# Controller plus direct power switch?



## major (Apr 4, 2008)

rickeolis said:


> Is it possible to run, say a 500 amp controller, but also have in place a high amperage capacity contactor switch to momentarily allow for full power flow from the battery bank to the motor?


Hi Rick,

It is called by-pass. Has been used on forklifts for years and years. With the GE controllers it was called 1-A by-pass.




> Could that hurt the controller?


Maybe. Some controllers are set up for it, like the GE. But most controllers for the EV converters are not. So you have to know what you're doing. I've seen a few guys do it on their conversions. But it is pretty uncommon. I suspect it would void any controller warranty 

Regards,

major


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## rickeolis (Aug 13, 2009)

Thanks Major!
The prices of high amperage controllers are so high that I was thinking this might be an option until I could afford a Zilla or Soliton1...
Most of my $$ layout will go into a new set of lithium batteries,, so cost is an issue.
Has anyone tried this?

Rick


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## Qer (May 7, 2008)

One major problem with Lithium and bypass is that the internal resistance of Lithium is extremely low so you risk serious over current and a contactor that's welded close and the only way you can stop the car is either an emergency cutoff switch or braking until the fuse blows.

With other words, I think it's a horrible idea that could prove lethal. I'd say you're better off saving money either by either buying a Curtis 1231C or similar first and then sell it later or buy a smaller pack that you extend later. Bypass contactors might be all dandy for fork lifts and golf cars that has lead acid packs with high internal resistance and low voltage, but it sounds like a catastrophe just waiting to happen in a Lithium powered car.


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## rickeolis (Aug 13, 2009)

I can see where that might be a problem-

Rick


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## 300zxev (Dec 5, 2008)

Hi Rickeolis

Here is a past post of it applied successfully ... ...
http://www.diyelectriccar.com/forums/showthread.php?t=27657

Was looking at applying myself ... but ended up getting a better controller.

Too much of a safety risk and the possibility of blowing up the components i DID buy ...


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