after 2 years of dependable use my lead acids have died. can i do better ?

[Jack Rabbit Off Grid]

Technically you have a generator. It’s not very efficient but would work in a pinch since you run a 12v system. Jumper cables and a Dodge.

Back in the day when I built my very first system in a 1973 Dodge class C. I used a 8d battery I got for free out of a friends boat. Mounted some real cheap solar panels on the roof and some cheap controller. I found my self in the same spot. The panels couldn’t keep up. Being I was a Diesel technician at the time. I replaced the factory Dodge alternator with a 160 amp one out of a KW T600 tractor. Couldn’t afford any fancy generator back then. In the morning if the battery was dead just fire up the gas guzzler 440 and let it idle. I even had the for thought to over drive the alternator so it would put out full power at idle.

 

[roaming ram]

The AGM technical document I linked indicated anything from about 10% DoD to 80% DoD would yield similar total Ah of cycling over life of battery. Deeper cycles mean you get your money's worth sooner and replace it sooner.

I think shallow cycling of lead-acid makes sense if you want enough storage for 3 days without sun; most nights, only cycles 15%. At that, quality FLA could lasts 20 years or AGM 10 years.

For Lithium, nightly deep cycling could last 8 to 16 years. Size for 3 days without sun, it is likely to fail of old age before you get your money's worth. So I wouldn't want to size for more than 1 day without sun. Optimum usage might be multiple cycles per day.

My preference is to oversize PV, which costs about $0.025/kWh over 20 years. Size battery to barely last one night. In this case, optimal system delivers target charge rate to battery, additional current only if loads are drawing power.
Some other tradeoff might be better fit for mobile syst

Technically you have a generator. It’s not very efficient but would work in a pinch since you run a 12v system. Jumper cables and a Dodge.

Back in the day when I built my very first system in a 1973 Dodge class C. I used a 8d battery I got for free out of a friends boat. Mounted some real cheap solar panels on the roof and some cheap controller. I found my self in the same spot. The panels couldn’t keep up. Being I was a Diesel technician at the time. I replaced the factory Dodge alternator with a 160 amp one out of a KW T600 tractor. Couldn’t afford any fancy generator back then. In the morning if the battery was dead just fire up the gas guzzler 440 and let it idle. I even had the for thought to over drive the alternator so it would put out full power at idle.

i actually have a dual alternator on that wagon stock. helps when winching, with extra lights and any additional current draws

 

[Solar Guppy]

Only use wet batteries if you can look at them every day and check the water levels. Your batteries died as you were away for months yet they were continued to have charge applied. If you don't want LFP, then your only option is agm. But in your cycling even AGM likely won't last any longer as the cycle count isn't a good match for this use case.

 

[chrisski]

i am seeing i really do not have many realistic options for my consumption other than LiFePo4's

I agree with this statement. If you can control heating and cooling for your lithium batteries, then there is only a very narrow set of circumstances where lead acid is better. Where lead acid works out better is for extreme cold where you can't reliably provide heating or cooling to your lithium battery pack.

Earlier this year, I switched from lead acid to lithium, and I enjoy the added capacity with less space and weight, along with the batteries lasting longer than a lead acid pack. Researching and building this heater could take weeks but could be worth it. I am not in an extreme cold area and won't charge my batteries if the battery temps get below freezing and I have two different thermometers to automatically shut off charging. One single thermometer shuts off the SCC, another two sets of two thermometers will trip the BMS. I forget what the max discharge temp is on my lihiums, but it's well below both freezing and record cold temps.

People make heaters to keep there battery packs above freezing in RVs that are stored for months at a time, so they can be reliable. If the heater fails, that causes the BMS to trip and stop charging.

 

[roaming ram]

Only use wet batteries if you can look at them every day and check the water levels. Your batteries died as you were away for months yet they were continued to have charge applied. If you don't want LFP, then your only option is agm. But in your cycling even AGM likely won't last any longer as the cycle count isn't a good match for this use case.

so you do not believe heated LiFePo4's would be a good fit if i stored them each winter and kept them trickle charged ?

 

[roaming ram]

I agree with this statement. If you can control heating and cooling for your lithium batteries, then there is only a very narrow set of circumstances where lead acid is better. Where lead acid works out better is for extreme cold where you can't reliably provide heating or cooling to your lithium battery pack.

Earlier this year, I switched from lead acid to lithium, and I enjoy the added capacity with less space and weight, along with the batteries lasting longer than a lead acid pack. Researching and building this heater could take weeks but could be worth it. I am not in an extreme cold area and won't charge my batteries if the battery temps get below freezing and I have two different thermometers to automatically shut off charging. One single thermometer shuts off the SCC, another two sets of two thermometers will trip the BMS. I forget what the max discharge temp is on my lihiums, but it's well below both freezing and record cold temps.

People make heaters to keep there battery packs above freezing in RVs that are stored for months at a time, so they can be reliable. If the heater fails, that causes the BMS to trip and stop charging.

not sure i can really afford it but battleborn has LiFePo4's that are heated and have a bms as well. i would like to know more about the thermostats you are using. i assume they just break the ground loop ?

