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super90ish · 03-08-2021, 11:33 AM

Hello,

I have 4 panels (320 Watts total) which I had converted into two briefcases, wired with plugs. I would like to buy the components to use them as a portable charger which I can use to charge batteries in other trailers which do not have solar. Besides the panels which I already own, I am not sure what I need to buy. I envision a setup with clamps which attach to the battery posts much like when you charge a battery at home from 110 wall power. Any advice would be greatly appreciated.

Thanks in advance,

Mark

warrantchief · 03-08-2021, 01:05 PM

You have a lot of options depending on how fancy you want to get. The controller that most airstreamers install is a Victron MPPT (https://www.victronenergy.com/solar-...-100-15-100-20). You could get two small ones or one bigger one to join all 4 panels together.

If you're not super concerned with efficiency and want to save a few bucks, there are endless inexpensive PWM charge controllers. Get the right size for you panels, make sure it's configured to charge the correct type of battery, bolt them to the back and hook 'em up to the batteries!

GetawA-S · 03-08-2021, 01:33 PM

Most of the ready made solar panel setups use SAE style connected cables. You choose the termination type for the batteries you are charging ( alligator clips, Zamp port, jack). If you can find a set ready made, it would probably be less trouble and more reliable than homemade (at least in my world). Go big (smaller gauge number) on the wires for efficiency and ability to add more later.

ROBERT CROSS · 03-08-2021, 03:17 PM

I charge thru the 7-pin with 2 Zamp 180w suitcase panels.👍

Bob
🇺🇸

Bob Schrader · 03-09-2021, 09:48 AM

Quote:

Originally Posted by ROBERT CROSS

I charge thru the 7-pin with 2 Zamp 180w suitcase panels.👍

Bob
🇺🇸

Bob, since all Bobs' are great minds thinking alike, assume you plug that into BC 7 pin plug instead of plugging it into the car, then the internal wiring, etc is all set? Brilliant and simple.

Thanks,

another Bob

BoscoMN · 03-09-2021, 12:50 PM

I like to go overboard in the area of safety and equipment protection. I recommend that if you have a cable coming out of the battery box to your controller that you have it fused near the battery connection so that the entire wire is protected. That way if it was to short out onto the battery box, trailer frame or on the ground, this fuse would blow and protect the battery. In the same manner, an additional fuse near the solar panel controller would protect the controller. This dual fusing will protect both the battery as well as the controller (both are generators of high current). Just remember that if/when you or the kids or a racoon cut the wire, you should immediately remove the solar panel current from going to the controller when it is not connected to a battery.

I went with the Victron SmartSolar Charge Controllers MPPT 100/30 as it will accommodate the 87 VDC open circuit voltage that 4 panels in series produces.

1StreamDream · 03-09-2021, 04:46 PM

Quote:

Originally Posted by BoscoMN

I like to go overboard in the area of safety and equipment protection. I recommend that if you have a cable coming out of the battery box to your controller that you have it fused near the battery connection so that the entire wire is protected. That way if it was to short out onto the battery box, trailer frame or on the ground, this fuse would blow and protect the battery. In the same manner, an additional fuse near the solar panel controller would protect the controller. This dual fusing will protect both the battery as well as the controller (both are generators of high current). Just remember that if/when you or the kids or a racoon cut the wire, you should immediately remove the solar panel current from going to the controller when it is not connected to a battery.

I went with the Victron SmartSolar Charge Controllers MPPT 100/30 as it will accommodate the 87 VDC open circuit voltage that 4 panels in series produces.

Regarding the connectivity into the battery box, I did something simple very much along the lines of what BoscoMN is describing. Its a home-made contraption based around PVC box and a standard Zamp plug, wired directly into the battery box, and mounted with VHB tape to the outside of the battery box. One thing not mentioned here is you sometimes have to be careful about the polarity of the connections. The solar charging path is the inverse of the normal load draw path, and manufacturers have built this into the construction of the cabling. I say this because I also connect my TPMS booster to this same Zamp plug when I am towing, but I have to reverse the + and - cables (on the TPMS booster) to make it work properly via this Zamp plug.

Note that my portable solar panels already has its own integrated charge controller, part of the "suitcase" package, so I don't have a need to wire in additional gear, but it sounds like you might need to do so.

SilverWind · 03-09-2021, 05:04 PM

Quote:

Originally Posted by ROBERT CROSS

I charge thru the 7-pin with 2 Zamp 180w suitcase panels.👍

Bob
🇺🇸

We use this setup with a ZAMP 160 to charge an AGM battery on our 68 Caravel.

GammaDog · 03-09-2021, 07:08 PM

I added an Anderson Power SB 50 (https://powerwerx.com/anderson-sb-connectors-sb50-50amp) to the outside of my battery box and to each thing I want to plug in. I can snap in my solar controller, a spare battery, jumper cables, a cigarette lighter, etc.

super90ish · 03-11-2021, 04:54 AM

All,

Thanks so much for all the advice....good stuff. These panels used to be on top of my trailer but after having a full Victron/BattleBorn/Renogy suite installed with new panels up top (Many thanks AirstreamNutsandBolts) I had them converted to briefcases. It dawned on me that I live in a sailing town (Annapolis is affectionately called a drinking town with a sailing problem) so I found my local Victron dealer, sent him a picture of the panels and he sent me links to everything I needed to get up and running. The panels were wired in series per briefcase and then the briefcases were wired parallel together. They already had Renogy plugs on them so I ordered a new Victron charge controller, appropriate wiring, plugs and fuse block. The only thing I have yet to purchase are the clips to connect to the batteries....I'm thinking old school alligator clips....unless anyone thinks there is a better solution? Again, thanks so much for the advice....love this forum.

1StreamDream · 03-11-2021, 05:34 AM

Alligator clips can work but not really ideal, couple things to be careful about. 1) you need a very good electrical contact to maximize energy transfer back into the battery, so when you clip to the battery posts or cables be sure the contact points are clean (no grease/oil/corrosion). 2) if your batteries sit in the factory supplied metal box, you need to be very careful about closing the lid and creating a dead short against the positive alligator clip. Even if you choose to leave the lid open, if a gust of wind causes it to drop you could get that problem and it could result in expensive damage. 3) the alligator clips and the wire from the suitcase back to the batteries need to be sized to carry the MAX possible amps that your panels can produce. Your description of a combination series/parallel panel arrangement might complicate that calculation so be careful.

ROBERT CROSS · 03-11-2021, 06:47 AM

Quote:

Originally Posted by Bob Schrader

Bob, since all Bobs' are great minds thinking alike, assume you plug that into BC 7 pin plug instead of plugging it into the car, then the internal wiring, etc is all set? Brilliant and simple.

Thanks,

another Bob

Exactly...the Zamp panels can be set for lithium, agm or wet cell and have done a very good job for the last 3 Seasons.

Bob
🇺🇸

On a sunny New England afternoon....