Use of rechargeables?

[PhotoWiz]

I note that members are using NiMh cells for a number of household devices (in addition to their very expensive flashlights!) And I'm wondering if the possibility of over-discharging cells in this sort of application is significant.

Members have mentioned children's toys for example. I'm thinking that young children could and probably would leave the power switch on for their battery powered cars, trains, games or whatever.

Even for a number of household uses, I would assume that batteries could be run to exhaustion unless there was some kind of regulation.

So is this a case of educating the users or is this really not a problem?

Bill

 

[HCaul]

It depends. Many modern (microprocessor controlled) electronic devices use "soft" on/off switching (with a momentary contact switch to turn the thing on and off); there's a (small) load on the batteries even when they are supposedly powered down. If you leave batteries in such a device for a very long time (like a year), they may overdischarge even if left off (of course, most rechargable batteries will run themselves down in a year anyway). On the other hand, many such devices will power themselves off (and greatly reduce the battery load) when the voltage drops below a certain point, and so will not tend to overdischarge cells if left on accidently for a few weeks.

H. Caul

 

[Sub_Umbra]

That's a good question. I'd say it depends on the individual devices and also on how many cells they use. As alluded to by another, I have a CD-MP3-Boombox that I only run on six NiMH d cells -- and it's always fine. It shuts itself down way before any damage is done to the cells.

On the other hand I had a 4AA light that would reverse the polarity of a NiMH cell in a heartbeat even if I was careful. I killed enough NiMH cells with that light that I eventually put only alkys in it.

I can't help but think that some toy and other non-light devices are also cell killers. I would also have very little faith in instructing a seven year old to stop playing the minute performance begins to fall off in the toy. For me, the safest route would be to individually test each toy or household device to see how/when they shut down before letting anyone use them with NiMH cells.

There also have been CPFers who have complained of a learning curve with their wives and kids where at first they just remove the dead NiMH cells from devices and just throw them away, forgetting that they are reuseable. Ouch!

 

[SilverFox]

Hello Bill,

Welcome to CPF.

I think the progression goes something like this...

New cells are taken care of and used in high power demand applications. After a while, they start to show their age. About this time, a newer higher capacity cell comes out and we just have to try them out. Rather than recycling the older cells, they end up in the kids toys for awhile.

When the kids ruin them by running them into the ground, we can yell at the kids with a smile on our faces knowing that we need to buy some new cells...

In the meantime, we endeavor to train our kids (and significant others) to shut things off when they are done using, or playing, with them.

Tom

 

[Sub_Umbra]

Silverfox,

That is really funny!

 

[PhotoWiz]

Silverfox,

Ah yes the unending quest for the new, more powerful battery — I had forgotton that factor!

Sometimes things are funny because they have a fair amount of truth in them. I suspect that's the case here.

I was in Wally World yesterday looking to see what low-discharge batteries might be in stock by now. I couldn't help noticing the lady standing next to me. She would pull a AA out of her pocket and compare with the blister packs, one by one. I finally asked if she needed some help. Apparently she had purchased some NiMH cells the day before and returned them when they wouldn't work in her camera. So she decided that she needed 1.5v cells vs the 1.2v listed on the rechargeable paks. After a few minutes discussion, I decided that the NiMH cells hadn't worked because she hadn't charged them! Didn't even purchase a charger with them. Of course, I then had to explain to her that the cell pack she was holding was an Eneloop pack and that they probably WOULD have run her camera right out of the box. Training is everything!

Bill

 

[AndyTiedye]

You just have to explain to the kid that it will go FASTER with fresh batteries!