M116A3 Build

[lfhoward]

Bruce, thanks for posting your results too. Super interesting to see another setup using beehive battery heaters.

I see Facebook posts of guys living in their vans his time of year and I don't know how they keep up with their energy use. They've got to be in open spaces with full sun all day long. I guess I'd be looking at tilting my panels if I was living in my van.
Bruce

Isn’t that true! I wonder if they drive around every day burning gasoline to charge their batteries, LOL.

One way I try to keep my battery heater from using up unnecessary power is to have it not only on a thermostat but also a timer. I only allow the battery heater to be on from dawn to 1 pm, when there is a payoff for spending the energy. The battery stays warm enough from 1 pm until later in the afternoon to soak up some additional sun. The timer in this case is one of my Raspberry Pi computers and an electronic relay.

[lfhoward]

That new parking spot did the trick!
62% SOC after 2 days.

Cloudy > Tree Branches

[bdosborn]

Holy cats! How can our loads be so close? Weird...

Bruce

[lfhoward]

:thumbsup:
Holy cats! How can our loads be so close? Weird...

My 6.68 watts consist of 2 raspberry pi computers, 2 Victron MPPT chargers, and a Victron BMV battery monitor. Are you running the same, except a Cerbo GX in place of the Raspberry Pi’s?

[bdosborn]

Cerbo GX, Victron MPPT controller, Victron DC/DC charger, Victron 712, Electrodacus BMS, and multiple USB charge points. So pretty close, I bet it's the Victron charge controllers that are the majority of the load. Next time I'm messing with the electrical system I'll disconnect them and see what they draw.

[lfhoward]

My system made a half a kWh today with its 210 Watt panel! The battery is now at 75% and it shouldn’t be long before it tops out. I have never been super happy with the settings of my chargers and battery monitor where they relate to calibrating the monitor when the batteries reach 100% charge. Many times in the past I would reach the absorption voltage and the monitor would never make it to 100%. So, I went back to basics and reviewed Andy’s settings here:

https://off-grid-garage.com/my-settings/

He does a great job of explaining what all the setting mean for the charge controller and battery monitor in the 2 linked videos. I was also able to translate some of his advanced settings over to my system, and a few things changed. I will be happy to see what difference it makes in a few days once the batteries reach their absorption voltage. Will the monitor self-calibrate to read 100%? It's been 50 days since the last full charge.

Bruce -- I am interested in what you are using for Absorption & Float voltage settings. Did you stick with Victron's default settings or reduce them to minimize wear and tear on the batteries? Mine are set to 13.8 & 13.4 volts, respectively (and the same as the voltages Andy uses on a per-cell basis). [Victron's LiFePO4 defaults for a 12 volt system are 14.2 and 13.5 volts, respectively. The advantage to the higher absorption voltage is a faster charging rate.]

[bdosborn]

I started with Andy's settings and tweaked them a bit. The Victron and Battleborn settings definitely didn't work for me, I had a couple of cells go *way* too high with those.


I can set the voltage levels for when the Electrodacus cell balancer works; I don't balance over 3.42V per cell. The cell voltages are just too far apart over that voltage for it to be of any use. Once the voltage settles down to float level it's usually balanced between 3-5 mV.


I did get the active cell balancer that Andy recommended, I left it on for a day or so and that helped my cell balance a lot. I did that about eight months ago and haven't used it since. I've been tweaking the MPPT settings a bit the last couple of days as I noticed that my cells have been in better balance at the end of bulk charging. I don't know if it's because my cells are balanced better or if they are colder but I can definitely charge the battery a bit higher than I could six months ago. I'll probably drop the absorption voltage down to 13.85V in the spring, just to be conservative.
Bruce

[lfhoward]

Bruce, I was thinking about how you used the BMV-712 battery monitor’s temperature relay to turn your battery heaters on and off, and I came up with a scheme to streamline my system and make it more efficient.

My current setup:
Raspberry Pi GPIO 3V power -> triggers Solid State Relay +12V power -> Inkbird Thermostat -> Battery heaters

New idea:
Raspberry Pi GPIO 3V power -> BMV-712 Temperature Relay -> triggers Solid State Relay +12V power -> Battery heaters

The switch would do away with the Inkbird Thermostat, which uses about a watt of power when on, regardless of whether the heaters are on. The new design also bases heating decisions on the same temperature sensor the solar chargers use, rather than a separate sensor connected to the Inkbird Thermostat.

I would retain the ability of the Raspberry Pi computer to set the time of day the heating system will be energized (just before sunup to 1 pm usually). This way I only run the battery heaters when there is a payoff (daylight to make power), since running them at night just drains the battery. The battery never gets into dangerously cold temps overnight anyway as it retains heat and cools down slowly.

I also like the idea of being able to use the VRM to adjust the temperature range or turn the battery heater on from my smartphone. The Inkbird Thermostat must be adjusted there at the trailer, but the BMV-712’s relay is totally remote control.

And the heating pads could easily be swapped over to a battery cooling fan in summer if desired.

See anything I’m missing?

