JK 4S 200A BMS

[Steve_S]

I really don't get the hangup on the Paralleled Battery Packs using JK or any other respectable BMS. As long as the system is properly "built" with equal length wire, each pack is independently fused with the "correct" fuse there really should be no issues, many of us are doing it.

Batteries in Series has always been a challenge and moreso depending on the chemistry involved and that has lead to a lot of "bafflegab" and confusion. With the Battery Tech we are using here which is mostly LFP, there is little need to place batteries in Series unless people are purchasing Prebuilts and even BattleBorn has made this clear as to limitations and they actually support limited Series Batteries. Below is an extract on Paralled Batteries.

Advantages​

The main advantage of wiring batteries in parallel is that you increase the available runtime of your system while maintaining the voltage. Since the amp-hour capacities are additive, two batteries in parallel double your runtime, three batteries triple it, and so on.

Another advantage to wiring batteries in parallel is that if one of your batteries dies or has an issue, the remaining batteries in the system can still provide power.

Disadvantages​

The main drawback to wiring batteries in parallel vs. series is that the system voltage will be lower, resulting in a higher current draw. Higher current means thicker cables and more voltage drop. Larger power appliances and generation are harder to operate and less efficient when operating at lower voltages.

How Many Batteries Can You Wire In Series?​

The limit on how many batteries you can wire in series typically depends on the battery and manufacturer. For example, Battle Born allows up to four of their lithium batteries to be wired in series to create a 48-volt system. Always check with your battery manufacturer to ensure you do not exceed their recommended limit of batteries in series.
note this, if the internal BMS' exceed their max voltage the Magic Smoke appears

How Many Batteries Can You Wire In Parallel?​

There is no limit to how many batteries you can wire in parallel. The more batteries you add in a parallel circuit, the more capacity and longer runtime you will have available. Keep in mind that the more batteries you have in parallel, the longer it will take to charge the system.

SOURCE: https://battlebornbatteries.com/batteries-in-series-vs-parallel/

There IS a GOTCHA with Parallel Packs in a Bank and this is what I believe is the underlying troublespot here.
Example: If a bank of 3 packs is running along and is at 75% and 1 pack disconnects for whatever reason, the other two will continue and take the extra charge/discharge without consideration. The "down" pack will remain at 75% until the problem is resolved (unless the failure is draining it). Once corrected and being put back "online" the SOC Differential can create havoc within the bank resulting either in a Surge out if the other 2 packs are at a lower SOC or a large surge inbound from the 2 packs because they are at a higher SOC. In Both of those instances, the Instant Rush can exceed the individual BMS capabilities resulting in Damage and even releasing the Magic Smoke.

This is one of the major downsides of using FET Based BMS', as Relay-based ones just drop the Relay/SSR instantly when required, disconnecting the pack and no FETS get smoked. In that instance the Relay/SSR Capacity is the limiting factor and which can be 200-1000A or more and why they are used in EV's that push/pull a lot of juice.

This is also another reason we "geezers here" also used to remind anyone building a Paralleled Bank to build it so that "any pack" within the bank can act as the "Last Man Standing", meaning that it could handle the Max potential Charge/Discharge of the system that it is supporting. This is not terribly difficult with a small system, but larger systems are not easy to do and sometimes impractical.

I hope this helps to clarify a few items.

 

[rhino]

the Instant Rush can exceed the individual BMS capabilities resulting in Damage and even releasing the Magic Smoke

There still seems to be some question under exactly what conditions this is even an issue with LiFePO4 since so much of the capacity range is in the flat part of the voltage chart.

 

[rhino]

I did find out that my Victron charge controllers didn't have an issue with the JK BMS disconnecting the battery for charging because I did not update the default max charge current high enough after I switched it over this morning. Panels were in full sun. Not sure why the default was only 60A (may even be lower than that) when the discharge default is 200A.

