[imported_JDMAC]

Maybe I'm going crazy over here. But aren't 7 cells supposed to put out 8.4 V? Why am I getting 9.6 V when I hook it up to my voltmeter?

[Daniel Yachnin]

8.4 volts is the nominal voltage of the battery. The voltage should never drop below 8.4 volts on a 7 cell or 7.2 volts on a 6 cell etc........

[jbrow1]

Batteries are always higher when they are fresh charged. After sitting or cooling down they will most likely be less or what they should be.

Oompa - it doesn't hurt the nimh batts to go below, they have to as they discharge. But below .9 volts per cell is when they get damaged. So a 6 cell pack X .9 = 5.4 volts
7 cell pack X .9 = 6.3 volts minimum.

I've watched plenty of fast oval guys take them down to .7 volts per cell.

[imported_JDMAC]

My charger discharges to 2.6 V. So I'll have to watch that I stop it at 6.3 V.

It's hard though, because when it's actually discharging it'll say 6.3 V. But then when I stop it and check the volts it'll say, 7.3 V or something. But I guess it's better to be on the safe side.

Oh but NiMh batteries don't need to be discharged before charging like NiCd do they?

[jbrow1]

Originally Posted by JDMAC

My charger discharges to 2.6 V. So I'll have to watch that I stop it at 6.3 V.

It's hard though, because when it's actually discharging it'll say 6.3 V. But then when I stop it and check the volts it'll say, 7.3 V or something. But I guess it's better to be on the safe side.

Oh but NiMh batteries don't need to be discharged before charging like NiCd do they?

It's called battery voodoo, and it's mostly for stock or spec racers. You don't have to discharge the nimh's before charging. It is good to do once in awhile though just to put a full cycle on the battery. The main thing with nimh's is to let them cool down after using them instead of recharging them right away. And no real reason to charge them over 5 amps unless you are stock racing either.

[imported_JDMAC]

Thanks for the tips everyone.

[akramer007]

the rule for it is your voltage divided by .85, so for example a 12v battery in your car when fully charged is over 14v, you can use a variable power supply as well to charge batteries, use the formula and set the voltage to that and the battery when finished will be drawing a very low current, at beginning will be i higher current, probably about 3-4amps and will gradually fall, another way to liven dead cells or batteries that wont charge is to put double the voltage on them for a couple seconds, usually happens to batteries that have been sitting in storage for a long time. i use this all the time at work to get some extra life outta batteries