pappyon said:
My car is normally only out of the lockup once a week to be driven a distance of about 4 miles, and invariably it is very hard to start in this weather.
On more than one occasion I have to call out the AA because it wouldn't start at all.
For how many miles would I have to drive the car and at what speed to ensure that the battery is well enough charged that it will start OK on the one day of the week that I want to use it?
Half an hour steady driving... no lights minimal other services.
When I had a dashboard guage, it took 7 miles rural / suburban to get the engine oil up to working temperature, that provided my personal measure of a short journey - where engine oil does not reach operating temperature.
Rough and ready electric stuff..
Say 0.3 mins total journey-starting motor usage, at 300 Amps, gives 90 Amp.Mins This must to be replaced, beside the other journey drains on battery power.
Let us say 4 miles at 25 mph av. (or about 2500 engine rpm ) = 9.6 mins, with an approximate alternator output of 12 A under those conditions.. approx' replacement of 9.6 x 12 = 115 Amp.mins, marginal for you.
If you drive a steady 30 mins (12.5 miles) at Av 12A replacement then we have a healthy 360 Amp.mins restoration...
30 minutes should pretty much even out the assumptions and guesswork above. Plus your engine will hopefully be up to full working temperature throughout, which is normally a good thing...
I am really trying to give you plenty of reasons for increasing your mileage and reducing the stress... It'll be there on the key all weathers !
