIMH 57g Hahnel 2350mAh NIMH 58g Sony 2000mAh NIMH/LSD 52g Maplin 2100mAh NIMH/LSD 56g LiDL "red" 2100mAh NIMH/LSD 55g LiDL "black" 2100mAh NIMH/LSD 53g LiDL "silver" 2400mAh NIMH/LSD 37g

I'm somewhat suspicious that the latest LiDL/TRONIC batteries are *so* much lighter, yet claim to have higher capacity ...

[PeterC]

Are those weights for pairs? I've just weighed some Eneloops:

2.4Ah 30g 1.9Ah 26g and Lidl from a few years ago 26g.

The 2.4Ah ones will run the toothbrush for 5 weeks.

[Andy Burns]

Yes.

I've just weighed some Eneloops:

[Robert]

Difference in case construction possibly ?

[Andy Burns]

I've peeled the foil wrapper off one, they are a full metal canister, but thin enough material that you can *just* feel it deform if you squeeze it between finger and thumb ...

[Brian Gaff]

Back in the old days of ni cads, it was common for the same cell sizes to just be put into the bigger bateries. Tandy used to do this a lot. their later ones managed to make aa batteries more powerful, and hence the C sizes got lighter for the same size/capacity. More space inside one supposes. also some of the berec hi power ones had vents and did lose weight over time as one supposes the elatrolyte boiled off to some extent.

I'd have though somebody might have this documented somewhere. the newer technologies seemed to change some years ago when te auto discharge rates suddenly stopped being a factor which effectively gave the same batteries more power. brian

[dennis]

The pre-charged ones (low leakage) have a different construction to the old ones. I have no idea if it makes them lighter as I have never looked into it.

[Syd Rumpo]

Is there a standard for measuring capacity, or is it a case of 'peak music power'?

Cheers

[Andy Burns]

Some of the 'intelligent' chargers will measure capacity, they run the cell down, then recharge it, e.g.

As that's on older video it think it's not the v2.2 firmware which altered the fan behaviour, but that chap seems to do reasonable multi-meter reviews and it's not in Russian which half of the youtube reviews seem to be.

Of course various factors such as the charge rate, discharge rate, whether they measure on the way in or way out etc result in different numbers, this site shows charge/discharge graphs

[Andy Burns]

I weighed a mixture of LSD ones and standard NiMH, before now only the Sony LSDs were lighter, and not by anywhere near so much.

Comparing LiDL's LSD types, the newest AA (18g) feel closer in the hand to the previous AAA (13g) than the previous AA (27g).

[Andy Burns]

Seems they only hold about half their rated charge ...

[T i m]

But I note that discharge test was done at C/5 and I'm not sure that is the right way to test that sort of cell (for capacity)?

Picked up 4 packs yesterday (reduced) and can test them at any rate I choose on my fancy chart-plotting rig. I'll test some and let you know. ;-)

Cheers, T i m

[RJH]

What does C/5 mean please? I've recently bought an Xtar VC4, and a problem with estimating the capacity is getting the battery down to a sufficiently low (about 0?!) level, then charging it back up.

I tried the charger out on some Tronic 4000mah Cs that I use in a DAB radio. The radio was showing 30% remaining, and the charger stuffed 2800 in. So probably not that far off.

[Andy Burns]

The 'C rate' is a measure of the time to charge (or discharge) a battery, relative to the rate to fully charge it in one hour, from there you can take multiples or fractions of the C rate.

e.g for a 2400mAh battery, 1C means a current (2.4A) that will discharge it in 1 hour, C/5 means a current (480mA) that will discharge it in 5 hours, 2C means a current (4.8A) that will charge it in 30 minutes ... in practice it's not actually linear like that.

[T i m]

... exactly (thanks Andy) and so for each type of cell the advertised capacity may be achieved at a maximum discharge rate.

Like one I think I remember is the 'Reserve capacity' of a Lead Acid battery is how long in minutes it can offer a current of 25A (which isn't down to 0V of course).

Model racing cells are normally designed to be used at fairly high rates of discharge (and charge) so may actually be capacity rated at 'C'.

For most of these general purpose rechargeable (and especially Eneloops) I feel their rating may only be seen at C/10 or some such.

Cheers, T i m

[T i m]

I'm not sure there are any rechargeable cells that should be discharged beyond a certain level. I NiMh for example wouldn't normally be taken to below 1V.

The problem with that is the battery capacity meter may be calibrated for say Alkaline cells (nominally 1.5V / cell) and you are using NiMhs which are nominally 1.2V/ cell. As few of these meters measure voltage drop V current / time but just the voltage, they probably aren't that accurate.

The only way to measure the true capacity of a cell (or battery) is to measure the power being delivered down to a specific threshold voltage over time and at the rate as suggested by the manufacturer.

A good example of that in action is the batteries used in UPS's. Say they are 7Ah lead acid batteries and you measure the UPS on-load as pulling 7A, you might assume they will last 1 hour ... not the ~10 minutes they actually last. ;-)

Cheers, T i m

[Andy Burns]

The small-print on the LiDL AAs says seven hours charging at 480mA, when the simplistic C/5 for 2400mAh would be 480mA; probably ties in with the higher internal resistance and heating reported by that budgetlight forum, 28% loss during charging?

[T i m]

Yup, it does seem to fit.

I've just put 12, new, Tronic 2400's on my Energy 16 charger and I might rig my discharge jig up over the weekend and capacity test a few.

Cheers, T i m