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Getting ready to Build 24v 2p8s LifePO4

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Hello, getting ready build my first LiFePO4 battery and nowhere do I see the exact one I'm doing. Everyone i see is using 8 cells, I'm gonna use 16 (2p8s)

Just bought 16 320ah LiFePO4 batteries, and that's it so far.

First question; having 2 strings of 8 batteries , should I have 2 BMS"s?... 1 for each string?(because ill have 2 separate 24v batteries)
also what do you guys recommend? want something affordable with Bluetooth.. as far as power consumption, we have a 750 sq ft house, run a dishwasher, microwave ,occasional air compressor for a couple min etc.. so ii don't know if that factors into the size of the BMS, but don't want one that's too small

Next, Any suggestions for a balancer? will i need 2? if so want

was gonna get a Victron Energy battery low cut-off thingy also

not even sure if i posted this in the right spot, but any help you guys got is more than welcome, Thanks much...


Next question, if I have 2 BMS how important is it to have a LVD?


Also, if a good BMS will equalize a battery bank, how important is it to get a dedicated balancer? ( I plan on doing it anyhow)..(2, one for each string).. is that just in case BMS craps out?
Also want to say you guys are awesome and this info is priceless. God bless you!
 
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You could do 2p8s with one BMS, but personally I'd go with two banks each 1p8s with each having their own BMS.

I'm a fan of a BMS being capable of more than your ever going to really pull from it.

Any particular reason you're going with 24V instead of 48V? All else being equal, a 48V system would have half the current draw so maybe easier to handle as far as wire thickness, fuse/breaker current ratings, BMS amps limits, etc. Downside to 48V is perhaps fewer options for inverters, switches, etc.
 
Hello, getting ready build my first LiFePO4 battery and nowhere do I see the exact one I'm doing. Everyone i see is using 8 cells, I'm gonna use 16 (2p8s)

Just bought 16 320ah LiFePO4 batteries, and that's it so far.
To the best of my knowledge there is not such thing as a 320ah cell.
I fear that you have been hornswaggled.
First question; having 2 strings of 8 batteries , should I have 2 BMS"s?... 1 for each string?(because ill have 2 separate 24v batteries)
8s2p is two 8s batteries in parralel each with their own BMS.
That is what I recommend.
also what do you guys recommend? want something affordable with Bluetooth.. as far as power consumption, we have a 750 sq ft house, run a dishwasher, microwave ,occasional air compressor for a couple min etc.. so ii don't know if that factors into the size of the BMS, but don't want one that's too small
You need to size the BMS(s) for the max continuous load.
Overkill makes a BMS rated for 100 amps and it is has a good reputation on the forum.
Lets say you can get 160 amps continuous out of 2 of them.
I'm de-rating a bit because the parallel paths may not be perfectly matched.
160 amps * 24 volts low cutoff * .85 inverter efficiency = 3264 ac watts continous.

The compressor will probably be the most difficult load.
The locked rotor amps required to get the motor spinning could be up to 5 times the nominal draw.
The best way to measure this is with a clamp meter that has the in-rush feature.
Next, Any suggestions for a balancer? will i need 2? if so want
For batteries that claim to be 320ah you may well need an active balancer.
This guy has tested a bunch of BMS and/or balancers.
was gonna get a Victron Energy battery low cut-off thingy also
You mean one of these?
Beware you can't put one of those in front of an inverter.
Also they are not bi-directional so your charge sources can't send current through it backwards.
There is a method to control your inverter without putting the battery protect in the high current path.
Your inverter needs to support remote-switching though.
I can explain further if required.
 
Hello, getting ready build my first LiFePO4 battery and nowhere do I see the exact one I'm doing. Everyone i see is using 8 cells, I'm gonna use 16 (2p8s)

Just bought 16 320ah LiFePO4 batteries, and that's it so far.

First question; having 2 strings of 8 batteries , should I have 2 BMS"s?... 1 for each string?(because ill have 2 separate 24v batteries)
also what do you guys recommend? want something affordable with Bluetooth.. as far as power consumption, we have a 750 sq ft house, run a dishwasher, microwave ,occasional air compressor for a couple min etc.. so ii don't know if that factors into the size of the BMS, but don't want one that's too small

Next, Any suggestions for a balancer? will i need 2? if so want

was gonna get a Victron Energy battery low cut-off thingy also

not even sure if i posted this in the right spot, but any help you guys got is more than welcome, Thanks much
Regarding the BMS, what is the watt rating on your inverter? The peak amps the inverter will pull will be a factor in selecting the proper BMS.
 
