You'll Get a Charge Out of This

Sometimes getting a kickstart back into blogging is all I need.  Sometimes it is as simple as some random heater salesman writing to me, saying he is on the edge of his seat, waiting for a new blog post.  I have spent my life always making it a point to respond well to flattery.

“So how is the van project going?”, you have asked…

Where I left off I had just gotten the charge controller wired up. The solar panels were about to start producing. I was writing that whole story in January, but when it actually happened was late fall 2017, six months ago.  Lets jump forward in time to now…

Something I was always bothered by was how little power I seemed to get out of my batteries.  I have four Trojan T-105 6v deep cycle golf cart batteries for a total of 450amp/hours (ah), or “a usable 225ah” of electricity. (Because whatever you have in your batteries, you can only use half their total capacity without damaging them)

Two and a half watts of mood in
the back of the van.

Let me put that into perspective.    If I have everything turned off, just the stuff that monitors the battery condition, the thermostat for the furnace, all the little LED lights on the USB charge ports.   I am using .16 amps of power 24x7.   So I take that .16 times 24 hours in a day and I know monitoring consumes 3.84ah.  The van could run it’s basic monitoring equipment without charging (not even solar) for roughly 58 days.

I am sitting in the van right now.  It is night and I have the joyous sound of a train going by my back window.  I have the white overhead LED “puck” lights on.  I got the mood-light’n on in the back.  I have my iPod plugged in.  I do not have my laptop plugged in.  —I don’t usually. What this all means is right now, with this stuff added in, I am using .81 amps.  If I had to take that times 24 again, it would add up to a much more significant 19.44ah but still, that is eleven days.  With the lights on continuously.

But that never happens.  Usually I have the lights on for about an hour.  I do some stretching.  I work on a few things.  A little music.  If I have a network connection my current obsession is SimCity Builder.  Then I crash out for the night.  Lets just say that takes two hours.  Take .81 times 2 which equals 1.62ah.  Add that to the 3.84ah I use for monitoring and that is 5.46ah a day.

We aren’t quite finished yet.  The furnace runs.  When it does, I add another 2.68 amps.  Which again, compared to some LED puck lights is significant, but it doesn’t run all the time either.  Right now, unbelievably the furnace is still running in April.  The typical run-time seems to be twelve minutes.  But, as far as how many times in a day?  I don’t really have that data.  That will vary with the outside temperature. Tonight it ran for the twelve minutes and off for thirty-five.  It’s a balmy 21 degrees out there because we are weeks into spring.  Back when it was really cold I never thought to run my stopwatch and get the numbers.  I would believe, for the sake of argument, it ran twice an hour.   By next year I will have some things in place to track both the exterior temperature and furnace runtimes.  For now I just have to guess.

A 1.6 watt LED "puck" light.

I am going to round the math a little.  It makes it easier to explain to you, plus I don’t have to go to the bother of displaying my ignorance if I do it wrong.  Remember, its ok to round your numbers but *always* round pessimistically.  Lets say that furnace runs 15 minutes instead of 12.  Fifteen minutes is a quarter of an hour, but it runs twice in an hour.  So I take the 2.68 amps and divide it by two, and get 1.34ah it uses.  To calculate the use in a day I take it times 24 and I have 32.16ah.  I need to add the 5.46 from the previous step and I have 37.62ah

Now we are really starting to take a bite out of those batteries.  The 225ah of battery power divided by 37.62 a day.   I should be getting six days.  Again, this is with no charging at all.  Like I don’t actually have 520 watts of solar panels on the roof.

I have a computer network, I was trying to run it 24/7 but that was consuming 1.76amps or 42ah a day.  In the fall with the still abundant sunshine, that was fine.  But once I started watching the power meter a little closer it was the first thing that had to go.

The control panel for the inverter.  

Let me explain a little what the computer network is, just to give you a little peak ahead. I have a Raspberry Pi (single board computer) based camera system to keep an eye on what is going on outside.  I have been meaning to post about that but only have that one partially written. I admit the computer network wasn’t well designed power-wise, and I was running it 24x7, but I thought I had power to spare.  I shut it off. 

