Hi Denis. I'm not an expert on these matters, so if I say something wrong here, I trust that someone else will correct me.
In my admittedly limited experience I have found that BMSes always use a little current from the cells they're monitoring. I see online that the MiniBMS idle current is 2.2ma. If your DC:DC converter was connected and supplying power to the truck's 12v system, that probably uses yet more current to maintain the body computer, radio presets, and so on. On modern vehicles something close to 100ma of parasitic loads on the 12v bus is not that uncommon. Accounting for DC:DC losses, that would be about 4ma on a 312v traction battery. Add the BMS self-load and you get about 4.5 amp hours per month, which doesn't seem like it'd be enough to run the battery flat over a winter. But you may have had other energy thieves. The MiniBMS manual also says that "After shutdown due to low cell voltage, a capacity reserve of approximately 1Ah per 100Ah battery capacity is left in the battery." The BMS draw drops to 1.2ma at low cell voltage. That is 864 mah (.864 ah) per month, so if indeed the truck did run the traction battery down to its BMS cutoff voltage, another month would just about do it in. I think that the first step is to see where you stand. You'll need to get to the individual cells by whatever means, and take a voltage reading from each. The vast improvements in range and utility of EVs in just the last few years have pretty well crushed the value of older used EVs. This is especially true of conversions, and yours is really a factory conversion, aka "Electric Powertrain Option" or EPTO. OTOH there does seem to be a devoted community of followers from this vehicle. My opinion is that if the range and utility still suit your needs, even if you end up having to replace the battery, you may be better off to try to fix it. You could look into replacing the cells with used or new Leaf or Volt modules. But before you panic, I suggest that you get to those cells with a voltmeter and a small parallel load (don't just use a high impedance DMM), and see what's really going on. David Roden, EVDL moderator & general lackey To reach me, don't reply to this message; I won't get it. Use my offlist address here : http://evdl.org/help/index.html#supt = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = When I'm asked when there will be enough women on the Supreme Court, I say "When there are nine." People are shocked. But there've been nine men, and nobody's ever raised a question about that. -- Ruth Bader Ginsburg = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
