Saturday, 10 February 2018

Solved battery problem

Very good session today, spoilt only by having to spend a maximum of 30 mins in the garage each time before coming in to thaw out.   Only outstanding problem was the battery draining overnight, so the first thing I did last Thursday was to get it tested at Halfords.  Passed with flying colours.   So there was obviously a current drain somewhere.   

When I took the battery out the tray was rusty and soaking wet, and the wiring was resting in it.  But when I wiped it the rust all came away and it cleaned up quite nicely.   I thought the water had come from the last time I filled her up, but when I looked closely I have a small leak in the washer bottle, so that wasn't helping.   I initially thought that was the reason for the current drain, but it turned out to be a red herring.    But glad I found it.

I'm the first to admit my wiring is 'ad-hoc' and really needs sorting out so I thought that might be the problem.   So I stripped all the diagnostic wiring out.
No, another red herring.
So then it was time to check the circuit.   By undoing the mounting of the isolation switch I was able to isolate the battery then bypass the switch by putting a multimeter across the terminals.   And Bingo, there was a 160ma drain.    That doesn't seem much, but in theory it should be zero, so needed investigating.

Now, I thought the only things that are live all the time are the 12V charging socket, which shouldn't take any current, the lights, the horn and the Voltmeter I had fitted, which should take zero current.   But then I realised that because the horn, the voltmeter and the oil pressure gauge are on the same panel, I had also wired the oil pressure gauge to be permanently live as well and I had no idea what the current drain on that was.    So I unplugged that and the drain dropped to 60ma, so that was a help.  Then just to check I unplugged the voltmeter and the current drain dropped to zero.   So my voltmeter does take a current drain of 60ma (cheap off E-Bay from China so shouldn't really be surprised).   
So both rewired to become active only with the ignition.

I then wondered if that was why my previous battery had started losing charge.   Luckily I hadn't taken it to the tip so for the time being I have put that back in to see if it holds charge.   I'll know tomorrow afternoon.

So everything replaced, with a cloth underneath the washer bottle as a temporary measure.   And the wiring tied up.   And extra insulation added to the positive terminal of the battery just to make sure.

No comments:

Post a Comment