starter contactor, inside or firewall mount?

tonyjohnson · #1 03-05-2007, 12:45 PM

I have room to mount my starter contactor inside my fuselage, near the battery which is located in the forward baggage are of my 8A.

Is there an advantage or disadvantage to having it there instead of on the engine side of the firewall?

Thanks,

Tony

Mel · #2 03-05-2007, 02:40 PM

Not much difference in length. One small advantage for the inside is that the cable running through the firewall is only hot during start. If you're thinking about temperature, it shouldn't be a factor.

Mike S · #3 03-05-2007, 03:54 PM

1. Ease of access for later service.

2. Foreign objects in baggage comp shorting out terminals.

Mike

tonyjohnson · #4 03-05-2007, 06:55 PM

Mel and Mike, thanks for your input.

Tony

tonyjohnson · #5 03-29-2007, 06:07 PM

I remember seeing information here that I cannot locate now about the two methods of wiring the alternator output. The traditional method is to bring the alt power to the main bus. The Nuckolls method uses the starter wiring to transmit the alt power to the battery. I think that in the Nuckolls method the alt output connects to the starter contactor forward of the firewall.

It would seem logical that if the starter contactor is located aft of the firewall next to the battery contactor, is it no longer practical to use the nuckolls method of running the alternator power through the starter wiring.

I thought George wrote a detailed (as always for George) description of the two methods, but I cannot now locate it.

Any thoughts would be appreciated.

Tony

N908RV · #6 03-30-2007, 08:16 AM

mounted my battery in the lower part of the forward baggage area.

Using the lower part of the forward baggage area gave me yet another place to run wiring thru to the firewall and made it a lot easier.

I made a mount for the battery to move it up about six inches from the floor and then used the longitudinal cross members (from the Firewall to the RV-8 gear box - one could use the bulkhead in the -8A) as a mounting point for both the master continuous duty relay and the starter contactor.

I also have an extra piece of flooring to the upper part of the baggage area to seal off the battery "box" and keep things out of there. Definitely don't want to leave that open as it has the potential to cause a short.