The second thing to be turned off was the inverter.  That’s the little box that turns the battery power into 110 volts for a microwave or coffee pot.  It only really needs to run when I am using one of those appliances though.   I only ran the microwave once a day unless it was full sun.  If it was cloudy, with a cloudy forecast, I didn’t run it at all.

But even with cutting all these corners, I could run the furnace and minimal lighting four cloudy days and the power meter percent charge would be in the low 60s.  Most of January was very cloudy here but I would typically get some charge every day.

When I am collecting solar, this looks great.  When it
drops to 70% as soon as the sun goes down, not so much.

I don’t have a refrigerator. Those things are total pigs even in the wintertime. So I am lucky there. I do run the microwave and that consumes tons of power as well but I only run it about ten minutes a day max. I don’t really have those numbers because I don’t have the monitoring stuff setup on the 110v side.  I also don’t have any exact data on how much I took in from the solar.  I just wasn’t ready to gather that information yet.  Given these facts coupled with some gut feelings, I felt like mathematically I should have had enough to run the van for ten days without even being especially careful. When I was actually living it, there was no way.

So that’s where it really just hung most of the winter.  It just wasn’t right I didn’t think.  But I have never lived this life before.  Batteries are not as efficient at low temperatures so I was thinking maybe that was the reason.  Then there was the fact I couldn’t do a whole lot anyway.  I didn’t know anyone with a garage that could fit the van’s height with the ladder rack and it was flipping -20 Fahrenheit outside.  So I just sort of limped along.

Just over 200 watts coming in off
the solar panels on a typical cold
January day.

Lurking in the back of my mind though, I suspected I had done something wrong in the initial battery wiring.  At the time though I really didn’t know who to ask.   When I was doing a bunch of research during the beginning of the project I found several companies who sold equipment. Those companies would not give me any information on how to wire up what they just sold me.  They would only tell me to hire an electrician.  I get it.  Liability.

In late January and early February we were going through a long multi day cold patch and I was burning propane like crazy.  There was one stretch where I went through a 20 lb propane cylinder in six days.   Sixteen below at night, getting “up to” -10F during the days.  Inside I stayed as warm as I wanted to pay for.  I would keep it set to fifty during the days when I was gone, then turn it up in the seventies when I was there in the evenings.  Back down to fifty at night when I was under the covers.  All in all it wasn’t bad. Surviving a winter in a van like this will be a story I will get milage out of for years to come. I had a few problems, the water tank froze up. I will cover that in a future installment.  I am going to have to do a little redesign there in the spring.  But the only thing was, it was bright and sunny every day. The solar numbers should have been looking fairly good.  I really shouldn’t have been having power problems but the batteries hovered around the 70-80% mark.

The frost line on the batteries.

One night I was doing a propane tank exchange and I noticed something odd about my batteries.  The two batteries on the drivers side appeared frost free while the two on the other side seemed frosted from the liquid level down.   Now in the van, theoretically the two sides *should* really be equal.  They are both in the back, under the bed, but I realized also there could be a ton of environmental factors that could be causing a slight temperature difference from side to side.  Even at eight below if the drivers side was parked in the sun, it *might* just be a little warmer.  If my insulation isn't quite as good on that side, I could be leaking warm air into that space from the interior of the van, etc.  Like I said, tons of reasons but I was really concerned. I started thinking maybe the batteries were not getting charged as well on that side and I was getting some freeze-up.

Just to give you some background information.   A fully charged, strong battery, won’t freeze even here in the frozen wasteland in which I live.  The strong battery freezing temperature is -76F air temperature and so far this winter (or any of the other winters in my lifetime) the air temperature hasn’t gotten quite to that point.  Windchill, sure we hit those temperatures every few years but windchill doesn’t matter.

With the frost showing up, that indicated to me I might have some freezing going on.  A sign the battery was weak and not fully charged.

Since the initial van research time I have moved more into the marketing phase of this blog I have found some new sources of information.   I found an internet forum and posted a summary of my situation and question there.   Within a couple of hours I had the answer I couldn’t find before.   I had in fact wired it wrong.