In my Kia bus, I have a 165Ahr AGM
battery at the rear, used for running an Evakool yellow fridge.
The
battery is charged via a Thumper "50A charge kit" as I previously had a 75Ahr Thumper here.
All connections are via Anderson connections.
I have a Projecta
battery protector in place between the
battery and the Evakool which I've jumpered to 12V. This is supposed to cut out at 12V and cut back in at 13V or so.
Given the capacity of the
battery, and the fact I maintain on weekends via a 240V
battery charger, I've never had reason to
test the
battery protector.
A few weeks ago we were on holidays with not a lot of driving. I had noticed the
battery capacity dropping and it eventually went below 12V cutting the fridge.
What I didn't expect is that when we took a half hour drive it didn't cut back in, with the voltage on the
battery when being charged at only 12.3V
Normally in my (limited) experience once the alternator kicks in the
battery shows a voltage as per the alternator output.
Even stranger, at the end of a 6 hour drive back from Coffs (to
Sydney), it was still only showing 12.5V.
To be honest I don't understand this. I've checked the alternator voltage (via one of those cig led thingies) and it shows around 14V or so at all times.
Once I got
home I put the
battery on the Projecta 30A charger and it was almost immediately showing 13+ volts.
I have a Redarc SBI12 which I had intended installing (mainly for the
battery override in case of a flat
battery - 40kgs is too heavy to move in case of a flat main
battery). Should I also upgrade the cables as I have some 6B&S left over from another job.
Or am I missing the point entirely and this behaviour is normal?