clarks conversion - electrical query

[cjm2009]

Hi, Long time no post

Recently I had a 150w solar panel & mppt controller fitted to my ex network rail clarks conversion T350.

The installer had issues working out where to wire the charge output. As an interim solution, he wired it to the feed for the rear interior lights (on the overhead electrical panel).

Both the starter and leisure batteries are wired in parallel on my van, and because the solar output goes to all batteries, the 'weakest' (starter) battery dictates the cut-off for charging, meaning that the AGM leisure batteries never really get charged beyond 80% off the panel. They read 12.7 at rest - which is 100% charged for the lead acid starter!

I was wondering if anyone else had encountered a similar problem, and knew where to connect the panel to bypass (if possible!) the starter battery, so it no longer dictates the overall voltage? Or is it possible to fit some sort of isolating switch to take the starter battery out of the habitation circuit altogether when we're parked up & camping?

20170621_172633.jpg

20170621_172640.jpg

[madmart132]

Hi I am not sure if by AGM batteries you mean gel batteries ?
If they are deep cycle gel batteries they should really be standing alone ie not connected to the main electric system.
I don't understand why the fitter connected it to the main system unless you asked him to ?
Without further information or pictures it is hard to advise you what to do

[Beaker]

I've just run into a issue with my solar set up and although not related to your problem, might offer a solution.

I hooked up my new leisure battery in the back of the van to the front of the two batteries under the seat via a M Power Voltage Sensing Relay. Running off the alternator for a few days to test it ,everything was working fine. When I connected my solar panel to the battery via the MPPT controller, my leisure battery was charging nicely, but my relay was now stuck open and the front battery under the seat charging as well. The float charge voltage of the solar panel was higher that the cut off voltage of the relay, so the relay would not close. This was last weekend during the hot sunny weather.

Concerned by the health prospects of the relay, I phoned the manufacturer (Merlin) who said it would be wise to give the relay a bit of a rest in extreme conditions, and suggested fitting a battery isolator between the relay and the leisure battery, and this is what I suggest you do too. Now I can completely seperate my leisure battery from the others when I want, and use the solar panel to help charge the van batteries when I want as well. A simple and cheap fix.

[cjm2009]

Thanks for the replies guys.

I've got a motorhome electrical expert coming out to look at the setup on Thursday morning. I'll report back with what he did to fix it (if he manages to).

[AK]

I fitted an isolator switch behind the drivers seat so I can isolate van batteries from leisure batteries

[cjm2009]

Well the bloke came out, and he was rubbish. He spent the entire day poking & prodding without actually achieving anything.

In fact, at one point he'd wired the solar output to just the interior lights.

Him: "Yeah, the solar panel is feeding your lights now. It's sorted"
Me: "That's great, but I usually only use the lights when it's dark."

So now I'm £100 down and nothing has changed

I think I'll just have to pull all the wiring and start again

[Beaker]

Here's a stripped down drawing of your battery setup with the VSR fitted between them. I'm assuming that your batterries are wired like this:



You should connect the positive and negative wires from the solar controller to the appropriate (+/-) terminal on your leisure battery.

All your lights, pump etc. connect to the leisure battery via your fuse box.

If you want to isolate the two batteries, cut the wire labelled AUX BATTERRY +POS on the above diagram and fit a isolator switch in place.

I used one of these:

http://www.12voltplanet.co.uk/marine-battery-isolator-switch-2-positions.html

It's such a pain when "experts" turn out to be charlatans. When I was looking at solar for my van, I took it to some expert motorhome place with a glowing reputation twenty miles away, who assured me they could sort it. They quoted me nearly a grand for a solar setup and leisure battery! The confusion on their faces trying to work out the existing twin battery setup under my drivers seat, convinced me that they were in fact, just winging it.

[the dutch guy]

why not use a dual sense relay? it would trigger on engine start and also charge the starter battery when the aux is getting full. most dual sense relays start triggering at 13.2v (on) and disable around 12.7v.

right now you have the solar on the wrong side of the relay if i understand your setup correctly.

and you always need a main swich to bypass the relay by hand.

[cjm2009]

The guy who came round to look at it fitted a dual sense relay - but apparently the output from my panel was 'too strong' to trigger the isolation (or something).

I've taken Beakers' advice & have ordered the isolator switch. Got to get my power steering leak fixed first though

[the dutch guy]

too strong panel is not possible. not unless you have 2kW of panels on your roof.

the function of the relay is to trigger when there is enough volts to charge the batteries (13.2v or more) and if you have a decent panel it might trigger it immedialty so you charge them both.
but if you use more power then the panel can deliver and the batteries (both of them!) start to drain the relay will disable when the voltages drops to 12.7v and disconnect the starter battery from the aux so only the aux drains.
the relay will kick back in when the load stops and the voltage recovers.
in order to prevent the relay from not disabling correctly you need to have the solar input directly on the load side of the aux battery wires and keep it as far away as possible from the relay.

[cjm2009]

too strong panel is not possible. not unless you have 2kW of panels on your roof.

the function of the relay is to trigger when there is enough volts to charge the batteries (13.2v or more) and if you have a decent panel it might trigger it immedialty so you charge them both.
but if you use more power then the panel can deliver and the batteries (both of them!) start to drain the relay will disable when the voltages drops to 12.7v and disconnect the starter battery from the aux so only the aux drains.
the relay will kick back in when the load stops and the voltage recovers.
in order to prevent the relay from not disabling correctly you need to have the solar input directly on the load side of the aux battery wires and keep it as far away as possible from the relay.

Yeah. He's wired the panel feed so the negative uses a shared earth & the positive is spliced onto the aux + feed from the relay itself. It would seem that the relay is always closed - so the panel is charging the starter & aux batteries, still. It might actually not be all that big a deal, but it bugs the hell out of me

I might have to just bite the bullet and run cabling through the roof & down into the battery cupboard straight from the MPPT.

[the dutch guy]

so the panel is charging the starter & aux batteries,

that is what it's supposed to do. and when you drain the batteries the relay disengages and the starter battery is removed so you only discharge the aux. when the aux recovers the relay gets triggerd again and both batteries get topped off. handy if you have the radio or other stuff that run on the starter on.

the only thing you might want to change is to put the solar positive as far away from the sense line of the relay as possible. that way the relay gets properly disconnected when the voltage lowers due to load. position of the negative is not relevant. the entire van is negative.