Earth lead corrosion leading to inverter not working

[Shaun Witts]

On a recent long weekend away without EHU, I was dismayed to get no response from my inverter on the first morning. No tea or coffee with our breakfast (I didn’t have a backup gas burner with me - which anyway wouldn’t help with my Nespresso machine, but at least the Mrs could have had a tea). So, I spent yesterday trying to determine the cause (Hoping that it wasn’t the very expensive inverter!)

I could measure 1.06v across the inverter input terminals, but the vans volt display was showing 12.4v for my leisure battery, and the internal lights and fridge were working fine. So I guessed at a poor connection to the inverter somewhere.
Unfortunately, my electrics were all done by Exploria as part of the conversion, with the leisure battery underneath the van between the rear wheels. As a result, I had no idea how everything was wired up, but I assumed that the power leads to the inverter came direct from the battery. Having the battery under the van makes for rather awkward access, but with the rear wheels on levelling ramps and the air suspension on max height (with axle stands in place) I was able to lower the battery to discover a heavy duty +ve cable going through a 225A fuse to the inverter (all looked good, and the other electrics are also fed through this fuse) and a solitary heavy duty -ve cable being fixed to the chassis. There is no direct -ve feed to the inverter.
So, the inverter -ve must be taken from another chassis point and sure enough with a bit of searching I found it just inboard of the right rear wheel arch almost directly below where the inverter is mounted in my van. With hindsight, I didn’t need to go to all the effort of lowering the leisure battery. Hey ho.
Once I had located this -ve lead mounting point on the chassis, the cause was immediately apparent as an explosion of corrosion at the cable end, and when I unbolted the terminal from the chassis, it just fell off the cable. I’m surprised even 1v got through!

This is looking up at the inside of the right rear wheel arch and you can see how much corrosion there is (and, yes, it’s a red cable, not black as you would expect for a -ve cable).

The removed cable in all it’s glory.

That is the worst case of vehicle cable corrosion I have ever seen, but the main leisure battery -ve to chassis cable looks fine, so why did this one corrode so badly. They were both done at the same time, less than 3 years ago.
I have ordered a replacement (black) cable, but what is the best way to prevent this happening again? Is it just a case of copious amounts of grease?

 

[DXX]

Use tinned copper cable not plain copper cable.
Silicone grease to keep water / oxygen out.
Heat shrink over the ends of the insulation helps, even better if self adhesive heat shrink is used.

 

[Loz]

I would make the connection inside the van

 

[Shaun Witts]

Use tinned copper cable not plain copper cable.
Silicone grease to keep water / oxygen out.

Tinned cable is what I’ve ordered - Silicone grease is best eh? Best I get some then.
Thanks.

 

[oldiebut goodie]

I would make the connection inside the van

WHS... why take the cable externally just to bolt to the body? It would have been just as easy to do it inside originally.
That cable looks like it is CCA ( copper clad aluminium ) which I personally would not use in such a situation. Is it CCA cable? I hate the stuff - a supplier sent me some once passing it off as copper, totally unsuited for vehicle use with all the vibrations. He refused a return so I had to just bin it.

 

[Shaun Witts]

WHS... why take the cable externally just to bolt to the body? It would have been just as easy to do it inside originally.
That cable looks like it is CCA ( copper clad aluminium ) which I personally would not use in such a situation. Is it CCA cable? I hate the stuff - a supplier sent me some once passing it off as copper, totally unsuited for vehicle use with all the vibrations. He refused a return so I had to just bin it.

I just tried scrapping the exposed wires at the un-corroded end with a sharp knife, and that does appear to expose aluminium…
That’s disappointing to say the least, as the remainder of the heavy duty leisure battery wiring is the same stuff. So from battery +ve terminal to 225A fuse in fuse box, and then out again to the inverter. The leisure battery -ve terminal to vehicle chassis cable is wrapped in cloth tape, which I assumed was for protection, but now think that perhaps it is to hide the same red cable.
So what additional issues am I likely to expect going forward from the use of this cable?

 

[DXX]

As you’ve found it’s prone to corrosion and as @oldiebut goodie said it’s unsuitable for situations where there is vibration like vehicles.
If the cable between the battery + and fuse fails you have potential for a fire. After the fuse you it’s better protected but no guarantee that the fuse blows before it ignites something.
Change it all would be my advice and sooner rather than later.

 

[Loz]

CCA and salt are perfect conditions for galvanic action leading to what you see in your photo.

