Join Date: Apr 2006
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Some of these new cheap chargers actually are pretty smart about reading battery voltage, but a hydrometer (I hate the acid mess) or voltmeter is a good cheap reality check.
You need to check the batteries with a simple load, like a car headlamp or clip-on spotlight, connected right to the battery terminals. If that stays bright, you know the batteries are OK, period. (A load tester isn't very expensive, but a spotlight can be used for other purposes.< g > )
If the batteries are OK and you still can't run things...you've got bad wiring someplace. Corrosion on the outside of the cable lugs? Or black rot inside the battery cables--if they are not made from tinned wire, they are rotting from the inside. Or further down the line, at a fuse link, at the A/B switch...somewhere there is a bad connection blocking the power.