Originally Posted by doughboy
Engine running volts shows the alternator is doing its job, but engine-off no-load voltage is not a very good indicator of battery condition, you need current/load to see how the volts drop to see if the battery is shagged.
Totally agree but you can tell from the off-load voltage if a cell has gone short (plate-fuse) because the battery will only show 10v. However, I'm showing my age as I doubt that happens any more with gel-filled "wet" cells.
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