timselectric
If I can do it, you can do it.
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- Feb 5, 2022
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- 18,622
I use 200a JK BMS's and have never had any issues.
To BMS or not to BMS? That is the question.
- Thread starter gnomie
- Start date
Pierre
Somewhere down South
- Joined
- Dec 21, 2019
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Like a fool I sold my one when I dismantled the battery. Now 6 months later I had to build another 48v battery and contacted JBD directly for a replacement. Apparently they no longer manufacture the contactor one. So , bought their latest end 2022 all solid state version. Worked fine for about a week and the Victron MuliPlus reported a ‘low battery’ alarm. Checked on the BT app - no alarms , battery voltage 53,8v , all cells fine with cell delta of 6mV , voltage on output terminals shows 16v , even shows current flowing out after I opened the fuse disconnect to the inverter. Unplugged / replugged the voltage sense leads and it worked for a day , then repeat of above. First time I ever had crap with a JBD BMS.
42OhmsPA
What's in a title?
Is this the one you're after?
Just found this amazing item on AliExpress. Check it out! $98.82 28%OFF | JBD High Power Smart BMS 7S 8S 10S 12S 13S 14S 17S 18S 20S 21S Built-in BT 200A Balance 24V-72V Liithium Battery for Inverter
That's the one I've been running, I just wish I could find the correct adapter for the BT module so I could connect them up to SA, I have 3 of the usb adapters sitting in a box.
That looks like the same thing Overkill sells.
USB Module for BMS – Overkill Solar
overkillsolar.com
42OhmsPA
What's in a title?
That's what I ordered but they don't work with my JBDs linked above, the connector size is different.That looks like the same thing Overkill sells.
USB Module for BMS – Overkill Solar
I know it's just a matter of finding the correct connector and rewiring but it's not on the top of my priority list.
42OhmsPA
What's in a title?
Yea. Somewhere I wrote down the pin out and connector size, it's just a matter of finding it and ordering them then unplugging the bluetooth module and connecting the usb module.
Pierre
Somewhere down South
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- Dec 21, 2019
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Maybe you are aware of this : That adapter is made to plug into the BT (UART) socket. You can only use one at a time.
Some models come with BT , RS485 and CanBus connectors if ordered so as per photo below. SA should be able to the RS485 socket. I am now looking into SA so I am unfamiliar with it.
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OK... so I ordered the Overkill BMS. How do I monitor and tweak it with a Bluetooth Android tablet? Never mind. Just downloaded and read the Overkill manual. WOW!!! No wonder you like these. Trying to make sense of the postcard instructions written by someone who had limited English skills on the last POS BMS was excruciating. The Overkill manual covers EVERYTHING in fine detail with eloquent explanations. Can't wait to get it hooked up. P.S. For now. I needed the battery to run my water well so.... I manually monitored a charge cycle with my volt/ohm meter up to 3.35V per cell then shut down the panels. All 16 cells were reporting 3.35. My well consumes 2500 watts for 90 seconds 4-5 times a day. I'm spit balling here, but I'd bet I can run the well for at least 2 weeks without any further charging. I'll have the Overkill up and running in the next few days. No point in taking any chances on a runaway cell when you've got plenty of charge to do the job until the BMS issue is resolved. Thanks for the tips.
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See edited comment. Thanks again.
I agree, you'll be fine riding bareback for a while, I'd check the individual cells every day just to be on the safe side. I have four of these Overkill boards. I call them boards because they look unfinished...like they're supposed to be inside something. Everyone who uses them just finds a way to attach them somewhere and forgets about them. I went high tech and use double sided tape.
One other thing, the folks at Overkill are very responsive to any questions you might have. Of course you can usually get just about anything you need to know here on the forum, but if you want to talk to Overkill, they won't mind at all.
Pierre
Somewhere down South
- Joined
- Dec 21, 2019
- Messages
- 1,130
I love all the work and effort Overkill puts into his business. Wishing I can support him more but being located in South Africa it is just too expensive with shipping etc. I source my products directly from JBD and firmly believe in their products.I agree, you'll be fine riding bareback for a while, I'd check the individual cells every day just to be on the safe side. I have four of these Overkill boards. I call them boards because they look unfinished...like they're supposed to be inside something. Everyone who uses them just finds a way to attach them somewhere and forgets about them. I went high tech and use double sided tape.
One other thing, the folks at Overkill are very responsive to any questions you might have. Of course you can usually get just about anything you need to know here on the forum, but if you want to talk to Overkill, they won't mind at all.
