The rac tricked me

[Justintyme]

Used to be the case you coukd check the fluid levels in the battery - the last few ive had show a coloured display to indicate the health of the battery (green = good, red = needs attention). In the colder weather, i check weekly along with tyre pressure and wipers.

I guess some people are too busy, or lazy, to run these basic checks.

Lots of modern high performance batteries are sealed for life....you cannot check the electrolyte . But they should have a "Green" window button on them to indicate charge condition.

 

[Justintyme]

If it were me I'd still get the battery tested to know one way or the other so that there is proof to back up the claim.

My 8 year old W212 can sit for a couple of months and will start just fine but it's on it's second battery.
When replacing batteries I always stick a printed label on them with the date changed and the dealer I purchased the battery from just in case I have any problems down the line.

Seems that there are batteries that you can do this with, but not all of them will do this.

 

[pmcgsmurf]

Seems that there are batteries that you can do this with, but not all of them will do this.

Sorry, do what, be tested, hold a charge for a couple of months or stick a label on?

Unless I'm confused you can do that will them all, of course a faulty battery may not hold a charge for a couple of months.

 

[markjay]

I have a couple of cars that are not in frequent use (belonging to other members of the family, but I am in charge of them). I fitted battery isolators, and the car can sit up to one year with the battery disconnected then start fine once the battery is reconnected. Not great for the tyres and many other parts, I know.... but car batteries do hold their charge well when no consumers are connected.

 

[markjay]

Strictly speaking, with some batteries, once they go completely flat.. they can't be re charged. This happened with me, bought a new car, and for awhile I once a week started and ran the engine on the old one. Then I got a bit lazy and the charging sessions f
got further and further apart, until the day came when it would not start, and not take a charge either... Then ( after I had bought a new battery ) I heard that a completely discharged battery could be recharge by charging it in tandem with a good battery. I don't have any proof of this though.

This is a different issue. On modern cars, the alternator will stop charging the battery if the battery voltage drops below a certain threshold (from memory I think it's 10V).

Connecting two batteries in parallel tricks the alternator (or rather, the ECU controlling the charging cycle), by presenting a good battery with 12V output, which means the charging cycle is resumed (and the flat battery will now get charged).

In other words, the alternator does not know it's actually charging a flat battery, because it 'sees' the 12V from the other (good) battery.

 

[GordonTarling]

Don't know if anyone's seen Abs' other thread, but he states - "Battery from 2003 replaced today, £150 RAC Varta installed." So, if that's a true date, then the old battery was 15 years old. I've never known a battery last that long, but I suppose it might be possible - Abs?

 

[clk320x]

Don't know if anyone's seen Abs' other thread, but he states - "Battery from 2003 replaced today, £150 RAC Varta installed." So, if that's a true date, then the old battery was 15 years old. I've never known a battery last that long, but I suppose it might be possible - Abs?

That was wrong Gordon, I assumed it was as it was OEM. But I see a receipt for anew one recently in the history

 

[Will]

How recently Abs, I can’t remember if it’s 2 or 3 years on batteries from MB but there’s definitely a warranty.

Did you see the pic I posted for the date code on the terminals?

Will

 

[Justintyme]

Sorry, do what, be tested, hold a charge for a couple of months or stick a label on?

Unless I'm confused you can do that will them all, of course a faulty battery may not hold a charge for a couple of months.

I was referring to your post where you have had cars that could be left without

Sorry, do what, be tested, hold a charge for a couple of months or stick a label on?

Unless I'm confused you can do that will them all, of course a faulty battery may not hold a charge for a couple of months.

Yes Patrick, That's what I was referring to...a battery that will last several months in a car that is parked up, and even after that time, it will still start up. After I bought the w212 last Jan, the A6 was parked up, but started regularly at least for awhile....but then the starting /running episodes became
further and further apart, until the inevitable happened... and it would not start, plus the battery would not charge, and had to be replaced. Neither was it an old or cheap battery, but there you go. That's life. Moral of the story is I guess, if the car is parked up ( and likely to remain so ) either disconnect it, or remove it and place it in another vehicle.

 

[Justintyme]

This is a different issue. On modern cars, the alternator will stop charging the battery if the battery voltage drops below a certain threshold (from memory I think it's 10V).

Connecting two batteries in parallel tricks the alternator (or rather, the ECU controlling the charging cycle), by presenting a good battery with 12V output, which means the charging cycle is resumed (and the flat battery will now get charged).

In other words, the alternator does not know it's actually charging a flat battery, because it 'sees' the 12V from the other (good) battery.

Thanks Markjay for your comment. Would this work when using an external battery charger, as in the workshop?

 

[markjay]

Thanks Markjay for your comment. Would this work when using an external battery charger, as in the workshop?

It should, because the trickle chargers don't normally 'object' to charging flat batteries, but I do not know for fact - plus it may depend on the type of charger used.

 

[E55BOF]

Is it then the case that if a battery is discharged to below 10V, and you jump-start the car by connecting a sound battery, as soon as you disconnect the jump leads the alternator will cease charging the discharged battery?

 

[markjay]

Is it then the case that if a battery is discharged to below 10V, and you jump-start the car by connecting a sound battery, as soon as you disconnect the jump leads the alternator will cease charging the discharged battery?

That's the theory... you shouldn't disconnect the good battery until the flat battery has charged sufficiently to allow it to continue charging on its own. My knowledgeable comes from Internet forums though, I didn't conduct any controlled lab testing as such...

 

[Deleted member 126251]

....................... Moral of the story is I guess, if the car is parked up ( and likely to remain so ) either disconnect it, or remove it and place it in another vehicle.

Or use a maintenence charger as most people, who have several cars (or lay a car up for winter), do to keep the battery in good shape.

 

[zipdip]

Well I have not had a rescue service con me into buying a new battery,but one of them is not doing it's job,yesterday at the roundabout at the Guildford Cathedral,a fairly new Alfa sports car broke down and I saw the guy use his mobile,and two hours later he was still there with no sign of a breakdown service.

 

[Petrol Pete]

Well I have not had a rescue service con me into buying a new battery,but one of them is not doing it's job,yesterday at the roundabout at the Guildford Cathedral,a fairly new Alfa sports car broke down and I saw the guy use his mobile,and two hours later he was still there with no sign of a breakdown service.

it was an Alfa Romeo, the rescue company probably thought 'why bother getting it running again ? he will only be calling us again tomorrow'

 

[Will]

It’d probably been fixed and broken down again?

 

[zipdip]

yes I do agree own a Alfa and you soon get on first name terms with the breakdown guys.

 

[shella]

I know this is old but The same thing happened to me today I was charged £155.00 I also kept the old battery and was told because I kept it It would be on the invoice I asked if there was a charge he said no. As you something was off. I am miffed. I only found this post by accident.

 

[clk320x]

I must mention I had the old battery refitted and it worked fine as long as I had the car, sold the car and included the new battery in the boot as a spare... never saw my money back unfortunately (life’s too short)