David Roden wrote:
On 23 Apr 2009 at 11:42, Christopher Zach wrote:Under load, you can go down as far as 10.66 volts per 12 volt battery before you run the risk of damage.
That sounds like a Hawker specification. A more standard number, nominal for flooded batteries, is 1.75 volts per cell *under load*. This is where you should stop as soon as possible to avoid the risk of reversing one or more cells.
Which comes out to 10.5 on a 12 volt battery. I like to be a bit above it.
Open circuit voltage is largely useless for this purpose.
Always is. So is pack voltage IMO; the pack can read fine while individual batteries are getting creamed.
I built a great circuit a few years back that would tell me when one 12v battery was going above 14.7 volts or below 10.6 volts with a single tri color LED. It was great! I used it on my elec-trak and knew to back off the throttle when a red LED came on. Likewise I knew the pack was charged when I saw three greens.
Actually, it would be better still if you'd look at each *cell*. Your battery's capacity is limited by its weakest cell. When the first cell in the entire pack hits 1.75 volts, it's time to pack it in.
Not easy to do with T105's, easy with BB600s. But even then you're looking at 30 monitors which each will take power.....
Chris