Lithium Battery Considerations for #586
My house batteries are on their way out. Currently they are 6 AGM batteries. I want to go with lithium and have read all of the posts here I could find.
I have 2 Magnum 3012 inverter chargers. One is currently used only for the 2nd Subzero refrigerator. The other powers the 1st Subzero refrigerator, the 120v compressor, and everything else a single inverter usually powers in a coach. I use ME-RC remote controls for each inverter.
Here are some points I’ve read about and figured out by reading my manuals and these forum posts.
1. I’ll have to use custom settings because the ME-RC does not have a preconfigured Lithium battery choice. The ME-ARC does but I’m not going to upgrade to those controllers.
2. I don’t plan on adding solar.
3. I expect we will boondock more since we are snowbirds and spend more time in cooler climates. We don’t need to run the air conditioning all the time like we did in Florida.
4. I have the big oil cooled alternator. I’m interested in NOT creating issues with this because of the low charging resistance in Lithium batteries.
5. I have the big blue isolator in the rear electrical cabinet. Alternator in post, a post for house batteries and a post for engine batteries.
6. The smartest guy I know said he went through alternators when he would boondock and just drive away the next morning letting the engine alternator charge the batteries. When he changed his MO to running the generator as well, his alternator issues were reduced (or eliminated). I don’t recall if this was on their first Newell and has been overcome when/if his second had the big oil cooled alternator.
7. If I remove the house batteries from the isolator and install a DC-DC charger (engine to house direction, 30 or 40 AMP) will this be a viable option instead of running the generator?
8. Should I set up my system to only charge the batteries from the 2nd inverter/charger because it would be more straight forward to monitor and control? As I ask this it sounds easier to manage this way but splitting the charging duties might keep heat down in each inverter/charger and battery cables.
9. My generator starts from the house batteries.
10. I don’t set the merge switch when hooked up to shore power. With Lithium when this is needed for starting the engine I should leave it merged for 20 minutes or so before attempting an engine start.
11. I’ll have to reconfigure my automatic generator start for the Lithium profile. I may upgrade to the Magnum AGS for this. I haven’t determined the original AGS settings capabilities yet.
Anything else I need to consider?
What has worked for you guys?
A couple of questions for you to throw into the mix.
Are you planning on running the minisplit on batteries? If so, what it the max time you would desire?
choice. The ME-ARC does but I’m not going to upgrade to those controllers. If the ME RC will allow you to program a CC/CV charge you are good to go
2. I don’t plan on adding solar.
3. I expect we will boondock more since we are snowbirds and spend more time in cooler climates. We don’t need to run the air conditioning all the time like we did in Florida.
4. I have the big oil cooled alternator. I’m interested in NOT creating issues with this because of the low charging resistance in Lithium batteries.
5. I have the big blue isolator in the rear electrical cabinet. Alternator in post, a post for house batteries and a post for engine batteries. You are going to ditch that isolator because it does not play well with Lithium
6. The smartest guy I know said he went through alternators when he would boondock and just drive away the next morning letting the engine alternator charge the batteries. When he changed his MO to running the generator as well, his alternator issues were reduced (or eliminated). I don’t recall if this was on their first Newell and has been overcome when/if his second had the big oil cooled alternator.
7. If I remove the house batteries from the isolator and install a DC-DC charger (engine to house direction, 30 or 40 AMP) will this be a viable option instead of running the generator? Since you have a 50DN, you will want more like 150 amp charge rate. 40 amp rate is 5 hour drive time to fully charge ONE battery
8. Should I set up my system to only charge the batteries from the 2nd inverter/charger because it would be more straight forward to monitor and control? As I ask this it sounds easier to manage this way but splitting the charging duties might keep heat down in each inverter/charger and battery cables. I would set them both up to charge, to minimize charge time while charging on the generator. I might set the cutoff criteria slightly lower on one of the chargers so that they don’t get in one another’s way at the end of the charge cycle.
9. My generator starts from the house batteries.
10. I don’t set the merge switch when hooked up to shore power. With Lithium when this is needed for starting the engine I should leave it merged for 20 minutes or so before attempting an engine start. Yes and here is why. With dead chassis batts and the amp draw of the starter, the lithium bank will pump monster amps into the wiring. You can easily blow the 300 or 400 amp fuse.
11. I’ll have to reconfigure my automatic generator start for the Lithium profile. I may upgrade to the Magnum AGS for this. I haven’t determined the original AGS settings capabilities yet.
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home )
7. Using a DC-DC charger should eliminate any issues with your alternator overheating. But your 50DN alternator probably would handle the charge rate. Overheating alternators doesn't seem to be as big an issue as it used to be. Perhaps the BMS internally limits charge rates? I guess it depends on which batteries you buy.
