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I'm a bit of a newbie to electrical work much more than Arduinos so I apologise if there's any inconsistency in what I'm asking!

I have a little electric vehicle project on going, a go-kart, I'm hoping to use electric motor with a built in controller that's rated for 48v at 30amps. It has over voltage protection built in and won't work if there's over 60v at the input.

The battery that I'm attempting to use to power it is composed of 18650 cells in a 16S8P arrangement which when fully charged outputs about 67.2V. And by now I presume you can work out the problem!

Is there any reliable way to step that 67v down to around the 48v mark at 30 amps? I've looked online for suitable buck converters and they either can't handle the voltage or they can't handle the amps. Can the ones I've found that handle one or the other be run in series or parallel potentially?

Many thanks!

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    \$\begingroup\$ There is somewhat a chance that your battery voltage will drop below that 60V mark when you draw 30A from them, you might want to think through that \$\endgroup\$
    – PlasmaHH
    Commented Dec 10, 2015 at 23:09
  • \$\begingroup\$ You're absolutely right it will, however in order to clear the overvoltage protection the motor needs to have the power disconnected so I can't get it to spin up. \$\endgroup\$
    – James S
    Commented Dec 11, 2015 at 1:06
  • \$\begingroup\$ Look into a buck controller chip which allows you to provide an external MOSFET or IGBT switch. Make sure you simulate your design as much as is feasible. \$\endgroup\$
    – Synchrondyne
    Commented Dec 23, 2015 at 9:07

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You could potentially put in parallel several Buck circuits to create the current you need, but I don't suggest it unless the controller has a Sync pin to synchronize current draw.

To be honest, it might actually be cheaper to build a custom synchronous buck circuit driven by a tiny micro controller. At 30A a synchronous buck design is a must, multi-phase might also be a good idea, though that makes it much more difficult to design. I know that's not the answer you wanted to hear, but your power requirements are too specific for a company to have invested in an ASIC for that.

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