 

[rickst29]

Initial Report with testing of low temperature charging protection. (FAILED TEST, unable to configure a proper temp value for LFP battery cells.)

The parameter Charge UPT(C), in my "new" BMS Android App and System software, has a minimum value of -10.1 degrees. This value is fatal for LFP battery cells, which must only be charged at temperatures at least a little bit above zero. It is very likely also involved in the new "heater" function.

Charge UPTCR (the charge circuit "recovery" temperature, following a low temperature shutdown) can be configured as high as 20.0 degrees, providing a good working range for that parameter. But the App interface indicates the charging circuit will remain active until extreme cold (worse than -10.1 degrees C) is present on temp sensors. I can't even test for that in the near future, having no "dry ice" in the house. The BMS defaults to -20C, and can't be configured to a number higher than -10.1 C.

 

[rhino]

The parameter Charge UPT(C), in my "new" BMS Android App and System software, has a minimum value of -10.1 degrees.

Here is screen shot of my original settings and was able to change the Charge UTP to 3C and the Charge UTPR to 5C:

 

[dtidmore]

Initial Report with testing of low temperature charging protection. (FAILED TEST, unable to configure a proper temp value for LFP battery cells.)

did you select the LiFePO4 button at the top of the screen prior to attempting to change the values?

 

[rickst29]

Here is screen shot of my original settings and was able to change the Charge UTP to 3C and the Charge UTPR to 5C:
View attachment 96842

NOW RESOLVED, but a problem does exist within the Android App. Upon pressing 'LIFEPO4' and changing default parameters within the same cellphone App session, the "setting error" occurs with a UTP value above -10.1 degrees. Switching back and forth between 'Settings' and Status' does not allow the parameter to be set higher.

But shutting down the Android App and then restarting it (without pressing 'LIFEPO4' and invoking default values a second time) allows the value to be modified to your excellent "production" value, and further restarts of the App also allow for further changes to the parameter, without provoking the error.

This is apparently an error within the cellphone App V4.5.1, which can be bypassed by invoking the App at least one more time after setting battery type. The programming issue is only exposed within the SAME Android Cellphone App "run" in which the battery type is designated.

I am unable to test the IOS App, not being in possession of a compatible phone.

 

[rickst29]

The Balancing Test. (Passed, with flying colors).

I "dragged" down the Voltage on the first cell of my battery pack, by connecting a high-wattage resistor on to that cell alone. BMS showed .4A of return current during that process. I pulled voltage to be about .06 low on on that cell. When I lowered the minimum balance voltage into an activating range, with balancing MOS turned on in the "Control" panel of the App, balancing current became shown on the App "status panel" - with values varying between .92A and about 1.12A.

I removed my resistor (which was quite warm to the touch, but far below its power limit of 100 watts). This allowed the cell Voltage to begin recovering rapidly, finishing the job in only 8 minutes. (My previous "Daly Smart BMS" would have required 4-8 days to finish the job, and it wasn't
tunable.) The Balance "status" was generally showing "discharge" but sometimes showed "charge". CMOS temps stayed very low on the otherwise idle battery pack, at only 27.2 C (with room temp detected as 20.7 on two mostly-idle cells.)

 

[rickst29]

The First Charging Test. (Passed, but the error log and display showed numerous 'abnormal' events.)

I attached a very cheap, low-power bench charger for this test. It is capable of creating voltage above 14.4V, but shuts down when battery current falls below about 0.5A. That shutdown occurred at total pack voltage of 14.22V per the display, an average of 3.543V per cell with a delta below the 0.010 limit I had set in the App. During charging from

(I calibrated 'voltage' and 'current' values via the Coulomb counter yesterday, before "blowing up" the Coulomb Counter with a surge from the "dying" Inverter. So the BMS App is now providing the best numbers which I can get. I'm sorry about that event, which prevents any further testing of the output current limits for this BMS unit.)​

During the charge process (initiated at pack Voltage 13.173 Volts), balancing occurred without issues from time to time, and with no interruption of the charging process.

