I drive rarely, so the car battery slowly discharges keeping the Engine Control Unit's memory intact.
In the past I used a battery disconnector to keep the charge up, but that meant poor starts after several days due to the ECU memory having been wiped.
What I'd like to do is either:
a/. connect a small 12v sealed lead acid battery to the car via the cigarette lighter socket, so that I could then disconnect the car battery to charge it from time-to-time, but retain ECU memory. The small battery would be recharged in the shed ready for use as and when.
b/. permanently fit a 12v sealed lead acid battery in the motor compartment, that would not go out of circuit when I use the battery disconnector to isolate the main battery. It would recharge in parallel with the main battery during driving.
My background is radio and electronics, not batteries and alternators. So could someone say whether either or both of the scenarios would work?
