Uncontrolled solar panels?

Submitted: Tuesday, Apr 30, 2013 at 11:08

ThreadID: 101938 Views:5259 Replies:3 FollowUps:7

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VistaMax

Hi All, or those with knowledge of solar panels and chargers

We have a VistaRV with a fixed 85 watt panel going through a CTek DC/DC charger. When we need more charge, is it advisable to also run a portable uncontrolled 80watt panel through the CTek charger. We have been told that if we run the controlled portable panel through the CTek, there will be no additional charge to the two x 110 amp batteries.
The manufacturer told us to use an uncontrolled panel through the inlet he provided, but a specialist 12 volt expert told us CTek are over rated and connect the controlled panel directly to the batteries.
Who do we believe?
Thanks
Max

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Reply By: Member - John and Val - Tuesday, Apr 30, 2013 at 11:45

Tuesday, Apr 30, 2013 at 11:45

Hi Max,

Unless there is a controller on the portable panel, it should NOT be connected directly to the battery, as it can overcharge and damage the battery.

I assume that the Ctek dc-dc charger is used to manage charging from the vehicle, and also has a provision to accept the fixed solar input. In this case it is probably a Ctek D250S, which is a very suitable choice. In this case the portable panel should be connected, together with the fixed panel, to the charger's solar input. Please confirm the model number so we can make suggestions with more confidence

I also assume that in your last few words you actually meant "uncontrolled" rather than "connect the controlled panel directly to the battery."

Think I'd be looking for a different "specialist 12 volt expert".

Cheers

John

J and V
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- Albert Einstein

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AnswerID: 510037

Follow Up By: Member - John and Val - Tuesday, Apr 30, 2013 at 12:03

Tuesday, Apr 30, 2013 at 12:03

On reading and re-reading your post I'm getting more confused! It comes down to this:

On the assumption that your solar controller is a D250S:

If you have a portable panel with it's own controller either 1) you should bypass that controller and feed the uncontrolled solar feeds from both fixed and portable panels into the solar input of the D250S, OR 2) if you must use the controller on the portable panel, connect that panel directly to the battery. You do not want the output of one controller feeding into the input of the other one

If your portable panel does not have an attached controller, follow 1) above.

There are other considerations, but a lot depends on just what controller you actually have.

Cheers

John

J and V
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FollowupID: 788075

Follow Up By: VistaMax - Tuesday, Apr 30, 2013 at 13:32

Tuesday, Apr 30, 2013 at 13:32

Thanks John and Val

we do have the controller you mention. D250S DUAL and 12 volt management system SMARTPASS.

Our current portable is controlled, which we must have when charging the auxiliary in the Troopy, but according to the manufacturer, should not be used with the CTek while it is controlled.

We thought we could change the portable panel to uncontrolled, and have an extension made to include a controller closer to the battery we are charging in the car. The "expert" did not agree with that. The way I read your reply, you agree with the manufacturer re charging the batteries in the camper.

I hope I have described the situation better this time.

Max

FollowupID: 788080

Follow Up By: Member - John and Val - Tuesday, Apr 30, 2013 at 14:22

Tuesday, Apr 30, 2013 at 14:22

Hi Max,

My confusion arose more from my own preconceptions, rather than your description!

I'd suggest that you try to establish a connection to a point between the panel and its onboard controller (i.e. the panel output = controller input). If that can be done you could take a feed from there to the solar input of the D250S, leaving the onboard controller (physically) in place. I think this is what the manufacturer is recommending. To charge the battery in the car, you could simply connect it to the output side of the onboard controller. Better still if you can move that controller closer to the in-vehicle battery as you propose. Then the raw panel output could be fed to the input of either the in-vehicle controller or the D250S.

Cheers

John

J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
- Albert Einstein

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FollowupID: 788083

Follow Up By: VistaMax - Tuesday, Apr 30, 2013 at 14:41

Tuesday, Apr 30, 2013 at 14:41

Thanks very much John. We now feel more confident of achieving what we want from the panel.

FollowupID: 788085

Reply By: Member - Phil G (SA) - Tuesday, Apr 30, 2013 at 15:08

Tuesday, Apr 30, 2013 at 15:08

Max,
I run a very similar setup - I have a Tvan with 65W roof panel hooked up to a D250S feeding a 130Ah AGM and I have a 120W folding portable panel as an extra.

Like you're suggesting, I sometimes use my extra folding panel unregulated - bypass the panel's regulator and hook directly to the battery - I measure a couple more amps going into the battery when I do that. BUT I only use the panel unregulated when the battery being charged is relatively flat and at zero risk of being overcharged by the panel.

I also keep an eye on the battery voltage - if the voltage at the battery terminals has risen to greater than 13.7V, then I slip the regulator back into the circuit.

AnswerID: 510043

Follow Up By: VistaMax - Tuesday, Apr 30, 2013 at 15:18

Tuesday, Apr 30, 2013 at 15:18

Thanks again Phil. In 2011, you helped us plan our Anne Beadell trip. All went well, and we hope to do it again next year, but from Coober Pedy this time. This year, it is the Binns and a bit of the Savannah.

Now, how did/do you bypass the panel's regulator? We never use the folding panel unless we are present and planned to watch its performance as you mentioned.

Cheers

Max and Val

FollowupID: 788087

Follow Up By: Member - Phil G (SA) - Wednesday, May 01, 2013 at 15:41

Wednesday, May 01, 2013 at 15:41

Gday Max,
Yeah I remember - glad it all went well! Can't help you with Binns except I've done the Old Andado section a few times - great drive - just be careful of some of the bulldust.

I bypass the regulator using a couple of small inline connectors called Deans plugs. There are many alternatives you could also use but here are some photos:

Using the regulator

Bypassing the regulator

Deans plugs used for R/C cars

Deans plugs can be bought from good hobby shops or on line at Modelflight:
Modelflight website

FollowupID: 788182

Follow Up By: VistaMax - Wednesday, May 01, 2013 at 15:59

Wednesday, May 01, 2013 at 15:59

Thanks Phil. We can see what you have done. However on our panel, the single controller is attached to one of the black boxes on the back of the panels. We don't mind going to the Home of 12 Volt now that we know the concept will work.
Max

FollowupID: 788185