In a message dated 26/09/02 20:16:29 GMT Daylight Time, [EMAIL PROTECTED] writes:
> Somthing is wrong here. I drive my Yts to 191 and let them sit for > hours. The amps taper down to about .4 to .5 amps, without Regs. How sharp is your transition from constant current to constant voltage? How easily can your batteries get rid of heat? My car and the Sparrow have well contained batteries. If the current is already dropping by the time you get to the gassing voltage you don't seem to have a problem Before I turned down the voltage on my charger my batteries were regularly getting to 35C or so. The chronic undercharging caused by mild thermal runaway has left my pack with wildly varying internal resistances. I drove to a local car show recently and came home on a rigid link due to a low battery. I tested the offending low battery on my ~55A loadbank and got a time to 10.5v of just 5 minutes. My recovery procedure consists of continuing the discharge at constant voltage, reducing the load current to maintain 10.5v until the current has dropped to a couple of amps. This can take most of a day! I then let the battery stand for an hour or so before connecting it to my 100A charger. This consists of three surplus PSUs I obtained through Lee Hart. Typically when first turned on the voltage will jump to around 14v and rapidly fall, usually to around 13v. I leave the charger on until the voltage stops falling and just starts rising before turning off and leaving the battery for another hour or so. I then turn the charger back on and let it run until the current starts to taper, before once again turing it off for an hour or so. I then run the charger again, letting the current taper to less then 1 amp. After letting the battery cool back to ambient I test it again. On this particular occasion the battery ran for 37minutes on the same load after testing. The PSUs have a soft transition from constant current to constant voltage, starting to taper the current at 14.3v or so. If you have dissipative regulators it tends to hold back a runaway. If you have a set of batteries which have developed higher internal resistances, they start to generate heat under discharge, making the charge problems worse. Paul Compton BVS technical officer www.bvs.org.uk www.sciroccoev.co.uk
