Multiplus Charger settings?

[pda1]

I've installed my Multiplus Compact 24v-2000

The batteries connected to the Multiplus are two Battleborn in series for a 24v system.

What I need to know are;

- In the Multiplus Charger tab- what are the settings? I'm getting conflicting information what they should be.

Thanks

 

[Supervstech]

Do you need general charge settings?
Lfp is 3.4v/cell float, 3.5v/cell up to 3.65v/cell,NEVER ABOVE 3.65/CELL

24V is 8 cells.

 

[pda1]

According to this from Battleborn from this document the charger Absorption voltage should be 28.8 and Float 27.6
My Victron MPPT has absorption set to 28.4 and Float 27. Those figures were recommended by BB.

Multiplus 24v-3000w charger settings

 

[Madcodger]

In general, I think it best to follow the recommendation of the battery manufacturer. They know THAT battery best. Victron is trying to offer a setting that works reasonably well for many different batteries of a particular type, but not your specific battery.

All that said, I think a lot of brain cycles are wasted on battery tweaking. I've fiddled around with programming my Multiplus based on a lot of theories, all backed by what sounds like good logic from the "gurus" here and on YouTube and other sites. At the end of the day, I probably won't know the "truth" for years, if ever. So, I just went with the battery manufacturer's recommendations and called it a day. And all seems well...

 

[pda1]

Well, I think in the final analysis you're correct. I've "worried this installation to death". So, here's what I did- called BB and the helped me reset all of the settings to what they should be.

My system's a simple 2 kW. Batteries and I DO NOT get along well. The sad commentary of my life is "dead batteries". That being said, I'd be more than concerned when the SOC got down to 85% during a cloudy day and I never ran the inverter at night. So, Battleborn techs told me, in essence, "you've got to cycle your batteries to a lower SOC". That's really relieving as I was certain I'd destroy them by dropping the SOC to 60% and lower.

We shall see.

 

[Rocketman]

With Lithiums (Battle Borns) don't worry about them too much - they are just fine getting to 10 to 20% - I assume you have a BMV or SmartShunt in your system so you know how full or empty the battery is.

Because I depend on my Batteries (Full-Time in a MotorHome, and I DIYed my own batteries), about once a year or so I do a battery capacity test.

This is my procedures: Fill the battery to the end of the absorbing period, disconnect solar (all my charging), then turn on all lights and use the inverter (I will usually bake brownies in my Microwave/Convention oven - just because...) Then when the batteries are getting under 20% I put on a heat gun on the inverter. I want the inverter using about 750 to 800 watts. I continue to drain until the inverter shuts off (low voltage) the first time. That is the end of the test - time to recharge. That's my useable capacity. I reset the Smartshunt with the new AmpHour level and have a discharge floor of 5%. Yes the "true floor" is more than that, but this is my useable capacity. I run the test the same way every time.

This helps me not worry that just because my battery level is a bit low, I really won't run out of useable power.

One thing you need to watch is to make sure the two 12v batteries are both at the same voltage - both on the Full end and on the empty end.

Good Luck

 

[pda1]

I "balance" them once per month.

 

[Madcodger]

Man, I feel like a neglectful parent... I set them up and tweaked and fretted for 2-3 months, before I finally said "to heck with it" (G-rated version) and just let the batteries and inverter and SCC all coexist without much more than glancing at the SOC on my phone and thinking, "Huh - that's lower/higher/about where" I'd have guessed. And then I resume life.

It'll be interesting to see how it all works out. When the SOC gets below 30% this winter the Multiplus will turn on the generator start relay, and that will actually turn on a z-wave dry contact sensor that tells my Hubitat automation device to turn on an AC switch back in the garage to feed power to the Multiplus. When it gets to 85% it'll tell it to turn off. I'll probably let it run to 100% every month or so just for good measure and curiosity. Other than that, the chips are gonna fall where they fall, in large part to see what happens.

Start the popcorn popper. Will report back. Please don't call battery protective services to report me.