diy solar

diy solar

JBD 4S 200A BMS

does anyone know the max amperage of the heating option? and what heating pads are most people going with?
Earlier in this thread someone mentioned it was rated at 8a. However, some reported zero output with heating loads above 4-5a.

We're using 4, 3"x4" silicone pads (24w pads wired in series/parallel = .5a/6w each) with a total load of 2a/24w with no problem. These heat 4 200ah prismatics just fine. Left outside exposed to 0f ambient temps overnight (inside a generic, plastic Group 24 battery box with a top), they kept the cells at 62f.
 
Last edited:
Actually, the design of these things must be changing by the hour. My model had the 2 tabs extending outward slightly from the case to where it can be mounted on terminal posts.
 
kept the cells at 62f.
My exact setup and mine has been down to 24F. Thermostats are C so I set at 3C in and 6C out (I'm more stingy with the heater current LOL) but it kept a steady 4-6C during the past freeze with the cells outdoors. I actually used external thermostats instead of the BMS heater tab and put one on 2 seperate thermostats at each end of the aluminum plate lining the bottom of 8 cells just for redundancy purposes. The temp read-outs on the cheap $5 thermostats show both the temp as it's being read and the indicator LED shows when the heater is engaged. Two 24W pads in series are enough if the case is well insulated. I designed mine just by experimenting so it's remarkable we came up with the same design.
 
s powered on when charge is applied AND temp is below the set temperature
Unless I am missing something, then this means it is a flawed design. The style heater that would be mostly used (silicon pad) would mean the heater power needs to be applied long before freezing temps occurr. Ali/eBay/Amazon sell the same low-end thermostat $5-$15 that works in C and will keep the heater pad under control.
 
I have the exact one in the photo.

A "gotcha" with one the one with the heater port is to figure out if it's the BMS battery probe or the BMS internal temp sensor that is reading the temperature to control the heater and where the BMS is mounted in relation to the battery.) I wasn't sure so even though I have the heater port, I just installed a $5 thermostat rather than experiment to discover how it worked, and that's since my BMS is outside my insulated battery case.
The two external temperature sensors control the heater pad port on our JBD 200a. It ignores the internal temp sensor and acts on whichever external temp sensor hits the target temp first.

We wired in a dpdt switch so we can choose either the BMS heating pad port (powered only by charge current) or an external thermostat (heating pads and thermostat powered by the cells via the C- terminal).
 
Last edited:
Unless I am missing something, then this means it is a flawed design. The style heater that would be mostly used (silicon pad) would mean the heater power needs to be applied long before freezing temps occurr. Ali/eBay/Amazon sell the same low-end thermostat $5-$15 that works in C and will keep the heater pad under control.
The design is intended to use as little power as possible, and prevent charging below a set temperature.
Since discharge is really not affected by temperature, it doesn't turn on the heater unless the cells are below the set temperature and there is a charging current. The theory being that when the sun comes up, and can charge the battery, it will use that power to heat the cells to the set temperature, and only once that set temperature is reached allow the charge to take place.

In other words, the design decision was made to only heat when it is needed, and not at any other time. This means it only heats when there is the ability to charge the battery, and can use the charge current to heat the battery (thus not depleting the energy stored in the battery already).
 
My exact setup and mine has been down to 24F. Thermostats are C so I set at 3C in and 6C out (I'm more stingy with the heater current LOL) but it kept a steady 4-6C during the past freeze with the cells outdoors. I actually used external thermostats instead of the BMS heater tab and put one on 2 seperate thermostats at each end of the aluminum plate lining the bottom of 8 cells just for redundancy purposes. The temp read-outs on the cheap $5 thermostats show both the temp as it's being read and the indicator LED shows when the heater is engaged. Two 24W pads in series are enough if the case is well insulated. I designed mine just by experimenting so it's remarkable we came up with the same design.
Yup, these 3x4, 24w pads in series heat quite well for the amount of current they use. Where/how did you mount your pads? I placed the pads directly to the cells.

We powered the heating pads continuously (with a power supply) to determine the maximum heating capability of the pads for this test. Used an uninsulated, plastic Group 24 battery box.

From your description, I believe we're both using the same thermostat. Works well. Got 2 for $10. Can't complain.
 
Last edited:
Earlier in this thread someone mentioned it was rated at 8a. However, some reported zero output with heating loads above 4-5a.

We're using 4, 3"x4" silicone pads (24w pads wired in series/parallel = .5a/6w each) with a total load of 2a/24w with no problem. These heat 4 200ah prismatics just fine. Left outside exposed to 0f ambient temps overnight (inside a generic, plastic Group 24 battery box with a top), they kept the cells at 62f.
can you link your pads please?

and do you know if these would work as well?

 
Last edited:
Yup, these 3x4, 24w pads in series heat quite well for the amount of current they use. Where/how did you mount your pads? I placed the pads directly to the cells.

We powered the heating pads continuously (with a power supply) to determine the maximum heating capability of the pads for this test. Used an uninsulated, plastic Group 24 battery box.

