Electrical

[Dolfin 0]

I am installing a electric start on a Rotax 532 (Avid).  What type of CB (fuse) are people using between the battery and starter button? Thanks!

[ChrisBolkan 130]

That is the "master fuse" which provides the buss its power for everything. I believe if you use that approach it should be panel mounted (I would use a 10-20A) breaker or fuse depending on your wire gage and sum of loads.

[ChrisBolkan 130]

Since the charging system can put out in the neighborhood of 15 amps with the 582, and since charging current will also be going thru that fuse, I would revise the fuse value to 15-20A, and use 10-12 gage wire for that run.

 

[Dolfin 0]

Thanks ChrisBolkan. Do people separately put a cb on the main battery cable (6awg)? On my old boat, there is a 60a cb within a foot of the battery before it continues downstream. Amazon has a marine type available (pictured). 

[1avidflyer 1983]

On my Kitfox 4, my AnP convinced me to put a starter solenoid type of switch on the positive main line coming from the battery.  A toggle switch supplies a ground to activate the switch.  That way, all power from the battery can be cut off at the flip of the toggle switch.  This is what I got and put into the Kitfox 4.  JImChuk

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[sioux201 84]

This is a great idea that most people miss, I had a starter solenoid lock in engage and on way to disengage, burned off the starter!

[wypaul 448]

If you put that solenoid (master relay) right at the battery there is not a hot cable in your aircraft when it is not in use, standard for aircraft electrical systems.

[1avidflyer 1983]

If you put that solenoid (master relay) right at the battery there is not a hot cable in your aircraft when it is not in use, standard for aircraft electrical systems.

That is pretty much how my AnP explained it.  I will use it on any future projects I do.  I have a couple of new larger circuit breakers like are shown in the post just previous to my first one.  The AnP said no, go with the master relay.  You can't easily shut the circuit breaker off if you need to.   JImChuk

[ChrisBolkan 130]

Dolfin, the problem with a circuit breaker in the starter motor loop is the potential for voltage drop. Voltage drop is very critical in starter loops and can result in slow cranking. For the same weight you can install a continuous duty master solenoid that will have minimal voltage drop. A lot of times in experimental aircraft master solenoids are not incorporated. Not sure why. It might be the weight. It might be the complexity. It is the safest approach though.