On Sun, Mar 2, 2014 at 12:59 AM, EVDL Administrator <[email protected]> wrote: > http://www.evdl.org/docs/deka-vrr.pdf
Thank you! I'd missed that document before. Now I've saved a copy. > Lower than you expected, no? :-\ Whoops, I abbreviated too much. I meant state of charge voltage. My charger isn't over-volting them. It probably isn't optimal since it maxes out at 6A instead of their recommended maximum of 30A; I've never measured it even reaching Deka's specified optimum charging voltages, let alone their maximum voltages. The open circuit voltages for at-rest state of charge they list are the same as the web page I found, which makes sense. For load discharge, since I am pulling 100A or more from 100AH@20H batteries, I'm not on any line on their graph on page 4. I'll have to record and graph actual voltage under load and correlate with that graph since I don't know what extrapolation from that graph might be valid. > Don't forget that these last two guides are APPROXIMATE. Voltage is not a > very good indicator of a battery's state of charge. A hydrometer is the way > to go, but you can't stick a hydrometer into a sealed cell. A better > indicator than voltage is an amp-hour or watt-hour meter. Ultimately, I would like to instrument this with a beaglebone black recording the voltage across the shunt, sampling rapidly, and also measuring voltage. With that, I could not only record watt-hours, but also apply the peukert exponent, which ought to improve accuracy. I have a few LED units sitting around (digital and bar graph) that I could use for it to display calculated SoC to me while I'm riding... But I've put off enough other projects that I'm now behind on that I think it will be a while before I get around to that. So for now I'll just be conservative and mow my lawn in two passes until/unless I'm confident that I can do the whole thing without exceeding 50% DoD. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
