Start Battery Issues

[barbara ann]

After finding that the start battery for our 6 cyl. Volvo TMD41 diesel engine had given up the ghost, I thought a new start battery would solve the issue. As usual, the problem may be deeper. I'm noticing that the new battery (not a high-quality one, since we're in Malaysia and the pickings are slim) is also not holding voltage. I will first try to load-test the new battery - to establish its worth, then check for current draw in the system. Then I will check all connections to the engine - especially the starter connections. After that I will test the voltage drop in the starter circuit. Any other ideas?

The second problem is perhaps related to the first. I recently had the alternator that charges this battery checked by an agent in Thailand, who gave it good marks. I was having problems charging the start battery with it, and it turned out to be a faulty crimp connection on the positive cable. Now I'm seeing something rather strange. At low RPM's the alternator is charging the battery normally. However, at higher RPM's the battery seems to be discharging. I am considering removing and bench-testing the alternator again, after examining all the wiring. Suggestions?

[DeepFrz]

Alternator belt slipping at higher RPM when the load gets higher? You should see belt "dust" if it is although if the engine is dirty you might not notice it.

You seem to imply that you have a separate alternator for the start and house batteries. If that is the case you might want to consider an Echo Charge for the start battery and only use the one alternator. Just a thought but it would simplify things a bit.