Charging a car battery by driving it

I have no idea of pappyon's personal circumstances (like the rest of us).

But I think the idea of a (portable) starter power pack is a very good one.

Easier than taking the car battery out and carrying it upstairs.

Seen them in Halfrauds and the sheds. I expect the AA man used one to start the car. Can usually be charged up at home with a plug, or from a cigar lighter in a running vehicle.

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go to halfords and buy a booster pack. They have a 12volt socket on the front which then you can buy a boost starter which is meant to plug into your cigerete light and someone else's to start your car. simply plug it in to booster pack instead and leave over night to swap the charge from the booster pack to your car battery. Do this once a month and you should be o.k. And also when not using booster pack leave it in your boot in case you do get unstuck. They only need a charge every month or so. Or tho if you using it to charge your battery i should charge pack up before and after use.Should get both items for under 50 quid.
What i would do is check that you don,t have a drain on the battery or get someone else to do so, a 1 amp drain on a battery over a week wont help it make sure you pop the front off the radio etc if it has a light on it that does not go off with the ignition.
Our fit a battery isolator there are only about a tenner !
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A battery isolator is a big switch that completely disconnects the batttery from the car. Heavy DC rating as it has to carry the starter motor current. Useful on racing and some old cars. Can make them difficult to steal if the thief is not expecting it. Will cause your clock, radio and some electronics to reset.
With the engine running, why don't you stick the car up on axle stands in the garage and put a brick on the accelerator pedal in top gear and leave it for half hour or so? :D Ferris Bueller style!
Do you have a way of getting a car onto axle stands when its battery is flat?
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 !
Softus said:
freddymercurystwin said:
Softus said:
Do you have a way of getting a car onto axle stands when its battery is flat?
Err, with a jack! Did you think I was being serious?
Yes. But in my defence, I'm a bit tired.
Serious or not - I'd like to know Softus' normal method of putting the car on axle stands (i.e. the one that requires a charged battery) :eek:
Yes, I'd like to know that as well. Maybe Softus has a set of powered stands. Presumably 12 volt.
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