Slow crank

T

Toffermora

Senior Member
VIP Member
T6 Guru
Morning all,

I have noticed now that it's getting colder the van has a really slow crank when it starts. It does start and it does it as soon as it turns over but it is slow. Looking at my bm6 readings the voltage drops from about 12.3 to 11.9 which I thought wasn't that bad but I have no idea how old the battery is so do you think it may require a new battery or could it be something else?
 
You can have 12V in a battery but nowhere near the power to crank a diesel engine. Eg: a little scooter battery would never start a van. And yes, cold weather will reveal issues with an unhealthy battery.
You could try putting the battery on a decent reconditioning charger. Get the battery load tested. Or finally, replace the battery.

This assumes the problem is the battery. Slow initial cranking could be other issues. Bad earth connection, bad positive connection, oil in the cylinders from worn seals... etc etc.
 
What year is the van ?

Is it the original battery (VW part number/sticker on it etc)?
 
It's 2017, it's not the original battery as its an RAC varta one but who knows when it was put in. I was thinking (hoping) it was the battery as it cranks fine when the weather is warmer, just noticed it the last couple of days as it's got colder.
I don't own a battery charger, so would have to purchase one, so is it cheaper in the long run to get a new battery?
 
Chargers are a lot cheaper than a decent start/stop battery. But it depends what’s wrong in your case.

I think owning a charger is essential. If you can spring for one you’ll always use it.

But a charger might just be a £50 way of proving you need a £150 battery.

It’s hard to suggest one over the other without knowing what the true problem is.

Here’s a story to help explain:
I had a T4 that had a flat battery that wasn’t charging. I replaced that battery and fitted a new alternator.
I then charged the old battery up and you know what it’s fine: it’s now in my T6 while I delay buying a new battery.
So maybe with a charge yours will be fine too. But it’s a big maybe.
 
If it’s of any relevance mine cranks over slowly on the odd occasion but it has always been telling me that the battery wants a charge! Once charged it’s fine….it doesn’t get used much and it’s standing with a dash cam always live, which will have a very minor drain anyway! Only ever use it for longer journeys and isn’t my daily driver.
 
Right well I have ordered a charger from Amazon, only a cheap one but seems to get good reviews, couple of stupid questions though, 1. Can I charge it while it is still all hooked up in the van or do I need to remove the terminal connections from the van before attaching the charger?
2. Do I attach the negative lead to the battery terminal or to a body connection? I know you shouldn't attach stuff to the negative but don't know about when charging!
Thanks
 
Leave mine connected right or wrongly and will trickle charge when topped up so can be left on. Does have the reconditioning feature but unsure wether or not that has happened if ever needed. Just plug in and connect at let it do its own thing!
 
Found this on my bm6 this morning

1000003070.png so hopefully will get it charged over the next couple of days and see how it goes
 
I'm getting the same slow start symptoms, but as the original battery is around 8 years old i think a new battery is the way to go. Always used Tanya Batteries for the motorbike and they have been great. I got their list of options for a T6 up, and was minded to go for Varta again, but see that the Yuasa has increased capacity, any tips or different supplier even would be appreciated.

FE66FOM/battery - VRM Search Result
 
I bought a charger and it has helped but the cranking amps are still down, fine once charged but leave it overnight and they drop. This is this morning:1000003222.png
 
A loss of cranking amps, not holding charge etc. I am quite sure your battery needs replacing.

If you have stop/start you should get a battery capable of this. A normal battery will work but have a shorter life.

I was going to get a BoschS5A11 for my stop/start T6. Cheapest source I found was ebay: Bosch S5A11 Car Battery 12V AGM Start Stop 5 Year Warranty Type 115 | eBay. - not an endorsement of the seller, I haven't used them.
 
Yea I have been looking at the Bosch S5a13, the battery group sell that for £180 with next day delivery so will probably get that, did see one cheaper but will take a few days longer to get here.
 
It may be that your battery has had its day. It is possible to be fooled after charging a battery that it is in poor health because it will often assume the recommended charge from what ever is charging it. Many years ago I was having problems cant remember when. The meters always showed good battery health after a long run or from charging it at home. A local garage found no problem and so it went on. It was only after removal and charging, leaving it for a day or so that I could see that it would not retain a worthwhile charge. Basically it was a cell down, it would still charge up and look fine for a little while but it had its day. Replacing it resolved all problems. I believe it was over a winter period when the problems started and as it has been said, that is the time of most demand.

I understand that they can be stress tested but it sounds kaput, If you replace it get the best you can from following advice on here.
 
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