build or buy?

[Prosolar]

I've always been a lead acid battery guy. I'm old school. However, I understand that one much change as we get older. That being said, I'm interested in dipping my toes into the Lithium battery chemistry.

Just to play around....

I started looking at cell prices. I DO NOT want to mess with Chinese supplies, and get wrong/bad/sub preforming cells/and or junk I can't do anything about. So I'm looking at a ship from USA Chinese cells.

Poking around the 'net, I find that current connection has 100Ah cells for $100 a pop. $1600 for a 48V battery.
That doesn't include the BMS, connectors, case, metering, gizmos and all the little pieces parts.

I can get an assembled, tuned, and ready to go 48V 100Ah server battery from various USA based sources for $1500—$1800.

Why do I keep reading about people here putting their own batteries together for cheap?

Am I missing something?

 

[Kornbread]

Although the price gap has narrowed considerably, IMO, it's still possible to diy cheaper than build. s&h can raise the price of a server rack battery $300. 280ah cells can be purchased from docan power US warehouse, for $149cell, and I 'think' that includes shipping.

Caution, not a math person ... feel free to correct errors.

One diy 280ah w/bms for ~$2600 14,336kwh $.181kwh
Two server rack batteries for ~$3300 10,240kwh $.322kwh

YMMV

 

[Prosolar]

Although the price gap has narrowed considerably, IMO, it's still possible to diy cheaper than build. s&h can raise the price of a server rack battery $300. 280ah cells can be purchased from docan power US warehouse, for $149cell, and I 'think' that includes shipping.

Caution, not a math person ... feel free to correct errors.

One diy 280ah w/bms for ~$2600 14,336kwh $.181kwh
Two server rack batteries for ~$3300 10,240kwh $.322kwh

YMMV

That's based on 16 cells in series for a nominal 48V battery, correct?

 

[Henderson]

I'm still in the DIY camp for batteries because it allows me to customize to my exact requirements and allows me to over engineer which is something I like to do because of the peace of mind it gives me. However, DIY batteries are a tremendous amount of work. Given the KWH capacity that I want, I don't like the idea of having too many racks around as most rack batteries are only 5kwh each. From what I've seen, the price difference favors DIY batteries the higher KWH you go especially once you surpass the 50 to 80KWH mark. When the average server rack battery starts coming in at 10 and 15KWH per rack battery, we'll have to see if the price differential still remains the same at the higher end capacities. The rack batteries out there currently though from the major players seem really well built.

 

[Ampster]

Why do I keep reading about people here putting their own batteries together for cheap?

Am I missing something?

Two years ago I purchased 42kWh of 280 Ahr batteries for $125/kWh. 100 Ahr at $100 is $312/kWh. Prices have gone up but not that much at scale. The smaller batteries are more expensive per kWh and I got a recent quote for cells shipped from China to my home, 105 Ahr at $67 each.or $200/kWh.

 

[Risky Rob]

I agree with you.

 

[Kornbread]

That's based on 16 cells in series for a nominal 48V battery, correct?

Yes. Not sure why it's called a 48volt battery though since 3v per cell is dead. Some of the server rack batteries are only 15s.
I agree with @Henderson, better value with larger size.

 

[OffGridInTheCity]

I just posted on another thread... I'm in into year 4, part-time, building my powerwall from 18650 2nd hand cells. I've processed over 12,000 and continuing. I've tracked my costs in detail.

I'm running about $200/kwh - including 18650 cells, cell holders, twist ties, busbars, solder, Batrium BMS, shelving, wire, tools, the whole list of parts. In other words, it has cost me about $2700 for each 13.5kwh of battery deployed.

If you compare that to the 5.1kwh rack LifePo4s that are popular right now (e.g. let's go with ~$1700) that's $4500 vs $2700 for 13.5kwh. That's an $1800 savings I get with my free labor.

Of course the 18650 cells (lithium ion) are not as long lasting as LifePo4, but I'm closing in on 30% DOD and very low C / cell which may get me 4000 or 6000+ cycles per some sources.

You may want to go LifePo4 - e.g. bigger cells, less work and longer life - but yes, you can save money DIY'ing you're own battery if you have the time (free labor). And if you're planning something large - e.g. 30 or 50 or 80kwh then it get's into real savings. If you're thinking 5kwh, then maybe just buy

 

[upnorthandpersonal]

Why do I keep reading about people here putting their own batteries together for cheap?

