bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
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izeman   10 GW

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Re: bluetooth BMS?

Post by izeman » Jun 11 2019 12:44pm

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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 11 2019 1:37pm

izeman wrote:
Jun 11 2019 4:35am
It STARTS, but it doesn't STOP if cell voltage falls BELOW that value. At least it seems it didn't do with my battery.
Then how is this useful? Seems to me the "stopping" is an indispensable part of the balancing process.

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izeman   10 GW

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Re: bluetooth BMS?

Post by izeman » Jun 11 2019 2:18pm

cycborg wrote:
Jun 11 2019 1:37pm
izeman wrote:
Jun 11 2019 4:35am
It STARTS, but it doesn't STOP if cell voltage falls BELOW that value. At least it seems it didn't do with my battery.
Then how is this useful? Seems to me the "stopping" is an indispensable part of the balancing process.
Theory is one thing. Reality a second one. I don't know if my assumptions are true. I am with you, that it doesn't make sense, but fact is, that the BMS was draining my battery pretty fast until i set it to how it is right now, and now everything works fine.

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Re: bluetooth BMS?

Post by john61ct » Jun 11 2019 3:40pm

The stopping should happen as a result of the biggest V delta falling within the tolerance spec'd by the user.

And of course only during the charging cycle unless you were manually monitoring.

Personally doing it that way, with a 4-6A balance current so it didn't take so long would be the way to go.

Not available in any BMS I've seen, but there are dedicated gadgets can do that.

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Re: bluetooth BMS?

Post by Taswegian » Jun 14 2019 4:46pm

Could anyone please advise on their approach to soldering the B- & C- wires to these BMS.

I have a couple from James at LTT power and the pads for these connections seem very small, there isn't much 'meat' around the hole to solder to.

Also, on one side they don't actually even connect to the main adjacent track, I suppose that's moot as Ill join it when soldering.

Hoping some others have pic of how theyve gone about it.

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thundercamel   100 W

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Re: bluetooth BMS?

Post by thundercamel » Jun 14 2019 8:37pm

I just poke a wire through each hole and solder both sides generously.
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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 16 2019 1:46pm

I'm wrapping up a build with a 14s 100 A version of these, and I'm having a problem with only the even-numbered groups balancing. Here are some plots over 24 hours with the even groups clearly converging on a balancing limit, while the odd cells just drift down a bit. I'm leaving the USB connected with constant monitoring by the JBD Tools software, so I'm not worried about the drifting, but the balancing won't be very effective if only half the cells participate.

The plots show charging, then disconnecting the charger, then static balancing.

Has anyone encountered and/or solved this issue?

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Re: bluetooth BMS?

Post by Compoundbike » Jun 16 2019 2:54pm

okay where should i start.. i have builded the XiaoXiang BMS, with cheap cells to a skateboard (Lanzhd not very drainable).
unfortunately battery was damaged and started to burn.

But after repalcing the Batteries and limiting the discharge to 20A instead of 40A it caused no problems.

Overall im impressed with this BMS you can also shut off the Battery via Smartphone. :thumb:

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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 17 2019 2:27pm

cycborg wrote:
Jun 16 2019 1:46pm
...I'm having a problem with only the even-numbered groups balancing...
Argh, after two days of this, the BMS spontaneously started alternating between even and odd groups for no reason that I can determine. If anyone else runs in to this, I can't tell you what to do about it, all I can say is there's hope :?

Edit: My guess is that the alternation was triggered when the voltage of the highest even group fell to the level of the highest odd group. In the plots, you can see that these are groups 8 and 11, respectively. The only evidence I have is that these groups are now at the same voltage, and still higher than all the others.

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Re: bluetooth BMS?

Post by john61ct » Jun 17 2019 3:07pm

Seems rational, bring the individual outliers toward the median before trying to get them all equalized.

Seems crazy to me they don't just go with 2+A balancing currents,

a bank that's not too far out of whack should take what 10-20min to get to within 1mV?

what would it add like $20 per unit max?

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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 18 2019 9:41am

I'm able to use the Xiaoxiang bluetooth app on Android with no problems, but not VBMS. I get the message "Auto Connect - Attempting to connect to the BMS" with a spinning indicator that just stays up until I hit the back button. Then I get a list of paired devices with a "Scan new device" button at the bottom, and when I tap this button, the button disappears but the list of paired devices stays up and no new devices appear, BMS or otherwise.

Is it necessary to pair the device in the bluetooth settings? When I try to do this, the adapter appears in the scanned list, but when I select it, I just get the message that the pairing request was declined, without being offered the chance to enter a PIN or anything.

If you're successfully using VBMS, what's the procedure?

I'm using the download link from this post, since I want to be able to test it before paying for it on the app store.

Thanks!

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flippy   100 kW

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Re: bluetooth BMS?

Post by flippy » Jun 18 2019 5:09pm

Yes. You need to pair it with your phone first. That is mandatory for every BT device. That is how it works. Pairing code is usually 1234 or 0000.

Sometimes you have to manually select the device in the list if it cant find it as vbms is programmed to look for a specific BT adress in your paired list. Manually selecting it solves that. But the BT has to be awake! It falls asleep after a few minutes of no current. You need to press the power button to wake it.


