Eneloop charging

[jsd]

I have a set of Eneloop AA and AAA and a Lacrosse charger. I use the batteries for my bicycle lights for commuting.

I am uncertain of how long I can operate my lights for between charges because I usually do not keep track. I charge my batteries once every two weeks, before they are depleted, because I do consider the lights to be a safety item. Maybe a silly question, but is there such a thing as recharging the batteries too often leading to decreased life? I mean even if I charge them once a week, I have enough cycles probably for a decade or two. Will the charge that each battery can hold decrease as the cycle count increases like my laptop battery?

I did once accidentally leave the rear light on in the garage and it discharged both AAA to 0.9V according to my DMM. Does doing something like this damage the battery? I read somewhere that NiMH should not be discharged to this level.

Whether or not my lights can be seen during the daytime, I have no idea, but I figure it cannot hurt and does not cost very much to do so since I already have the gear.

 

[bbb74]

The deeper the discharge once you start getting close to the end the more wear it causes, its probably better to recharge before you get to that point. Its worse to discharge cells till they are flat when there is more than 1 cell in the device, you can cause reverse charging which over time will damage the cells if they are of fairly different capacity. Charging every week would be no problem - 52 charges a year, eneloops should last you a goodly number of years. Yes their capacity will very gradually fall with the number of recharges. If they are going to last you a decade its not really a large amount of money per year you are talking about though!

 

[WDG]

I have a list of regularly used items that get charged cells swapped into every Friday, come hell or high water. Weekly's easy, as I never have to wonder if I did it last week or not.

With safety equipment especially, I want to always have a reserve of at least 50% capacity. (It actually comes in around 75% reserve, with my usage.) I also don't see any point in risking reversing a cell when it's so simple to keep them charged. I keep enough Eneloops on hand to have charged cells ready to go at a moment's notice, so I never need to wait for anything to charge. Swap 'n charge... Eneloops are ideal for this kind of use. 🙂

 

[bbb74]

By the way, most blinky bike lights aren't regulated, so the more charged your batteries are (hence they have a higher voltage), the brighter they will be.

 

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Can eneloops be charged in an energizer charger?

 

[Wrend]

Which Energizer charger?

Probably, yes, but I wouldn't really recommend it. I've charged some of mine once or twice with one of the Energizer NiMH chargers that came with some of the Energizer rechargeable cells. It was a relatively slow charge over all (something like 0.3C/h or so), but it didn't terminate the charge and the cells got very warm and I had to manually pull them out of the charger.

...

On topic: In general, more deeply discharging Eneloops isn't really much of an issue at all. If your cells aren't well matched in their state of charge then there could be some problems with reverse charging the ones that empty out first, but that's a little different.

If you're properly using your cells, you should get at least several hundred full charge and discharge (down to 0.9V) cycles from Eneloops.

My 2 year old first generation Eneloops have only lost about 1.1% of their capacity potential so far. They're also the ones that got kind of toasty on the Energizer NiMH charger.