DC2DC Charger earth.

[Dazzola]

Hi guys, I'm currently installing my Renogy dcc30s charger and have a conundrum with regards to the earth cable location, the instructions say to run an earth and positive cable from the van battery to the charger in the back of the van, positive is fine, but my question is, do I need the earth from the van battery? Can I not earth the charger to the chassis or leisure batteries instead, that means a much shorter cable and much easier cable route.
Cheers,

 

[RedFrame]

In my B2B installation instructions it clearly states "do not use a chassis earth", it doesn't however explain why.

It's not Renology but thought the info might help.

Cheers
Red.

 

[Dazzola]

Cheers Red, I suppose they have reason for it, so a 5mtr run of cable then! It's a bit tight so I'll run them down opposite sides of the van.

 

[XxAnthxX]

Cheers Red, I suppose they have reason for it, so a 5mtr run of cable then! It's a bit tight so I'll run them down opposite sides of the van.

The wiring diagram of the Renology dcdc30 shows the ‘common’ negative connected to both batteries and the solar……..but here is an extract from page 13 of the manual….

I think point 1 tells you all you need to know.

 

[Dazzola]

That's not the connection to the van battery from the charger though?

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[XxAnthxX]

That's not the connection to the van battery from the charger though?

It’s a common negative….there is only one negative pole on the the dcdc30 (no.4)

 

[Dazzola]

So why would they stipulate a direct earth from the starter battery? Belt and braces? It should work fine with a chassis earth but is there something I'm missing?
Cheers for the input.

 

[XxAnthxX]

If the dcdc30 unit was mounted near the cab battery you’d use the cab battery negative……if it was positioned near the Hab battery you’d connect it to the Hab battery negative. It’s just a negative.

Both batteries negative are linked though the chassis as all your 12v devices are.

Your more likely to suffer high resistance from a undersized long cable run than through the chassis.

Where did it stipulate direct earth from the starter battery?

 

[Dazzola]

Just a mo, I'll get a pic.

 

[XxAnthxX]

That one?

It’s just showing the negatives are all linked.

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[Dazzola]

 

[Dazzola]

That's what baked my turnip a bit, the entire van is an earth, unless you drop on a beam that's bonded instead of welded, which can happen.
I presumed there was a specific reason for the earth to starter, wavelength or oscillating signals or something else I know bugger all about!

 

[XxAnthxX]

I’m more intrigued as to why they‘re only showing you a fuse in the Hab positive and not the Cab positive

 

[Dazzola]

And it only comes with one big shiny gold fuse too, but I have others that I can use, protect the cabling!
Cheers for the help, it's given me headache today, but I can see how to do it now, Thanks!

 

[Hoovie]

I’m more intrigued as to why they‘re only showing you a fuse in the Hab positive and not the Cab positive

Indeed. Definately need a fuse both ends

On the long cable from Starter to B2B I usually fit a Fuse each end just for added safety (overkill maybe, but safety first )

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[Stealaway]

My Sterling B2B made me wonder about the negatives.
It states in the installation wiring diagram to take the negative cable to the starter battery first and then a negative cable to the hab batteries. ???
That's how I did but still don't understand why.

 

[Dazzola]

Well, finally got all the cable runs in, connected the pair of leisure batteries and got everything earthed and fused.
Bingo! Batteries charging and I didn't let any smoke out of the wires
All seems good, so now to tidy and clip everything up.
Cheers again for the input.

Daz.