M116A3 Build

[lfhoward]

Low temperature communication issues continue. The VRM can’t talk to the Roof Charger this morning, and that’s the charger with the battery heater attached. The charge controller turned on the battery heater before dawn on schedule and turned it off on schedule too, according to power readings from other devices. However, the battery temperature only got up to 34° because it was so cold to start with. I wanted to manually continue to run the heater to get the battery above 39°, as it wouldn’t take long, but I can’t contact the device. Now I’ve burned through 10% of the battery warming it to 34° with no chance at recharging today, unless communication returns. Those new Victron cables can’t get here fast enough. Also, the timer I ordered can’t get here fast enough. If the timer was installed I wouldn’t need to manually intervene to keep the battery heater running on a day like this. (The built-in streetlight function of the charge controller won’t let the load run during the day.)

[Capebuild]

I am totally amazed with your electronics/solar/Victron set up. I spent a bunch of time last night catching up on your posts (admittedly trying to comprehend everything). Not sure how you came to be educated with all this, but really cool! I mentioned I'm using many Victron components (BMV712, MPPT Solar charger, Batt charger, etc). When I finally get my system up and running I'll need to come back to your posts and get educated myself on what you did. Really great. Thanks for posting it all.

John

[lfhoward]

Hi John! Thanks for following my build!

I think you’ve made a great decision getting Victron equipment for your trailer. Even if you never set up any of this remote control stuff I’ve been doing lately (Raspberry Pi’s, VRM), the Victron controllers are efficient with energy, easy to use, and give great data and customizability with just Bluetooth.

Happy to help get your Victron equipment set up when the time comes, though! It sounds like you have a lot of the same components I do. Also, if you want beehive heaters and a thermostat to keep your LiFePO4 battery warm, I can walk you through that setup.

[lfhoward]

Now that it’s noon and the temperature is rising above 20°F I am starting to see all the devices on the VRM again. Check out all the lost data overnight and this morning. At minimum every hour should have a short red bar and there should be charging today but there wasn’t.



This is not to say the Victron devices themselves aren't working. They are. If I was standing next to the trailer I could go through the history on each device via Bluetooth and it would show they were on. What’s not working in the cold is just my remote monitoring, specifically the cable connections between each Victron device and the Raspberry Pi running the VRM. I will be replacing the cables with Victron ones next week.

[lfhoward]

John, you asked about cell balancing. Looks exceptional at the moment. This is from my Overkill BMS.

[John61CT]

Fantastic (lack of) delta, probably within precision error there!

Just keep an eye on that if you stay below 3.50Vpc for months at a time

but even a 50mV spread is really NBD

[lfhoward]

Snow is predicted overnight. I remotely turned the battery heater off so it won’t waste energy tomorrow morning when the solar panel will be covered with snow. This is the beauty of the VRM!

Also, today was a good charging day at nearly 400 watt hours (30 amp hours). Seems pretty good for January!

[lfhoward]

Trying a different parking space that gives me 5 hours of good sun instead of just 3 hours.



Tomorrow will be super cold again, but I am hoping to get positive amps by the end of the day even after subtracting the current used by the battery heater. Fingers crossed.

[John61CT]

Cold helps output

[lfhoward]

Cold helps output

Low of 11 tomorrow morning. If I can get the battery's temp up to 39 by the time the sun comes up, it could be a record breaking day. My weather app says sunny all day long, with a high of 28.

[featherliteCT1]

Sounds like your new parking spot will significantly increase your solar harvesting yields, hopefully enough that you will not need to be be overly concerned with keeping your battery(s) charged. My fingers are crossed for you!

[lfhoward]

Sounds like your new parking spot will significantly increase your solar harvesting yields, hopefully enough that you will not need to be be overly concerned with keeping your battery(s) charged. My fingers are crossed for you!

Thanks, I hope so too. I know that when the days get longer and battery heat is no longer required it will be no issue. But I want to see if I can make this battery setup work in January without periodic shore charging. The battery was at 75% this afternoon when the sun went down. I’ll report back on where the battery percentage lands tomorrow at the same time.

[lfhoward]

Solar charging is going great today! Good solar watts started coming in around 10 am. Now at noon here are the stats:



Just before the sun came up, the battery percentage was around 65%. Hoping to hit 80% by the end of the day.

[lfhoward]

I would call changing to this new parking space a smashing success. Here is how things ended up.



This morning I was looking at 65% full, now 88%! The solar panel made 660 watt hours today (50 amp hours!). It should be no problem maintaining the charge while the trailer is parked here.

[lfhoward]

Another good day of charging. I am getting to know the behavior of this new battery and the Victron solar charge controllers, so I have been keeping pretty close tabs on things as I learn. Maybe details like this will be helpful to others who set up a similar system.

Today of course the battery heater needed to get things warmed up before charging. The state of charge bottomed out at 79%, which is 37 amp hours below “full” (which we know is itself 16 amp hours less than really full, after the last automatic battery monitor synchronization). During the morning, charging ramped up to over 100 watts until about noon. At that point, battery voltage hit 13.8 and the system switched over from bulk charging to absorption mode. The charge percentage now reads 89% (19 amp hours below “full”). After 2 hours of absorption at 13.8 volts, it will float at 13.5 volts for the rest of the day. I wonder how I can get a 100% charge out of the system? I had reduced the target voltage from 14.2 to 13.8 last week. Is this the difference in getting those last 19 Ah? Or is this 19 Ah difference nothing but battery monitor drift and what it needs is to synchronize to 100% again?

Battery Gurus, please chime in.