Car Batteries

[Narnia]

I just know this will get the pulses racing in ED. My other three quarters had a new battery put in her aging car in January, I think. Having the habit of going abroad, sometimes for weeks on end, the last time she came back it was as flat as a squashed dodo. Fair enough I thought as it hadn't been used. On that occasion I got the rescue service to recharge it, drove around for a while and ended my trip at the local garage where it was fitted, just in case it didn't restart. It didn't. They kept it in overnight and all was well. Or so it seemed.

This time with her abroad again I decided to give it a run after about 10 days. It was flat again, or almost. I've two questions for any experts out there ( and not of the rabid rabbit type). One, why should a 'new' battery drain so quickly unless it was faulty in the first place? Secondly, do the battery rechargers on sale out there actually work? If they do, do they require being connected to an electricity supply or do you just charge them up first? (bonus question)

I'm fed up calling the rescue services or more to the point they are likely to be fed up with me calling them for the same reason. Also I don't wish to be indebted to the local garage who I think rip me off anyway with general car maintenence.

What do you advise/recommend please?

[david_carnell]

Sounds more like a faulty alternator or perhaps a drain somewhere rather than a faulty battery itself. I'd ask around for recommendations for a decent mechanic to have a look at it for you if you don't trust your garage.

Battery chargers are plugged into the mains.

[computedshorty]

Sometimes the radio is not fitted corretly bypassing the main ignition, when turned to very low tone or silent you might think it is off but it remains on draining your battery, also a door left ajar will leave an interior light on.

The heater uses a lot of the energy from the battery is that used a lot?

[HAL9000]

It could be a wiring problem: a short circuit through charred insulation can drain the battery. This happened to me - almost had to pay for a new alternator before it was properly diagnosed.

Also, note that batteries can be 'cooked' by charging at too high a voltage - the symptoms are as you describe - the problem could be a faulty limiter inside the alternator - in which case, the alternator has to be replaced.

[Narnia]

Would you expect a mechanic who suggested replacing the battery not to have considered the other options first?

[DulwichFox]

Car Batteries usually last 4-5 years.

A car battery like any other Wet cell should be charged at the 16 Hour Rate.

Therefore a standard 12 volt 80 Ampere Hour Battery should be charged at 5 Amps for 16 Hours. (Full Charge)

Many chargers available will deliver 3 - 5 amps so will give a good charge after 8-12 hours providing you

give the car a bit of a run after re fitting the battery.

Charging at a higher rate will cause Sulphation of the battery plates.

At even higher rates of charge, the plates will buckle and the sulpate break up and will sink

to the bottom of the battery and short it out.

The battery is then un repairable.

[HAL9000]

BTW - aren't almost all modern car batteries guaranteed for three or more years?

[trizza]

I had this with my old Fiat.

Potential issues:

1) Faulty alternator - not charging battery when engine is running.

2) Faulty wiring - usually associated with 1).

3) Power drain - the fiat would not start if I left the face panel of the radio on as this would drain the battery! Things like faulty boot lights that stay on when doors are closed can also drain the battery.

I am afraid you will need a decent mechanic to detect the issue...

[Ladymuck]

Narnia, does your other-three-quarters' car have an alarm? I had this problem for years - in the days of driving an old mini. It turned out that the alarm system, whilst good for keeping thieves off, was completely unsuitable for the little car: it drained the battery like mad, resulting in non-starters or even breakdowns at traffic lights. In the end, I simply decided to risk the car being stolen by leaving the alarm off. It did the trick.

[ruffers]

Ladymuck's just said what my first thought was - look for drain.

[Izodia]

On the battery charger subject...we recently bought a Jumpstart from Halfords. You plug it in in the house to charge it up and then take it out to the car. Worked perfectly.