M116A3 Build

[bdosborn]

You might mention in your write up that you don't *have* to make the ve. to USB cables, Victron sells them. It's just a lot more expensive than making them.

Bruce

[lfhoward]

You might mention in your write up that you don't *have* to make the ve. to USB cables, Victron sells them. It's just a lot more expensive than making them.

Bruce

Good point! I’ll make the edit. Thanks.

[lfhoward]

My second Sixfab project enclosure arrived so I transferred the Venus Pi from its small Canakit case into this.



I like the project enclosure because everything is protected inside, plus there is a cooling fan.

[lfhoward]

Update:

The Victron VRM with Sixfab cellular hotspot is ready to install in the trailer.



Left device = Sixfab cellular hotspot, generating a wifi network for the trailer.
Right device = Victron Venus solar/battery monitoring system, connected to the trailer wifi.
Center = fuse panel with 3 amp fuses

In the background is my 12 volt power supply. With both devices on, the total current usage is about half an amp (6 watts). Solar power generation from my 210 watt panel on the roof will easily offset this.

All devices above are fastened to a piece of 1/2” plywood, which will go in the back of the kitchen storage cabinet shown here on the side of the camper.

[lfhoward]

Today I installed the Venus GX and Sixfab Rasberry Pi’s.



I needed to redesign some circuits so that I could control the battery heater from the VRM, among other things. Here is the fuse box as it stands now. It’s definitely full. The battery heater and the Raspberry Pi circuits are connected to the solar charge controller load ports, so can be controlled/programmed remotely.



It took most of the day but I have the system up and running! The Victron VRM on my phone now shows me both charge controllers and the GPS location of the trailer. I didn’t have time to wire in the battery monitor yet. That one will take me a few more hours, because I need to run a hidden USB cord the length of the trailer.

[bdosborn]

[lfhoward]

The VRM system works great! Not only can I see data on the charge status of the trailer, but I can directly modify the settings on my solar charge controllers. One controller has the battery heater (beehive heating pads and Inkbird thermostat) connected to its load port. I am able to turn the battery heater on and off remotely, or set it up in “streetlight” mode where it comes on just before dawn to warm things up.

My battery heater averages 2.4 amps and raises the battery temperature 1°F every 8 minutes. Overnight lows here have been in the 20’s so 2 hours of warming is needed to get the battery up to 39°+ where the solar charge controllers allow charging. The trick is estimating whether those 5 amp hours used for heating are likely to be recouped by the sun— on a cloudy or stormy day no, but on a sunny day hopefully yes and more. Daytime highs have not been much over 39° by the afternoon so I’ve had little to no charging happening lately. Today was a sunny cold day, so I used the VRM to turn on the battery heater before sunrise. The battery warmed nicely, but no charging occurred! I found the solar panel had 3-4 inches of snow on it. Once I cleared that off, charging began as expected. Unfortunately I did not get to take advantage of the best hours of sun today, so I had a net loss of power (130 watt hours used, 30 watt hours recouped).

I want to get the BMV712 battery monitor hooked up to the VRM soon so I can see my battery capacity remotely too. In person at the trailer today I saw my battery’s state of charge was at 76% (of 156 Ah).

Another consideration is I’ve burned through about half of my 500 MB data plan already. It is not the trailer’s fault. I realized today my phone was automatically connecting to the trailer’s wifi when I was in range! Phones use up data super fast. If you use your phone to set up or test the Sixfab wifi, be sure to set “Join Automatically” to NO and set the network properties to “Low Data Mode” so your phone won’t use it to do a bunch if downloads in the background. Now I just need to be more disciplined to not be playing around on the VRM app all the time, so the remaining data lasts for the rest of the month.

[bdosborn]

Can you use the Raspberry Pi's Ethernet port to set up a LAN? Can you pick the WiFi LAN address? Can you have the Pi bridge to a local WiFi if one is present? I've been using my phone for WiFi in the camper but the Raspberry Pi approach is looking pretty cool.

Bruce

[lfhoward]

Can you use the Raspberry Pi's Ethernet port to set up a LAN? Can you pick the WiFi LAN address? Can you have the Pi bridge to a local WiFi if one is present? I've been using my phone for WiFi in the camper but the Raspberry Pi approach is looking pretty cool.

