Flat Battery

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Hi,

 

we've just bought a 2002 Galaxy 1.9 TDi Ghia, we bought it ex-company leasing, and we had borrowed it off its owner before we bought it so we know it quite well.

 

Its now suddenly seemed to start having a flat battery in the morning.

 

I've looked and looked and can't find anything left switched on (although I can hear a sort of whirring noise when the ignition goes off - but have put this down to the clock!)

 

but every morning now, the central locking unlocks, and all the lights on the dash come on, but bearly a groan when you try to turn it over - and then that clicking when it then doesn't have enough juice to fire the solenoid on the starter motor.

 

I jump started it the other morning - drove to halfords (about 10 miles away) and stayed there for an hour and it was flat again - I understand that Diesel batteries take a long time to charge?

 

some bod from Halfords came out with their battery tester and said the battery was good. I've measured the voltage at the battery terminals with the engine running and its 14.02 - which means the altenator is charging.

 

...anyone any ideas?

 

its driving me potty!

 

cheers

 

Graham

[Ivor_E_Tower]

Duff battery - get it changed but I don't know if it will be covered by warranty. Mine did the same - gave up when just under 3 years old (as taken from date of first registration, but over 3 years if taken by date vehicle was manufactured). Car refused to start in the morning, I jump-started it. It started OK at lunch-time same day and I drove straight to auto battery specialist to get it changed. Not too worried about haggling over possible warranty claim as relying on the car starting is more important that about

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thanks for that.

 

what battery did you get then, if there are concerns over the ford factory fitted ones?

 

should I go to halfords and look up the VW replacement ones?

 

Graham

[Ivor_E_Tower]

The original one in my Gal was a Varta, and guess what, the auto electricians fitted a Varta replacement as they reckon they are the best! The Halfords ones look OK, but I found out afterwards that my 2 local Halfords do not stock the right one and it would have to be specially ordered.

[Masked Marauder]

That sounds typical of a failed cell in the battery.

 

Does anyone know if the vehicle comes with a calcium battery btw?

[Richmond]

That sounds typical of a failed cell in the battery.

Would the battery then give 14.02V?

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isn't that more like the output of the altenator.

 

one time I measured the battery after it wouldn't start and it registered 11.54v

 

..so sounds like charge is bleeding away. (which made me think I'd kept leaving something switched on)

 

could be a failed cell in the battery - just that halfords said it was ok......although shouldn't really have relied on that now should I!!

 

;)

 

Graham

[Richmond]

isn't that more like the output of the altenator.

Yes, it is. Silly me. Batteries do seem to give more than the advertised 12V when fully charged, 'though. I can't imagine why that should be, electrochemistry always struck me as more of an art than a science.

[Ivor_E_Tower]

12 volts is not the "advertised" value; IIRC, the nominal value is 13.2 volts for a 6 cell lead-acid battery. To charge the battery you need a greater voltage, hence somewhere in the region of 14.5 volts from the charging circuit, which is the voltage that should appear across the battery with the engine running.

[rwtomkins]

I think all Gals now come with silver calcium battery as standard. Certainly mine did (a 2002 model). On voltages, for what it's worth, here's some info I posted on a previous thread some time ago. (Obviously the voltage across the terminals would be higher than 12.6 volts if the battery was being, or had just been, charged):

 

you probably all know this but i found the following info from www.autobatteries.com very interesting. a standard automotive battery is made up of 6 cells with 2.1 cells per cell, so it is fully charged when you have 12.6 volts across the terminals. a small drop in voltage makes an enormous difference to the charge, as follows:

 

at 12.6 volts the battery is 100 per cent charged

at 12.4 volts, the battery is 75 per cent charged

at 12.2 volts, the battery is 50 per cent charged

at 12.0 volts, the battery is 25 per cent charged

 

a car battery is considered charged at 12.4 volts or more. it is considered discharged at 12.39 volts or less.

 

it seems extremely improbable that you'd be able to turn over the engine with less than 12 volts across the terminals.

[ridway]

When and if you get a new battery, do a check to see what current is leaving it, in its quiescent state. That is with everything switched off. Radio off, doors closed etc.

 

There should not be more than a few microamps flowing away from the battery to power the ECU memory, alarm immobiliser etc.. Be sure to connect the ammeter in series and NOT across the pos and neg terminals!!! . Don't forget that batteries produce an explosive gas combination of hydrogen and oxygen so be aware of sparks when connecting and disconnecting.

