JKBMS Inverter Edition Problems/Issues | No Support / Help to fix major issues. - DO NOT BUY ! Warning (as of Oct.12.2024)
- Thread starter Steve_S
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In the first graph picture no load was on the battery as the sun was generous.
how do i get it to saturate my battery? mine still need to get balanced, but it hits my over voltage protection because one cell will be like .25v higher than the rest, so it never gets to the actual full charge.
This is with the time stamps, I could identify the 2 hour float interval and the 30 min. 'Emerg. time' seems to be included in it.
Hi, where do I access this setting? I'm having the same issues. Thanks.
Is your battery new?
When you run into an issue with a 'runner' like this, you need to set your OVP (over voltage protection) up toward the max, mine is 3.62, 3.65 is the max per cell you should set.
OVPR = over voltage protection recovery, the voltage where the BMS will 'release' the battery to accept charge again.
You need to charge at lower voltages and slowly bring the pack up in voltage. Once you hit around 3.43V/cell, you can have the balancer start running. This is what I would try, along with watching a few of Andy's JK videos, he does a nice job going over the settings and how they relate to each other.
- Charge to 54.8V. This is low enough it shouldn't trigger an OVP
- Increase to 55.2V <-- this is what I'd consider full, when charging amps <= 2A. Hold this voltage constant and let the balancer run. If the balancer can't sort it out in a couple of hours,
- Push to 55.6, then 56V and hold. You're slowly pushing up without big jumps if you have a cell that's a runner.
- If you get to 56V, hold and the balancer still can't balance out after a few hours, search for 'top balancing' on here. There are good guides. If you get to this point, you have to discharge and recharge. For me, I'd discharge the whole battery down to around 20% or your UVP (undervoltage protection). 2.5V is the floor for that setting. Then recharge back up at 55.2V and see where you're at.
define 'new'
the cells are ~2 years old, been sitting for awhile.
i have my overvoltage set at 3.67v, pretty much the max for these cells. since the delta i'm seeing is ~.25v from cell to cell, i'd have to charge to ~54.5 to start with, right?
I wasn't sure if you were building a new battery that hasn't been top balanced previously, so new would be set of cells not previously top balanced.
If you have a runner like that, discharging may be the best step. There's a notion of a bottom balance too, same idea.
The voltages are examples. Basically the idea is to keep the voltage below where you're having issues and gradually get your other cells to match the high one then let the balancer finish.
You can also discharge a single cell to pull its voltage down, but that's a bit of a hassle I think.
If you run the entire pack down and recharge we can see what happens. If it still won't balance, you may need a Neey or something to whip it into submission.
It sounds like the JK issue is more setting it up so you can get the battery where you want. And yeah, the abbreviations and all aren't the most user friendly. If you have the 2A balancer version, I'd hope it would be able to get your cells in line once you get the one pulled down.
Curious - what does the high one settle at without any load or charge, have you looked?
Voltage differences under load is often a connection issue.
I wouldn't bottom balance unless you routinely plan to run your batteries to 0% state of charge.
I wouldn't bottom balance unless you routinely plan to run your batteries to 0% state of charge.
was planning on keeping them between 20 and 80% for the most time to extend the life of LFP batteries, or is that not the case?
connection issue in sense leads or high current cables?
Latest thought on that is that they'll calendar age out before they cycle age out. I would top balance in your case. Be sure you charge high enough that the BMS and other components (shunt) can hit the 100% charge voltage so the state of charge resets.
Connection issue with the high current cables or the busbars between cells. Could be a balance lead too. Check all the cells using a volt meter to know for sure.
A runner can be a reflection of a number of things. It never hurts to check your bus bar connections, and then the BMS leads to make sure everything is secure. One clue might be if the resistance for one of the cells is higher than the connection may not be as good as it should be. There will be a range though so don’t be too concerned if there’s a small difference.
Well, not everyone might feel this way but it doesn’t hurt to perform a proper top balance just to get everything on the same level. Many are using the BMS instead, but I still like to do the top balance to make sure all the batteries are waking up after being in storage.
The other thing that could be a factor is running them at too wide a range. Steve has talked about this a lot and that is why he suggests the benefits of a tighter operating range which he refers to as a working range. Pushing cells too high on a regular basis might encourage a runner as well.
On the other hand, sometimes one might just have a bad cell. That happened with me when I had some CATL cells.
Well, not everyone might feel this way but it doesn’t hurt to perform a proper top balance just to get everything on the same level. Many are using the BMS instead, but I still like to do the top balance to make sure all the batteries are waking up after being in storage.
The other thing that could be a factor is running them at too wide a range. Steve has talked about this a lot and that is why he suggests the benefits of a tighter operating range which he refers to as a working range. Pushing cells too high on a regular basis might encourage a runner as well.
On the other hand, sometimes one might just have a bad cell. That happened with me when I had some CATL cells.
what do you mean by a tighter range?
rogerheflin
Solar Addict
You need start balance set to at leas 3.40 (and maybe 3.42) otherwise the balancer will attempt to balance when you are charging and under heavy charging any cells with resistance/cable length differences will get charge added or subtracted (depending on which cell the bms sensor connects to).
Other than that look OK?
The Balance Trig. Volt, which is the voltage difference between cells when the BMS will initiate balancing, is about twice as much as I usually see.
Cell OVP is normally 3.65.
Cell OVP is normally 3.65.
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RCinFLA
Solar Wizard
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- Jun 21, 2020
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Cell absorb voltage. What BMS tells inverter/charger to set (times # of series cells in battery) its charging absorb voltage to, assuming you have inverter communications to BMS.
I do have comms, what does absorb voltage do?
so far balance seems pretty good. However I noticed the voltage that my inverter reads is like .8v higher than what bms reads. And I calibrated the bms voltage with a meter
my sense leads are 12 gauge