10. Again the BMS should limit how many amps your batteries would put out.
Thanks Richard and Forest.
My mini split runs on 240v and my inverters are 115v only. If I hang another mini split in the bedroom it would be 115v. The current AGM battery bank would run it 6 hours or so without issue.
I have seen one inverter that is 240v but I'm not going to change to that at this time. Maybe if one of my current inverters goes Tango Uniform I will get the 240v inverter charger.
The ME RC is programable to CC/CV charge.
I set up the two charging profiles identically. It seems the first inverter is in float more often than the 2nd inverter. This is just an anecdotal observation. I'll look into this more during and after my install is done.
More to follow when I do the install and have some experiences with it.
Hank you say you have 2 inverters, have you read output voltage between each other? Could be you have split phase.
OK here is my stance on Lithium and alternators.
I know of a few lithium conversions that utilize the 50DN 270 amp alternator and as of now no one has had a problem with charging the batteries and destroying the alternator but also these folks have knowledge of electricity and mechanics so if a lithium bank were to be discharged to 0 potential they would find another source to bring them back to life slowly by current limiting. I build my own batteries and install BMS's that are programmable so this is a safety feature I use. On the BMS's I use you can limit the amount of charge current or discharge current. Example: If you have your charge current limited to 75 amps and your battery is discharged deeply and requires more than 75 amps it will turn off the charge current then wait for a set time you decide and and turn back on for a programmed amount of time then back off and so on and off which is charging the batteries as a pulsed type of current protecting the alternator from a consistent huge current draw.
I have a story for you. Our battery is 1200AH @ 24vdc Lifepo4 using 48 cells in series and parallel using 3 150A JK BMS's. On our trip here we stayed a LOVES RV spot in Hattiesburg MS this was the first time for us staying at a LOVES and when you pull into your spot you check in online and plug in hook up sewer water so on. We plugged in and never paid attention to anything so we ran the air conditioner till dark and during the night switched over to heat pump, got up the next morning made coffee, used the microwave, watched TV just as normal as you can expect then I happen to look at the victron panel and seen there was no grid and hasn't been since we arrived the day before the automatic transfer switch that when you check in didn't turn on. Our batteries were at 65% so all is well and I got a refund on the site (thank you Loves) so when I fired off the engine I looked at the BMS's and two of them was drawing 35-38 amps each but the third had went into over current at the programmed 40 amp over charge I had programmed and it did the on off thing for a few minutes then it went consistent charge. The 50DN will put out over 120 amps at idle!
If you buy a factory built battery and the BMS is built in then you have no way to program this but if you feel uneasy about it just put a resettable in line breaker to the current level your comfortable with, 150 amp is a good value.
(11-19-2025, 05:27 AM)Jack Houpe Wrote: Hank you say you have 2 inverters, have you read output voltage between each other? Could be you have split phase.
(Good Idea Here) If you buy a factory built battery and the BMS is built in then you have no way to program this but if you feel uneasy about it just put a resettable in line breaker to the current level your comfortable with, 150 amp is a good value.
Jack,
I haven't checked to see if the outputs are split phase. I haven't thought about the possibility of that. The two 115v breakers that feed the inverters are side by side in the breaker panel therefore I suspect measuring the pass through AC voltage between them will be 240v. I'll measure with a voltmeter to confirm.
The inverters are not connected to each other in any way except they share the same house battery bank.
Thinking out loud about possible issues running my 240v mini split off the inverters. If going from shore power or generator power to inverter I suspect the voltage would be 240. If I go from a complete electrical shut down (no shore or generator power nor inverting from either) the output of the inverters would not be 240 between them unless I'm super lucky. I wouldn't put any bet on that. The sequence to go all inverted would be to have shore power or generator power running and then shut the incoming power off.
I'll check the outputs and respond here with what I find.
My inverters do measure 240v between their outputs so I could run my mini split of them. They have a second output I can run into a circuit box w/breaker.
This model of inverter does allow 240/120 split phase for inputs and pass through but does not invert any 240v.
Yeeha! That is good news! Keep us tuned on the size of the battery bank your thinking with the price drop of lithium over the last couple years makes lithium within range of AMG price plus you get to use 30% more of the amp hours capacity.
Another member of the forum and I just installed a 20,000 watt hour battery bank that we built which will give him 16,000 watt hour of useable power so he could realistically run one of his AC units for 10 hours. I found running the inverter mini split system in both the Newell and the Prevost not to be the biggest load, the hot water heater is a battery eating monster along with appliances you don't think about like coffee pot, toaster and microwave. We have the original refrigerator in the bus and it draws less than 400w intermittently so that really doesn't count.
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