Because some of us, me included, get cells shipped from China (my last one was 32 280Ah cells for $4102 shipped to my door). That's $146.5 per kWh. Add a BMS, etc. and you're still well below what you can get off the shelf.

 

[Prosolar]

Because some of us, me included, get cells shipped from China (my last one was 32 280Ah cells for $4102 shipped to my door). That's $146.5 per kWh. Add a BMS, etc. and you're still well below what you can get off the shelf.

I can't argue the numbers, however that being said, in my original post, I don't want to mess with buying, shipping, and the total hassle of getting cells in from China. I've read so many posts here as well as dozens of Youtube videos about getting ripped off with bad, out of spec, damaged, and generally piss poor cells. And once you get 'em, you're stuck. There is zero recourse if what you get isn't what you ordered. Frankly, I'm too old to mess with China direct. That's why I asked about USA based shipment of Chinese cells.

I have the tools, talent, and most importantly—time.

And after watching videos from Andy's off grid garage, as well as ray build cool stuff, (and others!) I think it would a lot of fun to build a lithium battery.

To keep initial costs reasonable, I'm thinking of 100Ah 12V to begin with.

 

[SparkyJJO]

100Ah cells is not where the value is. per Ah they are one of the more expensive routes.

I bought 230Ah cells from Docan's Texas warehouse because at the time they were the cheapest per Ah from a USA warehouse that I felt I could trust based on others' reviews. Now prices have changed since then and I don't know what is the best deal per Ah right now.

 

[OffGridInTheCity]

I have the tools, talent, and most importantly—time.

It does take some time.

And after watching videos from Andy's off grid garage, as well as ray build cool stuff, (and others!) I think it would a lot of fun to build a lithium battery.

You bet, personally, I wouldn't do it if I didn't find it interesting/fun.

To keep initial costs reasonable, I'm thinking of 100Ah 12V to begin with.

Again, good plan in my experience. It's great to start of with a 1st, well defined battery, and you'll learn a lot the ins/outs and can decide on you're next move


In the US, the vendors I've used repeatedly for 2nd hand 18650 (and some have LifePo4)....
- Battery Hookup - https://batteryhookup.com/
- Battery Clearing House - https://www.batteryclearinghouse.com/collections/all

and this year I did my first order from
- Jag35 - https://jag35.com/

All 3 are reputable in my opinion, BUT you have to read the descriptions carefully and if they don't offer specifics then you can't expect specific results.

Not pushing these - and I'm sure there are other sources - just sharing what I've used

 

[Prosolar]

It does take some time.

You bet, personally, I wouldn't do it if I didn't find it interesting/fun.


Again, good plan in my experience. It's great to start of with a 1st, well defined battery, and you'll learn a lot the ins/outs and can decide on you're next move


In the US, the vendors I've used repeatedly for 2nd hand 18650 (and some have LifePo4)....
- Battery Hookup - https://batteryhookup.com/
- Battery Clearing House - https://www.batteryclearinghouse.com/collections/all

and this year I did my first order from
- Jag35 - https://jag35.com/

All 3 are reputable in my opinion, BUT you have to read the descriptions carefully and if they don't offer specifics then you can't expect specific results.

Not pushing these - and I'm sure there are other sources - just sharing what I've used

Thanks for your input. I'm going to stay away from the 18650 cells for the time being. Since the proposed battery will be living in the garage, and it gets damn cold in there in the winter, I think the best way to go is with the 100Ah (or higher) cells to get my toes wet. I completely understand that no matter the form factor, the cold garage will be an issue.

I've looked at some of the projects Jag35 had done, and it seems that he's always out of stock. I have to admit, and I'm NOT picking on him, but I don't like the way he runs high current (25A) though mounting standoffs. That's just me, I have to data to support my belief.

My current battery is a flood cell lead-acid with 880Ah of capacity. Derate at 50% discharge and I'm talking about 440Ah or about 23kW hours of capacity. If I go with lithium rack server batteries at 5.1kWh a pop, I'd need five at $1700 (or go cheap at $1500) and puts a dent into the checking account of $8500. Ouch!!

So that brings me back to giving a home-brew battery a shot. I'm going to start out small, and see how things go. I know the small capacity cells will be more expensive, but you have to learn to crawl before you can run a marathon.

