Battery Charge Loss Over Time

[Mr. Gruntsworthy]

I did a search (both google and here on the forums) but I'm not turning up any related questions and answers:

About two months ago, I charged my batteries for a game that ultimately ended up getting cancelled. Since then, my batteries have been sitting around collecting dust (figuratively speaking) since school's kept me busy. However, I'm finally out on a game again this sunday (Whitby, if anybody wants to join me), and I was wondering: From full charge, how much charge loss will the batteries have suffered just sitting around for two months? If I let 'em charge for 2 hours, will that top off the lost charge? Is that too much/too little?

(Conditions: 8.4v Nickel Metal Hydride [I forget the acronym] battery, 1500Mah, stored at an estimated average of 20 degrees celcius)

[yan101]

did you live them ''plug in'' or did you you remove them?

http://en.wikipedia.org/wiki/Nickel%...ydride_battery

''The significant disadvantage of NiMH batteries is the high rate of self-discharge; NiMH batteries lose up to 20% of their charge on the first day and up to 4% per day of storage after that. In 2005, a low self-discharge (LSD) variant was developed. LSD NiMH batteries significantly lower self-discharge, but at the cost of lowering capacity by about 20%.''

I am not sure it is up to date

[Mr. Gruntsworthy]

Unplugged. I always leave my batteries unplugged until just prior to gaming.

[coach]

Meh, I always top them up before a game. All batteries lose a bit of charge in storage. If i read your post right, you're likely using a wall wart since you are trying to calculate charge time. Go buy and use a smart charger. Takes the guessing right out of it. If it needs a full charge cycle, it'll fully charge them up. If they are holding a decent charge, it'll top them up and drop to a trickle charge so it doesn't over charge.

Cliff notes: use a smart charger

[Styrak]

If you left them for 2 months they will have lost a LOT of their charge. It's a good idea to top up batteries the day of or the night before a game. Even a week or 2 and you can lose charge.

[Hectic]

The good thing about NiMh batteries is they domt have a memory effect like Nicd (or whatever theyare called lol) but yes they do discharge faster on their own and can have a reduced capacity after long periods of low charge (so baisically they do to an extent have memory but not as bad as the nicd ones) best thing is once a week or two throw em on a charger to top em up and keep ek always topped up so they always have the maximum memory of what their "full" is.
No worries about discharging befor you charge like nicd, you just plug em inand charge em up to keep em full.

[Mr. Gruntsworthy]

Originally Posted by Styrak

If you left them for 2 months they will have lost a LOT of their charge. It's a good idea to top up batteries the day of or the night before a game. Even a week or 2 and you can lose charge.

Thanks for the replies guys. As far as the charge goes, the charge loss itself doesn't bother me--I have ample time and means to charge them--nailing down how long to charge 'em for without frying 'em was the issue.

If they've lost a lot of their charge, they should be easy to drain through a bit of target practice then.

[Styrak]

If they're NIMH you do not need to drain them first.

As for how long you have to charge them....that's what a smart charger is for. They cut off when the battery is full. If you're using a dumb/wall charger, get a better one or you'll destroy your batteries.

[TurlteRaph]

and smart charger will cut down the charging time as well

[coach]

Originally Posted by TurlteRaph

and smart charger will cut down the charging time as well

Yes and no. It all depends at what current output you set the smart charger.

[ThunderCactus]

I don't recall the exact number so don't quote me on this but I believe it was something like 15-20% per month for NiMH, and something ridiculously tiny for LiPo
It's a good idea to charge mini batteries at least once during the off season

And your drain always increases significantly in the cold with NiMH and NiCd batteries. So much that I wouldn't even consider running anything less than 2000mah for a short scrim.

[Hectic]

^that. But ill point out newer batteries (like the nimh made with the smaller cells) tend to last prety good.
Ive played 10 games this winter in temps from 0 to minus 15 and even im -15 my 1600mah nunchuks lasted all day without issues in 400fps setups. The only issue i had was with a large cell (4/5 D or whatever the heck its called) 1800mah nicd that died after an hour lol, and i was always under the impression that nicd wer more cold friendly then nimh. Keeping in mind the large cell bat was the stock echo 1 bat that came with my gun so who knows how long it was in inventory

[Mr. Gruntsworthy]

With a full charge from empty taking 6 hours; I figure a solid 4 hour charging would suffice to top them off?

[Cortexburn]

As thundercactus had mentioned, you can expect 10-15% loss a month (roughly) from sitting around. It's the nature of the technology.