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)