I see a 48v system in this guys future. Seems like the logical way to go. Especially if he finds his current 16 cells don’t provide enough capacity. it’s easy to add another 16s string vs adding more 24v strings due to current limitations.
 
My
You could do 2p8s with one BMS, but personally I'd go with two banks each 1p8s with each having their own BMS.

I'm a fan of a BMS being capable of more than your ever going to really pull from it.

Any particular reason you're going with 24V instead of 48V? All else being equal, a 48V system would have half the current draw so maybe easier to handle as far as wire thickness, fuse/breaker current ratings, BMS amps limits, etc. Downside to 48V is perhaps fewer options for inverters, switches, etc.
Current lease acid system(inverter etc) is all 24v . Also my emergency battery charger is 24v. And going to keep a select few of my current batteries as a back up, the others with dead cells are going bye bye. Thanks for input.
 
Regarding the BMS, what is the watt rating on your inverter? The peak amps the inverter will pull will be a factor in selecting the proper BMS.
My inverter is an Aims 4000watt with up to a 12,000 way surge for up to 20 seconds. It powers air compressor very easily, so I'm guessing most of that required surge comes from capacitors in inverter and not so much from batteries
 
I’d say two 100a or 150a BMS to help with surge current.

There are 200a JBD BMS but the verdict is out if they are up to snuff.
 
I’d say two 100a or 150a BMS to help with surge current.

There are 200a JBD BMS but the verdict is out if they are up to snuff.
I was actually just gonna pull the trigger on 2 of these from AliExpress, was gonna get the 200a, figured I'd go bigger,..
 

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My inverter is an Aims 4000watt with up to a 12,000 way surge for up to 20 seconds. It powers air compressor very easily, so I'm guessing most of that required surge comes from capacitors in inverter and not so much from batteries
Any surge that last more than a few microseconds will translate into a battery load. However, a 100 amp BMS should carry 200% or 300% over current for a handful of seconds, normally. So you would normally size the BMS for the full 4000w of the inverter. Your plan for 200a per battery string is more than enough.
 
I was actually just gonna pull the trigger on 2 of these from AliExpress, was gonna get the 200a, figured I'd go bigger,..
Such success with JK or JBD BMS on this site that it’s be tough for me to try a new brand.

I’m rarely a trail blazer when it comes to trying system critical electronics
 
Such success with JK or JBD BMS on this site that it’s be tough for me to try a new brand.

I’m rarely a trail blazer when it comes to trying system critical electronics
That purple BMS is very likely a re-badged Daly.
Daly BMSs have minimal balance capacity.
Those 320AH cells are probably going to drift more than a Daly can manage.
 
Regarding the BMS, what is the watt rating on your inverter? The peak amps the inverter will pull will be a factor in selecting the proper BMS.
Inverter is Aims 4000 Watt low frequency pure sine wave inverter/charger w. 12,000 watt 20 second surge
 
That purple BMS is very likely a re-badged Daly.
Daly BMSs have minimal balance capacity.
Those 320AH cells are probably going to drift more than a Daly can manage.
They will drift of he pushes the top end for that last 10% capacity, keep all cells at around 3.45v and his cells will be pretty balanced.

If he needs to active balancer are cheap.
 
They will drift of he pushes the top end for that last 10% capacity, keep all cells at around 3.45v and his cells will be pretty balanced.

If he needs to active balancer are cheap.
Cells will drift anywhere along the curve.
That means decreased capacity.
If you don't charge into the high knee, the BMS and/or active balancer can't do anything about it.
 
Quality cells that are top balanced should stay healthy or pretty happy under 3.5v at least that’s what I’m seeing in my cells.
 
Quality cells that are top balanced should stay healthy or pretty happy under 3.5v at least that’s what I’m seeing in my cells.
The voltage differential is only noticeable in the high and the low knee, but that doesn't mean the capacity differential isn't drifting.
You mention quality cells.
OP mentions 320AH cells, which to the best of my knowledge don't exist.
To me that is a huge red flag.
I would not be surprised is these cells test to 280AH or lower.
I would also not be surprised if the internal resistance is all over the road.
They may even come bloated.
The best case I can see is the cells having cosmetic defects.
 
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