I don't remember electrical issues
being discussed much on this list, but they probably should be
discussed more. :-) I'm a big believer in the Matronics
Aeroelectric list. The 'patriarch' of the list is Bob Nuckolls,
who has at least 4 decades of experience in the certified a/c
world, and wrote 'the book' on homebuilt electrical systems. No
homebuilt should be wired without it. :-) He sells printed copies,
or you can download it for free from the Aeroelectric web site.
Protecting B-leads has been discussed quite a bit over there.
Something that any circuit designer would say is that the circuit
protection protects the *wire*; not any devices in the circuit.
The alternator B-lead can be confusing, since the alternator is
supplying power. BUT, the wire should be sized to handle anything
that the alternator can throw at it. (Alternators are
self-limiting; they can only deliver a slight amount more current
than their rating.)
So the alternator can never damage the
wire. However, the battery *can* damage the wire, as Jeff
discovered. So....B-lead protection needs to be on the *battery
end* of the B-lead. Not at the battery itself, of course, unless
the B-lead goes all the way to the battery terminal. But where
ever the smaller sized B-lead is terminated, closest to the
battery. Sizing the protection could vary a bit, depending on what
type of device is used. Some fuses are quite fast acting, and need
to be up-sized quite a bit to avoid nuisance trips, but a lot of
the higher current 'current limiter' (hate that term) devices have
quite long time constants and can be sized at the rating of the
wire itself.
Jeff, congrats on getting it on the ground quick. If the relay
hadn't burned open, the battery would have been depleted pretty
quickly. Did your low voltage monitor light up?
Charlie
On 8/2/2018 10:44 AM, Andrew Martin
andrew@martinag.com.au wrote: