Quote:
Originally Posted by smac999
How big is the alt cable, pos and neg, from the alt to house bank? And what is the voltage at the back of the alt, (pos and neg at alt) and at the batteries while running. Measure both.
With a 180a alt. You should probably be 2/0 straight from alt to battery.
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smac speaks my mind. Also check for losses at the alternator terminal. This is a sticky wicket because the stock terminals are really too small for the size cable that is needed, so they often work loose. Grease helps prevent
corrosion but worsens the "working loose" problem. Some high-amp rebuilders use a nonstock oversize terminal, which helps.
The best thing to do is run welding cable or some other highly flexible stranded cable to minimize the stress on the terminal. Then you can run 2/0. You should also be running 2/0 from the alternator case to the battery -- don't rely on a ground connection through the
engine block at these amperages.
All the terminations matter a great deal in this situation, be sure everything is clean and properly crimped and torqued. An IR thermometer will show up bad connections. Check both the + and ground.