 

[roaming ram]

The AGM technical document I linked indicated anything from about 10% DoD to 80% DoD would yield similar total Ah of cycling over life of battery. Deeper cycles mean you get your money's worth sooner and replace it sooner.

I think shallow cycling of lead-acid makes sense if you want enough storage for 3 days without sun; most nights, only cycles 15%. At that, quality FLA could lasts 20 years or AGM 10 years.

For Lithium, nightly deep cycling could last 8 to 16 years. Size for 3 days without sun, it is likely to fail of old age before you get your money's worth. So I wouldn't want to size for more than 1 day without sun. Optimum usage might be multiple cycles per day.

My preference is to oversize PV, which costs about $0.025/kWh over 20 years. Size battery to barely last one night. In this case, optimal system delivers target charge rate to battery, additional current only if loads are drawing power.
Some other tradeoff might be better fit for mobile system.

i saw they have some advantages over lead acid. no water requirements, but almost double the weight. not a deal breaker, but a concern. my goal is to only use 400 watts of panels and find a battery or combination of batteries that can be fully charged or can handle a partial charge yet still handle daily requirements for a long weekend. i would think with me being a long weekend warrior i could get the charge state back to full during the week especially if i shut down the fridge when not in use.

 

[wiseacre]

so you do not believe heated LiFePo4's would be a good fit if i stored them each winter and kept them trickle charged

Unlike LA batteries a lithium doesn't need to be kept at full charge. They can be stored for long periods at a lower charge (60/70% ?)
I bought cells to build my own battery, they sat for a at least a year at 30% before I got them
( it was a bargain deal, no warrantee, but they turned out to be just fine)

not sure i can really afford it but battleborn has heated LiFePo4's that are heated and have a bms as well.

BBs are over priced IMO, I go with the SOK if I wanted a heated battery.
But really. you're going to want an insulated battery box anyway and adding a heating pad to use 'as needed'

my goal is to only use 400 watts of panels and find a battery or combination of batteries that can be fully charged or can handle a partial charge yet still handle daily requirements for a long weekend. i would think with me being a long weekend warrior i could get the charge state back to full during the week especially if i shut down the fridge when not in use.

So in all of this I haven't actually seen what your actual use is
I've gleaned
you had appx. 300ah at 12v or 3600wh of capacity
You may have used nearly the full capacity over a 3 day trip (not entirely since you didn't say they went dead)

Recommending a battery capacity is a wild guess at this point without knowing just how much power you use.
also it would be good to know what the max power/load you have
the 3 old batteries could deliver a sizeable amount of amps at a time
a single lithium battery is limited to commonly 100 amps (some higher some lower)
I'm assuming you don't need to draw a 100 amps at a time while camping although your 2000w inverter is capable of pulling about 167 amps
As long as your loads stay below 1100w at a time you're fine with a single battery

If the 3 old batteries saw you through a 3 day trip then a 300ah lithium should do you good
No heating but a chins 300ah, 12v battery may be the cat's pajamas
https://www.amazon.com/CHINS-LiFePO...ocphy=9005349&hvtargid=pla-1106935315637&th=1

---
EDIT: there is a heated model
https://www.amazon.com/dp/B09SX4NGDJ/ref=twister_B09T2QSBV3?_encoding=UTF8&psc=1
but I think think doing your own heating is better
---

of course that's back to an insulated battery box (easy enough to rough out with 2" foam board and some duct tape to seal cracks)
a heating pad used as needed (turn off fridge at night and plug in heating pad)
I mentioned I use a seed starter heat pad (25w, if used overnight it would be less than the fridge so there's no real net loss using it)
and not to forget, using some heated fire brick could go a long way in keeping the battery box warm)

 

[Shimmy]

so your quick math tells me i really have no choice other than to go with heated LiFePo4's, store them for the winter, get another set of panels, a new 30amp scc that records all my usage so i can get real time data and become a guru at this. haha

Don't necessarily need to store the batteries for the winter, just store a couple extra solar panels in the summer when you get plenty of sun. With LFP you have a higher charging uptake rate, so you can increase the winter array size.

 

[sparrowhawk]

There is one other option that I don't believe that has been mentioned. If you buy lifepo4 batteries you could keep them in the heated space with you. Just find a suitable place like under a dinette bench or something like that and as long as you are at a comfortable temperature they will be fine. And when you are not camping and they get cold just don't charge them.

 

[BradCagle]

If you go LiFePO4 try to get one with Bluetooth. This way you can fully monitor it from your phone.

 

[schmism]

i am good with spending 500 again, but would rather not spend a grand or more unless i am educated enough to make a better decision.

$500/2 years. 560ah LFP for $800 and they last 10 years. And you dont have to watch water levels, dont have to worry about sulfation, dont have to check SG.... FLA shouldn't even be an option your considering.