Overkill , keep up the good work.
Got the Overkill wired in this morning and everything is working fine so far. The Xiaoxing app is much better than the one Daly supports. The Bluetooth has better range. The balancer seems to work. My battery is 95% charged with a cell delta of 0.019 V. That's good enough for me. I was a bit worried about the surge load the well generates but the app reported a maximum discharge of 39A, well below the 100A rating and the 110A trigger. My Growatt hasn't cut out once from some false readings from the BMS. The Overkill did cut charging a few times as it approached fully charged and some cells were tripping the 3.65V trigger but it didn't completely shut down and charging resumed as soon as cells dipped back below the trigger point. I edited the battery info to reflect the 280ah configuration I'm using and changed C to F on the temp sensors and activated the 4th temp sensor (1 internal and 3 external). EZ-PZ. Time will determine the reliability factor, but the Overkill/JBD scores a 10 out of 10 for day one.I agree, you'll be fine riding bareback for a while, I'd check the individual cells every day just to be on the safe side. I have four of these Overkill boards. I call them boards because they look unfinished...like they're supposed to be inside something. Everyone who uses them just finds a way to attach them somewhere and forgets about them. I went high tech and use double sided tape.
One other thing, the folks at Overkill are very responsive to any questions you might have. Of course you can usually get just about anything you need to know here on the forum, but if you want to talk to Overkill, they won't mind at all.
Happy to hear things worked out for you, I know how frustrated you were getting. Been there...
What are your charge voltages set at? I've settled in on 54.8 for bulk (CV setting # 19) and 54.0 for float (Float # 20) in the growatt settings.
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Bossrox
Solar tinkerer
I have 3 300 a/hr 24v lipo4 banks & a salvaged tesla powerwall. All of them have a bms but 1 of my lith banks the bms is only used to monitor cell balance & the tesla the same. The only reason I have active bms's on the other lith banks is 'cuz they have some bad out of balance cells that can exceed the max volt limit during charge on some of the cells.
I have more a/hrs than I ever use so I'm not worried about hitting an under voltage event & the chargers are set to shutdown well under the max limit for the well balanced banks, so if you're fortunate to be in that state, I can confidently go without bms's on some of my banks but otherwise wouldn't.
I have more a/hrs than I ever use so I'm not worried about hitting an under voltage event & the chargers are set to shutdown well under the max limit for the well balanced banks, so if you're fortunate to be in that state, I can confidently go without bms's on some of my banks but otherwise wouldn't.
Bossrox
Solar tinkerer
JBD is all I use, gotten good service from them & the app is top notch.
I was wondering about that. Theoretically, you need 3.65V of charge to each cell to allow it to reach its full potential of 3.4V resting. 3.365X16=58.4V. I know that running that high of a voltage is going to (A) accelerate the charge (B) exacerbate the balancing and (C) generate a lot more cell overvoltage triggers and warnings. I just wasn't sure that anything less would be able to produce 3.4V at every cell. After watching the charge cycle a couple of times though I noticed that the top of the cycle gets pretty erratic with a few cells leading the pack to the 3.65V while others lagged a bit behind. I'm definitely going to edit 19 & 20 to 54.8 and 54 respectively and see if that keeps from stressing the batteries as much while allowing a complete charge without a tirade of cell overvoltage cutouts. Seems like slow and steady beats the fast and furious and my panels will definitely overpower the battery if not attenuated down some. Thanks again for a good tip based on experience.
Just reset 19 and 20 to your recommendations. Another question. At what point (xV) will the Growatt recognize that the battery is charged and quit charging AND at what point (yV) will it recognize that the battery can accept a charge and restart the charging current to the battery? I know the book says that the "Charging" light will quit blinking and stay solid green when the battery is charged. I just can't find the parameters for exactly what voltage the Growatt is looking for before it suspends the charging cycle or resumes it.
The only time you take your cells to 3.65 is when they're all in parallel and you're doing a top balance. There are tons of threads on this forum about state of charge, and it's subject to some debate, but anything above 3.5 is a fraction of a percent. The current should drop to almost nothing around 54.8 - 55.0 with the settings I use, and will sit at 54.0 as long as the loads don't exceed PV input. Even with no charge current, the voltages will settle down to 3.8 and you're at 99% SOC.
https://diysolarforum.com/resources/general-lifepo4-lfp-voltage-to-soc-charts-tables-12-24-48v.109/
