Solar with Lithium Battery

BFL13 wrote:
Here is some honest advertising by Relion LFP

"More Usable Capacity 25-50% more capacity than lead-acid equivalent"

The OP wants to camp off grid in a TC for a few days where he runs a few things but not the furnace or bigger inverter loads, so he seems to think one 100AH battery will be enough as long as he has enough solar to keep up. With furnace and the usual things, it takes one battery per day.

He could do his loads with two FLAs and "enough" solar. He is hoping the one LFP will do it, being like 1 and 1/2 batts, which it might with no furnace time.

The money side of things is obvious and up to the OP for what is "worth it" .

EDIT--"enough solar" is the same for either battery bank size. IMO he will need 200w or more and 100w is not enough. On my budget, YMMV, I would get more solar with the money I saved from getting FLA instead of LFP. But I am not the OP!

I do most of my camping in the warm weather months here in Colorado off grid. The furnace has run twice in my Lance 650. I have used a space heater that works more than sufficient in 20 degrees hooked to 30 Amp.

The lead acid battery dies after about 2 days with the 100 watt solar panel. I'm probably not the best steward of making sure the battery amperage and usage stays moderated.

Maybe it's just marketing. I have read that lithium batteries charge faster than lead acid. I also know you can take the lithium batteries down below 50% capacity.

I thought maybe someone was using a 100 watt solar panel and 100 Ah Lithium battery and knew how long/much it would run before needing to run a generator if at all.

The battery dies after two days with the 100w of solar, but you want to last four days and leave with the battery not down too far (50% with FLA or lower with LFP) and do a full recharge on shore power.

So you already know the 100w of solar can't keep up. with one battery, you should be recharging it every day with the converter powered by the generator. (doing 50-80s or 50-90s with FLA, or whatever with LFP) With solar you can reduce the gen time to maybe an hour in the morning and let the solar finish up the rest of the day.

You don't need more battery so much as more charging so it won't die. Your choice of gen times and amount of solar.

If that works then more battery will only be good to have if too many clouds, or your gen won't run. (extra battery is called "reserve" by solar folks)

2Noob4U wrote:

BFL13 wrote:
Here is some honest advertising by Relion LFP

"More Usable Capacity 25-50% more capacity than lead-acid equivalent"

The OP wants to camp off grid in a TC for a few days where he runs a few things but not the furnace or bigger inverter loads, so he seems to think one 100AH battery will be enough as long as he has enough solar to keep up. With furnace and the usual things, it takes one battery per day.

He could do his loads with two FLAs and "enough" solar. He is hoping the one LFP will do it, being like 1 and 1/2 batts, which it might with no furnace time.

The money side of things is obvious and up to the OP for what is "worth it" .

EDIT--"enough solar" is the same for either battery bank size. IMO he will need 200w or more and 100w is not enough. On my budget, YMMV, I would get more solar with the money I saved from getting FLA instead of LFP. But I am not the OP!

I do most of my camping in the warm weather months here in Colorado off grid. The furnace has run twice in my Lance 650. I have used a space heater that works more than sufficient in 20 degrees hooked to 30 Amp.

The lead acid battery dies after about 2 days with the 100 watt solar panel. I'm probably not the best steward of making sure the battery amperage and usage stays moderated.

Maybe it's just marketing. I have read that lithium batteries charge faster than lead acid. I also know you can take the lithium batteries down below 50% capacity.

I thought maybe someone was using a 100 watt solar panel and 100 Ah Lithium battery and knew how long/much it would run before needing to run a generator if at all.

you will get motr time out of the LFP, about double and a 100 amp solar will extend that a bit, but if you assume 4 hours of full charging and a bit of fringe you might get 4 days because of the extra amp from the solar. if you could I would look more at getting a bigger solar pannel and the LFP. the price of pannels are cheep now. grab a 325 watt pannel. I have 100 usable ah of lead acid in my camper with a 325 watt pannel and as long as I dont go two days in a row with out sun I can stay out for a long time using the furnace when the temps are right around freezing. two days of no sun and I still have some left but I am getting concerned. if you had two 100AH Lfp batteries and 325 or more watts of solar you would be set up pretty good. for me to do that with deep cycles it would weight 280 lbs and be the size of 4 gc batteries which I cant fit, but one could be had that would weigh about 48lbs and take up the space of one GC battery. realy it doesnt matter what kind of batteries you use if your not running microwaves and such, just shoot for a min of 100 usabe AH and better yet if you can get to 200 usable AH you will be golden with a deicent solar pannel.

Steve

Steve,

I want my RV to behave as if it were plugged into a 15 amp shore power outlet. That takes a large battery bank, and a way to recharge.

Each to their own! We all love camping.

My question is I have one 100 watt solar panel. What is the charge rate like?

