E-maxx0976

HOw do you determine Charge Amps for 6-Cell Batteries? What is the best for a 3000 NIMH Cell (Epic Dreadnaught) High or Low? i am running about 3.5 right now. If i lower it, will they last longer?


Please Help ME!
Al

guver

My Feedback: (325)

Yes, usually lower rates will be nicer on the battery. 3.5 is very good though, you will not hurt it at that.

fhm101

Lower amperage charge rates will make a pack last longer, but 3.5A is IMO too low for 3000 NiMh packs. You should be charging them at least 4 amps, but 5 or 6 would be even better. I've never charged my 3000 NiMh packs below 6 amps and they have already lasted longer than any of the 2400 NiCd packs they replaced which were also charged at 6 amps and lasted a very long time before they started falling off. I have an e maxx I built for my nephew to play with that runs off some 3000 Mah Epic stick packs I got from my LHS for $18.00 each. I've been charging these packs at 6 amps from day one and they are still delivering plenty of run time and punch. I do discharge them down to .9 volts per cell (average) before charging, always try to store than around half charged, and always allow them to cool down before charging.

Deandome

My Feedback: (1)

Sound's like you're talking about NiCads, fhm.

I just called Jeff @onlybatterypacks.com (great guy) and asked him, as I have a new 3000mah NiMH pack for my EZ start.

He said 2-3 amps is the best/most you should charge the NiMH packs, and that the lower # you charge, the longer your packs last & the longer your runtime. Higher amps give you more volts, but less capacity, which is why electric racers push their batts to the uper limits when charging. But for non-racing e-maxx and/or EZ Start use, 2 amps or less is the best for overall pack life AND longer runtimes!!

NiCads can be charged at 2X their 'output' (don't know exactly what that means...does 3000mah = 3 amps..that sounds plausible!!), where NiMH can only handle 1X the output.

Again, none of this is my opinion, it comes from a guy who makes RC packs for a living (good ones!!), and this was 5 minutes ago, so my addled brain hasn't been able to confuse/twist/forget his advice.

I forgot to ask him about discharging, though...I thought that you didn't have to discharge NiMH before charging. But I guess the car guys do that, so there hasta be some logic behind it, though, again, what they want/need outta their batts is completely differnt than what we're talkin' about.

Dean

guver

My Feedback: (325)

Nicads can be pushed to 3c, nimh can be pushed to 2c. It will diminish the battery quicker than chargeing at 1 c.

the 3000 batts in question though are nimh. 6 amps is "better" for puch, 3 amps is better for the battery.

Infinite Gundam

Can slow charging at say 0.5C help to equalise cell capacity in stick packs? As in over time, the difference in charges in cells will increase due to uneven self-discharge, can slow charging minimize this difference?

fhm101

I did quit electric racing before the advent of the NiMh cells and I was going on what little I've heard since then on how to treat the "new" cells. It appears I've been going about it all wrong.

Thanks for saving E-maxx0976 (and me) from my bad advice.

Now where did I leave that darn cowbell??

guver

My Feedback: (325)

Probably want to keep it to a 0.1C rate to equalise cells and then any amount of overcharge will not hurt the full cells and will still bring the lower ones up to full.

0.5 may also work.

E-maxx0976

Thanks Everyone, You guys are great! This is what forums are for....

Al