Tag Archives: Solar

Charging the batteries

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Be warned, this post is a bit heavy on technical issues and one image.

Life in a trailer, especially boondocking, requires monitoring your battery capacity and usage.  The first thing I did to help this when we had our ’92 25′ was get some Sears AGM batteries.  This gave me a larger capacity and less worry about them.  Changing both trailers to LED lighting helped a lot more.  We purchased a couple of generators to help with charging when we needed it and ostensibly run the air conditioners with two of them running.  I also purchased a set of portable solar panels.  I had all the pieces lined up for extended battery usage, except one.  Solar on the trailer.

This was accomplished early this year, shortly before we started our fulltiming/CalExit.  In our travels since May (2017) the solar panels have performed fantastically!  But events during our travels have made me rethink my charging methodology.

Before solar, there were two methods of charging.  When we were hooked into shore power, the converter/charger will charge the batteries and provide 12v DC power.  When towing, the tow vehicle will provide a small amount of charge through the 7pin umbilical cord.  I remember my father hooking up our station wagon to the trailer and letting it idle for extended periods to give the trailer a charge while boondocking.  I have not tried this method.

The converter/charger that came with the trailer was a single-stage charger, meaning it was either charging or not.  On or off.  This can wreak havoc with your batteries, especially if you leave it plugged in while ‘stored’, as we did.  I replaced the converter/charger with a multi-stage version.  This flavor will do a heavy, high amperage charge until the batteries reach a certain voltage.  The next stage is a consistent, lower amperage charge until a different voltage setpoint is reached.  The final stage is a trickle charge just to keep a preset voltage level.

The one issue/problem when adding a solar system, and its inherent charge controller, is to ensure that the two charging ‘brains’ don’t conflict with each other.  Luckily the solar charge controller is adjustable in what voltage it shuts off at.  This way I was able to research the voltage level for the shore power converter/charger and adjust the solar charge controller to just below that voltage.  That way, if we were on shore power the 110V converter/charger would do its’ high amperage charge and get it to a voltage higher than the solar chargers threshold and the solar charging would be negated.

What change have I made in charging the batteries?  Let’s lay a bit more groundwork first.

I no longer have 2 generators, I never did use 2 to run the air conditioner which made the 2nd one expendable.  After our 4+ months on the road I never used our portable solar panels, therefore they are for sale (contact me for more info).  We are now down to shore power charging, solar charging and generator charge (which is essentially shore power charging since the generator creates 110V AC).

The months on the road brought up some odd issues that have steered me to my new path.  We had problems with our refrigerator when we started that were hard to diagnose and explain.  It was not working when we left and started working mysteriously after we were in Arizona for a few days.  It got weird again in Texas.  When talking to the repair shop they mentioned that irregular 12V power has been seen to cause problems with refrigerator circuit boards.  I changed the shore power cables and it started working just fine, making me think it was the cables, but maybe it wasn’t?

We did great on power for about another month until we were in Williamsburg VA.  The spot for the trailer there was very shady and I noticed that the battery was down to about 82% capacity and the shore power was charging it slowly, if at all.  I immediately thought it was the shore power converter/charger and ordered a replacement.  Once it was swapped out, charging was back to normal.

That got me to thinking that maybe our refrigerator problems earlier were symptomatic of a failing converter/charger.  I am now fairly convinced that is true as the refrigerator has not exhibited any type of issues, even when the internal fins were coated with ice due to humidity.

When we were in New York and taking advantage of some courtesy parking, we had some issues with the 15amp shore power that was provided.  The electrical management system that I installed, before we left, would disconnect our power and reconnect continuously.  It made the power connection unusable so we relied upon the solar to take care of the batteries.  This allowed me to notice another aspect of the shore power converter/charger.  When it is in its’ first stage of charging it uses a LOT of amps!  I saw about 18 amps at one time!  That was overloading our 15amp connection.

My next thinking was if I could turn off the shore power converter/charger, I could then control when I used it and turn it off when we are on 15amp.  One option is to turn off the breaker but that would also make the inverter inoperative.  I didn’t want that.  I made my own solution.  I got some parts at Lowes and created a device that the converter/charger plugs into and then it plugs into the wall.  It contains a switch that I can easily turn on and off.

This relates to an ability for me to disable the shore power converter/charger when on a minimal power connection and allow the solar panels to exclusively charge the batteries.

The empirical proof is in.  For the last three weeks, we have been on 15amp power, with the shore power converter/charger turned off, and we have full battery power going into each evening.  I feel it is a great success.

