Must store lights for 5 months. Need advice about batteries

I'm concerned about my rechargeable batteries. Can NiCad, Nimh and Li-on tolerate a 5 month break? I have to temporarily move out for about five months and can only take a few lights with me. Any advice is appreciated.

Brightnorm

I know nothing of Lion battery, but of personal experience the Nic and Nim should perform very well as long as not exposed to vast temperature change during storage. I have early MAHA brand rechargeable batteries that do well with 6-12 month absence.The Nicad battery may hold charge longer in storage. Ni-mh has faster self discharge rate for me. This is only my experience with maybe 44 battery mixed total of standard size aa-d cell.

Re: Must store lights for 5 months. Need advice ab

Rechargeable alkalines generally stink, but have the advantage of long term storage after a recharge.
I still have some renewal alkaline D cells doing quite well after 3 years and 15+ charges.
I have no regrets on those.
A monthly topping off in a car/hotel charger would not be a miss for the other rechargeables.
In fact, some chargers are 12 volt appliances just needing a 12 volt adaptor to power them.

Good luck.
One more thing:
Your batteries should be fine for 5 months.
Just top them off before you go.

Re: Must store lights for 5 months. Need advice ab

li ion loses about 1% a month
nicd loses about 10% a month
nimh loses 30% first month, then about 15%/mo afterwards

Note: these are "decay" type discharge rates. Example:
Nicd, 10% a month, does not mean that 10 months will be dead
month 1:100%
month 2:90%
month 3:81%
month 4:72.9%
.
.
.
month 10: still has 34.9% left

In any case.... you should be fine UNLESS they are stored at high temps. That will accelerate the discharge. But..... even if they get really low, a nice slow charge will work wonders.

Re: Must store lights for 5 months. Need advice ab

Most products that contain batteries include in their operation manuals.. to remove batteries for long term storage..

Most batteries that are rechargeable recommend charging after such a long storage before using..

That's about all you need to know for the ones left behind.. are you talking about the ones bringing with?

-awr

Re: Must store lights for 5 months. Need advice ab

BN, those batteries will lose a lot of their charge if you leave them alone for 5 months. It's no big deal. Just charge them up when you get back.

Re: Must store lights for 5 months. Need advice ab

Hello Brightnorm,

There should be no problems with NiCd or NiMh cells stored for that length of time. As others have mentioned, just top them up before storage.

Li-Ion is a bit different.

It stores best at a 40% charge (3.75 - 3.8 volts per cell). Studies have shown that Li-Ion cells stored at 100% charge and high temperature (60 C) can loose 40% of their capacity in as little as 3 months. At room temperature the difference is less dramatic, but still exists. After 1 year of storage at 25 C, a 100% charged battery will be down to 80% of capacity where as a 40% charged battery will only be down to 96%.

Check here for more details.

Tom

Re: Must store lights for 5 months. Need advice ab

Thanks all for very helpful information

Brightnorm

Re: Must store lights for 5 months. Need advice ab

IMO, li-ion is the best option.

Recently I took one of 14500 out of the stock which I charged during H&M contest 2004 (July) and had a run time test with 350mA Lux and I got 600mAh equivalent total discharge. It is 85% of 700mAh battery capacity after half year.

As per Tom's calculation, 96% of 40% charged capacity gives 38.4% compared to 80% of 100% charge. So I would charge them in full and just keep in the light.

-- dj

Re: Must store lights for 5 months. Need advice ab

That's what is puzzling. Many sites recommend storing at less than 100%, typically 40% and cite the lower loss, but as you point out it is still far better to store full.

Perhaps there is another factor involved, like a more quickly deteriorating permanent capacity loss triggered by long storage at 100%?

I think I'll put my charged PILAs in the Fridge.

Brightnorm

Re: Must store lights for 5 months. Need advice ab

Hello DJ,

I would look at that information a bit differently.

I think they are saying that a cell that is stored for a year (at 25 C) starting at 100% charge will, at the end of a year, only be capable of 80% of the original capacity. On the other hand, if you store a cell at 40% charge for a year. You will be able to recharge it to 96% of the original capacity.

Tom

Re: Must store lights for 5 months. Need advice ab

Tom, thanks for the new info.

I certainly interpreted differently and now your information opens very different viewing angle.

If that is the case, it explains why all the li-ion cells from the factory are NEVER charged to full capacity.

So, if we are just going to store it for a long time, charge it to 40%.

But for keeping the batteries in the light, I still prefer having more juice available when I want to use.

-- dj

Re: Must store lights for 5 months. Need advice ab

Tom,

Based on your post I read the data again and noticed that critical word Recoverable capacity. Thanks for clarifying that point.

BN