R/C Tech Forums - View Single Post - Are my battrey packs messed up? 6 cell reading 8 volts charged, 7.5 discharged
Old 11-22-2009, 05:08 AM
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UltegraSTI
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most stick packs are cells that didnt come from the cream of the crop. so higher charge voltages are common (goin to 10v or 11.0v under charge load back in the old days). ur method of discharge is a bit deceiving to you. idk what charger your using, but if available use ur discharge function to take the packs down and see what the voltage is as ur doin so. u were measurin the packs at rest so i can be a bit deceptive.

issue occur in nimh when cells rear 0 or near zero (and seemingly need a 'bump' to 'wake up') which is BAD or when a cell goes far higher on voltage vs the others (say 1.7v or higher, i've seen em go to 3v underload) that equals VERY BAD. either case means chuck the cell.

sport packs can and will go higher 10v, but honestly good matched nimh cell really shouldnt go past 9.5v under charge load (near completion of charge) before start thinkin bout replacement.

general rule we had back then was save ur killer packs for big races, near new batteries that would peak as close to 8v and possible, hopefully no more than 8.5v. club racing, no problem packs that would peak from 8.8v to 9.2v. once batts went past about 9.3v, they were just practice units or we'd hand em off to a kid.

lotta folks (includin myself when i was a kid) didnt understand that a pack that peaks at a lower voltage is superior to that of a pack that goes out to 10, 10.5, or even 11v under load.

nimh still want to have a cutoff on ur discharge. .9v per cell. not .5 or even .7. .9 is the tool.

granted now with lipo thats all gone. love not havin to think bout it. can relax on raceday. as u can see i'm postin on here instead of preppin my batts for today.

onyx 230 charger (70bux) and 1 lipo (65bux for a good 1) is the whole day right there. no more 'battery cases' and 'discharge/equalizing equip'.

nice isnt it?

R
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