From your description, I believe we're both using the same thermostat. Works well. Got 2 for $10. Can't complain.
OTRwSolar, novice trying to follow this. Did you wire the 4 pads in series to the BMS or in something like a 2S2P configuration to the BMS?
 
Noticed our JBD 200a BMS (via the bluetooth Xiaoxiang app) displays 0 current when charge or discharge current is <.6a.

At first I assumed it may be a glitch in the app. However, I've noticed the BMS's low-temp charge current cut-off (and heating pad port) will not activate when cell temps are below the low-temp charge current threshold with <=.5a of charge current flowing (app continues to display 0 current). If charge current is increased from .5a to .6a (using a dc power supply), the current display on the app immediately jumps from 0 to .6a. At that very same moment, the low-temp charge current cut-off and heating pad port on the BMS also activate.

I would assume there is some chance of damaging lifepo4 cells with <=.5a of charge (float) current if cell temps drop low enough? If so, this could potentially be a problem.

This anomaly could also result in discharged cells if you had, say, .5a of discharge current over a week or so and weren't aware of it.

Considered calibrating the current using the Xiaoxiang app using some amount of current below .6a. Little reluctant to try that since current readings are accurate .6a and above.

Anyone experiencing this same issue with their JBD BMS?
 
Noticed our JBD 200a BMS (via the bluetooth Xiaoxiang app) displays 0 current when charge or discharge current is <.6a.

At first I assumed it may be a glitch in the app. However, I've noticed the BMS's low-temp charge current cut-off (and heating pad port) will not activate when cell temps are below the low-temp charge current threshold with <=.5a of charge current flowing (app continues to display 0 current). If charge current is increased from .5a to .6a (using a dc power supply), the current display on the app immediately jumps from 0 to .6a. At that very same moment, the low-temp charge current cut-off and heating pad port on the BMS also activate.

I recommend calibrating, and there is a sensitivity adjustment as well (I wouldn't recommend below .2 amps).

I would assume there is some chance of damaging lifepo4 cells with <=.5a of charge (float) current if cell temps drop low enough? If so, this could potentially be a problem.

Depending of course on SIZE of the cells, no, that is not going to damage them. Regular charging rates (.2C or above) are dangerous and will damage the cells. Below zero Celcius you must restrict charging current, but very low charge rates will not damage your cells according to everything I've read. Actually, I would start restricting the charging current at around the 5 degrees Celcius range. @upnorthandpersonal has tested this, so he could chime in. I'm in the Phoenix area, so there really isn't any ability for me to test.

Anyone experiencing this same issue with their JBD BMS?

Everyone, and it isn't restricted to JBD. Accurately measuring very small currents is quite difficult when the device must also measure very large currents. Like everything, it's a compromise.
 
Actually, I would start restricting the charging current at around the 5 degrees Celcius range. @upnorthandpersonal has tested this, so he could chime in.

So, the thing is that the internal resistance gets high as the temperature drops, which by itself already limits the current. I've got a video here showing that:


I'm not sure how very low C rates affect the cell, but from what I've read in the literature, low C rates are fine. 0 degrees C isn't a cut-off point, just things need to go slower at that time.

Having said that, I don't charge my batteries below 5 degrees C, and have a heater that kicks in when the temperature drops below that.
 
And also 0c is not a 'from there you can go full speed'.

Max allowed charge current is not allowed till approx 25 celcius or so, depending on the SOC.

Ganfeng has a nice table in their sheet


1648241273566.png

As you can see, at eg +10 celcius, its only allowed to charge up to 0.5C MAX.

1C charge can only be done within specs from 25 celcius.

it also shows, at -10 celcius, you still can charge with 0.1C on a low SOC.

As @upnorthandpersonal already mentions, 0 celcius is just 'a rough guideline', but its not a hard yes/no threshold.


Note: a lot of vendors don't have these specific tables in their datasheet, but I'm not aware of Ganfeng using any different chemistry compared to EVE, Lishen, CATL or whatever, so I assume this table can be used as a guideline for most LiFePO4-based aluminium cells. (although the exact values might slighly vary)
 
I recommend calibrating, and there is a sensitivity adjustment as well (I wouldn't recommend below .2 amps).
I noticed the idle/zero, charge and discharge current calibration in the Xiaoxiang iOS app (upgraded version), but don't remember seeing a sensitivity adjustment. Did I miss it, or is this only available in the android or JBD/Overkill desktop app?

Everyone, and it isn't restricted to JBD. Accurately measuring very small currents is quite difficult when the device must also measure very large currents. Like everything, it's a compromise.
Was hopin’ the JBD would be accurate at the lower current levels like the Daly 200a Smart BMS we used to use. After some tinkering with the Daly's dfitter current (using Sinowealth), managed to get the charge/discharge current accurate down to .1a.
 
Last edited:
Hi all,
Did anyone get JBD-SP04S034-L4S-200A, specifically 4S LFP 200A UART H model? (Note this model is different from 4S LFP 200A U 485 H, even though both ends with H = heating function. )

This post https://diysolarforum.com/threads/jbd-4s-200a-bms.27012/post-367484 has the manual attached for BMS model #
JBD-SP04S034-L4S-200A-200A-BU (according to the first page).

