Adding More Solar than 160 Watts

[John David]

Originally Posted by Brian B-P

Two panels directly connected together (such as to the same controller's input) will not "fight" each other - one won't confuse the other one - because they have no intelligence or logic.

Sorry, I didn't make myself clear. The case I was trying to describe was one panel thru one controller to the battery (controller set at 14.6 V)and a second, portable panel through another controller to the battery (controller fixed at 14.4 V). If both get sun the second one will not charge the battery as I understand it.

[John David]

I think I should have said two controllers fighting each other.

[padlin]

I believe Jon V ran into problems trying to use 2 controllers as you mention, if he sees this thread he might drop a note on it.

[Brian B-P]

Originally Posted by John David

The case I was trying to describe was one panel thru one controller to the battery (controller set at 14.6 V)and a second, portable panel through another controller to the battery (controller fixed at 14.4 V). If both get sun the second one will not charge the battery as I understand it.

I agree - this is two controllers, and they can have this compatibility problem. Two panels to the same controller is a different case, and it looked like there was a question about that, too, but no problem as long as the bases are covered.

[fudge_brownie]

Several comments on what has been said so far. I would use the heaviest gauge possible but some limitations come into play. First, follow what Eric is saying and use an external outlet/inlet with 8 gauge inside the trailer to the solar controller. This, like all solar runs should be kept as short as possible. For the outside cable it would be ideal to use 10 gauge, the difficulty is finding this in a two conductor. The second issue is weight, that is the reason why it is best to find two conductor, a length of 10 gauge wire, you would need at least 25 feet, is going to be real heavy and take up a lot of space and be a pain to handle. You might find something in the irrigation industry.

A better solution might be to use 12 gauge, however purchase a pair of 12 gauge extension cords at 25 ft. each. If the sunny spot only needs one cord you cut back on line loss. If you need a second cord you can easily plug a second one in and extend to 50' I find 25' is often not enough. The extension cords double up for those campsites when the power pole is a bit too far.

On your portable solar panel remove the solar controller that comes attached and immediately place it in a trash receptacle. It is worthless, both for its quality and for its location on the panel. In place add a extension cord replacement end, like you might use to repair a cord in your shop, Now you can plug your extension cord directly into the panel.

[skiman]

Originally Posted by fudge_brownie

Several comments on what has been said so far. I would use the heaviest gauge possible but some limitations come into play. First, follow what Eric is saying and use an external outlet/inlet with 8 gauge inside the trailer to the solar controller. This, like all solar runs should be kept as short as possible. For the outside cable it would be ideal to use 10 gauge, the difficulty is finding this in a two conductor. The second issue is weight, that is the reason why it is best to find two conductor, a length of 10 gauge wire, you would need at least 25 feet, is going to be real heavy and take up a lot of space and be a pain to handle. You might find something in the irrigation industry.

A better solution might be to use 12 gauge, however purchase a pair of 12 gauge extension cords at 25 ft. each. If the sunny spot only needs one cord you cut back on line loss. If you need a second cord you can easily plug a second one in and extend to 50' I find 25' is often not enough. The extension cords double up for those campsites when the power pole is a bit too far.

On your portable solar panel remove the solar controller that comes attached and immediately place it in a trash receptacle. It is worthless, both for its quality and for its location on the panel. In place add a extension cord replacement end, like you might use to repair a cord in your shop, Now you can plug your extension cord directly into the panel.

I bought 50' of red/black 10 gage speaker wire off eBay for outside wire. I believe Jon V used low voltage landscape lighting wire which is readily available at the home improvement stores. I think that is 10 gage as well.

[thoer]

I've measure the voltage loss with a 25' 12 gauge extension cord hooked directly to my panel as Paul mentions. I don't remember exactly what the loss was (yes I know it can be calculated also) - it was minimal enough (for me) since I use it on the INPUT side of the controller. My understanding - from some excellent posts Paul has made regarding this - is that the connections between the controller and the battery are much more in need of heavy gauge wire and as short as possible.

[Brian B-P]

Another source of two-conductor cable is auto/industrial suppliers (I use Gregg Distributors for this sort of stuff here, but every area should have their equivalent), who sell jacketed cable (such as Grote brake cable) for truckers... but I think it's most common in 14 gauge and I've only seen up to 10 gauge.

Addition on edit:
I see that there is 8 gauge cable of this type - also sold for trailers - under the "Deka" brand name (other gauges from various suppliers but 8 gauge from RedTrailers.com)

[alanmalk]

Originally Posted by John David

The case I was trying to describe was one panel thru one controller to the battery (controller set at 14.6 V)and a second, portable panel through another controller to the battery (controller fixed at 14.4 V). If both get sun the second one will not charge the battery as I understand it.

Actually, the statement "If both get sun, the second one will not charge the battery" is incorrect.

The voltages quoted above, 14.6 and 14.4 are maximum, or final voltages.
Until the batteries have reached a nominal "full" state, they will pull down the actual output voltages of both controllers. This is because the load that a pair of 6v deep cycle batteries presents to the controllers and solar panels is greater than the controllers can provide. As an example, while cranking the starter motor of your car the battery can only provide about 11 volts.

Picking some numbers from thin air: Batteries at 50% discharge will have a terminal voltage early in the morning (weak charging) of around 13 volts. As the day progresses, the % discharge decreases and the terminal voltage rises. Until the terminal voltage rises to 14.4, both controllers and panels are providing as much charge as they can, relative to the size of the panel and the sunlight hitting it. Or to say it another way, you are getting the charge that you paid for.

