The Anderson plug mystery deepens

[GregMilner]

Okay, this might be one for Drivesafe.

The Pioneer dealer today replaced the Redarc battery management system in the new camper trailer.
Tested it with his car, no problem at all getting charge from his Anderson plug to the trailer's BMS.
My car? Not so much.
Tested the Anderson plug with a test light, no problem
My Anderson plug has been wired (by Auto Spark) into the power supply in the cargo area in the rear right of the car's cargo area.
Is the issue a lack of amps at the Anderson plug?
The camper trailer dealer's son is an auto electrician. In a phone call, the son advised "Ah, Range Rover. The only way to get sufficient amps to the Anderson plug at the rear bumper is to run the power directly from the battery posts under the bonnet back to the rear."
Is this fair dinkum?
Anybody with experience re this?
We're heading off on a trip to Broome/Cape Leveque in July and would like to get this sorted prior to that trip.

[drivesafe]

Hi Greg and the first thing I would try is to see if you can charge the battery in the camper trailer without the BMS.

Under normal circumstances your RR easier puts out enough voltage and current to charge a number of batteries at the same time.

Next, also check to see if the DC/DC device is a "LV" version. With no load on the RR, it will run at a lower voltage if your cranking battery is fully charged.

And last but not least, the power connection you have is perfect for doing what you intend. You do not need to run cables from the cranking battery to the Anderson plug.

[GregMilner]

Do you mean plugging the camper batteries into my Ctek charger directly, bypassing the Redarc BMS?
The BMS charges the batteries fine when plugged into 240 volt.

[drivesafe]

The BMS charges the batteries fine when plugged into 240 volt.

How are the batteries charged while you are driving?

Are they connected to the BMS and the other side of the BMS is connected to your Anderson plug?

Or are your camper trailer batteries wired directly to the Anderson Plug?

[GregMilner]

Mmmm...don't know the answer to that. It's a Pioneer camper, made in Melbourne, with a Redarc BMS. Presumably, being Redarc, they've wired it in whatever the correct way is.
When we picked up the camper (it's a new one) last week from the dealer in Perth, he couldn't get the camper to charge from either his vehicle or mine (via the Anderson plugs at the rear of either vehicle) even though that morning his vehicle had been charging the camper batteries. So, this afternoon he came to our place and swapped out the BMS for a new one. Still no result.
He then discovered that the BMS he'd swapped out had blown a fuse in his car. Fuse changed, his vehicle then successfully began charging the batteries in the camper.
My car though doesn't appear to have a blown fuse, as we were still getting power to the Anderson plug at the back of the car. But it's still not charging the camper batteries, according the display of the BMS. Charges fine when plugged into 240V.

[DeanoH]

You may be getting +12v power to the Anderson plug but does it have a good earth connection ? One's not much good without the other :D

How about plugging a high(er) power load into the Anderson plug, a spotlight or headlight lamp for example and see if that works OK.

Where a low current device like a test lamp may not show up a high resistance connection (should there be one) it should be more apparent with a larger load.


Deano

[GregMilner]

Yes, that's the $64,000 question. I don't have anything of higher power fitted with an Anderson plug to test it, but I'm going to run it over to the sparky who fitted the plug a couple of years ago to test it. Thanks for the suggestion:-)

[Not_An_Abba_Fan]

I run an Anderson Plug on my Prado to charge the battery in the camper while driving too, and I have wired it directly to the battery through a circuit breaker. I always wire Anderson Plugs directly to the battery with 6mm wire. I don't know what size wire is run to the power supply at the rear of your Range Rover, but I'd say it was never intended to charge a battery with through an Anderson Plug. The length of that wire, plus the wire going to the plug, plus the length from the trailer plug to the BMS will all add to higher resistance. You will need to test the voltage at the BMS connection to make sure you are getting enough for it. Having power is one thing, having enough voltage to charge the battery is another.

[drivesafe]

Hi NAAF, the cable running from the cranking battery to the rear of an L322 is either 20mm2 or 25mm2, and is way thick enough.

Plus there are plenty of L322 Range Rovers with my kits in them, happily charging batteries in camper trailers and caravans.

I think Deano might be on to something.

You need to get the right earth point in the back of the RR or you will not have a decent earth return.

Greg, tell your auto elec that the bolts holding your rear bumper on are the perfect earth point, and they are M10 and are accessible by removing the plastic storage box, below the rear fuse panel.

[GregMilner]

Hi NAAF, the cable running from the cranking battery to the rear of an L322 is either 20mm2 or 25mm2, and is way thick enough.

Plus there are plenty of L322 Range Rovers with my kits in them, happily charging batteries in camper trailers and caravans.

I think Deabo might be on to something.

You need to get the right earth point in the back of the RR or you will not have a decent earth return.

Greg, tell your auto elec that the bolts holding your rear bumper on are the perfect earth point, and they are M10 and are accessible by removing the plastic storage box, below the rear fuse panel.

Onto it, on my way to see the sparky now.

[GregMilner]

As suggested, it was a bad earth connection. Took the sparky half an hour to figure it out after initially saying his original earth connection should have been fine.
Camper batteries now charging perfectly - thanks for your input guys, much relieved.

[Graeme]

Here was me thinking it rude to suggest that a sparky might not have done a proper job!

[GregMilner]

Here was me thinking it rude to suggest that a sparky might not have done a proper job!

I'm agreeing with you - on the inside:-)

[Graeme]

Several times I typed the suggestion then aborted the post, thinking it couldn't really be that basic. I used to get into trouble wanting to recheck other people's work from scratch when something didn't work, obviously not trusting the person's abilities, so try not to be so quick.

[GregMilner]

Graeme I often take suggestions I read on this and other forums to technicians and 'specialists' and get reactions ranging from a raised eyebrow to outright scorn. Today's reaction was at the lower end of the scale, but I could tell what he thought of my suggestion to check his own earth connection. Until he put a meter on the battery then checked the volts and amps at the back and suddenly discovered 'a discrepancy' of 2 volts. Something he should have checked two years ago.
Finding a better earth fixed the problem immediately.