Dual or Single Lithium Battery option

[Bread]

Getting ready to order a new Fleet Shell and trying to decide if I should upgrade to the dual lithium batteries vs the single that comes stock.

My 2014 Fleet Shell had a single AGM deep cycle battery and it did a great job powering my Engel fridge, fantastic fan and led lights. I had one 100 watt solar panel on the roof that kept everything running fine for weeks at a time when the camper rig was just sitting. That said, it was operating at the edge of its capability and several cloudy days in a row could be challenging.

I plan to run the same Engel fridge in my new camper, led lights, and two fans instead of one. Might also be nice to have enough juice to charge a phone now and then.

Thinking I will have 250 watts of roof solar this time (two 125 watt panels).

Should I upgrade to dual lithium’s?

 

[craig333]

You can never have too much but for your use I'm thinking a single 100ah lithium battery would probably be fine.

 

[nikonron]

A single I think will be more than enough, I run a single with ARB fridge, diesel furnace and LED lighting and never get it down to less than 75%. Personally I would build my own system, you'll have better components and do it for less dollars with a better job.

 

[Dirtroadsavant]

We have a 100 ah SOK battery running the lights, furnace, and 130l fridge. We’re out for 8-10 week trips and have never been below 75% and I am VERY happy that we are not lugging around more battery than we need. We have 160 watts solar on the roof and a 200 watt portable for cloudy days but have only used it once. Enjoy your new rig!

 

[Jon R]

This is really a question you should answer for yourself based on the type of trips you anticipate and the weather and sun where you expect to go.

I have pretty much the same loads as Dirtroadsavant. I live in Western Washington and do quite a bit of local camping, including in the off season, which means I can’t always rely on solar charging.

I use about 40 ah per day winter or summer. A 200 ah battery allows me to camp at least 4 nights in the clouds and trees without having to start the truck or use external power. 400 watts of solar panel allows me to recover at least a day’s worth of energy on cloudy days in March through October. A 30 amp dc to dc converter allows me to recover a day’s worth of energy in 90 minutes of driving.

Battery sizing should be based on your loads and on how long you would like to be able to go without any charging. For most people, especially those with solar who camp in sunny weather, 100 ah of usable energy is probably plenty.

 

[CPT Davenport]

No need for double lithium. I run a single 206ah SOK and have been very pleased. It fit perfectly in the same spot the factory AGM was in. Better to have the storage and not need it, then need it and not have it. No disadvantage really to having more available power except the weight (and higher cost I suppose). In my case the 100ah was 28lbs and my 206ah is 48lbs. Amazon.com

 

[Vic Harder]

+1 to what JonR said.

 

[campito]

I have a 2012 Fleet with 300 watts, one lithium battery. System installed by Zero Declination and they recommended one battery as more than enough. It runs my frig, heater, lights, charges my laptop, phone, ipad, headphone, and lots of rechargeable batteries for my various photography needs. Never come close to needing more. After 10 years of fighting power needs, my frig keeps temperature and I seldom look at my battery state anymore. I live in Bishop and frequent Death Valley and spend months in Canada last two summers.

 

[ckent323]

I agree with JonR.

We have two Lifeline 6v, 220Ah AGM batteries. They are 6 years old and even after two multi-month trips to Alaska and back they work great. Never discharged more than 50% and usually less than that. Always recharged everyday. 360W solar with Victron controller keeps them charged. The BlueSea ACR, protected by 80A resettable breakers at the starting battery and the house batteries, allow jump starting the truck or charging the house batteries from the alternator (however I have never needed to do either).

Yes Lithium would weigh less. Yes Lithium costs more. Yes, Lithium would require a DC-DC charger if I wanted to connect it to the truck (it has AGM start battery).

If/when my batteries reach end of life I will likely switch to AGM to lessen the overall weight and save on room. But that will come at a greater cost than replacing the AGM batteries. I can afford that but not everyone can.

There are other pros and cons.

Risk of an uncontrolled fire with Lithium is a real risk even of the probability is low. Cold weather performance could be a factor for a winter camper.

Either approach can work well.

I hope this is helpful.

Craig

 

[Jon R]

LiFePO4 batteries are much safer than lithium ion battery types. From lithiumhub.com:

Safe, Stable Chemistry​

Lithium battery safety is vital. The newsworthy “exploding” lithium-ion laptop batteries have made that clear. One of the most critical advantages LiFePO4 has over other battery types is safety. LiFePO4 is the safest lithium battery type. It’s the safest of any type.

Overall, LifePO4 batteries have the safest lithium chemistry. Why? Because lithium iron phosphate has better thermal and structural stability. This is something the lead acid battery type and most other battery types don’t have at the level LiFePO4 does. LiFePO4 is incombustible. It can withstand high temperatures without decomposing. It’s not prone to thermal runaway and will keep cool at room temperature.

If you subject a LiFePO4 battery to harsh temperatures or hazardous events (like short-circuiting or a crash) it won’t start a fire or explode. For those who use deep cycle LiFePO4 batteries every day in an RV, bass boat, scooter, or liftgate, this fact is comforting.

(End paste)

 

[Wandering Sagebrush]

Jon, thanks for posting that information. Much appreciated!

 

[Vic Harder]

+1 - thanks for dispelling the fire myth!