However, during charging, the Stats Display blinked a warning message (in red) about an "abnormal state" being detected. Each occurrence was automatically recovered ("cancellation") so quickly that I could not read the message. This message appeared at intervals between about 5 seconds and 40 seconds, for the entire duration of the charging cycle. In the "system" log, the first 50 messages record the detection and and cancellation of the error code in pairs, each pair of log entries occurring within the same second. Here is one of the log entry pairs. The gaps in time occur after the second message of each pair:

7. Before [3H11M29S] - [Abnormal coprocessor communication]
8. Before [3H11M30S] - {Abnormal cancellation of coprocessor communication]

I think that the 2nd message has a slight translation problem (word order), and could be perhaps be worded more clearly as "Cancellation of abnormal coprocessor communication".

In any case, I am unsure whether a problem is present in the unit, or whether the cheap charger is putting out far too much THD (i.e., 120-VAC "passing through" into the DC output. I do not have an oscilloscope for measuring that.

 

[Steve_S]

They REALLY have to get the Terminology, Abbreviations & the Correct Translations done and they'll shine much better.
"Interpretations" can result in some goofy things.

Thanks for the Continued Tests.

 

[rickst29]

They REALLY have to get the Terminology, Abbreviations & the Correct Translations done and they'll shine much better.
"Interpretations" can result in some goofy things.

Thanks for the Continued Tests.

You're completely welcome, it's been my privilege to write these test reports. (I will be working with Nami to create a formal "review" of the device in my name, from these reports, after I'm done testing the new "heater" function.) I intend to assist with a bit further with the English translation of the draft manual, and also to add the missing information about the default SETTINGS password.

 

[rickst29]

Cell "overcharge protection" seems to work great. My final round of testing (today and maybe tomorrow) will involve the new heater function.

 

[Steve_S]

You're completely welcome, it's been my privilege to write these test reports. (I will be working with Nami to create a formal "review" of the device in my name, from these reports, after I'm done testing the new "heater" function.) I intend to assist with a bit further with the English translation of the draft manual, and also to add the missing information about the default SETTINGS password.

I advise CAUTION on helping with Docs & Translations...
Experience Speaking here.. I tried to help Chargery and they became very active here & and took the user feedback to improve the product line and develop new product based on our input. I rewrote their manuals and clarified a lot of it and THEN the crap started and blaming, accusations and more... Which is WHY I backed off of here and only selectively assist the few when I "feel" up to it.

I believe that Lyuan Tech is still inclosing my ️ Luyuan Tech Basic Lifepo4 Assembly Guide which they had printed for inclusion for all battery cells sales. And I've even gotten crap for doing that....

So now, I have essentially terminated my longtime ways of OpenSource / Freeway NOT FOR Profit stuff as it is obvious that is unacceptable to far too many "Ferenghi" and they can honestly "stuff it". The side effect, info sources to help others = limited to very little forward.

 

[Steve_S]

Maybe a Wee Bit OFF-Topic but here is some Enlightening snaps. These are the TWO Used EV-LFP Packs of which #1 is the pack which got fully discharged to 1.1V +/- per cell by a Failed QNBBM Active Balancer and Fully Recovered.

174-1 Entering Float Mode. Detail Screen & Cell Screen








































174-2 Entering Float Mode. Detail Screen & Cell Screen








































I Hope this helps clarify some of the stuff discussed.
These "Just Entered" float about 5 minutes prior to Screen Caps taken. Within an hour the Delta will be around 0.005 /+- 0.002.

EDIT: After a Bit over an Hour (1hr 32min) in Float BELOW, Note some Heavy Draws also occurred during this period.

