I have this habit of charging my eneloops at 200mA if they are almost drained, i just can’t get myself to put them on 500mA because i get the feeling its harder on them.
Would i get more cycles if i use higher or lower charge currents (200mA or 500mA) on almost drained cells?
In the old days of NiCad AA lower charging current meant more capacity retention and longer life. Eneloops seem so indestructible and long lasting. I wonder if charging at a lower current makes much of a difference.
You could split the difference and charge at lower current for part of the cycle.
thats exactly what i do, a few hours at 200mA and the rest at 500mA
Don’t see how it could hurt it, it’s always less stressful to charge Li Ion at lower currents, so start low, then ramp it up to it’s full current charge seems actually like a good idea
What type of Charger are you using ?
Heat is the enemy. As long as they get charged and stay cool, it’s cool.
For a series PACK it may be better to slow charge (1/10C x 12-15 hours) to make sure they all get properly charged. This is more of an issue with lower quality or abused cells.
As long as you are charging singly that doesn’t matter as much.
Personally I charge mine at 600 in an 8-pack (older hobby NiXX charger, a good one). Individual cells charged on low in a MAHA MH-C808M.
The only thing I ever use the stock charger they came with is for boosting dead cells for a few minutes.
If I were going to go through the bother of changing rate I’d start higher and finish lower > less chance of damage at lower rates.
If you are using a ‘smart charger’ with delta-V termination it may not work right if you get much below 1/3C, depends on the charger and the cells.
That was going to be my response. I think that I’ve read about how the best chargers can terminate at low currentss, and I know the worst chargers don’t care and won’t terminate properly period. But any situation involving a medium quality charger or or somewhat damaged/worn cells could have charge termination issues at lower currents.
The higher the current, the more sure you can be about good termination. It’s a trade off 
I forgot to mention i am charging NiMH, my li ion i only have an ML 102 which is supposed to charge at 1A
Well, you did say eneloop.
I charge my fully drained eneloops at 6A, time limited to 20 minutes, with active fan cooling.
It’s abuse, but fully drained eneloops is what I take out of photo flashes, which abuse them even more with 10-20A discharge.
And, surprisingly, they still are alive, and 1900+ mAh after tens of 6A charge cycles…
i should hope they survive tens of cycles, i am hoping for close to 2000 cycles
I’d say they are approaching a hundred now.
And since I use them bi-weekly, 100 cycles = 2 years. I wouldn’t care about 40 year lifespan.
I doubt anyone has exceeded 500 cycles on NiMH in real life usage. Especially with such low charging currents, you’d spend most of their lifespan charging them ;D
I charge batteries every few days and i bet i have close to or over 500 cycles on some of my NiMH, when i was doing traveling jobs i was recharging the GPS batteries daily for a few months a year for several years (on 200mA smart charging)
Edit: maybe not over 500 cycles, but over 250 i’m sure
Well if they can do a hundred at 6A and not show any significant wear then I’d bet 1A would be no problem to them ;D
I also cook my Eneloops, but I don’t cool them.
They come out of my “15-minute” battery cooker really uncomfortable to hold. I don’t count my cycles, but I’ve never replaced an Eneloop because capacity became too low. In fact, I’m not sure I’ve ever gotten rid of any… some are rusty, one is smashed and won’t fit in tubes (only side-loading battery holders or really loose tubes)… but they still work and charge fine. I think I’ve got 4 Eneloops and 4 Duraloops that have all been in rotation for approximately 4 years. I also have a bunch of cheapy LSD cells which get used in the same fashion, as well as some duraloop-xx which have never seen any actual use beyond a few quick 5A discharge tests.
I do use mine in photo flashes. From my perspective, Eneloops have proven to be more than rugged enough to ignore maintenance. I’m not gonna make a special case for the cheap LSD cells just because I made the mistake of cheaping out on them. When they lose enough capacity I’ll replace them with quality LSD batteries.
i forgot to answer this, i am using a Lacrosse BC700
i topped up some cells at 700mA yesterday, they took 500mA of energy but got very hot so i think i will stick to 500 or less
I think Eneloops should not get very warm at 700mA. I really don’t know, but maybe they didn’t terminate. Are you sure they weren’t full when you started? Charging NiMH beyond their capacity does nothing but produce heat.
Do you have a temp gun?
they were at something like 1.3V when i started so not full but not close to empty, and i am told termination works better at higher current, and the charger does each cell individually and it terminated with only a few mA difference. I have never had eneloop used in the same device in series terminate at drastically different mA.
I don’t think higher amperage is needed for proper termination, but there have been some very passionate posts on BLF saying it does so make of it what you will.
You have a good charger. Depending on the condition of your cells it should be able to terminate at very low current, but I can’t tell you how low. If you look around you can find data about Lacrosse & termination rather than passionate posts.
Were the cells getting hotter than they do in a light such as your SA-22?
they were too hot to hold but not burning hot, so i would guess about 60-70ºC
The charger can do 200,500 and 700, i usually stick to 500 and 200 if cells are drained