 

[rubberlegs]

Will Prowse has several recent and interesting videos on Lithium-Iron-Phosphate batteries. He's more focused on solar charging at his home in Las Vegas then us RVers, but he recommends using them daily from 100% to 0%. They need to be balanced so 100% is good for that. And if not using them, keep them at 50%. The LiFePo batteries are quite different from the lithium batteries in your phone or some cars.

 

[ckent323]

I double checked and Jon R is correct, the risk of fire with LiFePO4 is low.

However, literature says that LiFePO4 batteries perform poorly in cold temperatures and are negatively affected by high temperatures. Exposure to direct sunlight can make these effects worse.

Advantages and Disadvantages of LiFePO4 Battery | LiFePO4 Battery

Advantages and Disadvantages of LiFePO4 Battery

www.lifepo4-battery.com

 

[rando]

I double checked and Jon R is correct, the risk of fire with LiFePO4 is low.

However, literature says that LiFePO4 batteries perform poorly in cold temperatures and are negatively affected by high temperatures. Exposure to direct sunlight can make these effects worse.

Advantages and Disadvantages of LiFePO4 Battery | LiFePO4 Battery

Advantages and Disadvantages of LiFePO4 Battery

www.lifepo4-battery.com

That is definitely true about cold temperatures, but it is more true for lead acid batteries. In terms of capacity at low temperatures, LiFePO4 actually retains more capacity than lead acid, at 0F LiFePO4 retains about 70% of it's rated capacity whereas most lead acid chemistries are down to about 50% of capacity.

There are limitations on charging LiFePO4 below freezing, but in 7 years of using an LiFePO4 pack in my camper (at least half of the trips with temps below freezing) this has never been a practical limitation.

While I am sure there are still some niche cases where lead acid makes sense, for most folks LiFePO4 makes much more sense for our campers.

 

[Wallowa]

LiFePO4 batteries are much safer than lithium ion battery types. From lithiumhub.com:

Safe, Stable Chemistry​

Lithium battery safety is vital. The newsworthy “exploding” lithium-ion laptop batteries have made that clear. One of the most critical advantages LiFePO4 has over other battery types is safety. LiFePO4 is the safest lithium battery type. It’s the safest of any type.

Overall, LifePO4 batteries have the safest lithium chemistry. Why? Because lithium iron phosphate has better thermal and structural stability. This is something the lead acid battery type and most other battery types don’t have at the level LiFePO4 does. LiFePO4 is incombustible. It can withstand high temperatures without decomposing. It’s not prone to thermal runaway and will keep cool at room temperature.

If you subject a LiFePO4 battery to harsh temperatures or hazardous events (like short-circuiting or a crash) it won’t start a fire or explode. For those who use deep cycle LiFePO4 batteries every day in an RV, bass boat, scooter, or liftgate, this fact is comforting.

(End paste)

Good review Jon....my BB LiFePO4 is 100ah [@ZeroDec] and has built in heater for use in winter....with 370w solar panels on top and DC/DC I can easily operate off grid for weeks....would add that I believe while the built in controller will stop charging below 25F [heater keeps it above 35F], charging at below that temp reduces battery life, and same for charging above, what 130F[ or so]....I do remember that letting a LiFePO4 battery cook at high ambient temps while not causing combustion can significantly reduce battery life....of course I could be wrong!

1 or 2 batteries? Well Li is a lot lighter, so weight not an issue, and as "Tim Taylor" sez what we need is "more power"! Two 100ah Li batteries would last a life time, or so I believe!

 

[Jon R]

I suspect Will Prowse’s suggestion to charge to 100% and discharge to low voltage level is based on optimizing purchase and operating economics for a grid-tied solar system. You want to use your batteries fully in that case rather than spend money on excess battery capacity, and you want to use the heck out of them and replace them when they fail.

For our use as campers, you never want to be out of battery charge, so you want a capacity margin you decide is reasonable for your usage scenarios. You also want to take advantage of the conservative large capacity and be nice to your batteries so they last as long as possible.

I set my set my charging voltages at 14.2 or 14.4 rather than 14.6, and I try not to use the bottom 20% of the battery (though I don’t fear using it).

 

[ckent323]

Rando,

I have not seen a post from you in some time. Glad to see you are still contributing.

Regards,

Craig

 

[Wyo4Life]

For my 2024 Hawk I ordered just the one Dakota Lithium battery option with the 250 watt solar panel on the roof. With the new Truma hot water heaters and furnaces, these campers seem to me to be so much more efficient than the units of just a few years ago.
I have not had any need for more battery power at this point. Now, I live in Wyoming where we get a lot of sunshine and my camper stays on my truck 24/7/365. We did just move into a new house which has a higher garage door so I can now park it inside, which will be nice in the winter. Still, as I write this I checked my battery level through my phone app and my battery reads 100% after sitting in the garage for the past three days.
Depending on what I am doing and where I am going, if I feel I need more power, I have a Honda 2000 generator that I have had for a number of years I will take along with me.

 

[pods8]

"Two is one and one is none" is always something to keep in mind. If I needed 200ah of battery I'd get two 100ah batteries just to be conservative. If I only needed 100ah and having an issue (rare) wasn't going to be a major problem then I'd just run the single, if avoiding a rare problem is worth $200ish of insurance then I'd run two 100ah even if I didn't need that much capacity.

I've been on a trip in the cold when a buddy lost a cell in one of his 6v AGM in his pair, really handicapped running the heater and such.