After a LITTLE over an Hour in Float: 174-1 below




























After a LITTLE over an Hour in Float: 174-2



























I believe this will answer most Q's. I will not add further as there really is no Point to that.
A Special Point. 174-1 IS the Pack that collapsed to 1.2Vpc +/- due to QNBBM Active Balancer failure,

 

[rhino]

Can something actively be reading from the JK BMS RS-"485" port and something else use the bluetooth at the same time? I know you can't have two bluetooth devices trying to talk to it at same time.

 

[upnorthandpersonal]

Can something actively be reading from the JK BMS RS-"485" port and something else use the bluetooth at the same time? I know you can't have two bluetooth devices trying to talk to it at same time.

Yes, they use different ports. Both can be used at the same time.

 

[Samcat]

I really don't get the hangup on the Paralleled Battery Packs using JK or any other respectable BMS. As long as the system is properly "built" with equal length wire, each pack is independently fused with the "correct" fuse there really should be no issues, many of us are doing it.

Batteries in Series has always been a challenge and moreso depending on the chemistry involved and that has lead to a lot of "bafflegab" and confusion. With the Battery Tech we are using here which is mostly LFP, there is little need to place batteries in Series unless people are purchasing Prebuilts and even BattleBorn has made this clear as to limitations and they actually support limited Series Batteries. Below is an extract on Paralled Batteries.



There IS a GOTCHA with Parallel Packs in a Bank and this is what I believe is the underlying troublespot here.
Example: If a bank of 3 packs is running along and is at 75% and 1 pack disconnects for whatever reason, the other two will continue and take the extra charge/discharge without consideration. The "down" pack will remain at 75% until the problem is resolved (unless the failure is draining it). Once corrected and being put back "online" the SOC Differential can create havoc within the bank resulting either in a Surge out if the other 2 packs are at a lower SOC or a large surge inbound from the 2 packs because they are at a higher SOC. In Both of those instances, the Instant Rush can exceed the individual BMS capabilities resulting in Damage and even releasing the Magic Smoke.

This is one of the major downsides of using FET Based BMS', as Relay-based ones just drop the Relay/SSR instantly when required, disconnecting the pack and no FETS get smoked. In that instance the Relay/SSR Capacity is the limiting factor and which can be 200-1000A or more and why they are used in EV's that push/pull a lot of juice.

Problem even with fast-acting Class-T fuses or SSR Relay is in rush current that can easily fry mosfet or SSR. And no communication between BMS in parallel setup. There are required good software algorithm for rhis to work and never let one bank if kicked out from rest of battery banks back online. Time for fast-acting Class-T fuses is enough to fry mosfet type BMS. I would advise on BMS that don't use mosfet and integration of fast-acting Class-T fuses as last defense. Regarding resistance with additional fast-acting Class-T fuses and Relays are sacrifice for safety that are easily dealt with. Now regarding EV battery packs and SSR Relays there is very strict software algorithm that will bring current draw down to safe limits before breaking down convention. And there is another layer of safety that use Pyro fuses that will brake connection if current cannot be lowered before cutting down power under high current demands. Mosfet type BMS should be substitute but not real way to manage multiple banks in parallel for full time off grid battery setup.
I could get on fire by other people here for what I suggest but I will be more than happy to answer any questions. Safety should be over anything else especially if you are using many parallel battery setups.

 

[Samcat]

Pyro fuses can be easily salvaged from EV salvage yards and some BMS out there have ability to setup this type easily. From my knowledge Batrium is one of them....probably more that i didn't have time to research. Infineon technology is what I'm very familiar with but this is another discussion.

 

[Steve_S]

Wink Wink Nudge Nudge I use MRBF Fuses. They had been connected to Battery Pack terminals, Now they are on the Busbar with my new config.
I've never had a problem, but then again the Busbars are fed to a Midnite E-Panel with a Monster 250A Breaker.
REF to the 250A Breaker:

Product - MidNite Solar

MidNite Solar Product Page.

www.midnitesolar.com

 

[upnorthandpersonal]

Problem even with fast-acting Class-T fuses or SSR Relay is in rush current that can easily fry mosfet or SSR.

