Mitch wrote:
Are you by chance not connecting the charger directly to the battery
terminals


I'm connecting the + to the battery's positive, and the - to a bolt
head on the engine block.

I'll try cleaning again.

But.....If the negative battery cable has an open contact at EITHER end,
that will prevent current flow to the battery.

The admonition about making the last connection (or first
disconnection)to a grounded metal surface OTHER than the negative
battery terminal stems from wanting to keep any spark which happpens at
that connection from igniting hydrogen gas emitted from the battery cell
vents.

It's a meaningful concern for high current flows such as those which can
occur when jumper cables are used which can cause a lot of hydrogen to
be emitted, but hardly worrysome for a "dead" battery which is only
going to receive a few amps from a charger.

Just don't put your face smack over the top of the battery when
connecting the charger to it's contacts, best to lean back and look
sideways just to be safe.

I've only seen one battery "blow up" myself and it was about 50 years
ago. I had a car with a top post 6 volt battery with a buggered up nut
on cable clamp. I was attempting to saw through the clamp tangent to the
post with a hacksaw and didn't watch where the front end of the blade
was. Sure enough, it hit the other cable clamp and jammed up the blade.
While I was trying to wrench it free I watched the blade get red hot,
and an ohohsecond later the top blew off one of the cells.

My guardian angel was laughing his ass off at me, but he was kind enough
to keep the sulphuric acid from spraying into my eyes. G

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.