Need a little help.... Deciding between these two, any help with some clarification? Thanks in advance guys!

[NickB369]

So I'm purchasing items for a DIY LiFePO4 battery, as I'm assembling a 24v, 800w solar system Will has made famous (the one HERE).

I found this 8 pack from his links, shipping from China (not sure if they're shipping from China yet, anyone?) that says it takes 2-3 weeks.

On Ebay there's this similar 4 pack that seems to be twice as powerful. I'm just a little confused by the way they're listed differently.

How many Ah are we talking for a 24v system on each of these? I feel mental here.... lol. I think that either the one from China is the best bet, and the Arizona Ebay option is 1/2 the power, or they're the same. If it's not one of those two, I may move away from solar power and just live in a tree.


Thanks for any help or info!

 

[MisterSandals]

I found this 8 pack from his links

Aliexpress says: 8Pcs 3.2v 100ah Lifepo4 battery Lithium iron phosphate cell batteries

You assemble the 8 cells in series and get a 24v 100AH battery.
You could also assemble 4 cells in series (twice) to make 2 12v 100AH batteries.
If you hook the 2 12v batteries together in series, you can also make 24v 100AH.

If you hook the 2 12v batteries together in parallel, you get 12v 200AH.

 

[NickB369]

Aliexpress says: 8Pcs 3.2v 100ah Lifepo4 battery Lithium iron phosphate cell batteries

You assemble the 8 cells in series and get a 24v 100AH battery.
You could also assemble 4 cells in series (twice) to make 2 12v 100AH batteries.
If you hook the 2 12v batteries together in series, you can also make 24v 100AH.

If you hook the 2 12v batteries together in parallel, you get 12v 200AH.

THanks for replying man! What's he using here then making a 2.4 kWh battery for $660? VIDEO

 

[MisterSandals]

That's a 26min video...
Lets figure it out:
2400w / 24v = 100AH
So yea, he is using 8x 3.2v cells hooked in series to make 24v.

 

[Bob B]

The best deals are a moving target .... depending on how fast you need them, you might also consider THESE from @Craig . 8 of these will get you 280 AH at 24V. You can get 8 for $1200 if you get him a deposit in the next week.
There are several threads going about good deals ...... start by watching new threads or searching.

 

[BarkingSpider]

For the same price, you can get over 2x the power. 280ah cells, top grade. This is the best value for money today. 100ah cells are very old tech.
Its even cheaper getting them from Craig as he gets a bulk shipment. Shipping is half the cost.

Szxuba Grade A Eu Stock Rechargeable 3.2v 280ah Lifepo4 Lithium 280ah Energy Storage Battery Cell - Buy Lifepo4 280ah Battery,Eu Stock 280ah Lifepo4 Battery Cell,Lifepo4 280ah Product on Alibaba.com

Szxuba Grade A Eu Stock Rechargeable 3.2v 280ah Lifepo4 Lithium 280ah Energy Storage Battery Cell - Buy Lifepo4 280ah Battery,Eu Stock 280ah Lifepo4 Battery Cell,Lifepo4 280ah Product on Alibaba.com

www.alibaba.com

 

[NickB369]

That's a 26min video...
Lets figure it out:
2400w / 24v = 100AH
So yea, he is using 8x 3.2v cells hooked in series to make 24v.

I can appreciate that your icon is captain obvious, but just to be clear, those 8 cells, you're only yielding a max of 100 aH stored energy at 24v? Does an inverter use 24v energy more efficiently than 12v? Like, does the V being x2 give you x2 "power storage" per se? It seems huge to have that little of a yield. Sorry for the obviously ignorant questions.

 

[NickB369]

The best deals are a moving target .... depending on how fast you need them, you might also consider THESE from @Craig . 8 of these will get you 280 AH at 24V. You can get 8 for $1200 if you get him a deposit in the next week.
There are several threads going about good deals ...... start by watching new threads or searching.

I messaged @Craig ! Keeping this option at the top. He said it would be at least 40 days though, I sort of need them before the end of May, sooner the better.

 

[Bob B]

I messaged @Craig ! Keeping this option at the top. He said it would be at least 40 days though, I sort of need them before the end of May, sooner the better.

Shipping is slow out of China right now ..... there may be some who are shipping fast, but you will have to pay a lot more. Most are taking 30 days or more.
Maybe someone will check in who knows about someplace shipping quicker.

 

[NickB369]

That's great to know man! The price is a bit higher with shipping, but still, not that bad for 8 cells. This seems to be the best deal so far though. I was hoping to get them in the next few weeks, so this may be the way to go.

 

[MisterSandals]

those 8 cells, you're only yielding a max of 100 aH stored energy at 24v? Does an inverter use 24v energy more efficiently than 12v? Like, does the V being x2 give you x2 "power storage" per se?

The “energy” stored is the same whether the cells are arranged as 12v or 24v.

Lets convert both to watt hours:
12v x200ah = 2400wh
24v x 100ah = 2400wh

Imagine if your battery were a 2400 gallon water tank. Would you rather supply water with a small hose (12v) at high pressure, or with a big hose (24v) at lower pressure?

