auxilliary battery

[bfoss]

I'd like to be able to use an auxilliary battery for starting the car but am not certain what is the best way to wire it. I'd appreciate instructions or schematic. Thanks.

[BUTCH STANLEY CFC 01]

You did not say what kind of car you have but on my Swift I wired into the hot battery cable terminal on the starter. I used a convient bolt, near the jumper plug, on the car for a ground. Think about having the plug parrallel to the centerline of the car, then if you forget to unplug it it will tend to self disconnect.

[Dale Carter]

Steve, I guess you're wiring to hot side of the selenoid on your superstarter. On my car, I have a relay (and a Lucas starter! Don't laugh, it's worked flawlessly for five years!) I run to the hot side of the relay and I also connect my oil pressure warning light there. That way, when the car is in the paddock and the master switch is off, you have a reminder (the warning light is lit) that you are connected to the booster.

[Jon Horgas]

How does one ensure that the car battery is not charging a jumper that may be of lower voltage? Isn't the jumper batter just left plugged in while on the pregrid, not just for start?

[Slebidia]

I have a very nice wiring diagram I got recently from another driver. If you e-mail me with your fax number, I'll send it to you.
Larry

[Charles Warner]

Steve,

Mine is wired somewhat differently, but appears to work well. The booster battery is connected first to a switch on the battery cart, then to the plug, which then goes directly to the starter. The earth from the booster battery goes via the plug to the earth of the chassis.

Starting can occur either from the car battery, or the external. Coil power only comes from the car battery.

In this way, any battery differental voltage does not cause a problem.

When the car is cold, or is being started in the garage, the aux battery is used. At all other times, the on board battery works fine.

[Dale Carter]

Hopefully, the booster battery is well charged for the race weekend! Everybody has their own approach to the use of the booster battery. In my own case, I use the booster when pumping for oil pressure and for other times on the race weekend when I'm starting the car in the paddock - but I never use it on the false grid - and that includes double weekends.

[Mike Ahrens]

If your car battery is run through your master switch like it should be, you just keep the switch turned off and run the engine off of the aux battery. Then just before taking off you turn the master switch on and disconnect the aux battery.

[bfoss]

The master on my car, a 32F, is on the ground side. Is this good? Bad? Doesn't matter?

[Mike Ahrens]

That is how mine is wired.

[RACERMIKE23]

Switching the negative side is much safer. My memory fails, but didn't Jake Lamont post a generic FF wiring diagram on the FFU? I haven't had time to look yet, but it should be archived there.