question

Does the caravan and the car have to be hitched up for the earth to work properly? And/Or.. should i have to wire as earth from the charging system to the chassis of the van for a common earth ?

the 7-blade has a heavy gauge ground wire in it, and is usually connected to the trailer chassis somewhere up front, then the rest of the electric distribution system is tied to chassis ground, in the back or something. at 15-20 amps, it only takes like 1/3 or 1/2 ohm of resistance to completely knock out the voltage.

Did you get a fix for this? I just installed mine in a landcruiser and am seeing similar issues. Is this an earth issue?

I am having the same issue. When I spoke to the company I bought it from they said it was highly likely that the is was being caused by an issue with the earthing point. I moved my earthing point so I was using the vehicle chassis ground stud on the rear pillar and then the charger appeared to work.

It appeared to be working normally, going through Bulk, Absorption and Float Charge stages and working correctly when the engine is turned off and on etc.

However, yesterday - despite nothing changing- the same issue began again where the voltage drops to around 7 volts, slowly creeps back up, it attempts to charge and just as the output voltage begins the input voltage drops to 7volts again.

So now I am truely stumped because it was working fine the day before, and then yesterday it began malfunctioning. Is it possible that it is a fault with the charger?

I will be following this thread for updates because it seems like a number of people are having the same issue, but cannot find a clear fix for it.

That sounds exactly what happened with mine. I did a 3 hour trip (lots of 100kmh / 65mph driving) and it worked fine - no issues - fully charged the battery. Then after a few days laid up, on the way home I saw that voltage drop - as low as 6 volts and it hasn't charged properly since.

Some noteworthy points though. I am monitoring the voltage of the 2 starting batteries and they are showing 13.4 volts and appear to be fully charged and charging from the alternator without issue. I 'd have thought if it was an alternator issue or battery issue, I'd be seeing issues elsewhere in the vehicle and I'd be having trouble with my starting batteries being charged properly and holding charge.

I did read in another forum that one person had the same issue and in his case, it came down to it being that his cabling was not heavy enough. At least in my case, I wouldn't think it is the cabling size as I used the old loom from the Redarc DC-DC charger @ 25 amps. Additionally, the voltage drop to 6 amps is way to much.

I guess its time to get out the multi-meter and try do some in-depth troubleshooting.

I can at least check my multimeter agrees / disagrees with what the Victron is telling me. I do note that I have a very heavy earth cable installed in the rear of the car - long before I got it. I'll try do some checking to make sure its actually doing its job. Also, I have a heavier cable I could use for testing so I might try that to begin with, but I really don't want to pull a new cable from the engine bay to the read of the car :-(

Given it did work and then it stopped, I'm leaning towards an earth issue... surely this couldn't be a unit fault could it?

I'll report back soon.

Well, the Victron doesn't lie.....
Kind of embarrassing to have to admit, but the cable that I thought would do the job simply didn't. At least for me, its a lesson in check, check and check again. The cable from the old DC - DC battery charger was simply not enough - not by a long shot.

My multi-meter was giving the same feedback as the Victron

For the sake of testing, I used both the black and red for the positive from main battery to the Victron Input and used a small earth cable from Victron to the earth chassis and it resolved the voltage drop issue immediately. I was getting a solid 13.1 volts at the Victron end

I'll be pulling a new cable in the next few days.

If your cable is too long and not heavy enough, you're gonna see voltage drop. The other kicker in it all is that an insufficient cable is gonna fry if you are not careful. I could see evidence of this near the connection to the Victron. All working okay now - I have dodged a bullet.

Finally - I apologize for hijacking this thread. This was not initially my question / issue.

I do hope that my experience will however help someone else.