Solar Install on Bobcat, Need Help.

[Rob in MT]

I have a Bobcat that I purchased new from ATC in 2011. I had them install the wiring for a future solar install, which consisted of a single copper wire. I had often wondered what I was going to do with the negative wire. I recently purchased a 100 watt panel and Wanderer controller from Renogy.

I'm still trying to figure how I can get it to work with the one ATC installed wire. I guess that's not true. If I connect the positive wire from the panel to the ATC copper wire on the roof, then attach this ATC wire to the controller, then attach the negative wire from the panel to the controller, it works fine.

However, what I want to do (as ATC has suggested and what has worked for them in the past), is not to connect the negative wire on the panel to anything, but rather run a copper wire from the negative port on the controller to a ground on the camper, leaving the positive as described above, and ground the panel to the roof. This has not worked for me.

I would really like to take the ATC approach, as I don't want to have to snake the negative wire from the panel on the roof to the controller inside the camper.

Renogy has said in need to run both wires from the panel to the controller to get it to work.

Any suggestions? Thanks.

 

[wildlife2019]

If I understand you correctly: You can ground the panel to the roof; but how is the roof continuity (continuous connection) made to the rest of the camper, which as you stated, the controller is to be grounded to?

 

[Rob in MT]

Wildlife, I really don't understand your question.

I grounded the panel to the tubular roof rack, which I thought I really didn't need to do as it, being metal, was already sitting (via the z brackets) on the roof rack. Regardless, I attached a wire to the panel to the roof rack.

Then I ran a wire from the controller to the window of the camper.

Are you saying because the roof is not part of the rest of the camper, that is an issue?

 

[Rob in MT]

Wildlife, thinking about what you said, I took the negative wire from the panel, the negative wire from the controller, and touched them both to the window, and it worked! So, in theory if I ground the panel to the camper (not the roof) it should work.

 

[Casa Escarlata Robles Too]

Rob I also have a Bobcat 09.
When we ordered it I had Marty also run a + wire for future solar.
When I got around to wire up my 2 panels ,a 45w and a 60w
both from Renogy with I think the same controller you are using.
I decided to use heavier gauge wire then supplied.
I think I used 10 gauge for both positive and negative.
The wires run from the panels through the right rear corner of the roof,
down the interior wall then outside the camper and back in near the right front
turnbuckle opening,to the controller in the battery box.
The panels are also secured to the roof rack.
This has worked well for me.

I diden't ground the panels to the camper just ran the negative wire direct from the panels to the controller.
Frank

 

[Alley-Kat]

There may be a negative wire behind the front lifting panel that connects the aluminium roof to the aluminium body frame of the camper. I believe that FWC's and ATC's are alike in this manner.

In this way ATC believes that you only need to have a positive wire from the solar panel to the solar controller AND then you can connect the negative wire from the solar controller to any part of the body frame of the camper, provided the negative wire from the solar panel is connected to the aluminium roof.

I found using the body frame of the camper as a negative connection to be problematic for me.
At the time I was using my Bobcat filled with electronic test equipment and the negative use of the body camper frame made too much background noise. While I'm not an electrical engineer I wonder if that perhaps some of the electrolysis that is evidenced by some camper owners is from using the body frame of the camper as a negative connection?

So, I was in the same boat as you, back when we both got our Bobcats, me in late 2010 and you in early 2011.

What I did was I ran a negative wire from the solar controller all the way up to the solar panel. Like Frank did, but a different route.

The route I used was up to the top of the body frame of the camper (above the battery compartment where my solar controller is located). Then along the side of the cab over-hang behind the thin wall panel to the back of the front lifting panel. I then made sure there was the same type of twist in the wire behind the front lifting panel as all the other wires there (lights, fan, etc.). I also did a little twist as the wire came out of the lifting panel (see photo below) and then punched a small hole in the roof liner to hide the wire inside the roof liner and fished that wire out of the roof to the solar panel.

Yes my roof liner material is different that what ATC uses. I liked this material better, so I gave them enough to do the job. It is very much like what FWC uses, and is flame resistant. If you want to do it this way get ATC to send you a small patch of the roof liner material in an envelope.

Otherwise, just re-read the 1st & 2nd paragraphs above.

 

[rando]

That is crazy that they only ran one wire to the roof for the solar panels, I am not sure what they were thinking.

There are several major issues with this - one as you found out the return current path from the roof to the camper frame is poor, or nonexistent in your case. The other issue is that some solar panels are positive ground which requires the charge controller to switch the negative lead from the solar panel. This means the solar controller can't disconnect the panel from the battery (as they bypass the controller through the camper frame) and you could cook your battery. Finally, the charge controller can't measure the current from the solar panel (which all MPPT controllers and some PWM controllers need to do) as they typically measure this on the negative leg of the circuit, which would bypass the controller in this configuration.

If at all possible, you definitely want to run two wires to your solar panel. Hopefully ATC isn't still doing things this way.

 

[Casa Escarlata Robles Too]

Like Alley-Kat the wires when they enter inside the camper have a BIG loop in them behind the rear lift panel.
So far works great.
Frank

 

[Vic Harder]

That is crazy that they only ran one wire to the roof for the solar panels, I am not sure what they were thinking.