Thanks to this forum, I understand that JBD-SP04S034-L4S-200A has several different variations (for example, some have terminal lugs sticking out, some not), but the manual only shows drawings for one of the variations.

Can someone confirm the drawings in the manual are the same as 4S LFP 200A UART H? I am having difficulty getting the drawings for this specific model from the JBD AliExpress store.

I am designing a Lifepo4 battery case. I need the dimensional drawings so that I would know how to mount the BMS.

Photos of your 4S LFP 200A UART H would be appreciated as well. ;)
 
Last edited:
Hi all,
Did anyone get JBD-SP04S034-L4S-200A, specifically 4S LFP 200A UART H model? (Note this model is different from 4S LFP 200A U 485 H, even though both ends with H = heating function. )

This post https://diysolarforum.com/threads/jbd-4s-200a-bms.27012/post-367484 has the manual attached for BMS model #
JBD-SP04S034-L4S-200A-200A-BU (according to the first page).

Thanks to this forum, I understand that JBD-SP04S034-L4S-200A has several different variations (for example, some have terminal lugs sticking out, some not), but the manual only shows drawings for one of the variations.

Can someone confirm the drawings in the manual are the same as 4S LFP 200A UART H? I am having difficulty getting the drawings for this specific model from the JBD AliExpress store.

I am designing a Lifepo4 battery case. I need the dimensional drawings so that I would know how to mount the BMS.

Photos of your 4S LFP 200A UART H would be appreciated as well. ;)
Our JBD 200a BMS has a heating pad port, UART port (bluetooth/USB), two external temperature sensor ports, and a BMS switch port, but no RS485 port (USB). Device name is JBD-SP04S034-L4S-200A-B-U (as per firmware). It has a build date of Dec 21, 2021, and has the B-/C- copper terminals that extend beyond the heat sink assembly (on each end) approx. 3/4" or so. Approx. dimensions including the extended copper terminals is 232mm x 105mm x 20mm. My guess, the unit labeled "4S LFP 200A UART H" at the Jiabaida Official Store on Aliexpress, is the same BMS we have.

As you mentioned, it appears JBD has recently started making this BMS with recessed B-/C- copper terminals, which do not extend beyond the heat sink assembly. I believe the dimensions for this model are 192mm x 105mm x 20mm. Not sure if JBD is continuing to make both models, or if this new model with the recessed terminals has permanently replaced the version with the extended terminals.

IMO, until stock flushes out at all these retailers, who knows whether you'll receive the recessed or extended terminal version. Up until a few months ago there was quite a bit of confusion how to order the model with the heating pad port.
 
Last edited:
Hi, everyone. Looking for some assistance. Cannot read (or write) parameters with the JBD or Overkill desktop apps using the UART/USB port on our JBD 200a BMS. I can access basic data such as cell voltages, SOC, etc. with both apps, but cannot read any of the setup parameters. For what it's worth, I'm using an Overkill USB/UART module. Had to swap out the JST PH connector on the Overkill to a JST PA to get it to work with the JBD 200a BMS.

I recently turned on the new, hardware-based passcode/password function on the latest version of the Xiaoxiang iOS bluetooth app which seems to be working just fine. No problems reading/changing parameters (plus monitoring cell voltages, SOC, etc.) using this app.

I tried entering this same passcode/password in the JBD desktop app (JBD Tools -V2.9-20210524), but no joy. I couldn't find a passcode/password window in the Overkill desktop app (Overkill Solar BMS Tools v2.1.1+3.g001ebb9).

Hoping the new Xiaoxiang's new hardware based passcode/password feature hasn't locked me out of the JBD/Overkill desktop apps.

Thoughts? Ideas? Thanks.
 
Hi, everyone. Looking for some assistance. Cannot read (or write) parameters with the JBD or Overkill desktop apps using the UART/USB port on our JBD 200a BMS. I can access basic data such as cell voltages, SOC, etc. with both apps, but cannot read any of the setup parameters. For what it's worth, I'm using an Overkill USB/UART module. Had to swap out the JST PH connector on the Overkill to a JST PA to get it to work with the JBD 200a BMS.

I recently turned on the new, hardware-based passcode/password function on the latest version of the Xiaoxiang iOS bluetooth app which seems to be working just fine. No problems reading/changing parameters (plus monitoring cell voltages, SOC, etc.) using this app.

I tried entering this same passcode/password in the JBD desktop app (JBD Tools -V2.9-20210524), but no joy. I couldn't find a passcode/password window in the Overkill desktop app (Overkill Solar BMS Tools v2.1.1+3.g001ebb9).

Hoping the new Xiaoxiang's new hardware based passcode/password feature hasn't locked me out of the JBD/Overkill desktop apps.

Thoughts? Ideas? Thanks.

Overkill doesn’t keep up with the latest software. I think I had to search the JBD/Lithium battery site to find the Windows software that supports the newer BMS versions when I wanted to change some parameters.

 
Back
Top