WH-P909 Alternator

Question for the brain trust.

Working on hooking up the alternator on my RV-14A. The WH-P909 wire goes from the alternator to through the firewall.

That doesn't make sense to me, and I can't seem to find a reference to it anyplace else. How is everyone else wiring the alternator power?

Thanks,

-Dan

Van's does not include the ANL Current limiter or ammeter shunt on their drawings. They show the Alternator wire going through the firewall. I connected it to the bar at the battery/starter relay then ran WH-P912 through the firewall to the Main Bus.

Thanks Glenn, that helps.

Do I need an ammeter shunt and an ANL fuse, it looks like they do the same thing?

Thanks,

-Dan

The ANL current limiter protects the B-lead incase of a high amp failure situation of the alternator. The shunt is used to measure current or amp draw. Whether you need a shunt or not really depends on your avionics set up and if you are intending to measure amp draw.

Ok,

Now it is coming back to me. finished my 9a in 2015 so did this before, but couldn't remember the details.

I'm running a VP/X so won't need the shunt, but will add an ANL fuse for overvoltage.

So basically I just need to tie the B-Lead back into the bar between the starter/battery relay, adding the ANL fuse before to protect against an overvoltage?

-Dan

dweyant said:

Ok,

will add an ANL fuse for overvoltage.

-Dan

Click to expand...

Dan,

The fuse will not protect against overvoltage. Fuses "blow" based on their rated amperage.

It's my understanding that an alternator can't produce much above it's rated amperage. Therefore placing the fuse close to the alternator is not the best place for it.

Excess amperage through the B lead can be caused by an internal short in the alternator or a short in the B lead itself. This results in the excess current flowing from the battery through the B lead. This calls for the fuse to be as close as possible to the bar between the starter/battery relay.