Next best LiFePO4 cells after A123 and Headway

[lettersize]

Guys, what is next best LiFePO4 cells for DIY battery pack after A123 and Headway?
I need 24v 75ah to 100ah battery. Continuous current = 30A, peak current = 60A.
A123 and Headway are out of my budget. What are the next best/cheaper options out there?

 

[999zip999]

Lifepo4 cells aren't that strong. Some lifepo4 can handle high output. But are a few headway, A123 and ? Headway are overrated. How many amps do you need for your build. Love my bolt together A123 24s heavy and should last forever.

 

[Hillhater]

30 amps from a 75ahr pack can be done with almost any cell you could buy.
So any other requirements ?...weight , size, lifecycle, etc ?
If you definitely want LifePo4 , just go with the Headway or CalB bricks.
..Personally , I would source 3 or 4 Leaf modules.@ $100 each !

 

[999zip999]

How hard is it to put a bms on those leaf modules ?

 

[lettersize]

Lifepo4 cells aren't that strong. Some lifepo4 can handle high output. But are a few headway, A123 and ? Headway are overrated. How many amps do you need for your build. Love my bolt together A123 24s heavy and should last forever.

Continuous current = 30A, peak current = 60A.
Yeah, A123 would be good. But they don't manufacture them anymore. All cells sold now are from old stocks/or returned/not passed quality test, right?
Also a bit expensive for me.

30 amps from a 75ahr pack can be done with almost any cell you could buy.
So any other requirements ?...weight , size, lifecycle, etc ?
If you definitely want LifePo4 , just go with the Headway or CalB bricks.
..Personally , I would source 3 or 4 Leaf modules.@ $100 each !

weight - any, size- any, lifecycle - best ratio of $ spent to lifecycles.
Leaf modules sounds very good. In fact that was my original idea to use either Volt pack module or Lead pack module.
But i am worrying about safety/fire. Leaf is Lipo, right? So lifepo4 would be safer?
Also if i decide to do Leaf modules pack way - what BMS would i need? and what charger?

 

[amberwolf]

Yeah, A123 would be good. But they don't manufacture them anymore. All cells sold now are from old stocks/or returned/not passed quality test, right?

Nope; A123systems.com still makes them (in Livonia, IIRC) and sells them thru their "sister" company I forget the name of.

There's a few threads discussing their present production and sales of cells; probably easiest if you just look for threads wb9k has posted in, about A123.

 

[dogman dan]

I'm curious what this is for. 24v 75 ah is about 2000 watt hours.

Using a typical prismatic lifepo4 20 ah cell, a 20 ah block would be 14"x3"x 6" tall. So three or four blocks that size. Naked pouches smaller, but still, a 2000 watt hour lifepo4 is quite a chunk, weighing about 40 pounds.

You could cut the weight and volume by more than 30% by choosing a magnesium chemistry. This would be worth it, for a bike or motorcycle.

If its a stationary solar panel power storage, then go with some large format prismatic lifepo4, something like used in the DIY electric cars. They come in various ah sizes. For less connections, I'd say start with whatever size is closest to your goal of 100 ah.

Not recommending this vendor, just putting the link to illustrate the type of 100 ah cell.
http://www.batteryspace.com/lifepo4-prismatic-module-3-2v-100ah-10c-rate-320wh-un38-3-passed-dgr.aspx

 

[lettersize]

I'm curious what this is for. 24v 75 ah is about 2000 watt hours.
Using a typical prismatic lifepo4 20 ah cell, a 20 ah block would be 14"x3"x 6" tall. So three or four blocks that size. Naked pouches smaller, but still, a 2000 watt hour lifepo4 is quite a chunk, weighing about 40 pounds.
You could cut the weight and volume by more than 30% by choosing a magnesium chemistry. This would be worth it, for a bike or motorcycle.

dogman dan - it's for cargo bikes.
"You could cut the weight and volume by more than 30% by choosing a magnesium chemistry" - yes, and what about the best $ spent / # of cycles.
It's first time i hear about magnesium chemistry - could you suggest the seller so i can check the prices?
Also what about safety.

 

[999zip999]

It also depends on where you live ?

 

[lettersize]

It also depends on where you live ?

USA, NJ

 

[Cephalotus]

My recommondation für 24V 70Ah =

Sony US18650V3 in a 7s32p configuration. Those 224 cells do cost 490 Euro in Europa (and this is incl ~20% VAT).

http://eu.nkon.nl/rechargeable/18650-size/sony-us18650v3.html

Very cheap, very safe, good enough, much more lightweigt than LiFePO4, good cycle life, no BMS required, so super easy to use...

If you build the pack well it will be almost impossible to get the pack to burn, no matter what you do with it...

 

[lettersize]

My recommondation für 24V 70Ah =

Sony US18650V3 in a 7s32p configuration. Those 224 cells do cost 490 Euro in Europa (and this is incl ~20% VAT).

http://eu.nkon.nl/rechargeable/18650-size/sony-us18650v3.html

Very cheap, very safe, good enough, much more lightweigt than LiFePO4, good cycle life, no BMS required, so super easy to use...

If you build the pack well it will be almost impossible to get the pack to burn, no matter what you do with it...

hm, that's the first time i hear about Sony US18650V3. So it's Li-Ion and it's safer than LiFePO4?
And where i can buy them? I guest Europe in not the source the coming from? It's reseller, right?
Just checked aliexpress: 224 cells will be about $950 including shipping to USA.
p.s. imagine it would be nightmare to build 224 cells pack

 

[dogman dan]

FWIW, that would be one of the magnesium types I was talking about. Lots smaller and lighter than lifepo4. I carry 33 ah of it (1500wh of NMC) on my cargo bike. Ready made packs like this using cheaper cells can be very affordable on Alibaba.

I wouldn't say no bms needed, but like any cell you can choose to be a human bms.

Cargo bike (or most trikes) can certainly handle the size and weight of 2000wh of lifepo4. But since it's not a stationary solar thing, you'd likely still benefit from two or more pouch cell packs, rather than large format lifepo4 prismatic cell. I had to ask, because you might have thought you could carry a huge heavy battery on a regular bike. But you could trailer a huge pack behind anything.

Pingbattery would be a starting point, but you can find similar cells packs less expensive from other vendors in china. Maybe two of these to start? http://www.pingbattery.com/servlet/the-15/24v-30ah-lifepo4-lithium/Detail That would be about 750wh each. About 30 pounds for 1500wh. Depending on your speed, that's 30-60 miles range.

But that's not DIY of course.

Re the cycle life, in my climate I get 3-4 years out of all chemistries. So I never get the real 2000 cycles from lifepo4. I'm in a very hot desert, so if I use my batteries in summer, they die faster.

 

[lettersize]

dogman dan thank you for your reply, NMC is the chemistry they use on Chevy Volt and Nissan Leaf modules, right?
It's one of the options i am considering.

What you think about CALB cells?
I've read people rate them better than A123(or chinese A123) on diy electric car forum

I wouldn't do it.... I spent a year on A123 20Ah prismatic cells and only have a small portion of a working pack, the rest is made up of CALB prismatics that perform well and were much easier to use.