Starter battery & alt. belt questions

[Nicola&Tony]

I'd be grateful for some help with these questions:

1. what's the minimum voltage in the starter battery that's needed in order to get the engine going?

2. what size alternator belt should be on an early dg? vw sold me a 10 x 1075 last July but the adjuster has been all the way up to the top since Jan. and the belt doesn't really have enough tension on it.

3. what's the lifespan of an alternator belt? Ours is 12 months old, has done 8,600 miles approx. and isn't frayed or split, but I can't get enough tension on it.

Thanks for any help.

Tony

[Red Westie]

Under load (whilst cranking) the starter motor drags a very high amperage from the battery (160-200amps) or more for a diesel.
So it is not suprising that battery volts drop at this critical starting stage.
Generally it is excepted that the minimum should be around 10volts.
As for the belt, just buy the next size down (around 10 x 1060 I guess) ideally one that takes the adjusting bracket towards the lower end of it's range.
Alternater belts should last 30-40,000 miles, which is a lot of years for most campers.

[Nicola&Tony]

RW, thanks for the info. We have an intermittent cold starting problem at the moment and I put a meter on the battery tonight and it read 12.4v with no load on the battery. I put another starter battery in (the one that we use as a leisure battery) and the van started first time. The voltage for this battery was 12.56v with no load.

I don't know how old the first battery is because it was in when we got the van nearly 2 years ago, so maybe the battery is on its way out (I'll check the electrolyte and put it on the charger). The second battery was bought by us 18 months ago.

I'm trying to work out if it's a dying battery or if it's not getting charged properly because of the alternator belt. I'll give the battery some tlc, put a shorter belt on and see if the problem persists.

Thanks again.

Tony

[Nicola&Tony]

Just looked on gsf website, they list a 10 x 1100 belt for 1.9 engines. Can't imagine how I'd get any tension at all on one of those!

Tony

[Nicola&Tony]

. . vw sold me a 10 x 1075 . .

Does 10 refer to the depth of the belt or the top width?

Tony

[bigherb]

10 is the belt width.

Battery no load voltages to check how charged a battery is.
12.6 or more 100% Charged
12.4 75%
12.2 50%
12.0 25%
11.7 0%

[Nicola&Tony]

Thanks bigherb!

Tony

[R0B]

to check if if your battery is knacked.remove it.put it on charge for 24hrs.check the voltage with a tester.leave it stood(not on charge) for another 24hrs.check the voltage again.if its lower than the first time you tested it.its not holding a charge.and you need to replace the it...

[Red Westie]

The most revealing battery test is to check the specific gravity on each cell.
Charge first then check each cell with a battery hydrometer (pretty cheap from your motorist place)draw some electrolyte from each cell in turn, fully charged shows 1.280 fully discharged will show 1.150, a tired or dead cell will show a substantially lower reading than the others (typically several all the same and then 1 or two much lower indicating a failing cell)
F.Y.I....the usual and flawed test 'Drop testing' is only really valid on a fully charged battery (a new but partially charged battery would fail)
Martin