 

[roaming ram]

I called renogy. My options are a second suitcase of 200 watt panels giving me 2kwh per day total or a single 320 watt panel increasing my output to 2.6kwh per day. I was thinking about going with the chin 300ah heated with bms. I have to look at the chin specs again but wanted to see what those of you with more knowledge and experience think of this possible solution. Thank you

 

[wiseacre]

be aware that the voltage is about double on the 320 and you'll need a separate charge controller for it
there's no problem running 2 controllers which if I'm correct you'd have either way
isn't there a pwm controller built into the 200w suitcase?
basically run the wires from the 2 controllers to a busbar then a single set of wires to the battery
do the same for the negative leads

a 4 post busbar would do,
each controller on a post (2)
a lead to the battery on a post (1)
a lead to the inverter on post (1)

Will (site owner) did a review of a different chin's model and was overall positive

realistically I doubt the total production estimates
that's basically saying you'll get full production out of the panels with 5 hours of ideal conditions.
I'd say 70/80% of that is more likely on a good day

Regardless, what you suggest seems sound to me for your use
if 300ah hours got you thru a 3 day trip before you should be fine with the extra panel production
any capacity not recharged during the trip can easily be done at home before the start of a new outing

 

[roaming ram]

be aware that the voltage is about double on the 320 and you'll need a separate charge controller for it
there's no problem running 2 controllers which if I'm correct you'd have either way
isn't there a pwm controller built into the 200w suitcase?
basically run the wires from the 2 controllers to a busbar then a single set of wires to the battery
do the same for the negative leads

a 4 post busbar would do,
each controller on a post (2)
a lead to the battery on a post (1)
a lead to the inverter on post (1)

Will (site owner) did a review of a different chin's model and was overall positive

realistically I doubt the total production estimates
that's basically saying you'll get full production out of the panels with 5 hours of ideal conditions.
I'd say 70/80% of that is more likely on a good day

Regardless, what you suggest seems sound to me for your use
if 300ah hours got you thru a 3 day trip before you should be fine with the extra panel production
any capacity not recharged during the trip can easily be done at home before the start of a new outing

I forgot to mention if I get the second suitcase I would get the 30amp mppt and wire the panels in parallel. If I get the 320 watt panel I will get the 40amp mppt and wire in series. both will have Bluetooth and renogy sells the y adapters so i will be able to monitor much more info and have a better understanding of my supply and demand.

 

[Jack Rabbit Off Grid]

I called renogy. My options are a second suitcase of 200 watt panels giving me 2kwh per day total or a single 320 watt panel increasing my output to 2.6kwh per day. I was thinking about going with the chin 300ah heated with bms. I have to look at the chin specs again but wanted to see what those of you with more knowledge and experience think of this possible solution. Thank you

I replaced my 4 6v in my RV with a single 300ah Chins. Well worth it.

until I got my 48v setup I was running my off grid tiny home with the Chins for Months.

 

[roaming ram]

I replaced my 4 6v in my RV with a single 300ah Chins. Well worth it.

until I got my 48v setup I was running my off grid tiny home with the Chins for Months.

just ordered the chin 300ah with bluetooth and bms today. tomorrow i call renogy for the rest. i think it will really help me understand the system better once i see how everything works. thanks !

 

[Jack Rabbit Off Grid]

just ordered the chin 300ah with bluetooth and bms today. tomorrow i call renogy for the rest. i think it will really help me understand the system better once i see how everything works. thanks !

You won’t be disappointed with Chins.The Chins I own is a older model with no Bluetooth or heaters. I just mounted mine in the under bed storage to keep it warm in the winter.

 

[pollenface]

What is the weight of the 140ah battery from Amazon? I think the first problem is falsely advertised capacity. A lot of batteries i see online are like this. A 140ah agm has to weigh at least 34kg. I bought a couple of supposed 170ah batteries once and they turned out to be 110ah and weighing only 27kg.

 

[Daddy Tanuki]

i get it. just dont know how reliable any lithium variety will be where you get winter conditions 6 months a year. that is why i am leaning in the 6 volt direction

I can not speak for premade packs, but I can say that my DIY pack handles -18°c (0°f) with zero issues here at fuji. elevation is 1200 m so about 4k ft and the wood burning season runs from later October to mid April so the Oct-Nov is generally 0~1°c through the night, then in mid Nov. through Mar it drops as low as -18°c and then slowly ramps up.

At first i ran the whole heating pad with buck converter(48vdc-12 VDC) and 12 volt controllers. when the buck converter burned up I rewired the pads all in series and the overall heat output dropped but I found I no longer needed the temp controller. just on 24-7 and shut off in spring. during the coldest months is pretty much held the pack about 70f through the day and maybe 60f at night.

if you can build a battery box out of the 4" blue foam and seal all the corners with spray foam or tape, you will find that a little power goes a long ways with zero issues.

Caveat, my system is 48 volts, with 7.6k of panels 6k aimed due south and 1.6 aimed due west to lengthen out the solar day. so I have power to spare.

as far as the premade server batteries with a metal case, a two or three of the heating pads on the outside of the case and the above mentioned blue foam box around it would be even better i think as the built in internal heating circuits will only kick in if needed....

just some food for thought.