Best method to test rechargeable AA batteries?

[Bennylava]

What's the best way to tell if your rechargeable AA and AAA batteries should be replaced? They tend to discharge on their own if I leave them sitting for a month. I know that's typical of rechargeable batteries in general.

But I've had some of them for a few years now, and it seems to get even worse as they age. The problem is, they're still not technically dead. You know, not dead dead. They can still be recharged and used. But then if I leave them in that little flashlight, or remote, or whatever for a month, they're dead the next time I go to use them. So I'm thinking that maybe they should be replaced, but it's a little hard to tell since they all discharge on their own anyway.

So it there a good tester or something that I could buy that would tell me for sure if they should be replaced? Or should I just wait until they don't hold a charge at all? That does happen eventually, but it seems to take about 5 years.

 

[HamAndEggs]

Get an Opus C3100, you can do a capacity test

I use mine all the time, works awesome

I also have a feel of them when they are charging during the test, if they are much hotter than the others I just kick that one

 

[Mike Folks]

Ask the manufacturer, but charge them, and test under a resistive load, the maker should be able to tell you the amount and wattage.

 

[Bennylava]

Get an Opus C3100, you can do a capacity test

I use mine all the time, works awesome

I also have a feel of them when they are charging during the test, if they are much hotter than the others I just kick that one

Yeah some of em get really hot. But iirc the battery charger itself can be responsible for that. Charging them too fast.

 

[HamAndEggs]

Yeah some of em get really hot. But iirc the battery charger itself can be responsible for that. Charging them too fast.

For the Opus I usually set it to charge all 4 at the same speed, so I can tell if one is a problem

So far my Eneloops have held up perfect forever, even my oldest one hasn't lost much capacity

 

[tre873]

What type of batteries are they? NiCad, Nimh, or Lithium? I have several Nimh that sit for 6-8 months before they are rotated in. They don't self-discharge very much.

 

[Rinspeed]

If you have rechargeable AA batteries that only last a month I think you need better batteries. Eneloops and GP Recyko is what I have mostly and in ten years I've never had to throw a single one out. They will easily last six or seven months on the shelf. I have an older LaCrosse NiMH charger that not only can test capacity but it has a refresh mode than can bring back older cells, that mode does take some time with charge and discharge cycles.

 

[MikeF2316]

Time for a flashlight that uses Li-ion batteries. They have a very low self discharge rate, so the light will work after months of sitting.

The fact that you have noticed a problem leads me to believe it's time for new batteries.

 

[Mikea57]

I used rechargeables in all of our wireless microphones at my church. I always dated EVERY battery I put in them rechargeable or not, but I found that the rechargeables seemed to last about 3 years, then they would start dying quicker than when new or not charging at all. I'd give them to a guy that would take them to have them recycled and grabbed new ones. I didn't need to take the chance of the battery dying in the middle of a service. Anytime there's ANY problem with the audio at a church service everyone's head is on a swivel and they all turn at the same time looking straight at the sound guy. Not a fun place to be...

 

[Mechanical Noise]

Alot of nimh/nicad chargers will do discharge tests to indicate the current capacity of the cell. You could charge them up, let them sit a few weeks and do a discharge test to get a number for the cell's self discharge. A discharge test is pretty simple and I don't think there will be significant difference between the testers.

Early nimh cells self discharged quickly. Newer production nimh cells are alot better and cells designed specifically for low self discharge, such as Eneloops, are actually pretty good. But I think any sort of nimh cell has too much self discharge for a flashlight or remote. I use alkaline batteries for that. Or Li-ion.

If a modern nimh/nicad is self discharging in a month, it's probably getting old. There's a chance that the device it's in is still discharging the cell even when it's "off".

 

[HenryAZ]

I use the Powerex-MH-C9000, which has been discontinued and replaced by the MH-C9000PRO, an improved model of the same thing. It is for NiMH batteries only. The Refresh and Analyze cycle is good for new batteries, but can be run any time. It runs them through extensive cycles of slow discharging and charging, and the final result is the actual mAh capacity of each cell. I have found in a pack of 8 new Eneloop Pros that they range in capacity from the low 2400s to some just over 2500 mAh. The nominal rating is 2500mAh. Having the actual capacity of each cell allows you to pair similar cells together.

 

[Bennylava]

Anytime there's ANY problem with the audio at a church service everyone's head is on a swivel and they all turn at the same time looking straight at the sound guy. Not a fun place to be...

Sit somewhere it's difficult or impossible to see you, so they can just look around at nothing. Or, have a 1.5'x1.5' sign made that is just the picture in your avatar. Then when all their heads swing around to look at you, hold up the sign in front of your face so that they can't see your head, only the sign.

Anyway thanks for the help all. As usual, it looks like my problem is thus:

I need better equipment!

A charger that tells you when they're dying, and a battery brand that is the best . I take it the Energizers and Duracells in the walmart checkout line aren't even in the running for top dog anymore.

 

[CTyankee]

Get an Opus C3100, you can do a capacity test

I use mine all the time, works awesome

I also have a feel of them when they are charging during the test, if they are much hotter than the others I just kick that one

I wasn't aware of these types of chargers. 99% of all my battery devices are powered by AA or AAA rechargeables, and have been accumulating them for years. I can't identify the older ones with the newer ones anymore. I'll probably go with a cheaper model designed just for those.

 

[Spacey_G]

The best method is a professional grade battery analyzer. At work we use one made by Cadex. They're not cheap though.

 

[TuxThePenguin]

typical NiMH should lose about 10% charge per month. "Low Self Discharge" (LSD) NiMH like Eneloop should last years on a charge, though they aren't quite as power dense (i.e. they hold a bit less of a charge).

None should fully or even mostly discharge in a month. Just replace them outright if yours do that. No need to test.

Some of my Eneloops are probably over 10 years old now. In fact, I don't think I have EVER had to discard an Eneloop to date. I also have some Tenergy Centura (also low self discharge) which have been doing OK.

 

[Citation]

The best method is a professional grade battery analyzer. At work we use one made by Cadex. They're not cheap though.

I've used the Cadex machines. They are nice. I don't recall the machines we had at one of my old jobs. They were very fancy rack mount machines.

For normal people use, I just replace my LeCrosse 1000 (died after 8 years) with an Opus 2400. The 2400 isn't as nice (or expensive) as the 3100 but I'm not interested in Li-ion cells so the differences are small.

The LeCrosse and Opus have capacity test cycles. The Opus also has an impedance test. While the capacity test takes several hours, the impedance check takes about 10 seconds. While not a perfect test, if you get a cell with impedance over 1000 mohm you can guess it's bad.

 

[Bennylava]

The best method is a professional grade battery analyzer. At work we use one made by Cadex. They're not cheap though.

Here's one

https://www.ebay.com/itm/CADEX-C740...543719&hash=item2115521daa:g:BfoAAOSwMtxXt7rc

 

[Citation]

I think I used both the Cadex 7200 and 7400. I wish I could remember the systems we had for testing. They were something like 40-50 bays in a rack. We had back up power supplies the size of a washing machine. We didn't want to lose over a month with of testing because the local power company cut the line.

 

[Rabid Badger]

If you think your batteries are **** they probably are. Instead of dropping $55 to test crappy batteries get one of these:

https://www.amazon.com/Panasonic-K-KJ17MCA4BA-Individual-eneloop-Rechargeable/dp/B00JHKSMJU

and two of these:

https://www.amazon.com/Eneloop-70-ZP2A-6D26-Generation-Pre-Charged-Rechargeable/dp/B00QVKA0IA

The Panasonic smart charger will take good care of your cells without any input from you.