Solar Install (Part 3)

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As we left our story I had just got the cables (battery, monitor, and temperature) ran to the back of the refrigerator through the underside of the dinette bench.  I showed Roxie the progress and she asked if I was going to put the controller under the dinette.

I said that I was going to put the controller behind the refrigerator and had already put a lock on the refrigerator door:

However, she had a really good idea.  By putting the controller, switch, and breaker under the dinette it was much more secure and more accessible.  All I had to put in the refrigerator area was the 2 gauge wires going to the top of the trailer through the refrigerator vent.  That proved to be a bit problematic.

In our ’92 the area behind the refrigerator was wide open.  Lots of room.  However, in the 2012 it appears that Airstream created more of a controlled updraft for more efficiency.  In looking at the specifications for the refrigerator they do have plans for a tight air draft configuration.  But this makes it harder, nearly impossible, to drop a cable behind the refrigerator.  But another problem was that I had the cable at the BOTTOM of the refrigerator!

I have to take the refrigerator out.  I have done it before in our other trailer and knew there weren’t too many screws, etc. holding it in.  It is just a larger one than our other one and much more cumbersome.  As luck would have it our son came by right when I was going to take it out. He was able to muscle it out and I had all day to work on it.  Alas, I did not take pictures.

Another issue was the gauge of wire.  At the top of the trailer, the combiner box attaches to the refrigerator vent but I could not bend the 2 gauge wire enough to get the combiner box cover on.  I had to use a smaller gauge for the combiner box, I chose 6 gauge.  It would still handle the current.

I followed her recommendation and mounted it all under the dinette:

Above you can see the solar panel cutoff switch, the solar panel controller, and the circuit breaker.

Also, the wiring behind the refrigerator is much simpler:

The next step was doing the panels on the roof but first I wanted to get some of the internal wiring cleaned up.  The set of three wires that go from under the dinette to under the couch goes along the base of the wall and needed some wire management:

There is also a set of two wires that go to the IPNPro Remote that I mounted on the wall:

Now off the panels on the roof.  I have 3 Grape Solar GS-160 panels to mount.  I had an idea where to put each of them but still had a bit of trepidation of the actual fitment.  Our son helped me with the fitting and bracket mounting since the panels are 26lb and awkward.  They went up very easily and the VHB tape worked well on most of the brackets.

We removed the panels leaving the brackets for me to secure further.  We decided to put two screws in each one and put a lap sealant completely around each bracket:

But there was ONE bracket that gave me fits.  Trying to put a screw in I hit something very hard and twisted off a head of one screw.  I tried to flip the bracket and another screw would not go in.  Great, now I have 4 holes to fill (maybe some FlexSeal Tape?).  I moved the bracket on the solar panel and was able to mount it finally!

Here are some shots of the panels:

Wiring is next.  I had to build a few MC4 cables to get to the combiner box but that was easy.  They hooked up just great and I was ready to flip the switch:

I go down to the solar panel isolation switch and turn it.  I check the voltage on the wires from the solar panels at the controller.  0 volts?  It should be around 15-20v.  I look at the switch and realize it was already ON and I had turned it OFF!  Ok, really turn it on now.  Now the voltage is 0.2v, still not enough.  I turn the switch off and check the voltage on the panel side.  18 volts!  Turn the switch back on.  0.2v.  OK.  That is enough for the night and I am losing the sun.

The next day with good sun there was still the same issue.  Time to call Blue Sky.  I talked to Ryan and he was extremely helpful.  He said it sounded like some type of wiring issue.  I wired the panels directly and not through the switch, same issue.  I was perplexed and Ryan was also.

On the controller, there are 4 places to attach the 2 gauge wires.  A positive and negative to/from the battery, which I knew was working fine since the monitor was working.  Another connection point was from the solar panels (PV – photovoltaic).  I looked at those connectors and saw something.  The wire I was using is stranded and about 3-4 of those strands didn’t fit in the negative connector but pushed out to the side and actually touched the positive connector!  There was the short!

I bent those wires away and the controller came to life!  I was slightly embarrassed but pleased that it was working.

Now I get to play with tracking the in and out of solar power energy.  As a non-scientific empirical test, I disconnected from shore power, turned on both Fantastic Fans and let it run all night.  In the AM I had 84% battery capacity remaining.  Once the sun started hitting the panels, the energy started flowing.  Here are some screenshots of the monitor at a peak time:

It shows the panels charging up the batteries just fine.  The batteries were fully charged up around noon that day.

I am pleased with the performance and very pleased that it is done!

Here are a couple of shots of all 3 panels on the roof:

Many thanks to the numerous blogs, videos, information that I used to plan and execute all this.