 

[oldiebut goodie]

The converter needs naming and shaming - that is risky cutting corners to save a few pennies. Can't see a reason for running it outside like that either other than incompetence.

 

[Shaun Witts]

The converter needs naming and shaming - that is risky cutting corners to save a few pennies. Can't see a reason for running it outside like that either other than incompetence.

They were named in the original post - Exploria of Brighouse.
Exploria did my complete conversion from pop top to VB air suspension on a new van. It may not have been all done at once, but apart from the later addition of a solar panel, all the electrics including the inverter were done at the beginning - even the wiring for the solar panel.
Are there any regulations or even industry guidance regarding such vehicle wiring?

 

[oldiebut goodie]

Missed that!
Did you get an electrical safety test report - it would be interesting to see if a qualified person signed it off.

I had both a gas inspection report and electrical safety report from my converter - I would expect Exploria to have done the same being one of the better companies.

 

[Shaun Witts]

Missed that!
Did you get an electrical safety test report - it would be interesting to see if a qualified person signed it off.

I had both a gas inspection report and electrical safety report from my converter - I would expect Exploria to have done the same being one of the better companies.

If I was given an electrical safety report, then I’ve misplaced it. But I have everything else including all the invoices so I suspect that I didn’t get one. I have no kitchen, so no gas report was required (though I do have one from the company that did the LPG conversion on my petrol engine).
I admit to being a bit concerned regarding the remaining cables. The terminals in the IP65 fuse box look good, and the +ve terminal to the inverter is inside so protected. But the battery terminals were covered so difficult to see as I didn’t fully remove the battery…

 

[oldiebut goodie]

Personally I would inspect all the cabling to check what has been used and replace as necessary - not the easiest of jobs tracing what someone else has done. Unless Exploria can inform you as to where it has been used ( and why ). I am only aware of CCA cable being used for sound setups in vehicles not power. ( I don't know why they like to use it other than saving money as you need a much heftier cable in CCA to cover the lower current carrying ability compared to the equivalent current carrying copper cable = maybe it is just that it looks pretty with its see through sheathing )

 

[Shaun Witts]

As I’ve said, the same cable is used from the battery +ve terminal to the leisure battery fuse box (see photo below) and then from the fuse box to the inverter. I can‘t tell what the cable is from the -ve battery terminal as it is wrapped in cloth tape, but it looks a similar dimension, so I suspect it is the same.

 

[oldiebut goodie]

The other cables look OK from what I can see - I would certainly change the 4 obvious ones, I can't see that they would have used proper cabling for the negative to battery either.
It makes me worry as to where else they have skimped. The tea-boy must have been let loose on that installation!

With a 225A fuse - I wonder if that CCA cable is even rated for 200A let alone 250.

 

[Shaun Witts]

I’ve not been able to determine the current ratings for CCA cable. The core is 10mm diameter, which is about 80mm2, but I can’t find any tables giving the current capacity for CCA.

 

[oldiebut goodie]

Best that I found years ago when I looked into CCA after receiving some.




Say between 2/0 and 3/0 - nowhere near 200A methinks.

 

[oldiebut goodie]

Have you got anywhere with Exploria as to why they have used CCA yet? Or have you just gone ahead and replaced it all?

 

[Shaun Witts]

I sent photos and an explanation asking if they could reassure me that the remaining wiring was safe to continue using. They phoned me back yesterday and apologised and agreed to replace it all. They could only suggest that the CCA cable was used by mistake.
So good for them. I can accept that mistakes are sometimes made, and it is good when a firm recognises that, owns up and offers to rectify.
I had already decided that I wouldn’t feel comfortable without changing all the wiring anyway (though I have only so far ordered a made-to-measure length to replace the defective bit). However to change it all myself would be a pain with the leisure battery under the van giving limited space to remove it, measure the cable lengths required, then order them and wait for delivery before refitting.
So my vans going in for Exploria to replace the cables next Friday meaning I will have good coffee for Busfest!
Hats off to Exploria - well done.

 

[slocumjoseph]

Just read this thread and realise it’s old and resolved now but might be worth mentioning though that I think LOZ cottoned the elephant in the room is galvanic action. I suspect the vehicle has been used in a salty environment frequently. The aluminium wire has been doing exactly what a sacrificial anode on a boat will do. Gradually lose its mass to the more noble metal, the steel of the chassis. I’ve seen1kilo sacrificial anodes virtually eaten down to their bolts in just two years.