Connecting Solar to two 12 volt batteries

DownTheAvenue wrote:
With two leads (one positive and one negative) coming off the controller, can I just hook one lead to one battery on the appropriate post, and the other lead on the other appropriate battery post?

Yes, but... A proper "balanced wiring" is when one lead goes to + on one battery, and another lead to (-) on ANOTHER battery. The loads should also be wired to +/- of two different batteries.

On a perfect day with no clouds and no shade 100W suitcase will harvest just enough for a die-hard minimalist to bring battery back to 99.9% in the evening. 200W flat on the roof would harvest more, in the same sun conditions.

Tilt doesn't matter (much) in summer and in the South where you are. Following the sun... Averagely lazy user changes the azimuth 2 times a day or less, this won't make much difference.

Saving money on $6 tube of sealant (with suitcase) - let's not go there... Solar suitcases cost over $2 per watt, while permanent installs cost less than $1.50 including all.

Connection of off-the-shelf suitcase to coach battery is a so-so, usually a pair of crocodiles of poor quality steel. Not very safe. Or via 12V cig lighter receptacle of the van (transitioned via non-waterproof SAE if they bothered to include one), if your receptacle remains hot with the ignition off. Unless your van has a dedicated exterior 12V receptacle specifically for this purpose.

Controller that you don't need to bring inside... Keep in mind that it is not waterproof.

Holes in the roof (for permanent system)... Depends on how old the van is. Doesn't matter after some time.

No installation required (for portable)... True, but dealing with portable will take much more of your time if you move around often.

On the "bright" side - pun intended :) - you can have it parked in the shade and keep portable in the sun, if cable length allows. This is about the only advantage (over a permanent install) that looks serious enough to me.

rjxj wrote:
Maybe you could use an anderson connector to connect the panels to the controller and have a quick easy way to disconnect.

I also like the convenience of a plug-in connection from the portable panel to the solar controller. I have a 150 watt panel on the roof of the trailer and a 100 watt portable panel. I ran wiring from the solar controller to the underside of the trailer. This wire has an SAE connector to easily connect and disconnect the portable panel.

That will work just fine and you will be able to track the sun for maximum efficiency. Some controllers need the panels disconnected from the controller before disconnecting from the battery. Maybe you could use an anderson connector to connect the panels to the controller and have a quick easy way to disconnect.

Distance and conductor size influence resistance so pay attention to length vs amperage charts when selecting wire. Being on the bigger side reduces voltage drop .

Pretty big difference in leaning the panels against the van or placing them 30 feet away.

Lwiddis wrote:
If storage is slim and the roof is available why suitcase solar?

No punching holes in the roof.
No labor to install, if hiring out the work.
No fishing cables down the refer vent.
No sealants or sealant tapes to buy.
No wall mounted charge controller.
No fishing cables behind cabinets.
Not restricted to a sunny camp spot.
Ability to "follow" the sun to maximize amp output.
Most suitcase units simply plug into a "solar ready" port or directly to the batts.

If storage is slim and the roof is available why suitcase solar?

DownTheAvenue wrote:
Will that charge both batteries at the same time from the controller?

Shadow Catcher wrote:
You will need to have a solar controller.

Sounds like he has that covered.

You will need to have a solar controller.

Yes, you can hook the positive lead to either battery positive post, and you can connect the negative lead to either battery negative post or any ground that is tied back to the batteries.

Jim

yes