Bruce

Yes, you totally can. You could pick up a local wifi on your Rpi and share it throughout the trailer via the ethernet port. Or you could plug in an ethernet cord from your house to the Rpi and have it share the internet over the Rpi’s wifi, becoming a wireless router. Or, in my case, I have an Rpi connecting to the internet through cellular and creating a Wifi network because I am not parked in range of any local wifi source. The SSH code to set the Rpi’s up in any of these ways is available online and not too hard to follow. And you can choose to set up static IP addresses if you want. I assume there would be a way to make an Rpi into an extender/repeater for your house’s wifi too, but haven’t looked into that.

[lfhoward]

Solar update: I got the trailer to collect 13 amp hours of power today by heating the battery before sunup! The heater took up 5 amp hours of that current, giving me a net production of 8. The sun is behind a tree now so not much more power will be collected today. The unfortunate thing is the two Raspberry Pi’s use 12 amp hours per day so I have a net power drain of 4 amp hours per day. It would be less of a deficit if the temperature was warmer and I didn’t have to run the battery heater, enough to break even. It’s because we are in the time of year with the shortest days! Today was not cloudy.

So, I have a couple of options.
Option 1: charge the battery every 2 weeks or so by plugging it in. I would need it to be plugged in for 3-4 hours (30 amp charger, 156 Ah battery).
Option 2: set the Raspberry Pi’s to not be on all the time. I could cut the power to them for 22 hours of the day by having them use the streetlight function of the charge controller.

I will probably go with option 1 later this week. I am still experimenting with the system and want to see data for what’s happening with solar. I have a few more cold but sunny days coming up where I want to try and optimize the system. Today I had it warming up the battery 2 hours before sunrise, which seemed to be a bit early compared to solar generation (good power starting at 8:30 am). Tomorrow I will try 1 hour before sunrise.

Later I might try option 2. The tradeoff would be I would only have remote control of the solar system for 2 hours a day, and it would only collect data during those 2 hours. But I would not have to visit the trailer and manually charge it.

Once the days get longer and warmer and the trailer collects more sunlight on an average day, the power consumption of the Raspberry Pi’s will not be an issue. I may be able to eke out a bit more daily power generation by positioning the trailer in a different parking space, slightly further away from trees. I have the roof panel tilted towards the south east to make the most of morning sun.

[featherliteCT1]

Great solar data and VERY interesting!

[lfhoward]

The pre-dawn temperature was in the teens this morning, so I only broke even replacing the battery heater energy with solar power today (and used up some additional amps on the Raspberry Pi’s).

So, today I charged the battery up using my 30 amp shore charger. It took about 3 hours to get back to 95%.

Next, I parked the trailer away from some trees that were reaching over the solar panel before. The previous position of the trailer relative to trees (before I cleared off the snow on Saturday).


The new position is about 3 parking spaces out from those trees, and gives a more unobstructed view of the sky. My best sun will be in the morning between 9 am and noon.


After about 1 or 2 in the afternoon, the sun will be at a right angle to the east-southeast tilted solar panel, and also behind the woods. At that point power generation will be minimal. At this point it is not worth continuing to heat the battery or continuing to run the Raspberry Pi’s to monitor the system. I can save 6-8 amp hours by turning them off overnight.


The app I’m using is called Sun Tracker AR. It’s super handy for positioning the trailer for maximum sun while camping.

Tomorrow starts off nearly as cold as today, but will also have nice and clear skies in the morning. I should see some good watts coming in between 9 and noon. It will be interesting to see how much difference the new parking space away from the trees makes.

[lfhoward]

One complication I just thought of:

The VRM hardware (Raspberry Pi’s) is connected to the load port on the AUX solar charge controller, which currently has no solar panels hooked up. I wonder if the controller will know when dawn is, so that it can turn on the Pi’s? Ha! If the VRM is not on at dawn, I won’t be able to remotely tell the other charge controller to keep the battery heater powered up after about 7:30 am. That will kill tomorrow morning’s solar generation before it begins. I’ll keep you posted with what happens.

[bdosborn]

I'll be using this on the van electrical, I wish I'd known about it for the trailer:

Nifty Heat Shrink Labels



Bruce

[lfhoward]

I'll be using this on the van electrical, I wish I'd known about it for the trailer:

Nifty Heat Shrink Labels



Bruce

Those are really great! It would make tracing your work at a later date a whole lot easier. If I had known about them I would have used them for sure.