[bdosborn]

I use the relay in the Cerbo to control the heaters, I'm not sure if the 712 has any relay logic for temperature. At least I couldn't find any in mine but I don't have a temperature probe connected to it, the probe is connected to the Cerbo. You might be able to share the 712 temp via DVCC to the Raspberry Pi Venus and then use that temp to control a relay. The Cerbo has 2 relays, I use one for the heaters and I'm saving the other on for a generator start/stop function, which has time of day settings. With a Cerbo you could run one relay through the other to get temperature and time of day control from a single Cerbo. That would work for the Raspberry Pi, assuming you have more than one relay. My Raspberry Pi Venus only shows one relay (but I need to update it) and maybe you have temperature relay logic for your 712 relay?

Here's my Cerbo relay settings:


My Raspberry Pi Setting (only one relay shows)


Here's the sequence I'm thinking you want:
Raspberry Pi GPIO 3V power -> relay 1 gen time of day run ->relay 2 temperature (possibly the 712 relay?)-> triggers Solid State Relay +12V power -> Battery heaters

Here's the gen start/stop quiet hours function:


Shameless plug for the Cerbo; the relays are good for 7 amps @24V so no additional relays are needed to control the 4 beehve heaters I'm using.

Hope this helps, I think you'll have to explore your settings and see what you've got available.
Bruce
P.S. Did you install the GUImods per Andy's video? Its pretty cool....

[lfhoward]

I went into the VRM Remote Console and found the relay settings. Like with your Pi, there is only one. However, I am wondering how the relay works on a Raspberry Pi. Is there a certain GPIO pin that energizes? Or two pins that get connected to complete a circuit?

On the Remote Console for relay settings, temperature is an option. However, it is not letting me use the battery temperature. Both of my RuuviTags are there, for indoor and outdoor temp. And I verified that DVCC is on and Shared Temperature Sense is enabled. No battery temperature though. That’s a head scratcher.

On the other hand, battery temperature is listed as the option for my BMV-712 battery monitor’s relay. My battery temperature sensor is plugged right into the shunt that feeds it info. This is on the VictronConnect app, not the Remote Console for the VRM.

The generator relay option has possibilities. Thanks for bringing that to my attention in the VRM remote console settings. I like how you can set the times of day. This is potentially easier than setting timed events in the other Raspberry Pi by using SSH.

P.S. Have not yet installed GUImods. Should I?

[bdosborn]

Is there a certain GPIO pin that energizes? Or two pins that get connected to complete a circuit?

Dunno, you'll have to do some digging on the Victron forum I suppose.

On the Remote Console for relay settings, temperature is an option. However, it is not letting me use the battery temperature. Both of my RuuviTags are there, for indoor and outdoor temp. And I verified that DVCC is on and Shared Temperature Sense is enabled. No battery temperature though. That’s a head scratcher.

I have two Ruuvi tags but I can only share the Victron temp probes that are connected to the Cerbo and the Multiplus inverter in DVCC. But the Ruuvi tags show up in the relay logic settings. Weird.

P.S. Have not yet installed GuiMods. Should I?

Yes, if for nothing other than it automatically re-installs the shutdown button when the system updates.
Bruce

[lfhoward]

Sounds like I am going to install GUImods then! I would love to have all the extra data it provides on the dashboard. From what I see/read, I need to install SetupHelper first, which installs from a flash drive. That takes some logistics and I might not get to it for a while, because the trailer is not parked at home.

Reading up on how the Venus GX handles relays on the Raspberry Pi, it does indeed energize a GPIO pin. A file that I can edit lives in the background and controls which pin. I am hoping GUImods gives me the ability to set more than one relay from the Venus GX, as that would simplify my wiring to eliminate the Inkbird Thermostat. Even if not, I can just run another set of wires to the other relay on the BMV-712.

In other news, my trailer battery hit 100% today for the first time since the middle of November! The sunnier parking spot did the trick.

Also, today I picked up a Victron SmartShunt from Craigslist.



I am thinking I can install it to use as a dedicated current monitor for either the shore power battery charger or the inverter. My battery charger is a Victron unit but doesn’t have a VE.Direct port. My inverter is a non-Victron unit, so can’t communicate with the VRM on its own. Whichever device I install the shunt on, I am hoping it will enable the “AC Input” or “AC Loads” section of the dashboard readout, which are blank currently:



I think those boxes are normally enabled for the MultiPlus, but I don’t have the space or battery capacity for one of those. I would eventually like to replace my inverter with a Victron Phoenix VE.Direct unit, which can communicate with the VRM. It’s also 10x more efficient at idle than my inverter now, because it has an Eco mode.



When I get this new inverter (someday, as it is pricey), my new SmartShunt will be dedicated to monitor the shore power battery charger. This is my 30A charger which is awesome but has no VE.Direct connection.



Looks like another electrical system modification is in my future!

[featherliteCT1]

Kinda like an electrical addiction ...

[lfhoward]

Kinda like an electrical addiction ...

Absolutely! Victron knew what they were doing, making an ecosystem of devices that talk to each other. I am sucked into the Victron Vortex.

[bdosborn]

Whichever device I install the shunt on, I am hoping it will enable the “AC Input” or “AC Loads” section of the dashboard readout, which are blank currently

Those values are reported by the Multiplus inverter/charger on my system. When the inverter is switched on it shows the AC power coming in to the inverter and the AC power being delivered out to the load.

Looks like another electrical system modification is in my future!

Let the mods begin!
Bruce