Jumping off the lithium ship

[sunsurfer]

The interstate battery I got dropped to 11V much faster from Costco I returned them. The only place I could find had

Shorted cell. I will bet you $10,000 it was the inner cell near the + terminal(?) if memory serves me correctly or the negative. point is, its always the same cell. Must be a design flaw. I have seen hundreds of them. Very common failure on the interstate "deep cycle" turds and others with the same manufacture.

 

[k490]

Shorted cell. I will bet you $10,000 it was the inner cell near the + terminal(?) if memory serves me correctly or the negative. point is, its always the same cell. Must be a design flaw. I have seen hundreds of them. Very common failure on the interstate "deep cycle" turds and others with the same manufacture.

Could be I called RV dealer said the duel purpose won't be as good for deep cycling.

https://www.interstatebatteries.com/recreation-vehicles/rv-batteries/dual-purpose

 

[sunshine_eggo]

NCM, LFP, FLA, AGM, NiMH... these are just a few of my favorite things... in no particular order.

@sunshine eggo tucks and starts dancing to Goodbye Horses...

 

[Substrate]

If LFP is out of the question, and with limited solar insolation, then AGM is the way to go. You need to beat the clock to reach a full charge as often as you can, and the low internal resistance of agm allows you to charge faster before the sun goes down. (typically compare 0.15C max charge rate for standard flooded, to 0.25c max for conventional recycled-lead agm due to lower internal resistance. See manual.)

Pure-lead agm's in really tight situations can be used, since they can typically be hammered at 0.5C to 1C. Good quality ones that is. But that means expensive pure-lead batts, and an array that can deliver that.

Also, one has to check the solar-insolation charts for their geographic location, and use the WINTER values, always. Just makes sense.

I've never had a problem with AGM, but maintenance is mandatory. Such as the all-important first-birth, or first FULL charge with an AC supply, and allowed to absorb for many hours. Then place into solar service. This would also happen at car-part parking lots, where the half-charged batt was taken from the rack, swapped into a vehicle, and never actually getting a FULL charge, ever. Now you have unbalanced (yes) cells, sulfation etc, and all the problems that follow.

So yeah, you are in a bind time-wise. LiFePO4 is NOT the danger that other lithium chemistries are, as much as lead saleseman try to make you fear it.

For this application, once the sales propaganda against LFP has been allayed, your application is screaming for LiFePO4.

MPPT controllers? The ones I use are not noisy. Unless you lay your feedline right across the terminals. What most complain about, and what the controllers ARE NOT DESIGNED FOR, is a direct-connect to a radio input paralleled via the battery lines during charge. They are designed to be connected to an isolated battery system not running a radio load in parallel.

If you are very concerned, you can simply use a pwm controller. OR, use two batteries. One one solar charge, and the other isolated and running the station directly, and swap positions when one needs to be put on an isolated charge.

 

[Zwy]

It is a good thing I don't have lead acid, the damage would have been irreversible. 17 days since 100% SOC and counting......

 

[Dagoth Ur Does Solar]

It is a good thing I don't have lead acid, the damage would have been irreversible. 17 days since 100% SOC and counting......

LiFePO4 chemistry really is amazing. The energy density, cost per kWh, ability to discharge to 0% SoC without seriously damaging the cells, lifetime capacity retention of the cells, safety compared to other lithium chemistries... It's the closest thing to the "miracle new battery technology!" that was in the news every day when I was younger- except it's real, and in consumer hands.

I don't judge anyone looking at using lead acid, but I really think you have to take a hard look and make an educated decision. I think for most people LiFePO4 should be the default choice, and that they only really be looking at lead acid or other chemistries if there are very specific sets of circumstances that justify it.

At any rate, if OP says they don't get a lot of good sunlight, isn't that an even stronger reason to go with an MPPT? I don't see any good reasons nowadays to go with a PWM controller over an MPPT.

 

[sunshine_eggo]

It is a good thing I don't have lead acid, the damage would have been irreversible. 17 days since 100% SOC and counting......

Pfft.

This is overstated. Most quality FLA have a full depth discharge cycle life of 500 cycles. Yes. 17 days of limited sun wouldn't be great for them, but you'd recover the vast majority of the lost capacity (which would be hard to measure) at the next equalization cycle. AGM/GEL would sustain minimal damage.

Yes. LFP is better in these situations, but lead acid fear mongering isn't warranted.

 

[Zwy]

Pfft.

This is overstated. Most quality FLA have a full depth discharge cycle life of 500 cycles. Yes. 17 days of limited sun wouldn't be great for them, but you'd recover the vast majority of the lost capacity (which would be hard to measure) at the next equalization cycle. AGM/GEL would sustain minimal damage.

Yes. LFP is better in these situations, but lead acid fear mongering isn't warranted.

It is day 19 or something and I have yet to hit 100% SOC. Was heavy overcast all day today and basically no PV yield. Tomorrow will make 20 days.

I'd still have to get thru absorption with lead acid and only then think about EQ. Might never get there as days go shorter with limited daylight hours. Takes a long time to finish absorption and another full day to really do EQ. I still have to power loads 24/7.