It might matter depending on how you are using the water and maybe it does not.
(This isn’t a perfect analogy i know)

A higher voltage system will deliver power with lower amps (pressure) which usualky run on smaller (and cheaper) wires.

The point i see folks saying you should have a 24v system is if you need a 3000w inverter.
Lower generally ok for 12v.

Is a 12v inverter more efficient than a 24v? I dunno, mostly depends on the quality of the inverter (they usually indicate efficiency so you can research that).

My big battery is 8x 200ah cells (2p4s) at 12v. Everything i have is 12v (not 24v) so its an easy choice. My biggest pure sine wave inverter is 1200w.

Hope this helps, sorry to ramble.

 

[Bob B]

Yeah .... If you wanted to use 12V instead of 24V you could get 4 of the 280"s instead of 8. That would give you 280AH at 12V.

That would give you more power than the 8 100 AH you were looking at to start and only cost you $600 if you go thru Craig.

 

[Craig]

Im not advocating for buying mine at all because I already have a huge order in the works. But I wonder how long shipping will be from these guys. Air shipping is not much faster right now if they are shipping by air. By sea should be similar to mine.

 

[NickB369]

The “energy” stored is the same whether the cells are arranged as 12v or 24v.

Lets convert both to watt hours:
12v x200ah = 2400wh
24v x 100ah = 2400wh

Imagine if your battery were a 2400 gallon water tank. Would you rather supply water with a small hose (12v) at high pressure, or with a big hose (24v) at lower pressure?

It might matter depending on how you are using the water and maybe it does not.
(This isn’t a perfect analogy i know)

A higher voltage system will deliver power with lower amps (pressure) which usualky run on smaller (and cheaper) wires.

The point i see folks saying you should have a 24v system is if you need a 3000w inverter.
Lower generally ok for 12v.

Is a 12v inverter more efficient than a 24v? I dunno, mostly depends on the quality of the inverter (they usually indicate efficiency so you can research that).

My big battery is 8x 200ah cells (2p4s) at 12v. Everything i have is 12v (not 24v) so its an easy choice. My biggest pure sine wave inverter is 1200w.

Hope this helps, sorry to ramble.

Thank you for taking the time. That helped a TON. Sincerely man. I appreciate it.

 

[NickB369]

Im not advocating for buying mine at all because I already have a huge order in the works. But I wonder how long shipping will be from these guys. Air shipping is not much faster right now if they are shipping by air. By sea should be similar to mine.

I reached out to a few buyers to see what they say, I'll probably end up going with you.

With that said, let's say there was a big-box store with a ridiculously forgiving return policy... could I build my system out with an AGM bank for the time being so that I have power on my rig and then swap out for the LiFePO4 bank when yours arrive... and you know.... take advantage of that return policy, lol.

 

[Craig]

I reached out to a few buyers to see what they say, I'll probably end up going with you.

With that said, let's say there was a big-box store with a ridiculously forgiving return policy... could I build my system out with an AGM bank for the time being so that I have power on my rig and then swap out for the LiFePO4 bank when yours arrive... and you know.... take advantage of that return policy, lol.

I was gonna suggest something like that. Not sure f that forgiving return policy would accept a used battery though for full refund usually it is a pro rated replacement.

 

[NickB369]

Yeah .... If you wanted to use 12V instead of 24V you could get 4 of the 280"s instead of 8. That would give you 280AH at 12V.

That would give you more power than the 8 100 AH you were looking at to start and only cost you $600 if you go thru Craig.

Still, 1000 bucks for that much power is pretty great.

Just to double-check my math, if I get 8 of those and ran them series/parallel for a 24v battery, I'd have 560 Ah of storage? Not bad.

 

[Bob B]

Still, 1000 bucks for that much power is pretty great.

Just to double-check my math, if I get 8 of those and ran them series/parallel for a 24v battery, I'd have 560 Ah of storage? Not bad.

That's right if you did 2P4S to make a 12V battery, you would have 560AH at 12V.

 

[Craig]

Still, 1000 bucks for that much power is pretty great.

Just to double-check my math, if I get 8 of those and ran them series/parallel for a 24v battery, I'd have 560 Ah of storage? Not bad.

8 cells only makes a 1p8s 24V battery or a 2p4s12v battery both have 6.7Kw of storage.

 

[BarkingSpider]

Go with 24v over 12v if you can, you get much more options for better equipment down the road. The initial cell costs are double, but If I was starting again I would now move up again to 48v. Your so much more efficient and can use bigger solar arrays when you use higher DC voltages.

I wish I could have those 280ah chinese packs, but the shipping and delay put me off. I went with BYDs for now and hedged my bets there will be some killer deals for batteries in a few years. Prices are dropping so fast and power capacity's are going up and up.

I bought my BYDs from TechDirect and they arrived in 2 days from California on a pallet. He tested all my units for capacity. $460 inc shipping each. I got 3.75kwh capacity from each unit in my tests. They should be good for at least a few years, maybe much longer. Their whitepaper quotes 10,000 cycles.

This is my 15kwh 24v stripped down BYD bank.