Interested in Lithium

[DesertRat87]

I currently run a Morningstar Tristar with approximately 800w of solar on the roof which feed (4) Trojan T105 6v batteries. My family and I do quite a bit of off grid camping, often times extending to 5-10 days at a time. The current batteries will probably get me by this year without issues however when looking at some of the Chinese lithium batteries one can’t help but be intrigued.

I do not have the cables to custom program my Morningstar controller and have reached out to Watt Cycle for their bulk/absorb/float rates and believe that I can get close enough with the preset options on the controller. The age old saying, more is better comes to mind being that I have room to replace the 4 lead acid batteries with 4 lithium however is that really needed? The lithium batteries have a much lower discharge rate so im leaning toward trying two and calling it a day.

I’m really looking at Watt Cycle, at $170 a piece for a 12v 100AH battery and watching the deconstruction videos showing that claimed features do in fact work I believe the price is worth the gamble. They claim 5000 cycles at 100% DOD, 6000 at 80% DOD, and 15,000 cycles at 40% DOD and provide a 7 year warranty…pretty good in my opinion.

My questions are this:
Is 200AH with 800w of solar enough to stay up or should I move forward and purchase 4?

Would I need to purchase a different inverter? Currently own a magnum 2000 and if not are there any settings that need changed to support the different battery type?

The controllers closest feature would be 14.4v bulk/absord with 13.5v float. Watt cycle states 14.6 +/- .2v is preferred and if I understand lithium float charging isn’t necessary.

Please forgive my ignorance, electrical components have never been a sting suit of mine. Appreciate any thoughts…I’d really like to stay away from replacing equipment at all costs however it was truly required if have to consider simply due to the discharge voltage capabilities of lithium vs lead acid.

[DarkSideJeep]

I just replaced the four L16 6V total 780 Amp Hours with 3 300AH WATT Cycle LiFePo4 batteries Total 900AH total. Along with that I replaced the two 100watt solar panels with two 400watt panels. I just spent 6 days boon docking at Quartzsite the limiting factor is tank capacity in all three tanks. I did run the generator, but I am sure in good sunlight conditions that would not be necessary as long as AC is not required.

[DesertRat87]

By tank capacity are you suggesting that 900ah weren’t enough to boondock for the entire trip? Did you have adequate sunlight during the trip? We boondock every Thanksgiving for 9 days. While I don’t mind the generator running at times I’m hoping that the 800w of solar will keep up the battery. My biggest concern is wondering whether or not 200ah is enough or if I should elect for more storage?? Lastly, would you recommend Watt Cycle or possibly another brand? I cannot allow myself to purchase battle born or equivalent at the price point when so many other lower priced options exist nowadays.

[hjabernathy]

I’ll risk throwing myself to the sharks and offer my experiences and opinions. I started RVing in a Bigfoot travel trailer on which I installed a solar power system. It consisted of two residential 260 watt panels, four Trojan 305 12-volt lead acid batteries that weighed 100lbs EACH, a TriStar 45amp controller and a 2800watt Magnum inverter. The system worked flawlessly for the five years that we had the trailer excepting one thing. One cell in one of the batteries failed in year four. Every time I had to move those four batteries was a major work order - 400lbs, need I say more.

In 2020, we purchased a 34’ Newmar motorhome. I installed a solar power system in that coach. This time I went to lithium batteries. I chose Battle Born. At that time, there weren’t nearly as many lithium battery manufacturers as there are today. I paid $890 apiece for the four 100Ah batteries deciding that I’d go with the best. I just purchased two more in late 2024 at $674 apiece and am installing them this spring to bring our total battery storage to 600Ahs. You get what you pay for in my opinion. I installed the batteries in the living compartment, under the lift-up sofa, so that I never have to worry about charging them in freezing temperatures. I used Victron components: 150/100 controller, 3000watt inverter, Cerbo GX monitor with the color touchscreen. Some would say that I go overkill when I use 4/0 cable between the batteries and the inverter, but I prefer no line power loss. I put two REC 365watt residential sized panels on the roof wired in series on tilt-up mounts.

