Weird starting/battery problem

[ghost123uk]

I would borrow a known good battery of a mate or relative to find out if it's the battery. That's a perfectly good but non technical way of finding out. Take care as some batteries have their +ve and -ve terminals the opposite way round. You wouldn't want to get that wrong !!

[domiles1]

Trouble is... everything is good now and working as it should. Van started first time today after sitting for a week, starter turned nice and quick. So I now don't have the problem, so borrowing a friend's battery would at this point tell me nothing. I am confused how the problem went away and can only guess maybe the cold was affecting the battery and now the weather has warmed up a bit......?????????????

[domiles1]

It happened again!
I charged battery and van started. I let it run for a minute and stopped it. Then it wouldn't start, it was sluggish. 3rd attempt and it was just clicking.

So I charged it up again over night and started van again but this time I ran it for a few minutes and manoevered the van around the street. Then turned off and it re-started for a second time fine.

It seems to me that if I start the van, the battery suffers so much that it needs a fair few minutes charging from the alternator to recover.

[AdrianC]

Is it the battery, or is it letting the engine cool down that's fixing it?

Do you have a leisure battery, or a second battery from another car, or a jump box?
If so, next time it won't start, IMMEDIATELY try to jump start it.

Don't charge the battery every night - just try to start it cold in the morning.

There's no way that running for a minute or two would drop the power in the battery - and you say the alternator's putting out 14v anyway. The battery's clearly holding charge at least briefly.

[domiles1]

I dont have a spare battery I'm afraid - it would help my diagnosis really wouldn't it!

I may not have explained it very well - what I am suggesting is that when the van is started for the first time, it takes a lot out of the battery and the battery can only recover properly if I run the van for a few minutes. its the times when I ran it only for 60 sec when it would not re-start. When I ran it for 5 mins, I was able to turn off and re-start it fine.
I'm thinking (with my limited knowledge) that the battery is past its best and is not really up to starting the van more than once and needs to spend a few minutes with the alternator to recover after each starting.

[AdrianC]

what I am suggesting is that when the van is started for the first time, it takes a lot out of the battery

Then you must be churning, and churning, and churning, and churning before it starts - you might want to address that problem first. Unless you are, then there really shouldn't be a problem.

[domiles1]

No, it turns for about 2 seconds and starts fine.
Then I turn off the engine.
Then I try to start it again and the battery is half dead and can barely turn the engine.
The only difference is whether I let the engine run for a minute or 10 minutes. If I let it run for only a minute before turning off, then it wont start a second time. If I let it run for 10 minutes before turning off, then it re-starts fine.

[AdrianC]

No, it turns for about 2 seconds and starts fine.
Then I turn off the engine.
Then I try to start it again and the battery is half dead and can barely turn the engine.

If you try to start it immediately.

Don't. Leave it alone. Walk off. Have a cuppa.

Try to start it the next morning, without having charged it again.

If the battery can really only supply 2 sec of starting, then it's utterly, absolutely, amazingly fubar - and I very much doubt that 2 sec would be at anything close to normal cranking speed.

[domiles1]

Will try that, thanks.
On the first attempt, it starts like a new battery, or at least it starts like it has always done for the last ten years.
Its just if I stop the van after a minute and try to re-start, then theres a problem!!!
I think you are right when you say batt is knackered.
I just need to be sure cos its a big expensive diesel battery!!!
Thanks.

[AdrianC]

I think you are right when you say batt is knackered.

I'm not saying that. Not yet, anyway. This feels more like starter motor than battery, to me.

[domiles1]

I disagree (but also I dont know much and am very grateful for advice) because charging the batt solves the prob, its like brand new again.
Then, after one start but not much running, its dead again. Thats why I think its the batt ???

[AdrianC]

I disagree (but also I dont know much and am very grateful for advice) because charging the batt solves the prob

But the battery charge isn't the only thing that's happening in that period. The starter is also sitting unused for an extended period. Hence the suggestion you try to start again tomorrow morning WITHOUT charging.

[ghost123uk]

I had a Scirocco once that did similar. (I still have the car) It would work all ok most of the time, but once in a while I would park it up, come back to it and the battery was flat. Did it say once every 4 or 5 "park ups". It could do it even in just 1 5 minute visit to a take out for instance. It turned out to have a faulty diode in the alternator and depending on what position the alternator "stopped at" it would be fine, or short the battery and drain it. Swapping the alternator cured it. Not saying this is what is up with yours, just information that might help.