how long to run the engine in car not in use

[JamesEB]

We are looking after a car for someone in hospital and the new battery went flat.

We were told to switch the engine on and let it run for a while regularly.

Please can someone tell me how often and for how long?

Thanks
JamesB

 

[JohnD]

not at all. Running the engine for short periods, in a car that is out of use, will cause acidic condensation in the engine, oil, and exhaust, leading to corrosion.

If you have, or can get, a battery charger, about once a month will do. If the battery is old and will not hold its charge, twice a month. Take special care to keep it charged in winter, as a flat battery is more able to freeze. A low power charger will do as you are not in any hurry. You will see the ammeter needle (or the indicator lights) on the charger drops down as the battery charges up, then you can disconnect it. Ordinary chargers should not be left connected for more than about 12 hours, overnight is usually enough. There are some quite expensive "smart" chargers that can be left connected permanently for laid-up cars, but you don't need one. Even a low-price 4-Amp charger will do a small or medium car in about 10 hours. very likely a friend or neighbour will lend you one, they are useful to have but very seldom needed. A battery will be damaged if it is left discharged over time.

At this time of year supermarkets often sell cheap chargers in the hardware aisle with windscreen wipers and motor oil.

BTW if the battery is new and went flat quickly, next time you charge it, go out after dark and look for something left on, usually the interior lamp or the light in the boot. An alarm sensor will gradually discharge the battery, but should take a couple of weeks. If you turn on the headlamps, and they have gone dim by the time you get out and look, the battery needs charging again. Also charge it up the day before your friend is ready to use the car again, for an easy start. It is possible to test a battery's state of charge using a voltmeter, but I don't think it is worthwhile in your case.

 

[Peter.N.]

..or you could fully charge the battery and then disconnect it, should stay charged foy about 3 months if its a good battery. I would concur with John, starting an engine from cold and leaving it running will do more harm than good.

Peter

 

[Burnerman]

As above, but I'll just throw a theoretical spanner in the works......
I had to look after someones Merc for a year - the car was garaged and I kept the battery charged.
Tried to start it, but the fuel pump wouldn't run until thwacked with a lump of timber.
After 6 months, the clutch friction plate was thoroughly stuck to the pressure plate and I had one hell of a job to release it.
The brakes were also stuck on, but they released with a clang without too much trouble......So - I'd use the car from time to time, maybe every couple of months for a 15 mile dry drive.
How long are you looking after the car for, James?
John

 

[chainsaw_masochist]

After 6 months, the clutch friction plate was thoroughly stuck to the pressure plate....

You should have tried this, John.

 

[Burnerman]

Aha the old phosphoric acid trick Bit difficult to access on the Merc!
Got it free by putting it in gear, clutch pedal down, handbrake off, cranking on the starter. Car jumping everywhere but it eventually came free.
John

 

[Peter.N.]

Yep, that's how I do it John. If you can get it on the road accelerating and standing on the brakes with the clutch depressed will do it in very severe cases.

Peter

 

[JamesEB]

..or you could fully charge the battery and then disconnect it, should stay charged foy about 3 months if its a good battery. I would concur with John, starting an engine from cold and leaving it running will do more harm than good.

Peter

Thanks but I don't know anything about batteries or how to attach them etc.

The car is having to stay outside.

Would taking it for a short run regularly be OK instead?

How far and how often?

Thanks for help
JamesEB

 

[Burnerman]

If you can lift the bonnet, you can attach a battery charger.....red wire to red (battery +) and black to black (battery -)
By all means take it for a 20 min run (so long as it isn't sorned), use the brakes well, get it fully warm.
(If it has alloy wheels, check the tyre pressures from time to time)
How long are you looking after the car for?
John

 

[JamesEB]

Thanks. How often does it need to go for a 20 minute run please?

We have it for good now

Thanks for help
JamesEB.

 

[JohnD]

this is the sort of battery charger that would do it
http://www.tesco.com/direct/ring-4-amp-battery-charger/775-9414.prd?pageLevel=&skuId=775-9414
It has two clips, that go onto the terminals on the battery, and is plugged into the mains (say, on the sort of extension lead you might use on a garden tool). As long as you remember not to start the engine before you remove it, you can lower the bonnet gently to protect the charger and plug from rain.

the one illustrated is reduced price and not the same shape body as the latest model, but the internal works are very simple.

It's a handy thing to have, in case you ever get a flat battery, not expensive for a low-power one like that, but you will probably find friends and neighbours have one and be willing to lend it.

Yes, a 20 minute run every week or two would do if you can't use a charger.

 

[Burnerman]

Is the make of car a secret ?!
Only reason I'm asking, some vehicles discharge their batteries much quicker than others, depending on their security systems ( Mercs for example may only stand for 2 weeks before the battery is drained)
If you do use a charger, probably best to disconnect it as JohnD says, but it doesn't really matter.
John

 

[JamesEB]

Sorry I hadn't seen you ask for the make. It's a 2.2 automatic Toyota Camry Estate. It's about 15 years old but in mint condition. The battery is new.

JamesEB

 

[Burnerman]

As you know, you can't push start an auto so I'd give it a run every two weeks.
Nice car, these - sadly have very little value now.
John

 

[JamesEB]

Yes, it is superb and looks and runs like new but has no value at all.

I noticed that the battery charger JohnD suggested says cars up to 1.6L? (before I said it is a 2.2). Can you suggest one for a 2.2 please?

JamesEB