Possible to re-wire the Zamp rooftop combiner?

[Kalashnikov]

Anyone know if it's possible to disassemble the factory Zamp rooftop combiner box? (3 port)


I'd like to wire the 'bare' connector to Negative and the 'shrouded' connector to Positive. (This is the way it's meant to be, no idea why Zamp decided to switch it...)

[Gsmblue]

Sae 80 connector has the negative side with the shroud. Zamp changed it to shroud the positive,

[AirMiles]

Not quite sure what is being asked here. The positive on the SAE connector that is plugged into the Zamp rooftop port is shrouded and the negative is bare when you use the yellow prewire as positive and the green prewire as negative (Like Airstream does). If you want to switch the Zamp rooftop positive/negative around, you could just switch the SAE connector like you want and switch the green and yellow prewire going into your controller. Just keep all positives going to positive and all negatives going to negative.

I put the positive lead from my solar panel into the shrouded side of an SAE connector, plugged the SAE connector into the Zamp rooftop box port, and then used the yellow prewire as the positive into my solar controller - copying how Airstream connects the prewire with the factory solar option. See this post for a complete description: https://www.airforums.com/forums/f44...ml#post2331527

[Kalashnikov]

Ok thanks all!


Per my understanding:
- On the Zamp combiner on AS roof, the Positive is male and Negative is female (but not visible since both shrouded)
- On the panel side, Positive is female, Negative is male


I bought this from Amazon, expect to simply connect the panel Positive to red


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[AirMiles]

Originally Posted by Kalashnikov

Ok thanks all!


Per my understanding:
- On the Zamp combiner on AS roof, the Positive is male and Negative is female (but not visible since both shrouded)
- On the panel side, Positive is female, Negative is male


I bought this from Amazon, expect to simply connect the panel Positive to red


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

OK, this helps explain your question. On the pictured SAE connector, I connected the positive output from the solar panel to the red lead and connected the yellow prewire to positive on my solar controller. If the MC4 connectors on your solar panels are reversed, then I believe you could just reverse the yellow and green prewires going into your solar controller. Just make sure the positive wires all align from the panel to the positive solar controller input. You can test which is positive with a multi-meter.

[Kalashnikov]

Ugh, it gets worse.

Panels:
Positive = Male MC4
Negative = Fem MC4

Y Connectors:
Positive = Male MC4
Negative = Fem MC4


I was hoping to 'direct connect' the panels to the Y, then from there directly to the combiner.

Diagram legend:
- Black lines are intended connections
- Black dots are places where I anticipated needing new MC4 connectors
- Circles are places where I thought I could direct connect...
- Pencil 'M' and 'F' are how the plugs would actually look unless I start swapping things around

[JMynes]

Originally Posted by Kalashnikov

Anyone know if it's possible to disassemble the factory Zamp rooftop combiner box? (3 port)


I'd like to wire the 'bare' connector to Negative and the 'shrouded' connector to Positive. (This is the way it's meant to be, no idea why Zamp decided to switch it...)

Don’t open the combiner box. Figure out your rooftop panel connections. It looks like you’re planning 3 series pairs of panels in parallel. Just be sure positive and negative are consistent for all three, and plug them in.

Now go to your yellow and green wires which (hopefully) are not yet connected to the solar controller. Check for voltage between green and yellow. If the reading is a negative number, swap the multimeter leads. Now the voltage reading should be a positive number. The red multimeter lead (assuming it’s plugged into the multimeter correctly) is touching the solar panel positive lead, and the black multimeter lead is on the negative. Attach those leads to the correct input terminals on the solar controller and that part is finished.

[Kalashnikov]

The current thinking:
- Won't swap the panel wires since there would be 6x2=12 to swap. Additionally they are crimped within the panel box, not very simple to undo.
- Can't use the little gender changer that came with the Y, not enough room (skylight in AS is very close to Zamp combiner)
- Likely will purchase some crimp-on splices at HD and just swap the connectors on the Y (ie. the MC4 ends)

[daleyocum]

Originally Posted by Kalashnikov

The current thinking:
- Won't swap the panel wires since there would be 6x2=12 to swap. Additionally they are crimped within the panel box, not very simple to undo.
- Can't use the little gender changer that came with the Y, not enough room (skylight in AS is very close to Zamp combiner)
- Likely will purchase some crimp-on splices at HD and just swap the connectors on the Y (ie. the MC4 ends)

What Airmiles is saying is just change what the convention combiner box on the roof is using for what’s positive and negative from what Zamp used and what is the convention. You’d leave your solar panels alone. Leave the combiner box alone. Then down side the trailer switch the OTHER end of the wires going into the solar controller. Yellow would now go to negative and green to positive.

