Well, a few things, 1. Your fully charged resting voltage seems awful low. You should be charging the cells up to 3.5-3.66v in the final tapering phase (175-183V)and then when the charger shuts off the cells should drop over several hours to a full resting voltage of 3.33V each. So your pack should be 166.67V, not 160V. At a resting voltage of 160V your pack is actually only about 50-70% full. A bad place to start pulling big loads. So that is where I would start. Is the entire pack not fully charged? or is one cell with low capacity hitting the top so hard the mini-bms is doing it's job and shutting off the charger before the rest of the pack is full? Maybe the mini-bms is protecting you from a battery fire every night.
2. Until you figure out what is going on in the charge cycle and get a handle on the resting voltages you really can't move forward to any sort of load testing. Why not just buy a PowerLab 8 and cycle each cell to find the capacity? In the long run it will save you money and more importantly, time. 3. EVwest has hammered their CALBs unbelievably hard under crazy current loads and they seem to be holding up. However, if cells are taken out of their "happy" zone either high or low, permanent damage can be done. Even with a bms, if the cells were not properly balanced they will be way off. More than the small shunts can correct. Did you balance the cells and make sure they were all balanced at the end of the charge cycle? 4. Again, to me, everything is pointing to issues during charging. Cooler temps and high loads are just symptoms of your charging problems. Good luck and let us know what you find. Marcus On Fri, Jan 25, 2013 at 3:48 AM, Martin WINLOW <[email protected]> wrote: > Hi Ben, > > What is the ambient temperature out there in Texas - when you are doing > your driving at least? > > The MiniBMS is fine if you have a system that you know works but, like > most of us, you are exploring uncharted territory with a donor and drive > train combo that has not been used before. Consequently, you really need > to know what is going on with your batteries on a fairly intimate basis > otherwise you are likely to kill one or more of the cells with your > 'experimenting'. So, I'd sort out a replacement BM(M)S as a top priority > and then at least you will be able to log data for later analysis to see > what is happening to the cells - if not on the move (not recommended unless > someone else is doing the driving). I'd suggest Elithion's products - not > tried them yet but they seem well thought out and not wildly ex'y. > > As David has mentioned, you are sailing very close to the wind with your > cells and their continuous current drain (particularly at freeway speeds). > My TS160LFPs could just about cope with my van at 60mph and it has a good > deal less drag than your Jeep. > > Personally I suspect that if your Texas temperatures are significantly > lower than they were 3 months ago, this is why you are getting low voltage > warnings at the lower current draws. Easy to see if this is right ... > leave the Geep in a heated garage overnight and then take it for a spin. > > Good luck. > > Regards, Martin Winlow > Herts, UK > http://www.evalbum.com/2092 > www.winlow.co.uk > > > On 25 Jan 2013, at 03:52, Ben Jarrett wrote: > > > > > > > So my Jeep is becoming almost non-functional. > > > > It used to be I would get a low voltage alert occasionally on the = > > highway when going 60+ mpg > > (where I tended to sustain 300+ amps for more than a few seconds when = > > accelerating) > > > > Now I get low voltage alerts from my BMS and from the Soliton for very = > > moderate acceleration > > and at much lower speeds (like 35 mph). > > > > I had someone test a few of my batteries, and they test came back pretty > = > > good. > > > > I haven't measured all of my batteries (I have mini-bms so it's hard to = > > know the exact state of things) > > but I feel that all of my batteries are basically sagging (vs having 1 = > > voltage drop in my system somewhere.) > > > > I'm not sure if I need a new battery pack or if there's something else = > > going on. My pack voltage drops > > from 160V to 120V during decent acceleration. This seems too much. It = > > seems unlikely that all > > of my batteries are bad though. > > > > What I would like to do is put my jeep on a full vehicle dyno and test = > > the voltage drop at various > > places to see if something else is awry. Not sure if this is possible, = > > but I'm not sure > > what other options I have (besides hooking up a few multimeters to = > > various spots, driving around, recording > > data, then moving the connections and trying again.) > > > > Any other ideas? > > > > thanks! > > > > -ben > > www.evalbum.com/4001 > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130125/051cc467/attachment.htm > > > _______________________________________________ > 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) > > -- Marcus Reddish *North Valley Systems LLC* Stevensville, Montana 406-360-8628 northvalleyev.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130125/1fc22940/attachment.htm> _______________________________________________ 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)