There are several major issues with this - one as you found out the return current path from the roof to the camper frame is poor, or nonexistent in your case. The other issue is that some solar panels are positive ground which requires the charge controller to switch the negative lead from the solar panel. This means the solar controller can't disconnect the panel from the battery (as they bypass the controller through the camper frame) and you could cook your battery. Finally, the charge controller can't measure the current from the solar panel (which all MPPT controllers and some PWM controllers need to do) as they typically measure this on the negative leg of the circuit, which would bypass the controller in this configuration.

If at all possible, you definitely want to run two wires to your solar panel. Hopefully ATC isn't still doing things this way.

+1

 

[wildlife2019]

Are you saying because the roof is not part of the rest of the camper, that is an issue?

Yes, I should have prefaced my original comment by saying that I'm not a Fwc or ATC owner and do not know about there current or past practices with this matter. In fact I was reluctant to offer up any advice for just that reason. But I do know that sometimes time is limited, and being ready to work on a project makes the feedback an especially welcome treat.

Well, it seems that others have more for you to chew on. I look forward to reading your positive outcome.

Best of luck.

 

[Rob in MT]

Well, it does work using the wire installed by ATC and grounding the panel to the roof.

I was only grounding the panel, using the grounding hole on the panel itself. When I used the negative wire it works fine. I can ground to the roof rack. Run a wire from the controller negative slot for the panel to the front camper window.

I haven't done a final install because I'm deciding how to install it. It seems running the wires from the panel direct to the controller seems much more appropriate, while doing all that grounding seems kind of hokey. I'm sure there was a reason for doing it that way.

Thanks for your assistance, it helped immensely.

 

[rando]

Double check that the controller goes into float charge at the end of a cycle and measure the float voltage. This is where the issue with the ground bypass of the control will cause issues. During bulk charge a PWM controller is not actually doing anything, so you won't be able to tell if it is working properly.

 

[Rob in MT]

I finally got around to doing the tentative final install.

Rather than drill a hole in the roof, I though I would try the ATC one wire method, grounding the panel to the roof and the controller to the truck body, which according to the controller lights looks like it's working. The charging light only comes on when I run the ground from the controller to the body.

However, when I hook up the load wires to the battery (on top of or below the + and - from the controller), the isolator clicks on and off every 30 seconds or so. And the charging light goes on without running the ground from the controller to the body. That doesn't seem right.

Now that I have this all hooked up, I'd at least to try to see if it will work, any ideas?

Or just do the two wire method?

Thanks for your help.

 

[Casa Escarlata Robles Too]

I finally got around to doing the tentative final install.

Rather than drill a hole in the roof, I though I would try the ATC one wire method, grounding the panel to the roof and the controller to the truck body, which according to the controller lights looks like it's working. The charging light only comes on when I run the ground from the controller to the body.

However, when I hook up the load wires to the battery (on top of or below the + and - from the controller), the isolator clicks on and off every 30 seconds or so. And the charging light goes on without running the ground from the controller to the body. That doesn't seem right.

Now that I have this all hooked up, I'd at least to try to see if it will work, any ideas?

Or just do the two wire method?

Thanks for your help.

IMO I would use the two wire method.
But that's just me thinking it is better.
Drilling a hole in the roof isn't a big deal.
I used a 5/8 bit then a piece of plastic tubing.
Pushed the tubing through the hole sealed it with
a good quality sealant.
Run the wires through the tubing and seal them also.
So far after 8 years no leaks.
Frank

 

[Rob in MT]

I think you are right about two wires.

When poking through the ceiling, do you run the tubing through the ceiling fabric? How do you keep the ceiling fabric from tearing more over time? I was thinking of running clear super tape on either side of the hole. Just cut a hole in the fabric?

 

[jimjxsn]

I am also planning to do the through the roof wiring on my Panther as I did not order it with the solar wiring option...

Here is Ski's description on adding wiring through the roof and hiding it behind the front lift panel.

As far as reinforcing the headliner, I used clear Tear-Aid repair tape to mend my old FWC headliner. It seemed to work fine and may be an option to reinforce the fabric hole.

 

[5outta6]

What size battery, type and brand battery are you running with your solar system?

 

[Vic Harder]

What size battery, type and brand battery are you running with your solar system?

It really varies. Most folks are running with AGM 12v batteries in the 80-120AH range. Some have LiFePo batteries, some have flooded leaded acid types (those need to be vented for sure!) I run dual 6v AGM 250AH Rolls brand batteries.

 

[Kodachrome]

However, when I hook up the load wires to the battery (on top of or below the + and - from the controller), the isolator clicks on and off every 30 seconds or so.

And all this time I thought I had a wonky isolator.

Since my Bobcat is in "Drydock" for the next couple months I will investigate this and make sure my roof wiring is right. I have no issues drilling holes, my cell booster antenna required it.

 

[5outta6]

I have a solar question: I have an ATC installed 160w solar panel. My voltage out of the battery is in the 15-17 v range when not under draw.

I have run my ARB frig for 3 days and the voltage meter reads 16.1 volts.....way high for a 12v AGM battery, I think.

input to the controller is 15.39 v and the output is 15.38 v...

these are the specs from the CMTP02 controller manual....

Is this output within the safe range.
equalization 14.8
bulk 14.8
acceptance 14.2 pwm
flotat 13.8
charge reconnect 13.0
discharge stop 11.2
discharge reconnect 12.6

This is the second controller and I'm haviing similar problems.

I have checked the voltage on the controller w/ 2 different meters which have given me the same voltage reading.

I don't want to 'cook' my battery ......

is my voltage off the battery high?

any ideas?

(note: I have read the solar page info and just get more confused....)