I know how to re-set the finish charge on the NG5, but I don't know how to turn down the 2nd stage of charging. Is it the same set of pots? I could understand the diagnosis of thermal runaway for my original question, but I didn't think of it on this one. The batteries have never felt more than slightly warm to my touch, unlike the Delphis, which got quite hot. The charger doesn't have to be switched off very long to go ahead and complete the charging cycle. Why does the charger work as designed if I re-set it? Michael B. [EMAIL PROTECTED] wrote:
> > Thermal runaway. > > See my post of 16/09/02; > > This precisely my experience with the Optimas. I specifically ordered a > temperature corrected NG3 for my car. Note that this is a proper TC NG3, it > won't work without the temp sensor plugged in. Unfortunately the TC NG3 uses > a higher voltage than the non TC version, it charges at 15v per block up to > 10C, dropping to 14.4v @ 50C. I've found this to be too high. If you knew > which was the hottest battery in your pack and had the sensor correctly > installed into the hole in the bottom of the Optima, firmly pressed against > the centre two cells, it might work fine. My batteries were going into mild > and controlled thermal runaway on almost every cycle. The energy going into > the battery was raising the temperature at least as much as it was charging, > so my batteries were getting cumulatively undercharged. Letting the charger > go into equalise makes the problem much worse. I never got stranded out, my > battery monitor hadn't showed any batteries dropping lower than about 11.8v > on a 50-60amp load, but it had shown larger than usual voltage differences. I > tested the pack and found six or so of the sixteen batteries were down to 30% > of rated capacity (at 55amp load, but full capacity at 5amp load). After > several months of nagging the UK Optima distributor, the problem was > transferred to JCI who were very helpful in diagnosing the cause. I solved > the battery overheating problem, by turning the charger voltage down. It's > interesting to note that I rarely used to see battery voltages above 13v in > the morning, but having tuned the charger down, I now see voltage around > 13.1v. I've been able to recover most of the batteries to decent capacity, > but the pack now has varying internal resistance and is very difficult to > keep in balance. > > 25/09/02; > > You can still have problems with the lower voltage not temp. corrected > version as they did in the Sparrow. Adding a temperature sensor did not cure > the problem. They managed to get a special algorithm that addressed some of > the problems. > > Paul Compton > www.sciroccoev.co.uk