I actually tested this. With a class-T fuse in each bank, I shorted the output of 2 paralleled 48V packs, each with a 100A JK BMS. Multiple times. Cost me a lot of money in Class T fuses (maybe this explains the current shortage)
Both BMS are still running without issues today.

 

[Samcat]

I actually tested this. With a class-T fuse in each bank, I shorted the output of 2 paralleled 48V packs, each with a 100A JK BMS. Multiple times. Cost me a lot of money in Class T fuses (maybe this explains the current shortage)
Both BMS are still running without issues today.

I have not tested this with this BMS but if this BMS can survive in rush current before fast-acting Class-T fuses burn out that is cool. But still is happening over mosfet and danger of having BMS going bad vs independent BMS module that uses heavy duty industrial-rated relays or other ways to trip high in rush current. Once Pyro fuses becomes available for aftermarket it will change how this battery systems are built .

 

[rickst29]

Initial test of new "Low Temperature Heater function": The BMS provides this function with no issues, running a heater pad at 2.9A for multiple minutes.

For this test, I attached a single "motorcycle seat" 12V heating pad, between the "12V" main output of the 4S test battery and the new 5-wire connection lug from the heater port. (This one: https://smile.amazon.com/gp/product/B084YXXM2P.) This pad is capable of 2.9 on that circuit, while running at its own "high temperature" setting. (I had first connected it to the main 12 main "P-", to verify that it would not exceed 3.0 Amps on coulomb counter, at the test battery voltage of 13.30 Volts).

Removing the temp probes from the battery pack, I inserted those a probes into a glass of ice to provoke "low temp charging shutdown". I had previously set non-default values of 5.0 C for shutdown, and 8.0 C for recovery. The charging CMOS was immediately disabled, with a blinking "low temperature" warning appearing on the Android App. The warming pad circuit was immediately enabled, with that 2.9A "heating pad current" show as a discharging value. The pad became warm, and cycled a couple of times from its own temp Sensor circuitry. The BMS "heater circuit" handled those stops and starts (within the downstream "heater pad) with no issues.

I am uncertain whether the output CURRENT and POWER limits (which have already been documented for this interface interface), can be protected from an over-current configuration by the BMS itself. To create such a test (for slightly more than 3.0A), I can a 2nd resistor in parallel with this heater pad. I will await confirmation from Nami (regarding the presence "3A" over-current protection within the BMS itself) before doing that.

 

[rhino]

My bluetooth is stuck on on the BMS and now I can't connect to it. Probably because I was trying to get the iOS app to disconnect from it but couldn't so I turned bluetooth off on the phone and now BMS still thinks it is connected to phone but phone can't connect to it now. Is there simply way to reset the bluetooth? I didn't want to pull the balance cables since I assume that would cut power to my inverter.

 

[rickst29]

My bluetooth is stuck on on the BMS and now I can't connect to it. Probably because I was trying to get the iOS app to disconnect from it but couldn't so I turned bluetooth off on the phone and now BMS still thinks it is connected to phone but phone can't connect to it now. Is there simply way to reset the bluetooth? I didn't want to pull the balance cables since I assume that would cut power to my inverter.

Do you have either the basic power switch or the small GUI power switch (button on the side), so that you can RESET the BMS without pulling the BMS header?

If not, pulling the BMS header alone (and letting the BMS "loose power" for about a minute) Might enable you to use my old "interface-free" Daly method: (1) pull the balance/power header; (2) plug it back in; (3) put a charger between main battery "+" bus and the and the "P-" bus negative bus,

I've restarted my "new-to-me" JK about 10 times, using both of the power switches, just for the heck of it - and to see that settings are retained.

 

[rhino]

Do you have either the basic power switch or the small GUI power switch (button on the side), so that you can RESET the BMS without pulling the BMS header?

Thank you so much! that worked with the GUI power switch and I didn't lose power