dovepa via EV wrote:
He says: Imagine that now you're driving your car, and let's say its 40 percent or 50 percent empty," de Callafon said. "You would have to charge it. Here you could actually take, if you have 10 modules in your car, and take five out — those are the ones that are empty — and put five in and you're completely replenished." -So, he is using all the modules at once to power the vehicle. De Callafon is developing a control system that'll manage groups of batteries. The modules can be older and newer. They can be full or partially empty. His system will allow different batteries to work together to feed an electric motor. -So, all the modules feed the motor not just one at a time. The control system manages power from the modules. The car has more than a dozen individual battery modules that work together to feed the engine. Each can be pulled out and replaced in less than a minute.
This is pretty much what I do with my Battery Balancer http://www.sunrise-ev.com/balancer.htm. It can monitor/charge/discharge every battery individually, up to about 30 amps or so.
My experience has been that it allows you to use a "mixed" pack of batteries of various capacities, ages, states of charge, etc. I drove for about a year with one "bad" battery (capacity about 1/3rd that of the rest) without any changes in the car's accelleration or range, because the Balancer was spending all its time "propping up" that battery with the rest of the batteries in the pack.
The result of this kind of aggressive balancing is that you can drive farther on a charge, and get more life out of the pack (continue using them even when they are old and have become too mismatched to handle without aggressive balancing).
But, I have my doubts about the described system. All batteries exhibit the Peukert effect. This means the higher the discharge current, the lower the usable amphour capacity.
Higher currents also shorten a battery's life for a couple of reasons. It causes internal heating, and higher temps shorten life. Since internal resistance increases with age, you also reach the point sooner where the internal resistance is too high to draw the curernts you need.
So, if you use one battery to drive your EV until it is "dead", then switch to a second battery and drive until it is dead, etc. you wind up with less range (due to the Peukert effect) and shorter life (due to heating and increased internal resistance).
PS: I have an EV book (c) 1910 that describes *exactly* this one-battery-at-a-time technique. It didn't work out then, either. :-)
--
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