Is my distrust for lithium unfounded?

[Substrate]

The silicate batteries come up often like clockwork here actually.

Basically an agm format with different electrolyte structure that allows you to discharge them down to very low volts without as much damage as you'd do to a normal agm. Not that any of your systems will actually operate at super low voltages. The LVD in your converter will kick off first. Your 12v equipment will shut off well before you take these to zero.

However, the different electrolyte is supposed to be more resistant to sulfation. Which is actually a good thing, since agm's are notoriously hard to properly maintain to get that last 1% of charge in, which walks down capacity. It may not be so bad, so interesting.

Still, one is dealing with lead-acid. The usual marketing tries to sell the consumer in a comparision to flooded lead acid, with "no pesky gas!", anti-corrosive, and all the usual stuff that they used to pump up for normal agm's. Kind of off-putting for those who actually know.

But hey, if it floats your boat, get some!

 

[toms]

The only expense that is relevant to me is cost per kwh used over the life of the system. Not possible to work out until every system component is dead though unfortunately - so you have to go by experience.

Where i am located, the cheaper initial cost systems have proven to provide expensive per kwh power.

 

[Danke]

Way to go! Where can we send your trophy?

Seriously though, why did you chose to ignore "your mileage may vary"?

I'm building a 42kWH pack for just a bit over $250/kWH and I will write 100% of that off as a business expense. That's $0 per kWh. I'll just keep the trophy.

“your mileage may vary”. So you are way overcharging your customers, got it.

 

[nicholasm]

I’ve installed many fully off-grid LiFePO4 systems over the last decade.

By far the most cost effective is to size your batteries to cover your maximum nighttime useage plus 20%. (with LiFePO4 use 80% SOC maximum)

Install enough PV to fully recharge your batteries at least 75% of the time.

Any extra power requirements come from generator runtime.

It is simple to calculate the cost difference between extra batteries / PV / hardware, and the diesel cost over a ten year period.

A well designed LiFePO4 system starts with commercial grade cells, and a proven reliable BMS.

I use LiFeTech cells and REC BMS.

Most of the systems i set up use Winston cells and REC BMS.

There are many different factors that will determine system setup - there is certainly not a “one size fits all” solution.

Having been putting these systems together for a long time, and living in a remote region where there are many off-grid systems has given me a good insight into what works long term.

I initially thought the BYD B-Box and Pylontech batteries would be a great idea, but have seen too many of them fail while the simple DIY systems using quality cells just work.

I totally agree with you when it comes to building you own LFP batteries my problem is that I need the system to be inspected and then insured I currently own my home outright and have the finances to do the preliminary renovations but I will most likely have to mortgage to finish the rest. So my battery system has to be listed. I spent a lot of time initially doing research on diy batteries and love the idea of being able to carry spair parts and knowing exactly how the battery is built and not having to go around begging manufactures for custom electronics and in Pylontech’s case what seems like custom cells.

While pylontech did well in this study it’s pretty evident that electronics are the weak point in lithium and being able to choose how good a bms you have is paramount to the longevity of the system.

 

[matt2006]

I totally agree with you when it comes to building you own LFP batteries my problem is that I need the system to be inspected and then insured I currently own my home outright and have the finances to do the preliminary renovations but I will most likely have to mortgage to finish the rest. So my battery system has to be listed. I spent a lot of time initially doing research on diy batteries and love the idea of being able to carry spair parts and knowing exactly how the battery is built and not having to go around begging manufactures for custom electronics and in Pylontech’s case what seems like custom cells.

While pylontech did well in this study it’s pretty evident that electronics are the weak point in lithium and being able to choose how good a bms you have is paramount to the longevity of the system.

The attached study, where did it come from?

 

[Nobodybusiness]

I am currently making a final decision between Rolls Surrette 2v 5000 series cells and Pylontech 3000c’s for my battery bank. My daily power budget is 25kwh and the battery bank will be sized for two days of autonomy. If I go the rolls route I would be using 24x 2v Cells 2190ah each for 113.9kwh 56.9 usable at 50% DOD 28.4kwh Per day. On the Pylontech side I would use 16x 3000c’s 3.3kwh usable for 53.3kwh usable, 26.3kwh per day. Just for context this will be tied to two sunny islands in split phase a 21kw solar array and a auto start diesel generator with 250 gallon fuel tank. Generator would auto start around 45% dod for the lead acid and 85% for the pylon just to be conservative. Everything will be housed in a temperature controlled solar room 25c 24/7 365. Now my main concern is long term reliability of of the system this will be 100% off grid primary residence. In terms of cycle like rolls are rated at 4200 at 50% did while pylon are rated at 6000 at 90% dod. My main concern with the Pylontech is unknow calendar aging and reliability long term of the bms. I’m looking to hopefully get around 15 years out of these batteries. Any opinions?

I seriously looked as Rolls early on.

The biggest cell they have is the 2YS62P.
At 20hr rate that’s 5054ah. 252 amps per hour.
48v=24 cells.
Let’s say 24*2.45v=58.8v*5045ah~300,000 KWh.
Substantial amount of power.

What’s your DOD? 50% 80%?

24 cells * $2115.00 (First place I found)=$50,760 plus shipping of 24*572lbs each=13,728lbs.

Just say buy 48v SOK server rack.
$50,000/$1700.00 =29 (probably cheaper in bulk)
29*5.12KWs=150,000KWH
29@122lbs =3,500 lbs

This is all assuming 48v system and buying big batteries obviously.

For me the thing was with lithium I can actually move the things without a crane, no maintenance and 100% discharge with no issues if I want.
If you buy smaller lead acid you can move them also.


You can always add another server rack.
Hard to do with FLA.

I was just trying to compare.

Granted a few negatives for lithium also.
Have to be temperature controlled to a point.
Have to concerned with BMS crapping out.

Lead acid will work pretty much no matter what.
EMP? No worries.

It all came down to maintenance for me.
Dipping a specific gravity in each cell on a X number of times a month or whatever it works out to be didn’t seem like much fun.

Plus if one cell goes bad? Well that really sucks..

The battery watering now can be pretty much automatic if you get the caps and Fill line.

Plus wherever you put them they are staying.
Absorbing takes a minute and you might not get that with Solar.
Just a thought.

It’s a tough choice but for me Lithium won out.

I wish you luck in whatever you decide.

This was just cost and some other things I thought about.
I’m sure there are many other things to consider that I haven’t.