[phil-l]

Then I'll mention a related item that was causing problems for someone else on this forum: The *other* end of the battery cables.

Check where the heaviest negative battery cable attaches to the engine block; it should be clean and tight.

The heaviest positive battery cable attaches to a terminal on the starter. Again, it needs to be clean and tight.

Try to check the battery voltages: A cheap digital multimeter can be had for under $10 these days, and can help solve many problems.