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mattsmith

Well Known Member
Hi everyone,
I am working on the FWF and wiring for my 8A and have a question about the shunt. I did a search to see how most are installing the shunt and see a lot of builders are installing a bus bar from the stating solenoid to a 60 AMP ANL fuse, another bus bar from the fuse to the shunt, all of this mounted to the firewall. this wont protect the cable from the battery to the firewall. my question is can I mount the 60 AMP ANL fuse at the master relay to protect the shunt, starting solenoid and the 00 wire from the aft mounted battery to the firewall? I only ask because I don't know if the fuse has to be closer to the shunt for some reason. I am using Vans wire harness with a aft mounted battery and Dynon Sky view. thanks for any help.
 
A 60A ANL isn't big enough to take the starter current, so can't be anywhere between the battery and the starter (same goes for the shunt). Most aft-mounted batteries don't have any protection, other than putting the master relay near the battery. The 60A ANLs are generally put between the alternator and the rest of the buss, in lieu of a main alternator CB.

Out of curiosity, why the 00 wire? Seems really big.

-Rob
 
Robb,
thanks for the answer and it makes sense, I knew there had to be a reason. I don't know if it is actually 00 I don't have the wiring schematic in front of me, just took a guess its about the same size as the whips we use on our welding lead.
 
Starter wire IIRC is #2, can go #4.

Re fuses and large wires, think through "what" you are protecting. It would be hard for a #2/#4 wire to make a good enough connection to earth to short out and melt the wire, or put another way, it could short to earth, and easily pass enough current into what it shorted to & create a fire there, yet never reach the Fuse value.

We enclosed the aft battery #2 wire in a plastic conduit, and then plastic bushings around both, through each bulkhead, for maxium protection.

I have heard it said you need 1 fuse "up" from the Alternator output e.g. 60A Altn, use an 80A fuse to cope with short term high loads, or rather, minimise need to replace the fuse ;)

HTH
Andy
 
Andy Hill said:
I have heard it said you need 1 fuse "up" from the Alternator output e.g. 60A Altn, use an 80A fuse to cope with short term high loads, or rather, minimise need to replace the fuse ;)

HTH
Andy
Click to expand...

Hi Andy,

I'm not sure this is necessary with ANL's. Have a look at the graph here: http://www.cooperbussmann.com/pdf/0810938a-26c4-44e2-a299-8962dd6ea9a7.pdf

It doesn't have a line for the 60A ANLs but it shows the 50A ANL taking 100 seconds to blow at 110Amps. It will blow much faster as the amps increase.
At the other end of the line, the 50A ANL is shown blowing in 0.02 of a second at around 1200Amps. Even the 30A ANL will take 100Amps for 4 seconds.

These ANL devices are current limiters and I don't believe they nuisance fail very easily. I'm planning on using a 60A ANL with my 60A alternator.

Cheers,
Steve
 
The #2 cable from the battery contactor to the firewall ANL connection has an easy life. With just a little installation care the chance of damage is low.

The #6 wire from the firewall ANL to the alternator B+ runs through a collection of hot things which shake around. The chance of insulation damage and a short to ground is much higher......in which case the ANL disconnects the #6 wire from the battery's huge available amperage.
 
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