Grounding to chasis, is there any need for additional one if leisure battery is linked to starter battery?
- Thread starter QPiepelr65
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- earth points transit
Yes, that’s just coincidence.
The 105Ah is the amount of charge the battery can store. The 100A max discharge current the the maximum current that the battery can supply.
A simplistic analogy is if we imagine the battery full of charge (100Ah) is a watering can full of water. Then the max discharge current (100A) would be equivalent to how fast the water could be poured out of the watering can.
QPiepelr65
Ford Transit Connect
Ok so I had wired everything up including a sturdy ground behind the driver's seat as per recommendations. Everything had been working swimmingly for small runs close to home the past few days but on a longer drive where I plan to leave for some time trouble struck!
I am guessing from the quick search online I have a ground loop due to more than one ground though open to other ideas but that seems to indicate what it is from the below and online cursory search.
The charger was working fine from what I could see in the background when I turned my head back then all of a sudden there was like the noise of a bit of gravel hitting the van. Now it could have been coincidence but when I looked back the lights on the charger were out!
I kept looking back when I got a chance and no lights. I picked an opportunity to park and indeed the charger seemed dead! So I got out the trusty multimeter to try and diagnose. I checked both fuses to charger, both positive from starter and leisure battery, with a continuity test on either side of the fuse and there was continuity. Rest of the system still has power so not the main system fuse either.
Now here things narrow down a bit. I am really glad I installed that isolater switch between the starter and the charger now, having questioned if it was going to be redundant, as it has helped me narrow down the cause.
So I have a battery cutoff for the whole leisure battery system of which the charger is connected to the positive busbar. I switched that off and everything goes off as expected. Now for the unexpected...when I switch off the isolator between starter battery and charger my whole system is lighting up! Not just the charger which would not light up at all so far but everything, the solar charge controller and mt50, the charger. Also they light up but only for a seond in couple of second bursts then go off again, like a heartbeat.
So what is causing this and how do I stop it?
If I turn the starter isolator off things all go off again. I can switch the main isolator back on and the main circuits, apart from the charger which remains dead with no indicator lights which it usually would show before this, even if starter isolator was off, and seems to function normally. If I switch both off again and then the starter on and main off then the same 'heartbeat' of power to the whole system.
You guys said that I should make the second ground in habitation space for my leisure stuff but isn't this precisely what is likely causing the loop, having more than one ground to the chasis? Very ironic if so!
I do think it was good to make a new clean ground for my habitation gear but it seems to have brought more problems, which is exactly what I was trying to avoid in the first place by suggesting just one ground to chasis.
I don't yet know enough about grounds to know how to further troubleshoot so please advise.
I am going to have to cancel my planned trip now until I get this fixed as want to be back at base to have access to workshop and since charging would have been essential while away which effectively takes me out of action until it is resolved.
It may be a simple fix but I don't know that at this stage and so have to go back to get it sorted.
QPiepelr65
Ford Transit Connect
Yes that is what I had planned. Do you mean you are using one ground chasis for everything or separate for vehicle electrics and habitation stuff?
If the former did you use the original one from the manufacturer or have you made your own?
The liesure battery is under my passanger front seat and is earthed to an OEM fixing point on the chassis under the same seat.
How come you're posting in this forum about a Ford?
I'm not trying to disuade you and while the concept of vehicle electrics is universal there are differences between earth locations for instance.
How come you're posting in this forum about a Ford?
I'm not trying to disuade you and while the concept of vehicle electrics is universal there are differences between earth locations for instance.
QPiepelr65
Ford Transit Connect
Well because as you say general electronics are universal and it is a simple 12v system. There is a subforum here for all other vans so I presumed this subforum too would cover all general electrics regardless of vehicle.
If the double ground does turn out to be the issue why is it that most van builders/dwellers do not mention such an issue as the common wisdom is to make a separate ground in the habitation space with no discussion of more than one ground or ground loops that I have come across.
Here is a diagram I just drew of the electrics. Yes there are fuses but it was so fiddly just to get this just know fuses are where they should be in the circuits and the right size and have checked them and not blown.
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It shouldn't matter where you fix ANY earth so long as it eventually touches the bare metal of the van bodywork, be that via a busbar or a direct fixing in the engine bay, the cab or the back of the van.
Loads of us have earthed our leisure battery and we dont encounter this ground loop you speak of.
My gut is saying you have a wiring issue. Maybe a loose connection or broken wire or even a short which would trip the electronics like you mentioned.
Best of luck getting it sorted and let us know how you get on.
Loads of us have earthed our leisure battery and we dont encounter this ground loop you speak of.
My gut is saying you have a wiring issue. Maybe a loose connection or broken wire or even a short which would trip the electronics like you mentioned.
Best of luck getting it sorted and let us know how you get on.
QPiepelr65
Ford Transit Connect
So having more than one ground is not necessarily the issue? Finding a short from what I have read about, seems like it would be a bugger to diagnose so I really hope it is not that.
I would start by fixing the above. A loose/lost ground will cause all kinds of mysteries.
Also 16 mm² is not much for grounding starter battery. T6 uses 35 mm² cable.
QPiepelr65
Ford Transit Connect
Well it is ford's own specs for the starter ground not mine and I guess they knew right.
There is no earth to the fuse box? Therer is a jump and the negative goes into the negative busbar.
Ok so I did a bit of fiddling with the wires before the light went down and it isn't even the ground from the negative busbar as I thought would be the cause!
I removed that and turned the starter to charger live wire on again and still the same intermittent power flickering of leisure devices!
What is even stranger is I removed BOTH negatives to the busbar, the starter negative and charger negative and STILL the same! So that is really a head scratcher now!
My worst fear is that the cables from the starter into the habitation space have fused or got exposed somehow as that was a pure nightmare to put in!
Dark now so waiting for a new day to tackle it again but since it isn't the ground then I think I am just going to have to figure it out myself by methodically going through connections removing them until the strange behavior stops and then looking at the circuit in question.
Somehow, as it stands, the starter battery is partially powering my leisure battery loads. Only partial because if I flick a light switch it won't come on however most standby lights will come on. Weird since the main leisure battery isolator is off and, as mentioned above, I removed both negatives from the busbar for starter and charger.
The starter is somehow making a circuit via the charger positive though but no idea where the negative route is coming from!
OK why have you got a ‘negative’ going to your fuse board?
QPiepelr65
Ford Transit Connect
Ok this is where I back out then because I am not familiar with fuse boards that have negatives. Or Transits.
A lot of fuse blocks have a negative busbar inbuilt. eg:
Blue Sea Systems 5025 ST Blade Fuse Block - 6 Circuits With Negative Busbar & Cover
Blue Sea Systems 5025 fuse block with six fused circuits fed from a common busbar input, plus integrated negative busbar, providing a compact fusing solution.
www.12voltplanet.co.uk
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