Although we enjoy boondocking with our lithiums (Battleborn), there are periods when we're hooked up to the pedestal at a park or on 50 amp here at home.
I reached out to BB to ask best practice in maintaining batteries during periods hooked up to pedestal. They advised weekly run down of house to 13.2v (about 80-90% SOC). Only consumes 10-20% of a full cycle. Then charged to 100% allows battery BMS to rebalance cells during absorption phase.
Longer times at 100% SOC allow battery to become imbalanced reducing performance until balanced.
We're limited in travels this year so glad to know how to keep this investment producing the long term results we expect.
Especially impressed with the personal phone call outreach from BB. They clearly want their customers to get the best from their product.
As always only my 2 cents.
Randy,
Thanks for posting this. I built my own LiFePO4 batteries so only have various forums for support. It is good to get this (second hand) information from the real professionals. I will take it to heart.
Richard
How are your batteries doing Richard?
Hi Tommy,
I am very pleased with them. I really enjoyed the experience of learning about and building my lithium batteries and I thank you for your help and encouragement to that end. I definitely do not regret the process but with all the excellent fairly reasonably priced drop-in replacement batteries available today, I probably would opt to just buy factory built (and warrantied) Lithium batteries.
Richard
I would think you can turn the float down to 14.0 or less when plugged in for large amounts of time... I leave a light on most times (except when sleeping. For the draw down.
I'm pretty sure Battle Born indicates that their batteries don't need to be float charged but recommends 13.8 V or less if you do float charge their batteries.
Thats why I leave a draw on mine.. DOnt have Battle Born though.
When i reached out to Battle Born, I was told not only that their batteries don't need to be float charged, but that float charging for long periods of time (such as when hooked up to shore power for weeks) can be harmful to the batteries.
You also need to keep in mind the 12v system is in use even when "Floating". Every time you use the interior lights/ Compressor and so on..
Like I said.. If you leave a Draw it will cycle.
I came to the bus and all of the electrics were shut down. The Lipo batt showed 8?volts . The solar chargers won't activate this low , so every thing was dead .
The only draw was the fridge at .8 amps and possibly the volt meter in the overhead cabinet was loose and warm.
This has never happened before withe the LA batts.
So the gen set won't start and I would have to start the engine to charge the system enough to get the solar back in action.
At this point , I removed the voltmeter , checked for draw and will shut down all of the chargers for the rest of today and monitor the system . I don't like that stress if total shut down and the solar useless.
Had this happen.. Put a charger on it and everything will turn on at about 10v ... Came home from vacation (remodeling the house) at 2am after 14 hrs of flying and my batteries were at 7v.. Took about an hour of charging and was able to get some lights and get the thermostats working.. Found and fixed my problem (transfer switch was bad and popping the breaker the inverter was on).
FWIW, BB told me that once batteries get too low they need to be disconnected and individually charged with an external charger. In fact they said to call if this happened and they'd walk me thru how to bring them back without damage.
Its bottom or top balancing. I like bottom as it gets the lows in place but really either works. The battery bms should take care of that.
Does anyone use a low volt disconnect? Like this? Amazon.com: Victron Energy Battery Protect 12/24-Volt 65 amp : Automotive (https://www.amazon.com/Victron-Energy-Battery-Protect-24-Volt/dp/B01N6ATT8C/ref=asc_df_B01N6ATT8C/?tag=hyprod-20&linkCode=df0&hvadid=216539147262&hvpos=&hvnetw=g&hvrand=16108012815668088369&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1015202&hvtargid=pla-369750032069&th=1) Seems as tho it might save a lot of batteries.
The low volt disconnect is built into the BMS of most lithium batteries, mine for sure.
Reading my shunt. It looks like I have a steady 13 amp draw. That seems like a lot even with the fridge running. Maybe my inverter is faulty ?
Without the inverter the draw is 3 amps.?
My Xantrex SW 3012 draws 5 amps even at idle. That is the specs for it, it is not failing.
Yes, that's the unit I included in my install.
EDECOA 2500W 5000 Watt Power Inverter Pure Sine Wave 12V dc to 120V ac LCD... (https://www.ebay.com/itm/233644494775)
I have 2 of these , 1000 watt for the fridge and office stuff. 2500watt for the AC and blender .
The idle amps are very low . Both tested the same at under 1.5 amps. My shunt reads not exact at that low of load but both read the same with no load . Spec says under .35 amps . Very possible . I really like them . Price is fair .
My house is under 4 amps with some of the LED lights on and with my tiny computer style pancake fans in the bedroom .
I thought that my cheap alternator maybe had a bad diode or some other failure. But it test perfect. My engine fans are also wired directly to the house batteries . Plenty of places for electric leaks .. Again, test showed zero draw unless running the fans . No relay draw , nothing.
The amp draw showed the largest load was my desk outlet. Computer charger, printer, sound bar, etc. Almost 7 amps .
So, turn off the desk plug, move the inverters so that I can use either and not require both to be on. Now my draw is about 5 amps when the fridge runs . That should keep the batts up for at least 24 hrs .