The controller, and those yellow/green wires, are the near the rats nest of low voltage wiring near the front of the trailer, usually the curb side, under a bed or bench.

[AirMiles]

I just cut off all MC4 connectors and spliced all my connections with waterproof butt connectors covered with heat shrink based on AmSolar's recommendation.

[Kalashnikov]

Originally Posted by daleyocum

What Airmiles is saying is just change what the convention combiner box on the roof is using for what’s positive and negative from what Zamp used and what is the convention. You’d leave your solar panels alone. Leave the combiner box alone. Then down side the trailer switch the OTHER end of the wires going into the solar controller. Yellow would now go to negative and green to positive.

The controller, and those yellow/green wires, are the near the rats nest of low voltage wiring near the front of the trailer, usually the curb side, under a bed or bench.

The Zamp combiner is no longer my biggest issue, it's that the connectors on the roof are not compatible.

Originally Posted by AirMiles

I just cut off all MC4 connectors and spliced all my connections with waterproof butt connectors covered with heat shrink based on AmSolar's recommendation.

Yeah I remember you saying that in another thread. But - I want to keep the system removable if possible, hence not planning on widespread use of splices.


Somewhat funny, there is endless gnashing of teeth over wire lengths & sizes, but all these splices & connectors are likely a greater source of loss!

[daleyocum]

That’s another fine option for others, to just splice on SAE pigtale wires with the polarity you want.

The cost of the solar panels and controller is probably something you’d pretty much get back when you sell the trailer if that’s your concern.

[Kalashnikov]

Ok so I wired my entire solar system using the Zamp combiner and AS prewire. The Victron will not start up although I see 40v across the prewire ends. Zero voltage potential across the MPPT PV inputs when connected.



If I bypass the combiner entirely (direct panel to controller) then the unit starts charging.


Anyone take the Zamp box apart? It's covered in goo/glue, even the screws. Are there screws that go into the roof?


Thanks

[Kalashnikov]

And what's all this clear crap inside the ports of the combiner? It's filled with gel. If that's conductive, I could totally see it shorting out something as well.

[ROBERT CROSS]

Dielectric grease..., I use it on all outdoor connections.👍

Bob
🇺🇸

[Kalashnikov]

Gathered the courage to pull it off. Here it is after the putty and screws are removed.










UN-fortunately.... we don't see the yellow/green PV prewire here! Dammit! Don't know what I'll do next. Go inside the camper I suppose, try to figure out where the yellow/green wires start. This is turning out to be a huge PITA.

[daleyocum]

That’s sure unexpected! I think all of us assumed the Yellow/Green wires would be found in there.

Since you see the 40v on the yellow green wires inside until they are under load (connected to the MPPT controller) that leaves me to guess that somewhere there’s a poor connection (high resistance) in that wire run down from the combiner box.

You could verify that by unplugging the solar panels on the roof, connecting the yellow and green wires together inside the trailer, and measuring the resistance between the two SAE pins on the roof. It should be essentially zero ohms. If it’s not there’s a bad splice somewhere, probably where those red/black wires splice to the yellow green. I have no idea where that is.

[ROBERT CROSS]

[QUOTE=daleyocum;2341406]That’s sure unexpected!

Not really....The "factory pre-wire" is really VERY pre, it ends in the reefer house. It's up to the installer to do the difficult wire snaking.🥴
I think they must have ignored their own wiring and just made a new run.🤓

Bob
🇺🇸

[daleyocum]

[QUOTE=ROBERT CROSS;2341418]

Originally Posted by daleyocum

That’s sure unexpected!

Not really....The "factory pre-wire" is really VERY pre, it ends in the reefer house. It's up to the installer to do the difficult wire snaking.🥴
I think they must have ignored their own wiring and just made a new run.🤓

Bob
🇺🇸

I can understand why the yellow/green wires terminate in some different places but why don't they go up to the combiner on the roof?

[Kalashnikov]

[QUOTE=daleyocum;2341726]

Originally Posted by ROBERT CROSS

I can understand why the yellow/green wires terminate in some different places but why don't they go up to the combiner on the roof?

So they actually do. I pulled hard on the combiner and the yellow/green wires followed. But no breaker.