I was unsure about the condition of my house and starting battery
. Spoke to a mate who is an auto electrician who offered to lend some some testing gear
But prior to giving it to me he got me to have feel of the sides of the batteries
He said "If they are sightly convex (popped out) the batteries
Mine certainly were convex. Its the cells expanding due to build up on them. Thus causing the battery
to physically expand.
I have diddled with boat electronics
and 12 volts for 30 years an this one never hit me. It was that moment when I thought "how did I not know this before- duh?"
Anywho,, Hope this snippit will forearm someone else in the future.