Itinerant1 wrote:BFL13 wrote:
We always are off grid except at home, so redundancy is good. Don't want to have to bail and go home early.
Itenerant1, how did the sequence work when you had your BMS shut-down when one of your cells "went rogue"? In particular, how did you get your Magnum to light up so you could use its charger with the House batts shut down?
This all happened while I was away working in a different state and wife was with the 5th wheel and going on 1,017 days of continuous boondocking and never an issue.
Cells didn't go rouge they shut off charging acceptance due to low cell temp (bms doing exactly what it was designed to do). The batteries were still able to power the rig "but" without charging time is against you. Once the cells warmed up above 32f solar started to charge but this was in the afternoon when it started charging. Generator ran out of gas and she couldn't get it going again. Next night before me coming home she called me and said the system shutdown "no 12v power". She had no idea why. This happened in Nov 2019 while in Kansas with nighttime lows between 7-11f, daytimes just above freezing (cold front dropped down).
Temporary solution... she winterized the trailer (we carry rv antifreeze with us during cold months), pulled out the big buddy heater.
Cause of the system shutting down was one of the senseboards on the cells stopped communicating with the cpu, it did exactly what it's supposed to do...shutdown (one of many safety features, if it doesn't see 20 cells it shuts down). Why did the senseboard die, I don't know why...age, electronic failure or just sheet happens?
When I returned I picked up a new eu2200i generator on the way back. I wanted to upgrade the eu2000i anyways this just sped that up.
First thing I did was put a multimeter on the pack and it was showing 13.28v so it was ok and had a charge. I talked to my installer and he explained how to bypass the cpu (bms) "but" doing this the 20 cells were unprotected.
Now for the next part of the problem, the batteries were not being charged from the Magnum inverter/ charger or solar. After talking to the installer and trying different things...nothing, no charging as if the system was dead but I could see the lights on the equipment showing power? In the meantime plugged in a car battery charger (10a) to the generator so not to kill the batteries while thinking about my options.
After thinking about this overnight, the next morning I went and looked at the Me-Arc setup menu for the system and everything was not as it was set up originally, it cleared itself back to factory settings. After 15 minutes of resetting all of the setup menu from before these issues started the system was back on line charging properly from both the inverter/ charger and solar. I was told that Magnum equipment will remember settings if this were to happen...well it didn't.
This was a inconvenience for sure, more for the wife than me because she was with the trailer and I was in a hotel room that night.
Leason learned from this experience.
Keep generator full of gas. ๐
How to bypass cpu.
Don't go off the word of others, check everything including settings.
Carry extra senseboards now.
Don't put off insulating compartment, tapped into furnace heat duct.
Everything thing is written down now with pics if I'm away and the wife has to do it. Good thing I wrote the settings down that were programmed originally because 3 years later I wouldn't of remembered them all. Hint to all write your settings down, you never know.;)
I like to think I was prepared but this showed the wink links that needed attention to. ๐
Something else between "dropin" and a more diy system is the control over exterior components verses the sealed box. It won't be the end of the world just some inconvenience, you hope anyways.
This is exactly why I went with a hybrid LFP-FLA system. Here is an voltage example of when the was a software SOC error. The LFP BMS shut down shortly after sun up charging started.
pianotuna wrote:
To use a phrase I started here, many years ago. "capacity is king". Design sufficient worst case capacity and add 10 to 20%. That may lead to lack of angst on camping trips.
Itinerant1 has done so, and any thinking person would do the same.
BFL13 approaches solar and storage from the minimalist point of view and has great fun doing so!
For those interested.
I had plenty of time on my hands yesterday so decided to do a daily use recording. I do this periodically so I can go back in time and cross reference loads to SoC to Voltage to see if anything is amiss or losing capacity.
This here also shows that unless you are coulomb counting it is almost impossible to get an accurate SoC to voltage especially if there is any charge/ load even a small amount will matter.
We normally would of run from the heat by now but I have a couple more days of business before moving to cooler weather. I did record what the solar was contributing during the day at recording times along with outside ambient temp (F). If you look at the remarks you'll see gen started for the air conditioner/ 120v loads and solar is just charging batteries/ 12v loads. Once the batteries are full the gen is turned off and batteries/ solar is running the entire loads for a couple hours, after that the gen is started again to keep the trailer cool for a short bit longer. Using the batteries till 65% +/- Soc gives plenty of power for the night/ morning till the sun comes up and recharges to do this over again. Saves a couple hours of gen/ gas each time if it's hot.
The microair add on last year is doing a great job of slowing the current from the locked rotor instead of throwing 200a at once.
Solar production past 2 days.
