Eneloop Optimal Charging Strategy

[TheWalkman]

I'm keeping some Eneloops in the fridge as back-ups / grab-and-go inventory. What's the best strategy to prolong life/ capacity?

Would it be best to fully cycle them every 4 - 6 months, top them up or put them through a break-in cycle (I have a Maha C9000)?

 

[etc]

As far as I understand, you got to periodically completely discharge them using the charger feature.

 

[redfish]

I'd think that in the fridge, Eneloops would have lost less than 10% of their charge in 6 months. So why bother with charging/refreshing? I'd just use them normally out of the fridge, re-charge, then put them back in the fridge.

The best thing about eneloops for me is that they don't require much thinking in using. Just charge, store, use, re-charge. Makes life simpler, doesn't it?

 

[barkingmad]

As far as I understand, you got to periodically completely discharge them using the charger feature.

That is NiCd batteries - NiMH should not really need a discharge cycle. Would not even bother with the fridge - Eneloops are rated at 15% discharge over a year at room temperature.

If you want some batteries for long term / emergency usage would recommend some Energizer AA lithium primary batteries (non rechargeable) as they have an even lower (very low) self discharge rate.

Otherwise have a few sets of Eneloops that you use and a set you store away and swap them over every 6-12 months.

 

[f22shift]

i tried the fridge once and didnt like the codensation. i feel it will corrode the parts. i just keep them in a cool place.
you could discharge a nimh once a month. it's not totally necessary like the nicad.
batteryuniversity.com has tons of info

 

[Eugene]

I've been just topping mine off every couple months. My system is two sets of rechargeable packs for each device so once a month I'll swap and top off, if I don't use it. If I am going to use a device, for example used my handheld CB a couple weeks ago because we were traveling with someone else and were outside of cell phone use so I topped both packs off. I made a small card that I stick to the packs with 10 lines so I can mark when I top them off and after 10 I can run a full cycle, though I need to edit my cards as I'm reading that every 20 or so cycles is the recommended.

 

[OhMyGosh]

I just bought some Eneloops with a 16 month old mfg date. They still had 60-70% charge. That is why I love Eneloops. My (standard) rechargeables have almost always died from age and negligence - not from to many cycles.

I think unused Eneloops are fine for a once a year refresh. I would go for a fast (2hr) charge-recharge though as this is better for breaking up oversize crystals. I think it is best to mix slow/fast charge/discharge. Fast helps with crystallization, and slow helps with anode/cathode/electrolyte balance/distribution.

I would second the E2 lithiums for standby emergency use. I just bought some that have an expiration date of 2021! They also have more energy stored than any other AA,AAA battery. They are to expensive for regular use though in my opinion.

 

[Eugene]

The thing with eneloop is they are new so no one really knows the optimal charging pattern, we just hope they follow what we have learned from traditional NiMH. My hope is that in 10 years I'll still have working batteries.

 

[TorchBoy]

I just bought some Eneloops with a 16 month old mfg date. They still had 60-70% charge.

My understanding is that all off the shelf Eneloops have about that. The most I've personally seen is 71% on six month old cells. The unofficial word is that they're only about three quarters charged at the factory. If so then after 16 months they're holding up really well.

 

[TheWalkman]

I just bought some Eneloops with a 16 month old mfg date. They still had 60-70% charge. That is why I love Eneloops. My (standard) rechargeables have almost always died from age and negligence - not from to many cycles.

To clarify, this is my reason for posting the question; I'm really asking what the best charging strategy is to prolong the life of the Eneloops assuming intermittent use of these cells.

I'm hoping to keep a set of Eneloops as my fully charged/ ready-to-go _backup_ batteries while using traditional, higher capacity NiMH batteries which I can quickly charge prior to scheduled event/ activity.

I, too, have found that I never get 500 - 1000 cycles out of cells though I take reasonable (but not obsessive) care of my batteries.

As Eugene said in his post, perhaps these cells are too new to really know what works best (or should they behave similar to traditional NiMH?)

 

[barkingmad]

To clarify, this is my reason for posting the question; I'm really asking what the best charging strategy is to prolong the life of the Eneloops assuming intermittent use of these cells.

I'm hoping to keep a set of Eneloops as my fully charged/ ready-to-go _backup_ batteries while using traditional, higher capacity NiMH batteries which I can quickly charge prior to scheduled event/ activity.

I, too, have found that I never get 500 - 1000 cycles out of cells though I take reasonable (but not obsessive) care of my batteries.

As Eugene said in his post, perhaps these cells are too new to really know what works best (or should they behave similar to traditional NiMH?)

As I said earlier in this thread - have a few sets of Eneloops that you use and a set you store away and swap them over every 6-12 months - or just top them up every 6-12 months if you only have the one set.

The discharge rate is quoted as 10% in the first 6 months and 15% total (not 15% extra) for a whole year (AFAIK all NiMH have a higher initial self discharge rate). In my experience many normal NiMH lose that in the first week.

 

[TorchBoy]

If you plan on storing them for six months or more I'd recommend a slow charge. 16 hours at 200mA (from empty). It gets them as full as possible while being as gentle as possible on them. [Insert something in here about also good for distributing electrolyte evenly within the cell being good for cell longevity - don't know if it actually needs to be done more than once when new.]