Solar Install on Bobcat, Need Help.

Do you know if your solar panel has one or two wires from the roof? If it only has one wire, then the issue is mostly likely that the solar controller isn't working correctly as the ground path between the panel and the battery bypasses the solar controller. Many solar controllers switch the negative side to PWM and disconnect the battery from the panel when the battery is the full. If there is another ground path, then the controller cannot disconnect the panel from the battery and it will way over charge, leading to what you are seeing.

The other option is a bad charge controller - which one do you have and was it installed by ATC?

Either way, it sounds like ATC either owes you a new battery and rewiring your solar correctly, or a new charge controller and battery.
 
Thanks for your reply.
I believe there are two wires from the panel to the controller. On the roof the solar panel plugs into a two pin connector into the roof.
I have measured the voltage at this point and it is the same as going into the controller.
A pair of wires come out of the wall and into the controller which is a CMTP02 controller:
http://diyprojects.eu/wp-content/uploads/2015/05/CMTP02-user-manual.pdf

I have said to ATC, a good panel with a ten dollar controller.....go figure.

When I first noticed this problems, ATC sent me another controller.
I think the controller they sent me was defective so I took the truck down to them and they installed another controller.
It seemed ok at their shop but not under real 'solar conditions', as the truck was not in the sun.

As I mentioned now Im back to the same problem.

At night the voltage drops down to 12.7 (with the frig plugged in and using some lighting).

{I should have mentioned the system has a battery isolator between the truck battery and the camper battery . It seems to get warm so Im wondering if the battery is back feeding into the isolator when parked and no engine on. }

I think it is the controller causing the problem.

so to recap: voltage in full sun off the battery : 16-17 v
at night 12.7v

This is read with a voltage meter off the battery....

When I pulled the fuse on the solar to the battery, I still had battery reading on the controller . when I disconnected the ground from the controller to the battery the controller went blank.

could this be back feeding to the controller through the battery ground?

With the solar disconnected from the battery it shows the same voltage going in and coming out of the controller. about 16+ volts....in low sunlight.

No solar battery now reads 12.7 v





tnx
 
I overlooked that you said which charge controller you have. That is definitely a el cheapo unit, but if you are seeing the same issue with two different controllers, then it seems unlikely that it is directly the problem.

A quick search shows that this controller does switch the negative wire to disconnect the battery when full:
http://www.cashin.net/CMTP02/CMTP02_solar_controller_circuit.htm

So I would still suspect the issue is the wiring and that there is another path for the negative current to flow besides through the controller. One way to test this would be to disconnect the negative wire solar panel wire at the controller (leave the positive connected). If the battery voltage stays high, then the negative has another way to make it to the battery besides through the controller.

From the discussion above, this is at least used to be a known problem with ATC campers, and it seems like they will need to rewire the camper.

The power to run the controller comes from the battery, so if you disconnect the negative on the battery side, I would expect the controller to shutdown.
 
Rando:
I have disconnected the ground from the panel to the controller and the 'solar indicator light' on the controller has gone off, so I don't think that the ground wire is the problem. (but what do I know).

the controller is still hooked up to the battery and the voltage on the controller battery terminals read 12.7, the same as my other volt meter.

I am going to leave off the ground wire of the controller until the sun gets higher to see what happens.

You mention the controller and trying 2 different ones; could they have produced a bad batch of controller, where all are bad?

thanks again.
 
The light won't tell you the whole story, as it is probably just connected between the two solar inputs to the controller, one of which you disconnected. If there is another path you will see once the sun gets high - if the battery voltage goes up, then there is another path.

Given how crappy this controller appears to be, I guess they could have had a bad batch. If it were me, I would ditch that thing all together, ask ATC to buy you a new battery and go buy a high quality controller like the Victron MPPT 75/15.
 
Waiting for sun to rise.

ATC didn't supply my battery. Do you think it is toast?

seems ok w/ solar disconnected.

thanks
 
Didn't see any rise in voltage with the ground wire off the controller for most of the morning so I reconnected it

meter read 14.20 volts at solar and 13.94 v from controller to the battery. so reconnected the ground wire.

voltage read 13.6 v @ 10:40am

11;15am still read 13.6

at about 12:25pm , outside temp 90 F, voltage read 16.5 v....................


I pulled the fuse to save the battery.....

I think the controller is bad

?????
 
5outta6 said:
Didn't see any rise in voltage with the ground wire off the controller for most of the morning so I reconnected it

meter read 14.20 volts at solar and 13.94 v from controller to the battery. so reconnected the ground wire.

voltage read 13.6 v @ 10:40am

11;15am still read 13.6

at about 12:25pm , outside temp 90 F, voltage read 16.5 v....................


I pulled the fuse to save the battery.....

I think the controller is bad

?????
Click to expand...

Was the battery showing 13.94V before you reconnected the negative wire, or after you connected it? Is is not super clear from the description.
 
battery read 13.6 disconnected from the solar controller.


