Car (or bike) Chat!

[dave2010]

i'd say 1500 to 2000rpm is about right.. a run is better tho all round, as ticking over speed isnt great for the car . brakes, springs etc need a workout too. at tickover if youve got a few things on like heater etc you may not actually charge anything

MMMmmm. So I shouldn't rev up our remaining petrol car to 3-4k for a few minutes then?

I've read that just starting a car is likely to take quite a chunk out of the battery, so not worth pussying around. Ideally it's best not to start a car if you're not going to drive it. However recently cars are often idle for a while, so things can go wrong. In normal times a petrol car would probably be driven at least once a week, and should go for at least 4 miles or so to keep the battery charged - ideally more and at reasonably high speeds - which also gets oil around the engine, stops the carbon from building up, and the driving probably gets rust off the brakes and loosens the suspension, and frees up the sterring a bit etc. AFAIK it's not a good idea to leave a car idle for a long while.

Clearly these are not normal times, and with our EVs we don't tend to drive the petrol Peugeot as much as we did before, so that's not so good for the poor thing. So sometimes I do rev it up to 3000 rpm on the drive for 2 or 3 minutes just to check that it's working OK.

Is that a bad idea?

[InThe Sticks]

MMMmmm. So I shouldn't rev up our remaining petrol car to 3-4k for a few minutes then?

No, it's utterly pointless at those revs.
If voltage was dependant on revs and the alternator wasn't regulated, you'd boil your battery dry in 5 minutes.
Leave it on tickover or better just go for a drive.

[dave2010]

No, it's utterly pointless at those revs.
If voltage was dependant on revs and the alternator wasn't regulated, you'd boil your battery dry in 5 minutes.
Leave it on tickover or better just go for a drive.

Interesting. Would 2k be any good?

Going for a drive hasn't been so easy over the last year - Covid restrictions, weather etc. Not so bad now though.
I never thought that tickover idling would do much good. If not actually going out, how long should idling be done to not run the battery down - given that starting the engine takes something out of it? Maybe it's pointless starting a car engine anyway if it's not going to go on a run, but I have noticed problems if the engine isn't fired up at least once in a while.

[rmcin626]

My Q5 is Audi today, for MOT and a couple of warranty checks, will be 3 years old in a couple of weeks only just passed 10,000 miles

[Beobloke]

There’s little point in running an engine at idle - many car handbooks specifically tell you not to do this to warm it up, for example. Sitting there revving it is even more pointless because, as above, the alternator’s electrical output is regulated. More revs don’t mean more/faster charging!

You’re far better off buying an intelligent battery charger and using it every couple of weeks to top the battery up and then driving the car once a month or so.

Some friends of ours are having some fairly major house renovation done and their house and driveway has been a building site for the last 6 months. As a result, one of their cars has been out of the way on our driveway since last September. Since then, I’ve stuck it on the charger for a day every two to three weeks and take it out for a half hour’s drive once every month to six weeks. It’s absolutely fine.

[Macca]

warming the car up:

[struth]

gave car another run and filled tank uop £20 for half a tank plus. that will last for a while

[Marco]

There’s little point in running an engine at idle - many car handbooks specifically tell you not to do this to warm it up, for example. Sitting there revving it is even more pointless because, as above, the alternator’s electrical output is regulated. More revs don’t mean more/faster charging!

You’re far better off buying an intelligent battery charger and using it every couple of weeks to top the battery up and then driving the car once a month or so.

The correct advice, thus is what folks should follow. Your first paragraph also outlines the indisputable facts! So only daftees sit and rev car engines in a futile attempt to 'charge the battery'...

End of subject. No more to be said on the matter

Marco.

[struth]

with the hybrid they suggest running car at idle with everything switched on.. this forces engine to run and charge

[InThe Sticks]

with the hybrid they suggest running car at idle with everything switched on.. this forces engine to run and charge

Yup, I've lost count of how many times I've mentioned that.