Continuing Solar Questions

[ski3pin]

Solar is not in the immediate plans, but I’ve got the camper interior ripped apart and I want to prepare for future options.

Our electric needs are minimal. Furnace only runs for initial warm up then we use the Wave 3. Lights are LED. Water faucet has a shurflo pump but is minimally used. Fantastic fan is used only when cooking. The new power draw is the TF51A IndelB fridge. I will set everything up and use it in a static garage situation and calculate power usage.

These are my two assumptions – big amp hour batteries are expensive and they have longer life when not drawn down often to low levels. Solar looks like a good long term option to longer battery life.

In all my reading about battery charging and solar in regards to camper use I am discovering a bit of leeway between optimal setup and what works.

I’m aiming to hit in the middle.

First thought/decision I’m tackling is panel placement. On the roof is easiest, permanent, and somewhat out of mind. Problem for me is older camper and need to run wires. Other option is a portable panel to set up for optimal placement for sun. Wiring would be easier. Downside is that we do not hang around the camper and trusting an anchoring system to withstand the kinds of winds we have experienced. Another downside is the possible tripping factor of the power cord on the ground.

I will probably go with roof mount. This brought me to my first question – solar charging as you drive and how do truck alternator charge and solar charging work themselves out. It would seem they are competing.

Thoughts/explanation?

Also, if this has been covered before (I couldn’t find it), please let me know.

 

[MarkBC]

ski3pin, I found that previous thread that I mentioned:
Multiple Charging Sources

 

[ski3pin]

ski3pin, I found that previous thread that I mentioned:
Multiple Charging Sources


Thanks Mark. This was the kind of discussion I was looking for; a lot of information to digest.

 

[Casa Escarlata Robles Too]

Boy Mark and Ski,that's a lot to digest.Not being a "sparky" a lot of the info seems way over kill,I also like to keep things simple.My system consisting of, 45W solar,120 W solar controller, 75amp Interstate AGM battery ,battery isolator,and the truck all seem to work.I seem to have sufficient power to run the minimum power users I have and keep the battery charged OK.
Ski as far as wiring.Since my panel is on the right rear of the roof rack,it's 24"x21" approximate size.I just ran a + and a - wire through the edge of the roof about 4" from the corner.Drilled a hole large enough to fit a piece of 5/8" threaded tubing,the king used for lamp bases.Attached a nut inside and outside, ran the wires through it than caulked with silicon.Once inside the wire has a large loop behind the lift panel to supply length when the roof is lifted.The threaded tube is like a weather head,all sealed and the wires won't pull out.I went with two wires directly to the solar controller as I didn't want to use the camper ground.I used #10 wire.Ran it down the inside corner than outside along the outside of the camper under the overhang than through the plywood side near the tie down door to the battery area and controller.
It was a pretty simple do and it works and water tight.Still keeping in the back of my mind the second panel,but we just don't have a need for that much solar out put.
Frank

 

[craig333]

Brings to mind a question I have. Dirt. Just how much does a nice layer of dirt cut down the panels power generation. I do hose mine off now and then but I wonder if its something to think about while on the road. I should do some tests.

 

[Casa Escarlata Robles Too]

Craig,I have solar on my house also and the company said just clean them once in a while.No specific time period.I clean mine on the house every 5/6 months,on the camper it sits under a tree so it gets more junk.I clean it every few months.I don't know how you would go about measuring the total out put.I would think a small film wouldn't matter much.Now if it had a build up of leaves ,dirt ,stuff that would block a lot of sun than I think you could see the the drop in out put.
Frank

 

[ski3pin]

<snip>
This brought me to my first question – solar charging as you drive and how do truck alternator charge and solar charging work themselves out. It would seem they are competing.
<snip>


I will provide some follow up. I did install a simple solar system. I will cover that in an upcoming separate post. Although I do not fully understand the competing mechanisms in my question above, this is what I have discovered. I use a simple 12V battery monitor to let me know the state of battery charge. Prior to solar install I saw a top level of 12.75 V on the house battery from charging off the truck alternator. With the addition of solar, after driving I now have a battery with a high of 12.96V. This tells me that solar is also charging the battery while driving. On our first trip with our solar setup and spending a couple days sitting in the same place I saw a consistent battery level at the start of evening chores of 12.96 V. On our recent trip to Lassen where we spent three nights, after sunset we started each evening with the battery at 12.96V.

 

[Hittheroad]

I will provide some follow up. I did install a simple solar system. I will cover that in an upcoming separate post. Although I do not fully understand the competing mechanisms in my question above, this is what I have discovered. I use a simple 12V battery monitor to let me know the state of battery charge. Prior to solar install I saw a top level of 12.75 V on the house battery from charging off the truck alternator. With the addition of solar, after driving I now have a battery with a high of 12.96V. This tells me that solar is also charging the battery while driving. On our first trip with our solar setup and spending a couple days sitting in the same place I saw a consistent battery level at the start of evening chores of 12.96 V. On our recent trip to Lassen where we spent three nights, after sunset we started each evening with the battery at 12.96V.


Having a solar panel and a truck alternator both charging the battery is really no different than having two batteries. Provided everything is hooked up correctly the two charging systems should cooperate rather than compete. Since the two systems will be running at slightly different voltages, and those voltages will be changing with engine load and cloud cover, there is some negotiation that the electrons have to work out but they are good at that - better than people.

 

[pods8]

I will provide some follow up. I did install a simple solar system. I will cover that in an upcoming separate post. Although I do not fully understand the competing mechanisms in my question above, this is what I have discovered. I use a simple 12V battery monitor to let me know the state of battery charge. Prior to solar install I saw a top level of 12.75 V on the house battery from charging off the truck alternator. With the addition of solar, after driving I now have a battery with a high of 12.96V. This tells me that solar is also charging the battery while driving. On our first trip with our solar setup and spending a couple days sitting in the same place I saw a consistent battery level at the start of evening chores of 12.96 V. On our recent trip to Lassen where we spent three nights, after sunset we started each evening with the battery at 12.96V.



1) You may not have ever fully charged your batteries before. My agms FULLY charged are about 13.06V.
2) There is something called over charge, its a falsy high voltage that is present when the higher voltage charger is removed but enough time hasn't passed for it to dissipate. For instance my charger float charges my batteries at 13.7V, if I remove that and then test my batteries right away they'll but up around that number and take a few hours to dissipate down w/o any load involved. Alternatively if you turn on your fantastic fan for a minute it should wipe out the overcharge and when you turn it back off the battery will show its true voltage. You may be seeing that at the end of the night before having any sources drawing on the battery. Or as mentioned you might finally be fully charged.