This system has performed outstandingly and flawlessly for four years. We are fulltime. We spend several months in RV parks in Arizona and California in the winter since we belong to an RV timeshare. However, we do most of our camping boondocking. I will NEVER return to lead acid batteries. The Battle Borns weigh 31lbs each; I can pick one up with one arm. However, I’ve never had to move them since installing them. I can also run the lithium batteries down to 20% without worries; however, I never discharge them more than 50% and rarely do I go below 60%.

Late in 2024, I switched to a JC Refrigeration 12-volt 17cf Dutchaire refrigerator, ditching our 12cf NoCold condenser nightmare. We are finally loving life in regard to RV refrigeration. The ice cream stays firm if not solidly frozen in contrast to the soft, or melted mess, from the NoCold. And the freezer never develops a thick crust of ice as the NoCold regularly did.

The SOC of the batteries rarely dips into the 50% range overnight since installation of the 12-volt fridge. It typically drops to the mid to high 60% or low 70% range which is just fine with lithium batteries. They will typically be fully charged in late morning or early afternoon with our panels tilted up in the dead of winter in the American Southwest. While traveling to the northern regions, Pacific NW and Canada, in summer months, we rarely have to raise the panels to achieve full charge by midday. Admittedly we haven’t traveled north with the new fridge yet. That’s coming this year when we make a return visit to Alaska.

I am aware that you were asking about Wattcycle lithium batteries. I did come across one review that was far from glowing; something about them coming upside down in the shipping box and this adversely affecting them. He wasn’t getting much help from the manufacturer. I can assure you that Battle Born answers their phones and provides wonderful customer service. I have no knowledge with Wattcycle batteries nor do I know anyone who has them. I do have a friend that went with low cost lithium batteries of a brand I’m unfamiliar with, four 400Ah batteries at $1500 each. He’s had them about a year and they aren’t charging properly nor holding a charge well.

[DesertRat87]

Thank you for the reply. I do have concerns with the Chinese companies regardless of their “warranty” claims. If they go under or change names, the consumer is left holding the candle. I’ll await some others who may have tried them, I’m still rocking my Trojan T105s which should last another season, maybe two, but I’m really wanting to jump on the lithium train. Thanks again.

[B-Man]

What amperage is the BMS in that battery rated for? Typically, the cheap Chinese batteries are limited to 100 amps. Your inverter will require way more than 100 amps if you load it up.

You should do some math and measurements on what your typical electrical consumption is BEFORE you buy any battery.

Usually, you would be better off buying a 200AH battery. Slightly larger footprint and usually available with a 200 amp BMS. Two in parallel will be 5,520 WH of available power.

Make sure your MPPT is capable of delivering that 800 watts of solar at 12VDC.

[SafariBen]

Originally Posted by DesertRat87

By tank capacity are you suggesting that 900ah weren’t enough to boondock for the entire trip?...

"Three tanks" refers to the water situation, fresh, grey and black water tanks.


None of us can tell how much electricity you use daily. Your current use with the current batteries is the best estimate, so measure that, with a shunt ideally, or by SOC of the batteries after a night of use, then repeat with a known load to that SOC.



Anytime anybody mentions 4 parallel batteries, you have to consider if one 48v would work better. Often you already have the other components, but from scratch, there's usually an advantage to 48V.

[Tony Ramirez]

DesertRat, spend Thanksgiving in the desert for a week also. Although I'm RATED @ 1100W of solar, the angle of the sun got me a max of 550W during last year's trip. If it won't break the bank, I would go w as much batt as you can fit & afford. JMO. I was able to fit 2 460AH batts in just a hair bigger than the footprint of 4 T105s, got rid of the other 2 105s, & now w my solar, RARELY worry about my batt levels.

Does your Magnum have a "Custum" setting? If so, you can set it to what the Batt manufacturer suggests. Mine like 14.2v Absorb, 13.5 Float.

[Stircrazy1]

Originally Posted by DesertRat87

The age old saying, more is better comes to mind being that I have room to replace the 4 lead acid batteries with 4 lithium however is that really needed? The lithium batteries have a much lower discharge rate so im leaning toward trying two and calling it a day.