(I'm looking at my notes now so I'm pretty sure) these were the voltage reading with the ground wire disconnected from to the battery from the solar controller. These readings were taken at 10:40 AM

14.20 v solar from panel to controller

13.94 solar controller terminals to battery with ground wire disconnected

battery read 13.6 with ground wire from solar to battery disconnected.


At 12:15pm in 90F temp, voltage was 16.5 on the battery with the solar connected. so I pulled the fuse from controller to the battery...

Tnx.


{BTW: If I change the controller , I'm probably going with the Victron MPPT 75/15}
 
If the battery is reading 13.6V or 13.94V after is has sat overnight, then it is being charged. The resting voltage without being charged should be something like 12.6 -12.8V. Unless you have another charge source connected, it had to have been charged by the solar panel - even with the negative wire disconnected.

Given that, I am still not convinced that you don't have a wiring issue, in which case replacing the charge controller won't help. Another way to test this would be to disconnect both the positive and negative solar panel wires from the charge controller and measure the resistance between the negative wire and the negative terminal of the battery. It should be an open circuit.

It is also weird that you appear to be getting different measurements at the charge controller (13.94V) and battery (13.6V). These should be the same - so check your wiring between the charge controller and battery.
 
The camper battery is hooked up to the truck battery w/a Aopec isolator. installed by ATC:
http://www.aopec.cn/fac/en/htm-products/pro-show.asp?pro_id=17

I un hooked all cables to the battery: voltage was 12.71, 12.81

I disconnected the two leads to the solar controller and hooked up meter for resistance test between the ground wire from the solar panel to the battery and the reading fluxuated between 2-3.
(My meter manual say "the resistance is usually 1 to 0.2 ohms for a standard pair of test leads.)

these are the current readings with everything connected:

battery 13.44v
solar in : 20.81
to battery from controller: 13.17

now to see what happens when the sun gets up high and the outside temp rises....

Now after being in the sun for about an hour, 10:00AM
the solar in reads 13.95
controller to battery 13.85

battery 13.7


10:51Am..... 88F temp outside
On for about an hour here are the readings now

controller
solar 14.62
to battery 14.45

camper battery 14.6 v


thanks for your time.
 
The resistance test confirms that you have a wiring problem. There is a low resistance (<2 ohm) path between the negative terminal of your solar panel and the battery. This allows the current flow to bypass the charge controller (which regulates the power to the battery by disconnecting the negative wire between the solar panel and battery terminals, but it can't do that if there is another path for current to flow) so the charge controller cannot stop the flow of power to the battery once it is full.

I would pull the solar fuse until you get this fixed as you are further damaging your battery by repeatedly overcharging it.

I have also not heard of AOPEC battery isolators before, but it appears to be a Chinese clone of the Bluesea m-ACR:
https://www.bluesea.com/products/7601/m-Series__Automatic_Charging_Relay_-_12_24V_DC_65A
 
Just spoke with Marty at ATC. They are going to check all the wiring and install a Renogy controller.

I'm lucky I'm only a little over an hour drive (in no traffic) to their shop.


just for my imagination, I checked to see if the mounting screws on the controller were grounded and they were.

So I checked continuity between the solar ground wire and the mounting screws and there is continuity.

Isn't the controller solar wires a complete circuit and not grounded to the frame? Just fishing for ideas what could be the problem.....
 
The negative solar terminal on the solar controller shouldn't be connected to the controller case. However the battery negative is usually connected to the camper frame, and you already determined that the negative wire from the solar panel is connected to the negative battery terminal, so it makes sense that when the solar panel is connected, the negative terminal of the solar panel has continuity to the frame.

Good luck on getting it fixed. It sounds like ATC screwed up on this one. If it were me I would be asking about them replacing my two month old and now abused battery as well.
 
This solar panel has a designated ground wire that is not connected to the frame. The battery separator is not part of the solar system nor is it connected to the solar controller. We did not install the battery in this camper or do a lot of the wiring. We will figure this out when the camper comes in. Marty
 
Actually an ATC employee did install the battery I supplied.....As for the "lot of the wiring" , there are two pairs of wires, all fused which go from the battery terminals to two 12v 'ports' .
With these two pairs of wires disconnected, the solar controller is still not regulating the voltage to the battery......
 
Took the camper into ATC this morning.

They worked on it all morning. I think they did find a problem somewhere and ran a new wire.

They also installed a Renogy controller (its a Renogy solar panel) & a new battery.

So far so good.

I will monitor the voltage to see what happens.

Once again ATC is easy to deal with and there was no question about anything. Good to see a company back their warranty without question.

Thanks Marty
 
Thanks for reporting back, and I am glad they fixed it without too much hassle.

Any more specifics on what the issue was with the wiring? It may help for other ATC owners who have the same issue.
 
5outta6 said:
Took the camper into ATC this morning.

They worked on it all morning. I think they did find a problem somewhere and ran a new wire.

They also installed a Renogy controller (its a Renogy solar panel) & a new battery.

So far so good.

I will monitor the voltage to see what happens.

Once again ATC is easy to deal with and there was no question about anything. Good to see a company back their warranty without question.

Thanks Marty
Click to expand...
ATC is a fantastic company to work with.
 
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