I have been communicating with a couple sellers now on Aliexpress. Prices seem quite varied and reviews are mixed on these batteries. I suspect there isn't a lot of standards or testing on actual claimed capacities. I would like to try a 12v pack or 2 before buying more and perform some tests to verify capacity. Has anyone done this testing before? I assume the ah rating is based on a 1amp draw for x amount of claimed hours. So would I hook up a 12 watt load (LED bulbs?) and watch pack voltage till it drops till below 12v? Or would I measure it till the BMS protection cuts in - (9-10v?). Some reviewers have found packs listed at 100ah capacity to actually have only 30ah cells inside, lots of misinformation.
Thank you, Dan On Tue, Mar 12, 2019 at 1:01 PM Jay Summet via EV <[email protected]> wrote: > > > On 3/12/19 9:59 AM, Dan Baker via EV wrote: > > > If I don't charge with my Sevcons and use the included individual 12v > > chargers, would there still be worry of connecting too many in series? > Is > > it charging,discharging or both the issue when connecting in series? > > That depends entirely upon the battery model/manufacturer and the specs > for that specific battery. If there is an issue, it would most likely > be an issue for both charging and discharging. > > The thing to watch out for is if the batteries have a MOSFET (solid > state switch) that is used to disconnect the battery when charging (done > charging, voltage too high) or when discharging (voltage too low). In > many cases, the MOSFETS are not rated for super high voltages. It may be > twice the working voltage or much higher (24,36 or perhaps 60 volt > rated). If your series pack goes above the MOSFET rating, it is likely > to fail spectacularly (short closed in the worst case) when it is asked > to disconnect the battery. > > If the batteries use relays or contractors, they may or may not be rated > for higher series voltages, you need to verify. > > In short, the electronics that are making these batteries "drop in > replacements" for a 12 volt battery are designed to work at that voltage > level...with perhaps a 2x or 4x safety factor (24 to 48 volts), but the > system was not designed for high voltage (72-144 or higher) to be seen > by the battery. > > The BattleBorn batteries for example use 60V electronics, and are rated > to be used in series up to a 48 volt system (They were designed this way > to be a drop in replacement for 12, 24, 36 and 48 volt solar power > systems....but many "auto starter" or RV replacement batteries gave no > thought about using more than one in series, or if they did, it was only > up to a 24 or 48 volt level.) > > Jay > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190313/9f300d12/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