I’m really looking at Watt Cycle, at $170 a piece for a 12v 100AH battery and watching the deconstruction videos showing that claimed features do in fact work I believe the price is worth the gamble. They claim 5000 cycles at 100% DOD, 6000 at 80% DOD, and 15,000 cycles at 40% DOD and provide a 7 year warranty…pretty good in my opinion.

My questions are this:
Is 200AH with 800w of solar enough to stay up or should I move forward and purchase 4?

Would I need to purchase a different inverter? Currently own a magnum 2000 and if not are there any settings that need changed to support the different battery type?

The controllers closest feature would be 14.4v bulk/absord with 13.5v float. Watt cycle states 14.6 +/- .2v is preferred and if I understand lithium float charging isn’t necessary.

Please forgive my ignorance, electrical components have never been a sting suit of mine. Appreciate any thoughts…I’d really like to stay away from replacing equipment at all costs however it was truly required if have to consider simply due to the discharge voltage capabilities of lithium vs lead acid.

first question, how low do your 6V batteries get now? if you are never below 50% then that is 200Ah (aprox) you drop them down so if you had 2 100AH life PO4 batteries they would be cycling down to 0 so you would have no reserve. so 4 would be the best option in that case. plus having 4 gives you extra capacity if you hit cloudy days. I size my batteries to last the average time of my camping trips just incase something goes wrong with the solar. I have had 3 days of overcast rain where I got next to no charging, so that is something to consider.

do you ever have a problem with not being able to run something with the inverter you have now? if not why buy another one, this one will actually work better as it will go longer before the low voltage alarm goes off.

you also have to look at the BMS output and make sure it is enough for your inverter, 2000 watts could pull almost 200amps when you take surge and inefficiency's into consideration so if it is 100A BMS you want at least three batteries and for the price might as well get 4.


those voltages will work just fine. 14.4 will still get you charged and ballanced and 13.5 is ok for a float.

[Stircrazy1]

Originally Posted by B-Man

What amperage is the BMS in that battery rated for? Typically, the cheap Chinese batteries are limited to 100 amps. Your inverter will require way more than 100 amps if you load it up.

You should do some math and measurements on what your typical electrical consumption is BEFORE you buy any battery.

Usually, you would be better off buying a 200AH battery. Slightly larger footprint and usually available with a 200 amp BMS. Two in parallel will be 5,520 WH of available power.

Make sure your MPPT is capable of delivering that 800 watts of solar at 12VDC.

he has a 2000 watt inverter so 166amps at 12.0V maybe a little more, he is planning on at least two batteries that gives him 200amps minimum, if they have a bigger BMS thats even more.

[DesertRat87]

Originally Posted by B-Man

What amperage is the BMS in that battery rated for? Typically, the cheap Chinese batteries are limited to 100 amps. Your inverter will require way more than 100 amps if you load it up.

You should do some math and measurements on what your typical electrical consumption is BEFORE you buy any battery.

Usually, you would be better off buying a 200AH battery. Slightly larger footprint and usually available with a 200 amp BMS. Two in parallel will be 5,520 WH of available power.

Make sure your MPPT is capable of delivering that 800 watts of solar at 12VDC.

The Watt Cycle batteries have a 100amp BMS like you suggested. Instead of a 200ah battery, wouldnt (4) 100ah units be best?

Originally Posted by Tony Ramirez

DesertRat, spend Thanksgiving in the desert for a week also. Although I'm RATED @ 1100W of solar, the angle of the sun got me a max of 550W during last year's trip. If it won't break the bank, I would go w as much batt as you can fit & afford. JMO. I was able to fit 2 460AH batts in just a hair bigger than the footprint of 4 T105s, got rid of the other 2 105s, & now w my solar, RARELY worry about my batt levels.

Does your Magnum have a "Custum" setting? If so, you can set it to what the Batt manufacturer suggests. Mine like 14.2v Absorb, 13.5 Float.

I am not sure on the Magnum inverter having a custom setting. I will need to run through the manual to confirm this. The solar charger has settings that I can tailor to but Im guessing the inverter needs to have this setting when hooked to shore power? Other than shore power charging, wouldnt the inverter just convert 12v power from the batteries to 120v inside the coach?

