NiMH battery question

[DoughDTD]

Is it bad for the battery to just drain a little bit of it and then recharge them? Lets say I pop them in my laser, freshly charged and then use the laser for a good 20-30 min. They are still going to work well, but will it be bad if I pop them out and charge them back to max again, so I can get my peak power output back?

I have a 15 min charger, so it doesnt take long at all to charge, I just wasnt sure if the batteries should be drained all the way, or at least close, before they get a recharge.

Gracias

-Dough

 

[Xenodius]

AFAIK, you can only get so many "initial" charges out of them, as in you can charge it from 80% to 100% 7 times, or 0% to 100% 7 times...

 

[DoughDTD]

is it only 7, or were you using that as an example....

for now i think ill just use them all the way up ;D

 

[Aseras]

topping the charge off is better than draining them completly. a full discharge and recharge really cuts into their life. 40% seems to be the threshold of longevity. the less you go below a 40% discharge, the longer they will last. Still we are talking at least 50 recharges for 90% capacity, and another couple hundred or so with less. I've got a set of sony nimh batteries that have had about 1,000 recharges since 2000 and they are still going strong.

 

[DoughDTD]

cool, i think then ill just run each set(i have 2 sets of 2, 4 total 1000mah duracells) for about 20-40 min or so, then top them off with a charge... if i ever see a noticiable dip in preformance ill just grab some new ones

on that note, i might get those ones from DX, just to see if theyre any good(i doubt 1350 mah, but they might be decent, good price too)

 

[flogged]

What aseras said. That's one thing I like about NiMH, you don't have to completely flatten them before recharging. In fact they last longer is you recharge them before they are half discharged.

 

[Things]

fast chargers will shorten the batteries life ALOT!! nimh's prefer to be charged slowly.

 

[Daedal]

Things beat me to it... it's bad to overload a battery with so much to charge it... Since you are only discharging very little of them, if you get a smart enough charger then it will only recharge the missing 10-20% of the battery as opposed to giving it enough juice to top it off all the way, as that too plays a role in battery damage.

--DDL

 

[DoughDTD]

you think i should get a standard charger then...they sell some on DX for real cheap, and I could use that instead of my 15 min fast charger...i didnt realize the fast charge was bad :'(im such a n00b!!

 

[Things]

fast chargers are allright, provided you almost completely drain the batteries before charging them. but they will still shorten the batteries life.

 

[Gazoo]

fast chargers are allright, provided you almost completely drain the batteries before charging them. but they will still shorten the batteries life.

Yup, that is true but according to what I have read elsewhere, it doesn't shorten the battery life much. The reason is the fast charger charges the battery up to 90%, and then goes to a trickle charge to charge the battery to full. Someone over at CPF actually tested this out...lol...I think he has a lot of time on his hands, but he does know a lot about batteries.

Personally I am using the Maha MH-C9000 and am very happy with it. I have also switched almost everything I can to eneloop rechargeable LSD batteries. I have found them to be very consistent, and holding up very well. In fact, they are nothing short of awesome, in my opinion.

 

[Gazoo]

fast chargers will shorten the batteries life ALOT!! nimh's prefer to be charged slowly.

This was true at one time, but times have changed. The recommended charge rate for newer NIMH batteries is 1C. However I usually charge at a .5C rate simply because I don't have any reason to hurry.

 

[Aseras]

overcharging and damaging the battery is the biggest reason for the memory effect, it's actually voltage depletion from cooking the battery. anyways most modern chargers are not going to do this, even the newer rapid chargers. they all are pretty good at just charging what they have too. the ones you have to worry about are cheap chargers and older chargers.

Nicad still need to be depleted before recharging, at least every few cycles. Nimh are happies being topped off whenever. lithiums are the same. all rechargables slowly loose capacity, mostly do to electrolyte evaporating and crystalizing and not longer being able to do it's job of making current.

you kinda need to shop around. Nimh is good for almost everything, i see very little reason to use Nicad over nimh. lithiums would be AWESOME, if they could get the votages and fromfactors to match standard alkalines.