 

[OffGridInTheCity]

Thanks for your input. I'm going to stay away from the 18650 cells for the time being. Since the proposed battery will be living in the garage, and it gets damn cold in there in the winter, I think the best way to go is with the 100Ah (or higher) cells to get my toes wet. I completely understand that no matter the form factor, the cold garage will be an issue.

For my Trailer, I use RV heating pads (https://www.amazon.com/gp/product/B07GW8ZX7X/ref=ppx_yo_dt_b_search_asin_title ) under my battery and the battery is enclosed in a box. These have thermostats to automatically turn on/off and are relatively low power - especially compared to the size of battery bank you plan.

What I'm trying to say, heating you're batteries may not be a *huge* deal. A LifePo4 battery at lower C will not generate heat / need air-flow to cool - so you can box it in and insulate and low levels of heat might do it for you

 

[Prosolar]

Gang,

I had a paradigm shift in my thinking.

If I go with, let's say four 100 Ah cells, then I'm kinda locked in. However, if I start with 280 Ahr cells, It would certainly be easier to add onto them if I decide to build a a 48V battery down the road.

 

[Kornbread]

Gang,

I had a paradigm shift in my thinking.

If I go with, let's say four 100 Ah cells, then I'm kinda locked in. However, if I start with 280 Ahr cells, It would certainly be easier to add onto them if I decide to build a a 48V battery down the road.

What are you going to do with the lead acid batteries?

 

[Nobodybusiness]

I'm still in the DIY camp for batteries because it allows me to customize to my exact requirements and allows me to over engineer which is something I like to do because of the peace of mind it gives me. However, DIY batteries are a tremendous amount of work. Given the KWH capacity that I want, I don't like the idea of having too many racks around as most rack batteries are only 5kwh each. From what I've seen, the price difference favors DIY batteries the higher KWH you go especially once you surpass the 50 to 80KWH mark. When the average server rack battery starts coming in at 10 and 15KWH per rack battery, we'll have to see if the price differential still remains the same at the higher end capacities. The rack batteries out there currently though from the major players seem really well built.

I bought some Global power 48vdc 400AH batteries a couple of years ago.

Each battery is a 16s4p config. 100ah cells.

They work great. Problem is each weight about 350 lbs.

I think most manufacturers build the 5kw version because of weight.

A 280ah battery (15KWH) with a case would be between 200-220 lbs depending on case thickness, wires, BMS, Ect.

Since most of us DIY we can move each cell (12 lbs) with ease.
Once you build it though it doesn’t usually get moved.

I think higher AH commercial batteries will come when we get a higher density chemistry.

Just my 2 cents

 

[Prosolar]

What are you going to do with the lead acid batteries?

They are running my off gird system right now, and they should last for another 10 years. The lithium battery will be for a redundant system.

 

[Xhumeka]

I can't argue the numbers, however that being said, in my original post, I don't want to mess with buying, shipping, and the total hassle of getting cells in from China. I've read so many posts here as well as dozens of Youtube videos about getting ripped off with bad, out of spec, damaged, and generally piss poor cells. And once you get 'em, you're stuck. There is zero recourse if what you get isn't what you ordered. Frankly, I'm too old to mess with China direct. That's why I asked about USA based shipment of Chinese cells.

I have the tools, talent, and most importantly—time.

And after watching videos from Andy's off grid garage, as well as ray build cool stuff, (and others!) I think it would a lot of fun to build a lithium battery.

To keep initial costs reasonable, I'm thinking of 100Ah 12V to begin with.

If you stick with the recommendations of this forum, you can reliably order from China, it's just the 60 day wait that's a bummer.

I just built a 280Ah 12 volt battery with 250amp BMS for $700 USD all-in. I used the cells described as "grade b" from Luyuan for $111 each plus shipping. The capacity was claimed to be 275Ah or better, and my own capacity tests confirmed this.

There's no vendor selling 275Ah, 250amp capable 12-volt batteries for even close to $700, so DIY is the only option for this price point.

 

[Prosolar]

If you stick with the recommendations of this forum, you can reliably order from China, it's just the 60 day wait that's a bummer.

I just built a 280Ah 12 volt battery with 250amp BMS for $700 USD all-in. I used the cells described as "grade b" from Luyuan for $111 each plus shipping. The capacity was claimed to be 275Ah or better, and my own capacity tests confirmed this.

There's no vendor selling 275Ah, 250amp capable 12-volt batteries for even close to $700, so DIY is the only option for this price point.

do you have a link to these cells?