On 14/12/2020 13:04, R D S wrote:
Our car is stop-start, it hasn't performed this 'feature' for many
months. I believe this to be a symptom of the battery not being at it's
best.

It was clicking the other day rather than cranking the engine over,
worked OK upon retrying. Taken it for a couple of decent runs since
(because it's been largely short runs all year, due to the obvious),
it's been OK.

I happened to have a meter in my hand today so checked it and it's
reading 12.1v which is quite low. Battery life generally being 4-6 years
and us having had the car 4.5 years i'm thinking shall I just replace it?

Advice is to trickle charge it first but I haven't a charger and I don't
want to buy a charger *and* a battery.

I use a cheapish (£40 or so) Optimate bike maintenance charger on my
wifes Fiesta "stop-start". Works a treat. It only puts out 0.22A (220mA)
max, but that's enough to keep it topped up and keep the dreaded "Low
Battery Voltage" (or similar) warning off the dash. Alas due to the
dreaded C-word its not driven very often.
If you use one connect the positive to the battery terminal but the
negative to the vehicle chassis not the battery terminal.
Why? Most modern cars have a charge current detector/sensor on the
negative terminal. That way the cars ECU knows the battery is being
charged and its state of charge.
With 220mA max current it can be left connected whenever the car is not
in use. Just hang a label over the steering wheel to remind the driver
its there and must be disconnected not dragged down the road. :-)


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