[ausev] controller amps

[Chris Robison]

tomsmail at wtez.net wrote:
> Does anyone have direct experience with Zilla low voltage transient
> current draw on a 9" motor?  I'm wondering how much above 500 A to expect,
> with an aggressive (street, not pro drag racing or anything) driving
> cycle, and if this merits a 1KA current shunt.

A 500A current shunt is fine in this situation.

The real limitation for shunts is temperature. The resistive material in 
a shunt has the somewhat unique property of having a fixed resistance 
over a relatively wide temperature range. Once you exceed this range, 
the resistance changes, which not only makes the reading inaccurate, it 
damages the shunt.

A shunt in open air can be run typically at 75% of its marked measuring 
capacity continuously, without overheating. A 1K Zilla can pull up to 
800A from your batteries, and will pull more current in general from a 
lower-voltage pack. However even a fairly low-voltage EV won't draw more 
than the max continuous current (375A for a 500A shunt) for more than a 
few seconds while accelerating. While you're pulling less than this 
amount, the shunt has time to cool off.

(Hint:  don't put your shunt inside a sealed enclosure.)

   --chris