Lawrence Winiarski wrote: > Maybe for vehicles with close enough voltages, all that's necessary is to > connect the packs together to equalize them?
In fact, fast charging has been done this way by EV racers and hobbyists. The internal resistance of the batteries themselves handles most of the voltage drop between the packs. It's sometimes called "dump" charging. If the two packs are nominally the same voltage, the initial peak current is huge; but it drops exponentially over time until the two equalize at the same voltage and state of charge. It can take a long time to reach this point, so it's only useful to get a relatively small amount of charge in quickly. But if you want the receiving pack to end at a higher state of charge, the sending pack needs to have a slightly higher nominal voltage. Dump charging works; but only if everything is right. With no fuses or circuit breakers, things can go very wrong if there is a failure! > Yeah, the pack swap has lots of prob if you aren't swapping your own pack... I agree. The problems aren't with the hardware; they are with people. When the same person or business owns both the EV and its packs, battery swapping works. Thousand-pound lift truck batteries are swapped in just a few minutes every shift. Or your Ebike battery runs down, so you pull it and pop in a fresh one in second. Given human nature, I suspect that battery swapping only works for a rented or leased EV. Then the same entity owns both the vehicle and battery. Lee -- Excellence does not require perfection. -- Henry James But it *does* require attention to detail! -- Lee Hart -- Lee A. Hart https://www.sunrise-ev.com _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
