QUCC or JK BMS

SparkyJJO

I have that name for a reason.
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Ohio
I'm considering the following setup:
16 EVE230 cells from powerwholesale
8kW Outback Mojave inverter (whenever it becomes available)

I was looking at using the JK 200A BMS for the cells, partially because I like the 2A active balancing feature it has compared to JBD.

1645731664059.png

Then I started doing some math, and got concerned. 8000W / 48V = 167A

"ok-ish" - not great, but technically within specs and I'm unlikely to be pulling 8kW sustained for any length of time. But, throw efficiency loss into the mix...

8000W / 0.85 / 48V = 196A

That's awful close to the 200A rating. Now, am I going to be pulling that much from the inverter on any regular basis? I doubt it. If I was, that battery bank wouldn't run very long, and once I start adding additional banks with additional BMSes then the power draw is no longer a problem. But, still, at least in theory, I could pull near the limits and that's concerning to me.

Alternative is this QUCC (which may be a JBD?) BMS. It has an option of a 200A or 300A relay contactor with a peak 600A. That should do it just fine, but it has low balancing currents. Hopefully it is ok if I get good cells. Or, maybe pair it up with a separate active balancer?

1645731746146.png

So, which BMS would you guys pick? Or a different option?
 

BentleyJ

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I like the concept of a separate high current contactor rather than power FET's on the PCB. I'm using a ZEVA BMS with a 200A golf cart contactor along with a JK BMS brand 2A active balancer only. The problem with the balancer is that its either ON or OFF. When on, it balances all the time and doesn't have a user setting so it only balances at the top & bottom. Not sure but I believe the JK BMS active balancer combo does have a user setting for when the balancing cuts in and cuts out but which is a nice feature. However, I agree with your assessment that the JK BMS probably isn't the best choice for 200A worth of current.
 

SparkyJJO

I have that name for a reason.
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I found a smart 1A or 2A balancer, so that would give control over the balancing timing vs the "dumb" ones. Costs a lot more though.

1645797783899.png
 

BentleyJ

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I found a smart 1A or 2A balancer, so that would give control over the balancing timing vs the "dumb" ones. Costs a lot more though.

View attachment 85214
This is a Bluetooth active balancer, the same one I'm using. It is sold by various companies with no branding but if you check it out, ultimately it traces back to the JK BMS company. As stated previously, this is a good balancer and works well. BUT, Unless they have upgraded their firmware there is no user setting for Top & Bottom balance voltage thresholds. Its either ON or OFF. If balancing continues during the FLAT part of the chg/discharge curve then the cells are actually being unbalanced. What I've decided to do is charge our stand-by batteries once a week by manually turning on both the Inverter charger and the active balancer and then manually turning both off once the cells show as top balanced. Off Grid Garage detailed this issue a while back.
 

RV10flyer

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Mar 8, 2021
Messages
732
I use both. My JK BMS is the only one out of the 160 ea 280aH cells that can keep its 16 cells balanced properly above 3.5V/cell. All cells came from two highly recommended vendors. I'm glad I didn't choose the cheaper cells. QC is seriously lacking now in the goods coming in.
 

Henderson

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Jan 9, 2022
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I use both. My JK BMS is the only one out of the 160 ea 280aH cells that can keep its 16 cells balanced properly above 3.5V/cell. All cells came from two highly recommended vendors. I'm glad I didn't choose the cheaper cells. QC is seriously lacking now in the goods coming in.
@RV10flyer Just out of curiosity, how do you have your 160 cells configured? Do you have these as 10 separate batteries with the JK BMS on each? I'm trying to determined what battery capacity (Ah) should match what balancing current. I'm designing my build which will have a max of 128 cells but I don't want to have 8 separate batteries but will do either 2x 4P16S or 4x 2P16S. Before I finalize, I'm trying to determine if a 2A balancer is enough for a 560Ah or 1120Ah (doubtful on this one) battery or would I need a higher balancing current. I would ideally prefer the 2x 4P16S option but I'm not sure if a say a 2A or 5A balancer would be enough.
 

SparkyJJO

I have that name for a reason.
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Messages
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Ohio
I went with the 300A contactor JBD/QUCC. I am hoping I don't regret not getting the JK.

I would think if you need more than 2A balance current then your cells are really not very good. Just my gut feeling, no experience behind it.
 

Henderson

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Messages
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I went with the 300A contactor JBD/QUCC. I am hoping I don't regret not getting the JK.

I would think if you need more than 2A balance current then your cells are really not very good. Just my gut feeling, no experience behind it.
Ok, thanks for the feedback.
 

RV10flyer

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Messages
732
@RV10flyer Just out of curiosity, how do you have your 160 cells configured? Do you have these as 10 separate batteries with the JK BMS on each? I'm trying to determined what battery capacity (Ah) should match what balancing current. I'm designing my build which will have a max of 128 cells but I don't want to have 8 separate batteries but will do either 2x 4P16S or 4x 2P16S. Before I finalize, I'm trying to determine if a 2A balancer is enough for a 560Ah or 1120Ah (doubtful on this one) battery or would I need a higher balancing current. I would ideally prefer the 2x 4P16S option but I'm not sure if a say a 2A or 5A balancer would be enough.
yes 10 separate batteries, 10 separate BMS's. One JK BMS with 2A balancing. If I had it to do over again I would've chose 10 JK's! Six out of 10 batteries have runners. If I had JKBMS is on those other six, I would say that the JK could keep them in line.

I would never want to have cells wired in parallel. I want to be able to monitor each individual cell.
 
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