Originally Posted by Stircrazy1

first question, how low do your 6V batteries get now? if you are never below 50% then that is 200Ah (aprox) you drop them down so if you had 2 100AH life PO4 batteries they would be cycling down to 0 so you would have no reserve. so 4 would be the best option in that case. plus having 4 gives you extra capacity if you hit cloudy days. I size my batteries to last the average time of my camping trips just incase something goes wrong with the solar. I have had 3 days of overcast rain where I got next to no charging, so that is something to consider.

do you ever have a problem with not being able to run something with the inverter you have now? if not why buy another one, this one will actually work better as it will go longer before the low voltage alarm goes off.

you also have to look at the BMS output and make sure it is enough for your inverter, 2000 watts could pull almost 200amps when you take surge and inefficiency's into consideration so if it is 100A BMS you want at least three batteries and for the price might as well get 4.


those voltages will work just fine. 14.4 will still get you charged and ballanced and 13.5 is ok for a float.

I am not sure on the true percentage on a full day or weekend of dry camping. I just installed a blue tooth monitor as I was wondering the same thing and will get a few changes to test this out over the coming months. With the current set up we are able to run everything in the coach including the mircrowave, nothing to this point has given us issues.


I really need to do some more research and document the performance of the current 6v system before moving forward. Some days were in the side by sides all day and the solar is more than enough, other days my wife will stay at camp and watch a movie etc so I need to document both scenarios before jumping in. Worst case scenario is we fire up the generator, I guess my concerns are damaging the LA batteries by using them below 60%...maybe I should not be too worried at this time and I wont know until our next trip.

[Tony Ramirez]

On your Magnum screen, push Setup, then rotate knob to Batt Type. If the last option is custum, push the knob to select that & you can set the voltages. If there's no "custum", you might be out of luck. But if you can set your solar for the recommendedsettings, you should be okay. When on shore/gen, it would charge, just not bring them up to 100%, which is fine.

W 400AHs of Lithium, you're almost doubling the amount of "Usable" AHs than the 4 T105s. Voltage curve is MUCH better for all the electronics, plus less telling the DW "Turn that Off".

[DesertRat87]

Originally Posted by Tony Ramirez

On your Magnum screen, push Setup, then rotate knob to Batt Type. If the last option is custum, push the knob to select that & you can set the voltages. If there's no "custum", you might be out of luck. But if you can set your solar for the recommendedsettings, you should be okay. When on shore/gen, it would charge, just not bring them up to 100%, which is fine.

W 400AHs of Lithium, you're almost doubling the amount of "Usable" AHs than the 4 T105s. Voltage curve is MUCH better for all the electronics, plus less telling the DW "Turn that Off".

I have the options of Gel, flooded (selected), AGM, AGM2, and nothing else. Editing this response as I reread the your reply. Ill do some digging to see if a plug and play upgrade from Magnum exists for a reasonable amount of money to satisfy our needs.

[Mark_K5LXP]

I guess my concerns are damaging the LA batteries by using them below 60%..

You are not damaging LA batteries even if you take them to 0%. Really. The 50% Rule does not apply in this application (and nearly any other one). If you're stopping short of 50% all you're doing is inconveniencing yourself by not running your stuff, and taking lots of unused capacity to the recycler when they fail for other reasons.

My take on it would be to crunch some usage numbers and see what your typical Ah draw is on a given trip, and also peak amps. You might have a 2K inverter, but do you ever draw 2K out of it? Maybe half that to run a coffee pot or whatever? That makes a big difference in the required delivery and capacity of any battery bank.

Another observation is the specific charge profile for the Li battery is for 100% charge, all the time. When you're boondocking with solar, it will be a rare occasion if you care about ever reaching 100% with any regularity. Generally an AGM charge profile will get you nominally 90% without trying, if that 10% margin makes a difference then you're cutting your capacity requirement very close. My vote would be to run it and see how it does for you. Daily charging to ~90% with solar would be a home run, my bet is you'll be lucky to hit that day to day on just solar. Check the box if your solar supplements your use during most or all your trip. If you break camp at the same time your batteries go flat, that's all the better it needs to be.

Mark B.
Albuquerque, NM