Now after some hours at the end of a sunny day, the batteries are close to full and the terminal voltage rises above 14.4. At that point the lower voltage controller tapers down to no contribution. But you don't need it - nearly full batteries won't accept the high current that discharged batteries do.

It is whole combination of panel-charger-battery that need to be considered.

But all that said, I can't think of any reason to spend extra money on two controllers, assuming that one can handle the input/output current from two panels.

--
Alan

[alanmalk]

Originally Posted by thoer

I've measure the voltage loss with a 25' 12 gauge extension cord hooked directly to my panel as Paul mentions. ...

Thicker ( $$$) wire is always good. But there is a time and place for a smaller wire.
I am using 30 feet of 8 g wire from the portable panel to the trailer. For the last 2 feet (under the seat) I change to 12 g. The reason was so I could insert two wires into the screw connector on the controller input. (It is not big enough to accept 2 "full size" wires.) There will be a price to pay in terms of voltage drop - maybe around an additional 10 milli-volts. Absolutely trivial voltage loss, and the amperage from the 150 watt solar panel is well below the recommended limit for 12 g wire. (25 amps per 2002 National Electrical Code.)

Bottom line - the longer the wire, the more important the gauge, but there is a reasonable time and place for smaller wires.

--
Alan

[John David]

Thanks to all. I'll be running both the fixed rooftop panel and the portable panel thru the main controller. If the suitcase portable has a controller I'll remove it and replace with a male 110 plug,then extension cord(s) to an ETI installed plug and run to the controller.

John

[thoer]

John - have you talked to Reace about installing the receptacle on the trailer and wiring to go into the controller?

[skiman]

Originally Posted by John David

Thanks to all. I'll be running both the fixed rooftop panel and the portable panel thru the main controller. If the suitcase portable has a controller I'll remove it and replace with a male 110 plug,then extension cord(s) to an ETI installed plug and run to the controller.

John

It would be best to use something besides a 110 volt plug. Too much risk of someone plugging in real 110 volt power accidently. There are special purpose low voltage connectors out there. I used an SAE connector like my little panel came with. Murphy is alive and well.

[Jim Bennett]

What is a good waterproof DC power inlet? Most of the ones I see are meant as outlets. I would not want the end of the cord from the portable solar panels to be exposed like on devices that plug in.

[thoer]

Originally Posted by Jim Bennett

What is a good waterproof DC power inlet? Most of the ones I see are meant as outlets. I would not want the end of the cord from the portable solar panels to be exposed like on devices that plug in.

Jim this is the best one I have so far located: MinnKota 12V

It takes up to 8 gauge wire or even 6 on the plug side with an adapter.

I sent that link to Reace to see if he will install it for me when the time comes - haven't heard back yet.

[John David]

An Anderson plug connection would work well. 15$ -- Rated 50 A and accepts up to AWG 6 wire. here's a link.
The 12 Volt Shop Htmls/webcat2003/plugs2.html


I have talked to ETI about them doing the wire run from main on-board controller to outside of trailer. I feel its important to get ETI to do all wiring inside the trailer and FRP shell drillings during fab as these tasks done afterwards are problematic.
We may go with a typical power cord outlet interface. The same kind that ETI uses for the cord to connect to RV sites. The Anderson plug would be loose inside the cavity. Just flip up the cover, reach in an pull out the Anderson and connect, then close the cover with a small horseshoe hole for the #6 cable.

[thoer]

John are you confident in the Anderson connection being good for repeated connection/disconnection cycles?

[Jim Bennett]

Originally Posted by thoer

Jim this is the best one I have so far located: MinnKota 12V

It takes up to 8 gauge wire or even 6 on the plug side with an adapter.

I sent that link to Reace to see if he will install it for me when the time comes - haven't heard back yet.

As this is an outlet, and not an inlet, I worry about the exposed hot contacts from the panels. I would prefer an inlet fitting, where the male contacts are housed inside the trailer side connector, and the cable end has the female contacts.

I know it is not a huge deal with it being just 12V, just something I was hoping to avoid.

[Jim Bennett]

Originally Posted by John David

An Anderson plug connection would work well. 15$ -- Rated 50 A and accepts up to AWG 6 wire. here's a link.
The 12 Volt Shop Htmls/webcat2003/plugs2.html


I have talked to ETI about them doing the wire run from main on-board controller to outside of trailer. I feel its important to get ETI to do all wiring inside the trailer and FRP shell drillings during fab as these tasks done afterwards are problematic.
We may go with a typical power cord outlet interface. The same kind that ETI uses for the cord to connect to RV sites. The Anderson plug would be loose inside the cavity. Just flip up the cover, reach in an pull out the Anderson and connect, then close the cover with a small horseshoe hole for the #6 cable.

Using a covered hatch with a loose cord end is a workable option. I would much prefer something you just plug into though.

Let the search continue.

[John David]

Yes, these are used widely on portable power boxes with removable cables for starting cars. They connect the box to your cable clamps. BTW you can get them for AWG#8 to 4 if desired. Using the std ETI flap cover for RV park power connection I would probably make the Anderson plug connection and shove the plug inside the trailer . That way t he connection is not exposed to the elements. ETI says installing the connection on the trailer shell is a $35 option. They install the cover thru the shell at my specified location, run the wires from the main controller and cap them inside the trailer at the cover. I add the Anderson connection at my leisure. Using the std ETI cover also gives me another access port into the trailer which is nice.
The Minnkota plug looks good too and provides a smaller footprint but is limited on wire size. I'm also a little worried that it will look like a 110 V connector and may be mis-used. With the Anderson there is no chance that a 110 could be connected.
John