nickceouk wrote: ↑Jan 19 2020 10:16am
To keep things civilised I would need to use the EVstreet chargers infrastructure.
what specifically is the capability of those chargers?
do they have a dc output? or ac only? what are the specifics of the output(s)?
i tried to find them on google, but all i found were references to them in various other sites, and not an actual site for them, or any specifications.
Question is how to charge 72v 40ah setup at 10min or less?
Battery pack when in use would be x100 10ah Yinlong cells : 25s4p for a 72v 40ah battery pack.
To charge in 10 mins I somehow need to pump in 72x40x6= 17'280 Wh
that's quite a lot of power. for example, i have four meanwell hlg-600h-54a led psus that make a pretty good totaly sealed, potted, weatherproof / vibration resistant charger that runs on either 120v or 240v (autoswitching) for up to around 58v at 48a, which is only around 2784w. together they weigh around 30lbs, iirc, and would be a block about 8"x12"x7", if I'm remembering the dimensions correctly.
to get 17280w out of that would need more than 6 of those blocks. so it would weigh nearly 200lbs, and be huge. i'd guess they generally cost at least $100 each new, so that's also really expensive, at least $2500. these aren't the right voltage for you, but you can use other versions that will give you the same capability; it'll still be about the same cost, volume, and weight, though.
i'm sure there are chargers that are more efficient and so would be smaller for the same capabilities, but probably not that much smaller. they could be a lot lighter, if they weren't sealed / potted, but that is what makes the ones i have more suitable for travelling. you might shave a third or perhaps even half (maybe not) the weight; the volume however will probably still be similar. dunno if they'd be any cheaper.
if i had to spend that kind of money, and take up that kind of weight and volume, i'd rather just carry more battery, and charge overnight whenever i had to stop to sleep anyway.
the question comes up....you have a battery with almost 3kwh of capacity. what is your wh/mile (or wh/km) expected to be? knowing those will give you your range. if you don't have enough range, but adding just a little more battery would give you the range you do need, then doing that will probably be cheaper and smaller and lighter than a superfast charging pack.
then use a standard charger for the overnight charge, and for opportunity charging along the way whenever you happen to stop for lunch or whatever.
One idea was that I can rewire the cells prior to charging so that the 100 cells become a 100s1p at ~240v DC. Perhaps flipping over the "battery pack" box cover coukd make this reasonably practical(reverse of box cover(top& bottom) would be different pattern to achieve 100s1p ...)
that kind of change means disconnecting and reconnecting all your high current connections every time you charge. this is virtually guaranteed to cause connection failures at some point, growing from minor to major over time. how bad a problem and how quick a problem develops depends on the actual connection method.... how the problem affects your system depends on exactly which interconnects begin to fail and how they do so.
people *have* done this sort of thing, usually using a connector block, like keyed andersons or the like, that simply wires out the cells individually (or groups of them, etc), and then a block "plug" that goes into this that is wired to hook them up as either charge configuration or dischare configuration. this type of system is relatively easy to fix by replacing conntacts when they act up, or the entire block if necssary.
my question is...where are you getting the 240vdc from?
