ElectricMotorcycleForum.com
Tech => Home Brew => Topic started by: TurnNBurn on June 07, 2012, 03:08:06 AM
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I've been hearing about rapid chargers for cars that can fully charge a battery in 15 minutes. I've been reading some DIY EV Bike blogs and most say average charge time is 4 or 5 hours. Is there a way to speed up the charging process? Maybe double up on electrical outlets or is there any way at all to rapidly speed it up? Is the technology not there or is it a cost-for-parts thing?
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normal 120V receptacles are 1500W max, so that's about all you can charge from.
Then there's batteries and how much they'll accept. You can't just charge as fast as you want. The datasheet lists a C-rate for charge and discharge. Stay at or under that value.
example:
Your batteries are 2C charge rated.
You are running 40Ah batteries, 24 in series. 2C would be 80A at 72V which is about 5760W. Your normal 120V receptacle is right around 1500W, so you can really only get a charger that does 1500W or below, unless you choose to ONLY charge with 240V, then you could get a 240V 30A receptacle and a 5000W charger and you should be able to charge in 30 minutes.
This all decreases the life of the cells though, the faster you charge or discharge the worse it is for life.
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Unfortunately I'm in las Vegas and I have yet to see a single charging station.
Actually, not true. I saw one while I was at the Nissan dealer. But that was it.
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On the plus side, since bike packs are 1/3rd or less the size of car ones, even a 120v outlet for a couple hours can give a decent boost. It's one of several reasons I was more interested in e-bikes than e-cars.
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1 hour of charging on a motorcycle should get you about 10-15 miles using 120V, depending on the charger you use. My Delta-Q is 1000W, but I sell Elcon chargers that are 1500W. Higher if you want to use 240V.
15 minutes is a bit wishful.