Never pay for vbms, just use the versions posted here.
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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 18 2019 6:13pm

flippy wrote:
Jun 18 2019 5:09pm
Yes. You need to pair it with your phone first. That is mandatory for every BT device. That is how it works. Pairing code is usually 1234 or 0000.

Sometimes you have to manually select the device in the list if it cant find it as vbms is programmed to look for a specific BT adress in your paired list. Manually selecting it solves that. But the BT has to be awake! It falls asleep after a few minutes of no current. You need to press the power button to wake it.


Never pay for vbms, just use the versions posted here.
Thanks for the reply. So you haven't seen the behavior I've described?

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Re: bluetooth BMS?

Post by MJSfoto1956 » Jun 18 2019 7:42pm

flippy wrote:
Jun 18 2019 5:09pm
...You need to pair it with your phone first. That is mandatory for every BT device. That is how it works...
Well, you are "technically" right, but the advice above might lead to confusion for certain setups.

To wit: Neither my PowerVelocity app nor Xiaoxiang app should ever be directly paired via my iPhone's BT settings -- the apps themselves will do the pairing for you when you launch them. In fact, the PowerVelocity app will remember the pairing even when disconnected or turned off.

YMMV.
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flippy   100 kW

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Re: bluetooth BMS?

Post by flippy » Jun 18 2019 10:21pm

That is a apple thing, apple ignores normal BT regulations on their devices.

on android apps are not allowed to pair on their own, something something security....
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Re: bluetooth BMS?

Post by eee291 » Jun 19 2019 6:21am

flippy wrote:
Jun 18 2019 10:21pm
That is a apple thing, apple ignores normal BT regulations on their devices.

on android apps are not allowed to pair on their own, something something security....
You're wrong.
Go back a few posts I've mentioned how to connect to Xiaoxang BMS more than once and it does not involve pairing it in the Android Bluetooth settings.

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flippy   100 kW

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Re: bluetooth BMS?

Post by flippy » Jun 19 2019 6:38am

i know the app, and it does pair the device and releases it again when you close the app. you can see this when the app crashes for example and it doesnt disconnect the BT pairing.
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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 19 2019 6:41am

flippy wrote:
Jun 19 2019 6:38am
i know the app, and it does pair the device and releases it again when you close the app. you can see this when the app crashes for example and it doesnt disconnect the BT pairing.
Maybe this is one reason why the app isn't on the app store and must be installed from the APK.

Anyway, no one else has my issue of not being able to pair the device via the system BT settings?

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izeman   10 GW

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Re: bluetooth BMS?

Post by izeman » Jun 19 2019 7:04am

cycborg wrote:
Jun 19 2019 6:41am
Anyway, no one else has my issue of not being able to pair the device via the system BT settings?
Imho you can't pair through "Settings", and this is NOT how it's intended to work. You open the app, it connects, and then it disconnects again after you close the app. No code needed ever.

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Re: bluetooth BMS?

Post by cycborg » Jun 19 2019 7:11am

izeman wrote:
Jun 19 2019 7:04am
Imho you can't pair through "Settings", and this is NOT how it's intended to work. You open the app, it connects, and then it disconnects again after you close the app. No code needed ever.
I'm trying to use VBMS on Android. Is that what you're talking about?

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izeman   10 GW

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Re: bluetooth BMS?

Post by izeman » Jun 19 2019 7:18am

Not sure what the name of the apk was. The "official" Xiaoxiang app on Android.

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Re: bluetooth BMS?

Post by eee291 » Jun 19 2019 7:19am

cycborg wrote:
Jun 19 2019 7:11am
izeman wrote:
Jun 19 2019 7:04am
Imho you can't pair through "Settings", and this is NOT how it's intended to work. You open the app, it connects, and then it disconnects again after you close the app. No code needed ever.
I'm trying to use VBMS on Android. Is that what you're talking about?
We were talking about the Xiaoxang BMS or JDB BMS.
I have experienced something similar to what you are saying. When I bought a 24S BMS that could do 20S-30S I connected only 12S to see if I can change the parameters. The Bluetooth module was flashing but I couldn't connect to it not even with the PC module, not until I connected the full 24S.

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Re: bluetooth BMS?

Post by larsb » Jun 19 2019 8:27am

I use the 24s Smart BMS together with the VBMS app on android.
Works for me. I sometimes have to search for the BT, confirm with password 1234
This BMS to avoid any confusion:
https://www.aliexpress.com/item/32826820690.html
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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 19 2019 9:58am

larsb wrote:
Jun 19 2019 8:27am
I use the 24s Smart BMS together with the VBMS app on android.
Works for me.
I'm using the one pictured below from LLT Power (purchased via the JBD Store). I think the problem is that these are shipped with a proprietary BT module that only interfaces with the "official" Xiaoxiang app. This post indicates that these BMSs were previously shipped with generic BT modules, but the modules included now are not programmable.

So likely your model, and possibly older models like mine, allows pairing through the system settings, which then allows them to work with VBMS. It's looking like VBMS isn't an option with my proprietary BT module, though.

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Re: bluetooth BMS?

Post by Headrc » Jun 20 2019 8:08am

Are you happy with that LLT BMS? I was considering buying one and trying it.

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