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JK BMS Current Consumption (JK-B2A8S20P-H)

Ok, this thread has me a little concerned. I haven't been following all this, but on 9-May I bought a new JK-B2A8S20P. I didn't actually want the new model with heater control, but they had stopped selling the previous model. My intent is to take this up to our cabin in August and replace the existing BMS on that 8S system with this one, as I've been happy with the previous model on my 8S system I have here at home. But if this new one is going to have an excess current / over-heating problem, that will really ruin the trip.

Is the issue of high current draw only with 4S systems? Aside from making the trek up to the cabin (6 hours each way) and failing, or having to install it in place of the working one I have here, is there a way to tell if mine has a problem?
 
My new ordered JK-B2A8S20P BMS arrived. Actually it is a JK-B2A8S20P-H with heating function wich I don't need and did not order, but that's ok.
So first things first! Current consumtion in idle (no BT connection, PowerOn Button unplugged, nothing connected at "P-"):

62mA at 13.2V wich gives 818mW.

Still not nothing, but way better than the old one!

Some Serial Numbers:
Value"old, defective, high consumption" BMS JK-B2A8S20P"new" BMS JK-B2A8S20P-H
Serial Number20422152592062015167
Hardware Ver.V11.XWV11.XW
Software Ver.V11.12V11.17H
Standby Current Consumption1.65W (125mA @ 13.2V)0.818W (62mA @ 13.2V)

According to my Aliexpress Message Center "the new replacement Chip" seems to be shipped. I will post an Update if and what arrived ?
 
With the Softwareversion (V11.17H) seems to be some new information available on the main page. I think I understand "Heat Current" and "Heating Status" but what does "Charg. Plugged" mean?
Screenshot_20220720-122328.png
first I thougt it will detect if I am Charging the Battery (Daly and Jiabada do) but as you can see from the screenshot, I am charging at the moment with around 200W but "Charg. Plugged" still says: "Not Plugged"
@Nami perhaps you can tell?
 
satmaster2000 said:
With the Softwareversion (V11.17H) seems to be some new information available on the main page. I think I understand "Heat Current" and "Heating Status" but what does "Charg. Plugged" mean?
View attachment 103342
first I thougt it will detect if I am Charging the Battery (Daly and Jiabada do) but as you can see from the screenshot, I am charging at the moment with around 200W but "Charg. Plugged" still says: "Not Plugged"
@Nami perhaps you can tell?
Click to expand...
Hey @satmaster2000 - I have a couple of questions. First, what's up with your cell #2? There is no cell voltage displayed for that cell. Second, what app version are you running?

I have an older JK-B2A8S20P that I've been happy with (although I guess I'm not sure of its power consumption). I've been running app version 3.7.4 with it. I also got a newer JK-B2A8S20P-H. Like you I didn't order the H, but got it anyway. The two extra items on the screen you showed kinda imply a new app. Since I have two of these, I'm hoping I can use one version of the app to talk to both.

Edit to add: I have not connected up the new one, or I guess I would know if my current app works with it.
 
Horsefly said:
Hey @satmaster2000 - I have a couple of questions. First, what's up with your cell #2? There is no cell voltage displayed for that cell. Second, what app version are you running?

I have an older JK-B2A8S20P that I've been happy with (although I guess I'm not sure of its power consumption). I've been running app version 3.7.4 with it. I also got a newer JK-B2A8S20P-H. Like you I didn't order the H, but got it anyway. The two extra items on the screen you showed kinda imply a new app. Since I have two of these, I'm hoping I can use one version of the app to talk to both.

Edit to add: I have not connected up the new one, or I guess I would know if my current app works with it.
Click to expand...
Hi Horsefly!

Yeah Cell #2 must just have switched to blinking blue while I made the screenshot! :ROFLMAO:

I use the app on an iPhone as well as on android. On the iPhone i already had version V4.7.4 (just noticed there is an update, now its V4.7.7 )
On the Android I was running something older (now 4.7.6) the older version did not show switches for the heating function, but the heating stuff on the mainpage was shown.
Screenshot_20220720-200144.png

By the way: any idea about that "Charg. Plugged" thing?
 