OP wants to use AGM, I wish them luck if a streak of low PV yield comes along a few times in the winter like this year may very well have. No EQ happening unless the battery manufacturer has it in the manual that it can be done.

Yes, the fear mongering is warranted. If someone wants to move back to lead acid, they should be aware of the pitfalls.

 

[Al Simerz]

My experience differs to many. I've been running small 12V solar systems around the farm for 20+ years. Multiple sites, multiple systems used primarily for keeping electric fences running and water troughs full. These systems are complete set and forget and are as simple as a 150W panel into a 20A MPPT into a 100A SLA or AGM, (depending on the site). These batteries can all survive about 3 days, maybe 4 without a full recharge. They operate in temps between -5C and about 65C. Several of these batteries are over 15 years old and the newest is about 5 years old. They don't cause me any issues and work without me checking them more than twice a week. (Although admittedly I can check that they are operational by seeing how much water is in the troughs or touching the fence.)

I'm not against lithium, although in Australia their prices is extremely uninviting even with any advantages taken into account. I am actually considering lithium setup for a different task in the workshop. But while these other SLA nd FLA batteries are still working, do what is required and owe me nothing I think replacing them with lithium would be silly.

Everyone has different needs and different systems. I know guys running 12v systems in yatchs in the tropics who are moving away from Lithium because of the heat and humidity. But that doesn't mean everyone should, nor does it mean everyone should run what I choose too.

 

[davo99]

Well i may be set in my ways but theres a reason or two. For the spirit of this thread Im gonna rock the boat here and pick on LFP
1. My current Trojan battery bank is probably older than the company itself that your LFP battery came from. Let that sink in for a second.
2. My BMS will never fail because i dont have or need one.
3. They will not drift out of balance, they actually self balance in absorbtion mode just fine.
4. I can go to the cabin in Feb when its -10F flip the switch on and they work, i really dont care what temp they are.
5. My $15 ANL fuse will keep my house from burning down.
6. Twice a year I dump a .99c gallon of distilled water in them. The people who say they make a mess spilling "acid", what!? Why are you adding acid? You just add water, if you spill it, get some paper towel....its just water.
7. They handle surges for large inverter loads and are not limited on discharge current to 100a or 200a.
8. My 24v system voltage can drift all over the place if i screw up a setting, its really not critical in the short term. I can go down to 21v during a large load and i can crank it up to 34v with the generator and nothing shuts down unless I want it to.
9. Any ol forklift charger off Craigslist can be a "chargeverter".
10. When its time for new ones, maybe around the 10 year mark, the recycle money will cover my gas to get new ones. With LFP you will likely have to pay out of pocket to recycle and who knows where you can take them to do that. Yes they do fail. Do you really think your "grade A" cell from alibababa is immortal?

I know I know y'all are gonna come back with round trip efficiency and cycle life and bla bla bla.... the same argument can be had for a prius vs a pickup truck but they just have a different purpose and one doesn't replace the other.

Well said!
I stay out of these discussion for the most part now. Sick of people with no Flucking idea always pushing the mythium side and talking absoloute BS about LA because they want to be seen with the " In " crowd or are just plain ignorant.. Be ok if they aregued facts instead of fantasy but they don't.

All good, the more people that use lith, the more cheap FLa's for me to pick up for peanuts.

 

[OffGridForGood]

They operate in temps between -5C and about 65C.

I know guys running 12v systems in yatchs in the tropics who are moving away from Lithium because of the heat and humidity.

Sodium Batteries.

 

[HarryN]

It is a good thing I don't have lead acid, the damage would have been irreversible. 17 days since 100% SOC and counting......

View attachment 258713

I view solar as a way to "run the generator less", it is more challenging to take it to zero.

So with that philosophy, in the winter just run a generator for 2 hours each morning to do bulk charging and let the sunshine do the finishing stage charging.

Yes I know it isn't perfect, but for many situations, it is good enough.

 

[RV8R]

I view solar as a way to "run the generator less", it is more challenging to take it to zero.

So with that philosophy, in the winter just run a generator for 2 hours each morning to do bulk charging and let the sunshine do the finishing stage charging.

Yes I know it isn't perfect, but for many situations, it is good enough.

Exactly

We All Have Different Needs/Wants !! - It isn’t a one size fits all situation with Batteries.

We have an off grid cabin in Canada

We have Rolls AGMs

We typically use the Cabin sporadicly “April to November”. It can get 3’ of snow in the winter time & temps bumping -30C.

So far the AGMs have been good to us.

Battery Choice - Really Depends upon what is needed & how the system is being used.

Our Cabin Upgrade;

Thread 'Tiny Cabin - What To Do'
https://diysolarforum.com/threads/tiny-cabin-what-to-do.85978/

If the sun isn’t shining, we are using a generator regardless of AGM or LFP .

And if the Sun is shining - No Generator needed for AGM or LFP.

Unless there is a real Need, my preference is to have a dumb battery that can deal with the Canadian Cold;