Rechargable Battery Question

[Jerry1]

I'm hoping someone can help me understand an issue I've had with a rechargeable battery. As described in another thread, I've switched over to rechargeable batteries. I also got a nice charger. The question revolves around some older batteries that I had and tried to use.

I had some older NiMh AA batteries that were sitting around so I charged them on a basic charger. and they appeared to work. No data at this point. Then I got a new charger and decided to do a refresh of these batteries to see what that was all about as it is a function on the new (better) charger. I ran the refresh and it indicated that the batteries took about 2300 mAh which seemed good as they are rated at 2500 mAh.

So I put them in my wireless keyboard and in less than a week, they were dead. I'm not too concerned about the batteries, but I'm trying to learn what happened. I thought that if they refreshed, they'd operate well, but that did not seem to be the case at all. Can anyone help me understand what's going on? My google searches just keep bringing up how to increase the battery life of a phone. No exactly the issue I'm trying to solve.

BTW, I'm recharging the batteries now and they are over 1800 mAh, so they do appear to be taking a charge.

 

[easysurfer]

Sorry as probably doesn't answer your question.

For comparision, how long do batteries usually last in the wireless keyboard?

Also, what brand is the older NiMh AA battery?

I noticed that brand matters.

Years ago I bought some low discharge batteries at Menards. This was the brand they sell (forget the name). There was a noticeable difference in how long they lasted vs something like an Eneloop battery.

 

[Jerry1]

Regular alkalines would last more than a year. Basically, I don't remember them running them out. I'd just change them so they wouldn't leak in my keyboard.

The brand is Energizer, but they're a few years old. Probably more than three years old and had sat for a long time, probably without any charge. They were some DW bought for her camera and stopped using because she got a new camera.

 

[Palmtree]

It's better to think of them as wooden buckets. The older they are the more they are prone to leak. A new battery can take a charge and hold it for a long time. Old batteries can still take a charge but tend to self discharge more and more rapidly as they age.

 

[easysurfer]

Is the Energizer a low discharge battery? That may play a factor too. Though only lasting less than a week seems a bit short.

I have a wireless mouse, that I use a 1900 mAh low discharge Eneloop battery. I haven't actually timed, but my estimate is I get about 2 weeks before I need to swap with a fully charged one. I don't turn the mouse off but let that self sleep when not in use. The Eneloop I notice does last longer than other brands. Since I almost have fully charged batteries trickle charging, I switching an drained vs a full one is hardly even a thought as that's become automatic.

 

[RobbieB]

Keyboards are very low draw, mine is solar powered with a 2032 coin battery backup and I never replaced the battery. My mouse is powered with 1 AA and lasts about a year and I never turn it off.

 

[FlaGator]

Been using low self-discharge batteries for 10+ years, but far from an expert on NiMH chemistry.

My guess is your Energizers are not LSD, and their age and sitting unused has reduced how long they will hold a charge. Energizer once sold a 15 minute charger for use with those batteries (photo shoots I guess).

If you have a "refresh" cycle on your charger it may be worthwhile to see if that improves how long they hold a charge. Otherwise, I would recycle them.

 

[Jerry1]

Yeah, I’ll go back to alkaline before I’ll change out a battery every two weeks. Especially since an alkaline lasts more than a year. The keyboard must use very little power.

 

[GrayHare]

Then I got a new charger and decided to do a refresh of these batteries to see what that was all about as it is a function on the new (better) charger.

The charger could be the source of the trouble, especially if you see the problem happening with another set of batteries. Improper charging can cause crystals to form inside the battery that will trigger a quicker than usual discharge.

 

[Midpack]

Also, what brand is the older NiMh AA battery?

I noticed that brand matters.

+1. We’ve been using rechargeable AA, AAA and other sizes for years. We started with Energizer, Duracell and Sunpak batteries and they didn’t last long between charges and after a few years they wouldn’t hold a charge. Bought some Panasonic Eneloop batteries - FAR better, and I wouldn’t buy any other brand for now.

As you probably know, rechargeable batteries seem to discharge more as a function of time whether they’re being used or not, unlike traditional single use batteries IME. So we use rechargeables for items that draw continuously like remotes, weather station, clocks. But for infrequent use items like flashlights rechargeables don’t make sense - they go dead after a few months whether you use them or not. So the flashlight may not work when you most need it. We don’t charge rechargeables until they’re needed because we noticed we’d charge them to have them on hand they might be dead or low just sitting for six months.

 

[easysurfer]

Yeah, I’ll go back to alkaline before I’ll change out a battery every two weeks. Especially since an alkaline lasts more than a year. The keyboard must use very little power.

A better comparison to alkaline would be to use a good fully charged low-discharge rechargeable like an Eneloop to see how long that lasts rather than against an old battery.

As mentioned earlier, not all rechargeables are the same. Whereas, for the most post, I think alkalines are pretty close.

I have low discharge AA Rayovac batteries for the keypad of a safe and they last over a year fine. They go down to about 50% in a year.

 

[Jerry1]

. . .Bought some Panasonic Eneloop batteries - FAR better, and I wouldn’t buy any other brand for now.

Most of the new ones that I bought were Eneloop. I did by some Eveready's (not the ones I referenced in this thread) because they were on sale at Costco but all I'll be buying in the future, now that I'm set up, are Eneloops unless something proven to be better hits the market.

GrayHare,
I'm going to give the charger the benefit of the doubt as it is new, a well regarded model (Opus BT-C3100) and it charged them on the 500mA setting.

 

[Jerry1]

A better comparison to alkaline would be to use a good fully charged low-discharge rechargeable like an Eneloop to see how long that lasts rather than against an old battery.

As mentioned earlier, not all rechargeables are the same. Whereas, for the most post, I think alkalines are pretty close.

I have low discharge AA Rayovac batteries for the keypad of a safe and they last over a year fine. They go down to about 50% in a year.

I'm sure my newer ones would last much better. Out of being curious, I'm trying to understand why the refresh cycle seemed to indicate that the batteries were good, at least they took the charge, but then failed to perform well. I think Palmtree may have made the most sense (to me) with his analogy to a wooden bucket. Similar to saying it's just that they're old, but with a better visual to explain what age is doing to impact the performance.