Battery charge issues

Evening folks, hope everyone is well, been having a few issues with our girl maintaining engine battery charge, bought a solar trickle charger to keep it topped up bit came to start her again today and flat as a pancake again. Neighbour a few doors down that's got a v dub asked if I had checked the Earth strap as that would stop the alternator charging the battery (it's less than a year old) now I haven't cos I am at a total loss as to what I am looking for, Google tells me it goes from the battery "tray" area down to the top of the gear box. We did have the gear box out a few months ago and I'm wondering if the connection isn't as good as it should be or if the strap itself has passed its best. Anyone with any knowledge of what I'm looking for or even pictures would be fantastic. Many thanks in advance :-)

All sorts of other things wouldn't work if the earth strap wasn't connected, so it's unlikely to be that. No harm in checking though, but someone else will have to tell you where it is. Broadly, you're looking for a braid or fat cable which runs from the battery negative terminal to the gearbox casing. It may be loose, it's unlikely to be worn out.

The battery is virtually new so it's not that. That leaves:

1) Something's flattening it - disconnect the negative terminal next time you park it and if it's still charged when you come back to it then that's probably it. Difficult to find though - you need to pull out fuses while measuring the current until it drops.

2) The alternator isn't connected to the battery. Measure the voltage at the alternator positive terminal and make sure it's the same as the battery voltage, near as.

3) The belt is loose / worn out. Check it but if in any doubt replace it. If it's at all loose it's worn out - they don't really stretch.

4) The alternator is broken. Most alternator failures don't illuminate the lamp, so that's quite likely. You need to measure the charging voltage. It varies depending on load, engine speed and temperature, but if it isn't about 14 Volts pretty soon after starting then it's probably broken - shorted windings, worn out brushes or a broken diode.

How old is the vehicle, and how many miles on it? Might help to pin it down.

Richard.

As Richard has said, unlikely to be broken but I had a T3 (also known as T25) VW and the earth strap was notorious for corrosion around the gearbox end which would impact on charging and starting. I don't know your van so can't help out on where to look.

She's a year 99 and about 175k on her, tbh the radio sometimes cuts out when you switch the wipers on and re sets itself as if not enough power to it, driving home tonight I didn't even have enough power in the battery after 8 miles to power lights and wipers so somethings not right, sadly I'm in overly mechanically minded tho I have changed the glow plugs and some other routine bits one her, I do have a test meter but ideally I need to find a diagram of the engine bay to know where things are :-D I managed to find what I believe is the braid strap by torchlight and it feels almost like soft fabric to touch, I would of thought copper wire would feel more rigid? It's VERY flexible almost like a tiki torch wick would feel? Hard to gauge when I don't know what one should look like, it's about and inch n half wide but then goes to right hand side of engine bay and bolts to it, from that tho it drops to a much smaller cable size and across to battery area. Thanks for the suggestions folks will crack open the test meter when I get 5 and keep things crossed :-)

Harper22 wrote:It's VERY flexible almost like a tiki torch wick would feel?

It's not that unusual for the earth strap to have a loose braided outer covering, so that water cannot sit inside the outer and corrode it away. However, if you grasp the whole thing (i.e. outer and inner together) it should feel fairly rigid, even if the inner is also braided.

Hi, As you seem to be short of electrical power whilst driving that suggests to me the charging circuit is at fault unless the battery has experienced a total failure which would be highly unusual.

The first check I would make would be the battery voltage whilst switched off an when running. You should in a healthy system find figures of around 12v with everything off and 14v ish when running & charging.

Assuming your charging voltage is low, I would reitterate what others have said - check all connections to the alternator and from it to the chassis / gearbox, they need to be reasonably tight, free from corrosion and protected with a smear of grease. Next check the battery connections in the same way ensuring that the -ve cable has a good connection to the chassis as that can be an issue.

I would also check that the aux belt that drives the alternator is appropriately tight - does it make a noise when you rev the engine?

If you can't find anything obvious, it might be worth having an auto electrician test the alternator for you.

Hope this helps...

had a bit of a tat under the bonnet today and traced where the earth goes too and from, all the connections look rough and rusted so think that's something to check, randomly my spanner set has gone walkies so wasn't able to do much as needed to get to work, had her on trickle charger overnight and got her started today, strangely I much of moved something as the battery light didn't come on as per the norm lately but when I went over rough roads in her the light flickered from dim to bright and then off again on smoother roads so i'm more inclined to think there's a dodgy connection along the line??? any thoughts :-)