24 x 200ah cells to make biggest ah 24v battery.

Absentrush

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Please can someone kindly assist?
I now have 24 x 200ah 3.2v LIFEPO4 cells and want to make the biggest+safest AH 24v battery I can from that lot. I would dearly love to see the arrangement plan and BMS's involved.
Thanks guys ;-)
 

Sanwizard

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Buy three good bms's,( I use Heltec/JK) and make three 8s strings connected in parallel using high amp busbars. Monitor SOC with a Victron 500a Shunt. Every cell monitored and protected. Use non-conductive heat resistant sheeting between and under cells.
Protect all terminals and connections.
 

Horsefly

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Buy three good bms's,( I use Heltec/JK) and make three 8s strings connected in parallel using high amp busbars. Monitor SOC with a Victron 500a Shunt. Every cell monitored and protected. Use non-conductive heat resistant sheeting between and under cells.
Protect all terminals and connections.
Hey @Sanwizard - I agree mostly with what you said. Almost entirely. However, Heltec/JK BMS requires - unless I've missed something - a 40V-100V power supply. So if you have an 8S / 24V LFP pack, you have to add a boost converter to get 40+V to power the BMS. Doesn't seem very efficient. I am sure that Heltec/JK are great BMSs. I'd just suggest they currently are only suitable for a 16S / 48V battery.
 

Sanwizard

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Hey @Sanwizard - I agree mostly with what you said. Almost entirely. However, Heltec/JK BMS requires - unless I've missed something - a 40V-100V power supply. So if you have an 8S / 24V LFP pack, you have to add a boost converter to get 40+V to power the BMS. Doesn't seem very efficient. I am sure that Heltec/JK are great BMSs. I'd just suggest they currently are only suitable for a 16S / 48V battery.
I just said thats what I use. They do work at 8s also, as proved by Andy at the off grid garage, and you are right, JBD would be simpler in an 8s config.
 

Martijn

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Hey @Sanwizard - I agree mostly with what you said. Almost entirely. However, Heltec/JK BMS requires - unless I've missed something - a 40V-100V power supply. So if you have an 8S / 24V LFP pack, you have to add a boost converter to get 40+V to power the BMS. Doesn't seem very efficient. I am sure that Heltec/JK are great BMSs. I'd just suggest they currently are only suitable for a 16S / 48V battery.
Newer JKs should support 24V as the power supply, it was a recent change.
 

Martijn

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Martijn

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Wow! Really? Do you have a link to these new ones? The JK BMS web store (jkbms.com) doesn't seem to show these new ones.
Alternatively, there's this one (also a JK variant)
 

Horsefly

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Well, thanks for that @Martijn. Funny that they are on these other sites, but JK's own site doesn't have them.

They still remain a bit pricey, but I'll have to consider them on my next 8S build. As it is I have an excess of JBD / Overkill BMS's, so I need to resist the temptation to buy another BMS. :whistle:
 

Martijn

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Well, thanks for that @Martijn. Funny that they are on these other sites, but JK's own site doesn't have them.

They still remain a bit pricey, but I'll have to consider them on my next 8S build. As it is I have an excess of JBD / Overkill BMS's, so I need to resist the temptation to buy another BMS. :whistle:
I'll be buying one this week so I'll try it out when the cells arrive. Kinda ruined my 250A Daly BMS during a firmware update 😩
 

ShockinglyAverage

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I'll be buying one this week so I'll try it out when the cells arrive. Kinda ruined my 250A Daly BMS during a firmware update 😩
Are you buying the minerals one? Please let us know if it works on 24v without having to step up to 40v as I just purchased one but don't have my cells yet to test it. It didn't say anywhere on the listing that it required 40v to work but the "instructions" (such as they are) say it does so now i'm concerned.
 

Sanwizard

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I believe the JK's just need a voltage of around 5V over pack voltage. A 9V cell usually works fine.
 

ShockinglyAverage

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I believe the JK's just need a voltage of around 5V over pack voltage. A 9V cell usually works fine.
That’s to initially turn it on. But the information provided with the bms states it needs to be supplied with 40v+ to power it after initial turn on.
 

Martijn

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Are you buying the minerals one? Please let us know if it works on 24v without having to step up to 40v as I just purchased one but don't have my cells yet to test it. It didn't say anywhere on the listing that it required 40v to work but the "instructions" (such as they are) say it does so now i'm concerned.
Just purchased one from the HankzorBMS store, I was told starting voltage has been lowered to 20V.

Checked the manual, it says 20V:
 

Horsefly

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Watch Andy's youtube channel off grid garage. He tested it as an 8s, and it worked fine at 24V.
The video I saw him using it on a 12V pack but he used a boost converter to get 48V out to power the BMS. I guess I don't recall him also doing an 8S pack.

The description of the JK BMS pretty clearly state that it needs a 40V-100V power supply.
 

Horsefly

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Just purchased one from the HankzorBMS store, I was told starting voltage has been lowered to 20V.

Checked the manual, it says 20V:
The HankzorBMS seems to be a derivative of, not a rebrand of the JK BMS. I guess I'm not too sure about it, but I'll wait to hear you report on how it works, and if it works with no 40V+ power supply.
 

ShockinglyAverage

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I just received this from the seller I purchased mine from and it looks like it accepts 20-40v so we should all be good.

Now does anyone know if the RS485 port on this bms will talk to a Growatt? And if so, what all that would entail as far as setting it up? I'm communications protocol dumb.
 

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Martijn

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The HankzorBMS seems to be a derivative of, not a rebrand of the JK BMS. I guess I'm not too sure about it, but I'll wait to hear you report on how it works, and if it works with no 40V+ power supply.
The Minerals one is also based on JK. I'm not sure how they're doing that, but the HankzorBMS store lists them as "JK BMS".
 
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