sdowney717
Guru
- Joined
- Jan 26, 2016
- Messages
- 2,264
- Location
- United States
- Vessel Name
- Old Glory
- Vessel Make
- 1970 Egg Harbor 37 extended salon model
Unless your ammeter has an external shunt, and uses voltage sensing shunt leads to the ammeter display, these dash mounted ammeters can induce lots of voltage drop in the B+ wire of the alt.
Voltage drop is quite possibly why you're only ever seeing a max of about 30-40A. If you're talking about a MAXI fuse holder for a 78A alt I would suggest a fuse with the correct AIC to be direct connected to a battery bank. The MAXI has a max AIC of 1000A which is not suffucuent for direct connection to a bank.
A 78A Delco can easily pump out 78A +/- if properly wired, and the bank can accept it. System voltage drop will have it hit the limit voltage and start current limiting considerably earlier. It's not uncommon to see an alt with bad voltage drop hit the voltage limit, at the alt end of the circuit, almost immediately. This limits how much current the battery will accept and we see low alternator output and longer charging times..
An MRBF terminal fuse holder & fuse can be mounted directly to the battery and would allow for a larger fuse. It also has an AIC rating of 10,000A that is appropriate for a battery bank connection.
It is properly wired, a 4 gauge wire. I never see a super high draw since the batteries don't accept a huge charge and I do not have a huge amount of DC appliances. I know I have good grounds since I have good voltage coming from them. I have burned up a few drive belts in the past. One reason is I needed to modify the narrow pulley to use a 1/2 inch belt. Originally these motors used a Motorola 50 amp with external regulator. I put in the Delco since IMO, they are better than what I had.
I do not have the starters fused. I do have 3 fuses coming off the selector switches.
I have a 100 amp for the Lectrasan, a 150 amp for the house feeding the main DC buss, and 350 amp fast blow fuse feeding the 3000 watt inverter.
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