 

If the meter is reading anything greater than say 10 milliamp (0.01A), probably less I would start looking deeper into whether there is a fault. If the gal is drawing current when your absolutley sure everything is switched off it is more than likely you will have another knacked battery in a year or so. Especially if the car is stood for long spells.

 

The best check is by comparison. I was going to get a figure for you but then realised yours is diesel and mine is petrol so they will differ anyway. With winter approaching this info from variants could be quite useful in finding faults with charging systems and batteries info.

 

As an aside having a knacked glow plug will take its toll out of a battery. Does your gal start well after the glow light extinguishes? It should fire in less than a second if working well; even in cold weather. A problem with aglow plug or plugs, combined with short runs in winter will soon see off a good battery espescially as the winter approaches.

 

Maybe willing members could post quiescent battery drain currents next time they feel the need to disconnect the battery. I'll certainly post mine, as an addendum to this thread, for the 2.3 ghia petrol when I service and change the oil at the weekend.

 

Rich

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ok, now have a new battery.

 

its funny, looking in the galaxy engine bay I was CONVINCED that the battery in there was bigger than a standard car battery, so when I went to my local motor factors, told 'em what I wanted, they produced a battery according to there bible - and I said "nah, thats much too small, it currently has a bigger one" - so they trotted out varying sizes of battery, and I plumpled for one that I thought was right - a 95Ah battery - as it turned out (not the 70Ah I had asked for)

 

...of course, getting the battery home, and taking the old one out, I now realise its EXACTLY the same size as a normal car battery! ;)

 

fortunately, the plate for moutning the battery fits the new one exactly - so I dumped it in.

 

haven't tried measuring the current - perhaps will give that a go.

 

cheers for the advice

 

Graham

[Ivor_E_Tower]

FYI - if you go to a proper auto electricians, they stick a "dummy load" across the battery terminals which measures voltage under load and also shows up which cells (if any) are duff as they tend to "fizz". When my battery went u/s last December, none of the cells fizzed but the voltage was down, and I knew I wanted a new battery as the old one packed up over night (car had been fine the previous day and I knew I hadn't left anything switched on; headlamps, dash lamps etc were all at normal brightness even though there was insufficient power/voltage to operate the starter, just a clunk from the starter solenoid trying to engage).

[iainkirk]

My battery expired at 12 months, as did a few other people's.

 

With the assistance of an in car fridge being the common cause...

 

The don't half sh@g batteries when they flatten them, it would seem!!!

[Masked Marauder]

Well calcium batteries will not properly re-charge from flat without the use of a special charger. Perhaps that explains the short life, not dead, just sleeping....

 

In any case Calcium batteries should have a three year warranty.

[rwtomkins]

Mr Marauder is correct in theory but after running my calcium battery completely flat a year or so ago by leaving the lights on overnight, I did manage to recharge it with a conventional charger set to supercharge and have had no problems with it since. So sometimes, it seems, you might just get away with it.

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funnily enough - in august we went camping - with a plug in fridge, and we accidently left it on and flattened the battery!

 

...all makes sense now.

 

Graham

[Guest V6KID]

Exactly the same happend to me this year - 3 year old battery and replaced it in France for EUR 100 - seems the factory fit is not the best.

[Masked Marauder]

The trouble with any CAR battery is that it needs to provide a lot of amps at once. To do this the battery is made up of lots of thin plates in a mixture of 35% Sulfuric Acid (H2SO4) and 65% distilled water (electrolyte.) But the down-side is that when the battery is deep discharged, sulfur molecules come out of the acid and form on the plates. That reduces the battery's capacity. In severe cases with a silver/calcium cell, that can be by as much as 40% on the first occasion!

 

To recharge the battery fully you then need to use a special "pulse" charger. This re-energises these sulfur molecules and knocks them off the plates back into the electrolyte where they re-form sulfuric acid. Some chargers have this fitted to enable fast charging without damaging the battery. Perhaps that is how Mr Tomkins managed to re-charge his on "Supercharge" setting!

 

DEEP CYCLE batteries (often known as "Marine Batteries") have very thick plates and are designed for a long, slow discharge rate and do not suffer from sulfur build-up nearly as badly. These are the batteries best suited to leisure use and powering accessories in a split-charging system. They are more expensive, but are not damaged by full discharge.

[rwtomkins]

Very interesting, Mr Marauder. I wonder, would the car's own alternator provide this "pulse" charge effect and cure the battery if you jump started the car or got just enough charge into the battery to fire up the engine?

[Masked Marauder]

No it does not, it simply supplies a constant voltage/amperage regulated by the diode pack on the alternator.