BMS w.bluetooth - question

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Feb 7, 2021
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I have to replace the garbage BMS in my battery by a decent one.
(if interested in details, have a look at my build thread)

Actually I am thinking about this one:
https://www.aliexpress.com/item/4001192978656.html
The type is JK-B2A24S-20P - it is a recommendation by the seller of the ANT BMS, which is too big for my battery case.

But now I am wondering if I can use bluetooth at all, if the BMS is sitting inside my sheet metal battery case?

The seller says "yes"-but I would love to get some opinions from here,
since my experiences with chinese sellers aren't the best...
 
If the case is completely enclosed, you might have to run an antenna out from the board itself to the outside world.

If it's not completely enclosed, you may get enough connection for very close usage, like while riding, but not when off the bike. May also be directional if the opening(s) in the case only allow signal in/out for a particular direction.

If you have a BT device (speaker, headphones, etc) you could put it isnide the case, and close it up (with or without your bike battery in it) and see if your phone/etc can still connect, and if range/etc is all normal or not. If it performs poorly or not at all, then you'll likely have similar experience with a BT BMS.
 
Elektrosherpa said:
I have to replace the garbage BMS in my battery by a decent one.
(if interested in details, have a look at my build thread)

Actually I am thinking about this one:
https://www.aliexpress.com/item/4001192978656.html
The type is JK-B2A24S-20P - it is a recommendation by the seller of the ANT BMS, which is too big for my battery case.

But now I am wondering if I can use bluetooth at all, if the BMS is sitting inside my sheet metal battery case?

The seller says "yes"-but I would love to get some opinions from here,
since my experiences with chinese sellers aren't the best...

I use JK BMS JK-1A24S-15P 150a continuous discharge. It works absolutely perfectly. The app is very solid and friendly to use. Bluetooth connection is very strong. It penetrates thru my deck and I can connect to it from the other room in my house. I wouldn't worry about being able to connect, it's a strong signal. I will probably never use a different BMS in the future for any battery I build. I made a few modifications to the output wires. I needed them to protrude at an angle so there wasn't a 90 degree bend in them, so I soldered new output wires to the busbars at an angle. Their little display is amazing as well and has an on/off button for powering the BMS on for the first time and also for turning it on/off as you please (no self drain when off).
I have a buddy using a different version on the JK BMS, smaller version, and other friend using their 2a active balancer only with no BMS. We are all very satisfied with them. The build quality is actually insanely good. Everything is overbuilt and I found no solder blobs on the PCB.
If you can fit the JK, absolutely go for it and pick up the small display while you're at it.
AliExpress ICGOGOGO store or Hangzor store are both great
Quick tips, always keep discharge and charge ON while riding. Discharge obviously to provide voltage/power and charge for Regen to work. I keep balance off while riding. Discharge wires are common charge wires, so there is no separate P- wire for charge logic. The active balancer will kick on when your delta voltage difference is reached, whenever you have it set to. The BMS/display can be calibrated in the app, to display the correct voltage and amps. In the 45 days I've had the BMS hooked to my new battery, the balancer has never once needed to kick on since my cells are very well matched and never go beyond the .010v difference I have set in the app. This BMS works perfectly in sync with my Nucular controllers and "charge thru controller" function since the discharge wires are common as charge wires as well.
This BMS has exceeded my expectations in every way. Any questions about it, just let me know
 

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Thanks, this is very helpful ! :bigthumb:

I have bought the battery with the shitty BMS because I am a beginner.
The idea was to concentrate on the motorbike conversion,
and avoid out the battery problems by buying one.
Too bad the battery manufacturer cheated me this way.
(have a look at my build thread if interested in the details of that story)

My concern is now to exchange the bad BMS by a good one,
and I would really love to avoid taking the battery cells out of their box,
because it is a very tight fit
and the battery builder has used lots of glue/sealing or whatever.
I tried to scratch away as much of it as possible,
but I am afraid there is more of it down in the unaccesible gap
between battery pack and metal case...

Here is a picture of the open battery box with the damaged BMS.
I tried to number the balancing wires.
Would you agree that I could simply cut the balance wires
and use them for the new BMS?

And do you have any idea what these two black cables do, which I have labelled "?" ,
and what I should do with them when the bad BMS is gone?
Just insulate them and forget about them?

damaged-BMS-open-numbers.jpg

And as for the display:
I have also been thinking about buying it together with the BMS.
But I would love to keep the battery ready for easy taking out.
If the battery is connected to the bike via the display cable,
a second plug (except the main power plug) would be required for that.
Do you think it would be possible to install a plug/socket connection
outside the battery case which would allow me to quickly disconnect BMS(battery) and display ?
(considering that I am an electronics dummy....)
 
The ?? wires are probably for an NTC thermistor or a high temp cutoff. If they're shorted, it's a cutoff.
 
Elektrosherpa said:
And as for the display:
...
Do you think it would be possible to install a plug/socket connection
outside the battery case which would allow me to quickly disconnect BMS(battery) and display ?

I can answer this question now by myself:
After having a closer look at the product pictures available in the www,
I can say that there is a sturdy looking plug in course of the cable
(additional to the plus at the end, where it is meant to be plugged into the BMS)

So no worries abt. that, and I ordered the BMS + display today...
 
Since the top cover of my chinese battery didnt provide enough space
for the JK BMS and all the necessary connectors,
I have built a new cover from 1mm steel sheet metal:

Battery-Cover.jpg
(old cover and new one in process of making)

Battery-NewCover.jpg
final state

I did a short test (not driving, just spinning the wheel)
and "Amperry417" is right- the bluetooth is strong enough
to pass through the completely closed steel sheet metal battery case.
Might have to do with the fact that the power wires are used as antenna for bluetooth
(at least that is what the seller of the JK BMS had told me in the ordering process)
 
Amperry417 said:
Their little display is amazing as well and has an on/off button for powering the BMS on for the first time and also for turning it on/off as you please (no self drain when off).
....
Any questions about it, just let me know

As described in the last posts, I have purchased and installed the JK BMS, together with the display.
Generally it is working very well.

But the display is disappointing:

Inside my workshop it looks good - but when riding the bike outside in bright daylight, I can hardly recognize anything.
The display is simply way too dark.
Or did I miss that there is a way to adjust its brightness ??
 
Elektrosherpa said:
Amperry417 said:
Their little display is amazing as well and has an on/off button for powering the BMS on for the first time and also for turning it on/off as you please (no self drain when off).
....
Any questions about it, just let me know

As described in the last posts, I have purchased and installed the JK BMS, together with the display.
Generally it is working very well.

But the display is disappointing:

Inside my workshop it looks good - but when riding the bike outside in bright daylight, I can hardly recognize anything.
The display is simply way too dark.
Or did I miss that there is a way to adjust its brightness ??

The small display is sort weak in the sunlight. I use mine basically as a backup display (I have a Nucular display as the main) and mainly have the small LCD screen for the power on/off switch for BMS main power. I just noticed JK BMS came out with a larger LCD display that looks really nice. If that is your main display for voltage and capacity it might be worth looking into
 

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