My experience here is,one 100 watt 23% efficient panel brings in on average 50-70 watts while two would more than doubles that..My opinion is based on what I have seen with my panels,I would need atleast two 100 watt panels to keep up with a heavily used single battery know matter what type..

So my theory is, 200 watts of solar per battery and of course the sun plays a big role...

My panels are portable because of where I use my TC..I'm just hesitant to put one on the roof..The hole thing with lithium vs lead acid vs how much solar get's confusing with many different opinions..I have panels for the roof saved for later on Amazon and just can't poke that button...

Good luck

+1 what Steve said.

Compares with our TC set up designed to last four days off-grid at dog training place with no gen and get home with batts not dead yet. Needs 200AH or more of battery bank (any kind of battery--pair of 6s is best bang for buck) and the 255w panel. If overcast, can't do it without some battery charging. Run the truck engine is one way. (No room for a portable gen with all the dog crates)

Idea is you lose some capacity every day where solar does not restore all your useage, but you don't get too far down by the end. Go home, plug in, and get a badly needed full recharge. A battery monitor helps keep track of how that is working during the four days.

On the edge if one LFP will be enough. Risk is if not then you have to get another one just like it--can't get a cheapo for the second one and mix them. Big bucks for two! You could just get two 6s and know that will work, but might be a space or weight problem in your TC. You can run 6s down below 50% to get more AHs and not kill them so that gives you some wiggle room.

pianotuna wrote:
Steve,

I want my RV to behave as if it were plugged into a 15 amp shore power outlet. That takes a large battery bank, and a way to recharge.

Each to their own! We all love camping.

dont forget we are in the truck camper forum right now, no such thing as a large battery bank unless you use LFP.

this is what started my whole lookng at LFP in the first plce. with two big 6V GC batteries which I had to put in my storage commpartment as they wouldnt fit in the battery compartment (Yes I have an older camper) I can only muster 105AH of usable capacity. I do have a 325 watt pannel on it with room for another and a 40 amp Mppt controler, so getting sun it isnt bad at all, kept it at 100 every day, but as I found out last fall at around freezing at night when I am running the furnace after two days of no sun and or a shady campsite, I was down to about 60% which means I used 80 of my 105 availble AH. the only way for me to get a big bank would be to build two 280AH LFP batteries an put them in the same space, but I think if I just build one that will be good and I can get my storage space back.

Steve

You can take a pair of 6s down below 50% without much penalty in number of lifetime cycles, so that would be the first choice IMO. However once that low you can only run low amp draws, not the inverter which will alarm off depending on load and how far down you are in SOC.

LFP (and SiO2 within reason) will be happy to go to a low SOC and still keep the voltage up to allow the inverter to operate.

The real problem is recharging the batts of whatever type when they need it if you only have solar and it is overcast. We have no room for a portable gen in our TC, so that leaves running the truck. Low amp long time recharge not so good.

LFPs are not going to change that. You could still be sitting there with the batts out of AH and no sunshine. You might get an extra overcast day out of it with LFP, but then what? If you have a portable gen, you could have used it two days ago with your pair of 6s.

Seems the LFP option would make sense given the right scenario though.

BFL13 wrote:
You can take a pair of 6s down below 50% without much penalty in number of lifetime cycles, so that would be the first choice IMO. However once that low you can only run low amp draws, not the inverter which will alarm off depending on load and how far down you are in SOC.

LFP (and SiO2 within reason) will be happy to go to a low SOC and still keep the voltage up to allow the inverter to operate.

The real problem is recharging the batts of whatever type when they need it if you only have solar and it is overcast. We have no room for a portable gen in our TC, so that leaves running the truck. Low amp long time recharge not so good.

LFPs are not going to change that. You could still be sitting there with the batts out of AH and no sunshine. You might get an extra overcast day out of it with LFP, but then what? If you have a portable gen, you could have used it two days ago with your pair of 6s.

Seems the LFP option would make sense given the right scenario though.

yup, I totaly agree, unless you have the ability to assemble your own LFP batteries, in that case you can make a 280 Usable AH battery that is 1/3rd the weight and less than 1/2 the size of thoes 6V batteries, with almost 3 times the usable AH, which even with out solare would give some one a extended outting. they allso will run an inverter right down to the bitter end with out it alarming depending on how the battery is set up. if your using every last AH, then they would go to about 10% before the inverter starts alarming.

in the truck camper would where we are all about weight, size and capacity, I dont see a better battery. Led acid if you are going for maximum life you can only use 50%, Sio2 are heavier and bigger than lead acid (just a bit) and let you use 80% of the capacity with out shortening the life. but LFP are lighter, smaller and give you 100% of the capacity for 4000ish cycles and more if you only use 80%.

Steve

Steve,

SiO2 are slightly lighter than lead acid, and slightly smaller. The 100 amp-hour jar is a Group 27 iirc.