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Re: [EVDL] Battery & motor shunts

Hello David,

I would not do this type of installation with a standard ON-ON switch or
even some ON-OFF-ON toggle switches. Some of these switches may be a
made-break type where you could have both circuits on at the same time.

I would use a larger heavy duty switch that has more spaces between the
terminals where it has a mechanical interlock to prevent both circuits to be
on at the time or when this switch fails which may connect battery and motor
circuits together.

One time we had a very large industrial transfer switch fail when the
mechanical switching mechanism fail and blew all the circuit breakers.

If this type of switch fails, than you could have the battery current
bypassing the controller and go directly to the motor and will burn up the
sense wires if you do not have them fuse.

I fuse all my sense wires with a 1 amp fuse which is size to protect the
sense wires.

Roland


----- Original Message -----
From: "David Nelson" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, March 08, 2011 10:40 PM
Subject: [EVDL] Battery & motor shunts


> A friend of mine is converting a Dodge Neon using a Warp9, Syncromotive
> 700A
> controller, and LiFePO4 batteries. I was recommending to him that he have
> a
> battery current shunt and motor current shunt. I believe he will be
> limiting
> battery current to around 300A. He already has a 500A 50mV shunt. I was
> suggesting that he go with a 1000A 100mA shunt in the motor loop so that
> he
> can use the same analog 500A gauge with a toggle switch. The reason I was
> suggesting the 1000A 100mA shunt is that the meter should still read 500A
> at
> 500 motor amps but that the 1000A shunt can better handle the short spikes
> up into the 700A range where as the 500A shunt might not do so well. I'm
> trying to avoid the driver having to do a mental doubling of the meter
> reading when on the motor shunt.
>
> Will this work as expected?
>
> --
> David D. Nelson
> http://evalbum.com/1328
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