10Kw motor needs 200A start, is there a capacitor for this?

Thread Starter

Rideagiant

Joined Apr 22, 2017
3
Rookie "reventor" with a capacitor question...

I'm reinventing a drive system from a GM stop/start alternator to drive an a/c compressor. The manufacturer states that it needs a 200Amp start load to get spinning. It's a 24V or 36V system, with a 10kw motor driving the alternator.
My question is if there is a start capacitor that can handle that load and is it affordable (~$100)?

The system uses its own LiIo battery pack that will self charge via regenerative braking (which I do not think I'll be able to utilize). I'll be charging its battery array with an onboard generator.

Everything I research doesn't talk about this size/output. Help would be greatly appreciated!
 

crutschow

Joined Mar 14, 2008
25,267
Unlikely to find a large enough capacitor at your price ballpark that will work.
Your best bet is probably a battery sufficient to handle the surge.
 

Thread Starter

Rideagiant

Joined Apr 22, 2017
3
I plan on powering the unit with a car battery array of 2-3 full size batteries, so they have a CCA rating of at least 550 ea., would that do it you think? Is that the same kind of start power needed?
 

crutschow

Joined Mar 14, 2008
25,267
I plan on powering the unit with a car battery array of 2-3 full size batteries, so they have a CCA rating of at least 550 ea., would that do it you think? Is that the same kind of start power needed?
Since 550 is more than 200, that should be more than adequate. :D

But note that standard car batteries are not designed to be repeatedly discharged, as your application would likely do, which will significantly shorted their life.
Much better to use a deep-discharge type marine battery, such as this.
 
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Thread Starter

Rideagiant

Joined Apr 22, 2017
3
Thanks. I'll look into that one.
I'm not actually going to use it for stop/start, it'll run for 1-3 hours at a time and the batteries will be charged by my generator which is running at the same time.
 

crutschow

Joined Mar 14, 2008
25,267
Thanks. I'll look into that one.
I'm not actually going to use it for stop/start, it'll run for 1-3 hours at a time and the batteries will be charged by my generator which is running at the same time.
Okay.
If the batteries will never be significantly discharged than standard vehicle batteries should be fine.
 

DickCappels

Joined Aug 21, 2008
6,535
To answer your question about using a capacitor: Yes, you can. I remember reading an application note from a supercap manufacturer a few years ago in which they described using banks of supercaps to start diesel locomotives on cold mornings. It took a startling number of thousands of amps. Probably much more expensive than the battery method.


 
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