Ni-mah Poor performance

[bling_it]

Hi all,

I have a Nimah race pack which is good quality and i charged it watching that it did not heat up while charging. I used my 1700 race pack then used my 3000 Ni-mah for the first time and it lasted about a quarter of the time. Have i bought a dud or do they need to get slighlty warm whilst charging?

 

Over to you

 

Bling_it

[MikeT]

Are you using a PEAK CHARGER to charge your NiMH? If you are using one with a wind-up timer, this will be specified to give out a certain charge in the time it is " unwinding "  1400 per say.

[bling_it]

I have a decent (ish) peak charger and it stopped after about 45 mins so i assumed it was charged. I think the battery was left totally flat for a week which i think may have ruined it :-( . I prefer Ni-cads as they are much less agro and more durable than the Ni-mahs which cant overheat or be left flat, they seem to much like hard work for a slacker like me! 

[HunterZero]

Your charger may have a safety timer that stops the fast charge after 45 minutes. You might be able to peak the battery by restarting the fast charge after it cuts out, but I'd suggest trying a different charger. What is the fast charge rate of your charger, is it about 3A?

Is there a hobby shop near you? They may be able to give it a charge for you.

While charging, NiMH batteries will be cool through the first 2/3 to 3/4 of the charge, but will warm up when they start to approach full charge. They will be warm to touch when fully charged, but when overcharged are damaged at a lower temperature than NiCD. The maximum temperature for NiMH will be around 45C or 113F. Over 52C/125F you're risking damage to the battery.

- James

[bling_it]

Thanks hzero i will let it get a little warm and try it again see if i can make it last abit longer!

[bender]

As you said leaving it dead flat isn't a good idea, as it may take several cycles to get back up to scratch... or you may have permanently damaged it[]

For racing, the preferred method after use is to discharge to 0.9v per cell, then leave it. If you are going to charge it again later in the day then use a Novak Equalizer (or similar) on the pack before re-charging.

If you are not going to use the cells for more than a week then it's suggested you partially charge them, putting about 30% of their total capacity in.

 

[Shodog]

You might just have a bum battery.  I have a couple of NiMh batteries that just don't perform that well.  I have found that the lower end $20 NiMh packs just don't do it.  You really get what you pay for. 

[Lemming]

Hi all,

I was using a Ripmax Pro Peak 2500 (not the varipulse) one on my Vapextech 3300 nimh batteries and they were either overheating or not taking a full charge all the time.  Kept getting false peaks.

Since I bought the BMI Digipeak charger, they have been perfect.  They each charge up to between 3400 and 3600 without issue.  Seems that the Pro Peak charger is OK for Nicd and lower end Nimh batteries, but useless for the bigger capacities.

Hope it helps

Steve

[theshopkeeper]

Those Ripmax pro peak chargers cause more trouble than anything else I find, I'm not sure if they're just slightly older tech or what.  Virtually every NIMH pack I get back that "doesn't work" or "doesn't hold charge" has been charged on one of them but we give them a couple of charges on either an Ansmann ACX1 or a BMI Mini Peak and the packs tend to be fine.

[Lemming]

Glad it isn't just me!  Was beginning to think I was going nuts until I got my new charger.  These are the business!