It’s Snowball all right – and you weren’t wrong about the battery. See the following from the central character’s wife.
"The first thing you do, my boy, is make a replacement for that so-called battery in our car. I’m tired of having the clunk die in the middle of traffic".
And from the younger generation
Colquhoun’s eldest son Robert dropped over to find Arch tinkering with his rickety ’48 Chevrolet. “Dad says you’ve got a new kind of battery” - - I’d like to buy a big piece of the stuff from you - - To run my hot rod off it” said Rob from the lofty eminence of sixteen years.- - [Rob] also discovered, more or less clandestinely, that such a car would go up to 200mph on the straightaway.
That was until his father confiscated it.