Solar charge controller: external vs trailer mod?

[mwolf]

Hi all!

I have a 2018 Casita Liberty Deluxe, which has an external Zamp solar plug. My understanding is that I need a solar charge controller to use a solar panel, and I'm planning to buy a separate controller and a panel, rather than an "all in one" solar suitcase. For the moment, I'm not intending to modify the Casita, and I'll just plug into the external solar plug. But I'm wondering what the pros/cons might be of installing a charge controller "hardwired" into the trailer's electrical system, and whether the possibility of a future permanent solar charge controller install should affect the choice of charge controller I pick now.

If it matters, I have the stock Parallax Power 7100 series converter the Casita came with, and then I've also installed a Victron BMV-712 battery monitor. The prior choice of the Victron battery monitor is causing me to lean towards a Victron solar charge controller as well.

Thanks in advance for any opinions,

-Michael

[Gerry]

There must be a controler in the system already otherwise you would cook your battery. I have a 100W Zamp movable panel and the Zamp controler in my Casita and it works very good. We were in the woods of Maine for 2 weeks and had enough power for lights (LED) Max fan, heat, and water pump for showers and dishes and older wet cell battery never got lower then 12.7 V.
I really only had full sun for 3 hours a day and the rest of the time it was sun though the trees and the one day it did rain we took it easy on the power usage and didn't have a problem/

[EllPea in CA]

Well, I will follow along with this thread.

[John in Santa Cruz]

So is that Zamp connector wired to the battery? if you stick a DC volt meter into it, do you read your batteries current voltage?

if yes, then you have two chioces.


1) disconnect it from the battery, wire the zamp to the PV input on a solar charge controller, and wire the output of the solar charge controller to the battery, then plug a naked solar panel into the outside of the zamp

or

2) get a solar panel with an integrated charge controller that you can plug into the zamp.

[mwolf]

Originally Posted by Gerry

There must be a controler in the system already otherwise you would cook your battery. I have a 100W Zamp movable panel and the Zamp controler in my Casita and it works very good. We were in the woods of Maine for 2 weeks and had enough power for lights (LED) Max fan, heat, and water pump for showers and dishes and older wet cell battery never got lower then 12.7 V.
I really only had full sun for 3 hours a day and the rest of the time it was sun though the trees and the one day it did rain we took it easy on the power usage and didn't have a problem/

My understanding was that the Zamp (SAE?) plug on the Casita is directly wired to the battery, as Casita sells Zamp "suitcase" panels that have a charge controller built into the suitcase. But if your Casita has a Zamp charge controller already built in, then perhaps mine does as well. I was already planning to try and trace the interior wiring, and now that seems especially needed.

[mwolf]

Originally Posted by John in Santa Cruz

So is that Zamp connector wired to the battery? if you stick a DC volt meter into it, do you read your batteries current voltage?

if yes, then you have two chioces.


1) disconnect it from the battery, wire the zamp to the PV input on a solar charge controller, and wire the output of the solar charge controller to the battery, then plug a naked solar panel into the outside of the zamp

or

2) get a solar panel with an integrated charge controller that you can plug into the zamp.

Yup, that matches my understanding as well. My question is really about what the pros and cons might be of "external" vs "built-in" charge controllers. And I'm also curious if people think the desirable features of a charge controller are different if it's intended to be permanently installed, instead of an external solar charge controller that's unplugged when the solar panel isn't being used.

I can think of two potential differences:

1) An external charge controller would hopefully have a better IP rating to resist water, as it has more chance of being exposed to the elements.
2) An internal charge controller might benefit from being part of an integrated family of devices. For example, I believe Victron charge controllers could get battery temperature data from my Victron battery monitor.

But I suspect there might be other considerations I haven't thought of.

-Michael

[Gerry]

I am no expert on Solar but I remember when I first got my Zamp system, I set up my panel, that doesn't have the controler built in such as a suit case system with a built in one, in the sun and tested the lead wires out of the panel and got a reading of 23 volts.
As said above, this would have cooked the battery dry.
after installing the controler in camper and testing the 2 heavy wires going to the battery, i got a reading of 14.2V
As said, I am no expert but have read in many posts the the voltage drop in small wire from panel to battery may be a factor also may be a factor.
My Zamp install instructions said that the wire from the Controler to the battery should be #8 stranded or larger.
Advantage of my controler is also will go from charge to maintain all on its own and it is all inside my Casita hanging on the wall, out of the weather, and with a tap of a button I can see just what is going on.

[mwolf]

Originally Posted by Gerry

I am no expert on Solar but I remember when I first got my Zamp system, I set up my panel, that doesn't have the controler built in such as a suit case system with a built in one, in the sun and tested the lead wires out of the panel and got a reading of 23 volts.
As said above, this would have cooked the battery dry.
after installing the controler in camper and testing the 2 heavy wires going to the battery, i got a reading of 14.2V
As said, I am no expert but have read in many posts the the voltage drop in small wire from panel to battery may be a factor also may be a factor.
My Zamp install instructions said that the wire from the Controler to the battery should be #8 stranded or larger.
Advantage of my controler is also will go from charge to maintain all on its own and it is all inside my Casita hanging on the wall, out of the weather, and with a tap of a button I can see just what is going on.

I haven't tested my Casita yet, but I understand that the Casita Zamp plugs have reversed polarity, because Zamp solar suitcases have reversed the polarity of the SAE connector. Did you find that to be the case when you installed your charge controller?

[Gerry]

as said I am no expert and i really never tested the polarity ,,, I just hooked it up as instructed from paperwork ... LOL unlike most people I do read the instructions when it is something new to me ,,, LOL
This may be true and maybe the controler takes care of this reversal but controler has came with color coded (one black and one Black with red line), wire with the plug end to be mounted to side of trailer and then a + and - terminal to go out to Battery.
Easy-Peasy

[John in Santa Cruz]

the problem with the SAE connector that Zamp uses, it was intended for use from a power source to a load. On power source side, the plus pin is internal and the ground pin is external, while on the load side its reversed. When you have a charger like a solar panel and a battery, BOTH sides are hot, so on one side, a live positive pin would be exposed.