Ok, so now I've installed the newer (with heating) version, and it didn't work with my older App that I have been using with my older (pre-heating) BMS. So I installed the new app on and old phone, and verified it works with the new BMS. Does anyone know if the new version of the app (4.7.6, on Android) works with the older versions of the BMS? My main phone currently has 3.7.6 of the app. Before I replace it with the new app, I'd like to know I don't need to carry around my old phone just because of the incompatibility.
 
Well, I've somewhat answered my own question, and the answer is less than satisfying.

I've found that the ENJPOWER version of the app (3.7.4) works fine with the old version of the JK-B2A8S20P, but is not compatible with the newer JK-B2A8S20P-H. I've found under Android 10 (on my older Moto G7 phone) the latest version of the app (4.7.6) works with both the old BMS and the new one. However, under Android 12 (on my current Moto Edge [2021]) the 4.7.6 app works fine with the newer JK-B2A8S20P-H but does not even see the older JK-B2A8S20P. Fortunately, it seems I can have both versions of the app installed on my Android 12 phone, and so I can still connect to both BMS's, but I really didn't want to keep both versions of the app. Oh well.

Reading through previous messages, I see that some people had problems with Android 12 but most seem to have worked through it. I tried changing permissions and such, but nothing seems to help. I also tried to clear the cache from the old app, thinking maybe it was interfering with the new app. Again, no help. Anyone have any ideas?
 
I see in the new manual, they quote: Power consumption: balanced state 8mA@100V, Non-Equilibrium State 7mA@100V.
Does that equate to: 16mA@50V, 32mA@25V and 64mA@12.5V?

My BD6A20S10P uses just over 27mA@26.5V or 715mW not balancing (Non-Equilibrium State). So it seems ok I think (if my maths is right).
 
Last edited:
Hi,

can any body give me pls. a hint what heater pad he will use with this BMS?

Regards
 
juf said:
Hi,

can any body give me pls. a hint what heater pad he will use with this BMS?

Regards
Click to expand...
You can use any heating pad you want as long as you use a relay to control the heating pad. I think they are limiting the 100W but I could not find that in the documentation. If you use a relay you can go higher than that.
 
You really don't need a big heater if you put your cells in an proper insulated box. I use 7W polyimide heater on mine (not with the heater output on the BMS because mine don't have it but with a simple electronic thermostat) which keeps the batteries warm even in the worst conditions.
 
I use two 12V 12W heater pads (these) under my 8S 24V battery in an insulated case. In my tests, it kept my cells between 50°F and 60°F (10°C and 15.5°C) with the temperature outside the box below freezing, and it consumed roughly 4Ah @ 24V every 24 hours to do it. I also didn't use the heater version of the JK BMS.
 
juf said:
Hi,

can any body give me pls. a hint what heater pad he will use with this BMS?

Regards
Click to expand...
I have one of these 'motorcycle seat' heating pads on each of my 4S battery packs. https://smile.amazon.com/gp/product/B084YXXM2P/

Within each pack, the cells are "standing" in vertical orientation, with the center of of heater pad underneath, and two ends reaching partway up each "side" with all 4 cells exposed (not the "end sides, consisting of only one cell each). The total amperage of 3 heater pads exceeds the 3.0A limit of the heater interface, so I use the heater heater interface to activate an automotive-type Relay connection instead.

My packs are within an RV, and aren't used in winter months. (That's unlike the much larger configuration use by @upnorthandpersonal).

That heater switching Relay used to be controlled by an external thermostat on the Coil circuit connectors. I have removed that thermostat, instead connecting "12v" to one side of the Relay coil and the heater interface from the JK BMS (installed in one of the packs) as the coil ground. In "production", it has only become active on one very cold morning at high altitude so far, but it all worked great.
 
Last edited:
Have they changed the heating algorithm yet? The last I heard, it used the low temp cutoff for activating the heater. It would turn off the charge and turn on the heater. Then when the low temp recovery temp was reached, it turns off the heat and on the charge. I would much rather see a heat on temp that was a few degrees above the LTC so that it would prevent the charge cutoff.
 
hwse said:
Have they changed the heating algorithm yet? The last I heard, it used the low temp cutoff for activating the heater. It would turn off the charge and turn on the heater. Then when the low temp recovery temp was reached, it turns off the heat and on the charge. I would much rather see a heat on temp that was a few degrees above the LTC so that it would prevent the charge cutoff.
Click to expand...
That's the behavior of mine, but I have not attempted to perform any microcode updates subsequent to its arrival in early June.
 
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