Question re Solar Panels and Projecta DC20 12v-12v charger

[NotGlamping]

Hi all,

Just purchased a camper trailer second hand (Lifestyle Extenda Elite).

It has 2 x 100Ah Calcium batteries, a Projecta DC20 12v-12v charger running to an Anderson plug at the front of the trailer. We had a brake controller and Anderson plug fitted at on the tow vehicle for hookup to the CT for charging of CT batteries while travelling etc.

Ok, question is, with portable solar panels. Can I hook the solar panel direct to the Anderson plug at the front of the CT? This plug/cable runs direct to the Projecta DC20 charger which runs to the batteries. As far as I know, the Projecta DC20 does not have a solar input, and hence no MPPT or solar-specific regulator. Naturally the solar panels do have a regulator bolted onto the panel leg frame.

Does anyone know if I can just hook up the solar panels, using the solar panel's regulator direct to the Anderson plug on the CT and hence run that regulated power feed from the solar panel through the Projecta DC20? In theory, that would be running the solar supply through two regulators would it not? Or should I bypass the regulator on the solar panels (simple to do on the panel I am purchasing) and feed that solar supply via the Anderson plug and use the Projecta DC20 as the regulator instead? Would that work?

The solar panel seller suggested just to bypass the Projecta DC20 and hook direct to the batteries via alligator clips, but that's a little inconvenient as I have to run cables somewhere through a door of the CT tent and leave the battery compartment door hanging open inside the tent which is inviting trouble (especially with young kids running around).

Any advice appreciated.

[CQuinn]

The Projector DC20 is a DC-DC charger designed to run off a voltage source such as an alternator and correct for voltage loss that may occur in cabling from the alternator to the secondary battery. Your solar panel is a current source and will not match with the DC20. The regulator on the solar panel is probably a pulse width modulated output chopping the current flow to suit the state of charge of the battery.

The two aren't going to talk together in my opinion. Optimum solution is to replace the DC20 with a unit that has a solar input and maybe that can be considered down the track. I think the best solution would be to run a cable for the solar panel anyway and use the regulator on the panel. You haven't stated what size you panel(s) are but the cable from the solar panel doesn't have to be super heavy and you can tolerate a bit of voltage drop from the panel. The DC20 can remain connected and the solar panel connects directly across battery terminals (via regulator) as suggested by the supplier. there needs to be a fuse at the battery end of the cable.

Hope this helps

Craig Quinn

[GEOFF.PAULINE]

Following on from Craig , I assume the solar panel will be used at a Campsite and not while travelling as the dc 20 will charge from the Alternator.
If this is the case then just use the Alligator Clamps and the Panel's Regulator.

A Ctek D 250S Dc- Dc charger will allow Alternator and Solar charging at the same time if you are Driving.

Geoff.

[robcaz]

The Projecta is a DC to DC charger, ie charges the camper battery from the vehicles alternator.

You will need to connect your portable solar panel with the regulator on the back, direct to the battery. Most run a short cable of say 6mm twin core sheathed from the battery positive & negative terminals to an Anderson to make connection easy.

[Maxandmargaret]

I have a Project DC20 and find it excellent. Mine is in the back of the Pathfinder and charges a 120ah agm battery, also in the back of the Pathfinder. It runs the Engel 45.

I use my 120w solar with the regulator immediately adjacent to the CT battery. It seems to be enough for our needs.

Per advice from Colin Rivers, who spoke at Tumut meet, I have abandoned any connection between the car and camper.