What BMS should I get?

RossA

New Member
Joined
Dec 2, 2021
Messages
13
I ordered 8 304 AH LiFePO4 cells from Docan Technology (Shenzhen) a few days ago. They told me that they will be arriving in their texas warehouse within a few weeks and then off to my house. I want a 24v system and so I was originally planning on an 8s system. I keep seeing issues with the Daly BMS's which is unfortunate. I wanted 200A of discharge capability but I can't find a 200A discharge on a JBD. There is one way I could get 200A discharge by making a 2p4s bank instead with 2 4s 100A JBD BMS... but that complicated things a little bit.

What would you do? I've seen great things about this supplier on this website but want to be able to test the cells properly as soon as I get them. Considering they could be to my door within the next few weeks, I'd like something that I can buy from a US distributor.

I still need to buy the powersupply and capacity testers, but those are more easily found within the US.

Thanks!
 

smoothJoey

Hoop Dee Doo!
Joined
Nov 30, 2019
Messages
9,870
Okay, Thank you!

Those all seem to be for Lithium ion cells rather than the LiFePO4 cells that I have.
That bms is for lifepo4(LFP) cells.
Its the most popular bms on this forum actually.
I'm referrring to the overkill bms.
 

MurphyGuy

GOD ALMIGHTY
Joined
May 20, 2020
Messages
1,044
Okay, Thank you!

Those all seem to be for Lithium ion cells rather than the LiFePO4 cells that I have.
They are programmable through their settings to work with any Chemistry.

You set min and max allowable voltages, balance voltage, min/max pack temperature, etc.

These are the three high quality BMS's.. not Chinese garbage.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
That bms is for lifepo4(LFP) cells.
Its the most popular bms on this forum actually.
Yes, the overkill BMS is for LiFePO4 cells. The Rec, Orion, and Batrium BMS were what I was referring to.

Isn't the overkill BMS just a rebranded JBD BMS? The cost difference is pretty substantial.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
They are programmable through their settings to work with any Chemistry.

You set min and max allowable voltages, balance voltage, min/max pack temperature, etc.

These are the three high quality BMS's.. not Chinese garbage.
Interesting, I guess I needed to look a little closer. Thank you.
 

MurphyGuy

GOD ALMIGHTY
Joined
May 20, 2020
Messages
1,044
Interesting, I guess I needed to look a little closer. Thank you.
They also have CAN communications so they can work with the higher quality inverters as well.

I use REC on my system, which is a 25kWH lithium pack from a Chevy BOLT, and two SMA Sunny Islands.

They ARE more expensive.. but you're not passing current through them, they require an external relay like a KiloVac.

Here's a pic of mine.
 

Attachments

  • Post3.jpg
    Post3.jpg
    484.4 KB · Views: 12

smoothJoey

Hoop Dee Doo!
Joined
Nov 30, 2019
Messages
9,870
Yes, the overkill BMS is for LiFePO4 cells. The Rec, Orion, and Batrium BMS were what I was referring to.

Isn't the overkill BMS just a rebranded JBD BMS? The cost difference is pretty substantial.
Yes it is.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
They also have CAN communications so they can work with the higher quality inverters as well.

I use REC on my system, which is a 25kWH lithium pack from a Chevy BOLT, and two SMA Sunny Islands.

They ARE more expensive.. but you're not passing current through them, they require an external relay like a KiloVac.

Here's a pic of mine.
I'm sure they are awesome, and when working with Lithium Ion cells I'm sure its mandatory since those cells can be so unstable if not properly taken care of.

Unfortunately, my budget doesn't really allow for a BMS like that when people have had good success with JBD BMS on systems more similar to my own.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
That bms is for lifepo4(LFP) cells.
Its the most popular bms on this forum actually.
I'm referrring to the overkill bms.
Sorry, one more clarification. Would I need two separate 4s BMS since the batteries would essentially be configured as 2 12v batteries in series. Each 12v section would need its own BMS right?
 

smoothJoey

Hoop Dee Doo!
Joined
Nov 30, 2019
Messages
9,870
Sorry, one more clarification. Would I need two separate 4s BMS since the batteries would essentially be configured as 2 12v batteries in series. Each 12v section would need its own BMS right?
Yes 1 bms per 4s battery, 2 in total.
 

hankcurt

Solar Addict
Joined
Feb 11, 2020
Messages
128
Location
Nebraska, US
Check the specifications on the BMS you are selecting carefully. Only certain BMS models are designed for series operation. They have to have a higher voltage FET for current switching than ones that are not designed for series operation.

JDB as a 150A bms that is designed for up to 4 individual 4s batteries in series. https://www.lithiumbatterypcb.com/p...0a-constant-current-for-power-conveter-12-6v/

I'm not endorsing this particular merchant. I've done no business with them.
 

smoothJoey

Hoop Dee Doo!
Joined
Nov 30, 2019
Messages
9,870
Sorry, one more clarification. Would I need two separate 4s BMS since the batteries would essentially be configured as 2 12v batteries in series. Each 12v section would need its own BMS right?
Sorry my mistake, my recommended setup requires 16 cells and 2x 8s BMSs in parallel.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
there is a 200 amp jbd BMS but its new and the forum does not have a lot of experience with it yet.
I'd love to get that one, but I can't even find it on Alibaba, let alone a US vendor.

Does anyone know if the JBD 120A 4s BMS off of Srikobatteries can be connected in series safely?

Or there are the BMS on battery hookup. Wondering if a 4s 100a BMS there would be able to handle series as well.
 

RossA

New Member
Joined
Dec 2, 2021
Messages
13
I'm now looking at the JK 8s 200A BMS which the Offgrid Garage really recommends. It is a little bit more expensive, but has the active balancer built in.
 
Top