New SOK Bluetooth BMS for DIY

[corn18]

If the Bluetooth BMS's are still in your batteries, can you verify in the app at what current do they cut off for each battery? If they are sharing the load exactly then that's 105 amps which is about 15% different than what I measured at about 120-125ish amps.

I'll take a closer look the next time I am at the camper.

It is a PITA to get the BMS to reset on both batteries after it shuts down for over current. I have to unparrallel them and reset each one with the SCC individually. That sucks.

And the BMS on both batteries will go into protect when I flip on the main battery switch if I have not precharged the inverter caps. Another PITA to deal with.

 

[Koert]

And the BMS on both batteries will go into protect when I flip on the main battery switch if I have not precharged the inverter caps. Another PITA to deal with.

These batteries just don't seem well designed for use in a camper. Far better suited for use as something like a power wall.

 

[corn18]

These batteries just don't seem well designed for use in a camper. Far better suited for use as something like a power wall.

The original BMS works well for a camper. Not sure I like the new bluetooth BMS.

 

[Koert]

There are reports of charging and discharging limits that cover a huge range, and well above the advertised specs. The higher limits are probably what I had stashed away in my brain when I ordered four of these.

I just did a test on a single battery, one of my new 206Ah Bluetooth/Heater batteries which was fully charged yesterday. (For simplicity's sake, I used the BMS's Bluetooth for all readings - I trust it.)

With the battery connected it to the main bus, I turned on the inverter and the induction cooktop. After adjusting the inverter's Low Battery Cutoff, I was able to get up to 108A continuous discharge and brought the battery down to 80%. That matches the spec for 100A Maximum Continuous Discharge Current.

Then I connected the inverter to shore power and changed the inverter's charging current setting to 80A. The actual charging current was almost 74A and held there while the battery charged. Not as good as I would like, but far better than the 50A in the specs. When I increased the charging current by connecting a solar panel, the battery immediately cut off.

The good news is that will allow me to use my existing chargers without the batteries turning off. The bad news is that it doesn't give me any additional headroom for increasing my charging capabilities.

The extra 24 amps of charging has me feeling better than I did this morning, but I'd still like to return them if I can.

 

[joshwalee]

FYI for anyone running these batteries. The Android BMS app updated yesterday and will no longer connect. I've cleared app data and reinstalled with no solution. I've reached out to the app developer and hope to see a fix soon.

 

[jfitch]

I wonder if you can get an older version. In the Play Store, I see version 1.0.12 updated on Feb 23, 2022.

 

[joshwalee]

I wonder if you can get an older version. In the Play Store, I see version 1.0.12 updated on Feb 23, 2022.

I show 4/25/22 for that (the current) app version. We shall see if I get a response or if an update is pushed to the Play Store.

 

[Koert]

The Apple app store has Version 1.0.4, released 2 months ago

There is another app called EE-BMS that looks to be the same. The reviews indicate that it works with Chins or HiMassi batteries.

 

[joshwalee]

The Apple app store has Version 1.0.4, released 2 months ago

There is another app called EE-BMS that looks to be the same. The reviews indicate that it works with Chins or HiMassi batteries.

View attachment 92687

Found the app. Unfortunately it can see the SOK BMS, but cannot connect.

 

[joshwalee]

I did receive a response from the developer contact. The video linked in my post above was shared and I was assured an engineer will address the issue. I will report back once I'm able to confirm operation. FWIW, I am on a Pixel 6 running the latest Android 12.

 

[joshwalee]

Update: No further responses from developer contact. No updates to app in the Play Store. I've scoured the night for any open source coding without luck, and have been unable to find a previous app version published anywhere. I have also tried every BMS app available on the Play Store and questionable 3rd party downloads with no connection success (in many cases no detection). So now we have a BLE BMS with no BLE connection abilities. I wonder how many Android users will return their batteries? I've rolled back app versions in the Play Store and know it is pretty easy. At least I know why you pay more for BB...

Second approach: Contacted us.sokbattery.com by email and outlining app and discharge current inconsistencies (even though I purchased from currentconnected.com). I'm interested to see the supplier response.

 

[jharrell]

At least I know why you pay more for BB...

Battleborn makes a good product and all, but you would be in the same boat since they don't even offer a bluetooth version as of yet. I do imagine if they ever come out with one and app it will be more polished and better supported, if...

I do wonder if BB has the shutdown issues with inverter caps and generator starting, accord to their specs, which are usually very accurate, they have no overcurrent protection for 500 milliseconds which should cover a lot of high surge conditions, also their BMS restarts after 5 seconds, no need to wake it up with another source. From everything I have seen there is nothing physically special about their BMS, they just have a more forgiving software tune and are ok with the FETs taking high surges once in a while.

Would be a shame to have SOK be held back by over conservative BMS software when the hardware seems top notch.

 

[joshwalee]

Battleborn makes a good product and all, but you would be in the same boat since they don't even offer a bluetooth version as of yet. I do imagine if they ever come out with one a BT version and app it will be more polished and better supported, if...

I do wonder if BB has the shutdown issues with inverter caps and generator starting, accord to their specs, which are usually very accurate, they have no overcurrent protection for 500 milliseconds which should cover a lot of high surge conditions, also their BMS restarts after 5 seconds, no need to wake it up with another source. From everything I have seen there is nothing physically special about their BMS, they just have amore forgiving software tune and are ok with the FETs taking high surges once in a while.

Would be a shame to have SOK be held back by over conservative BMS software when the hardware seems top notch.

I agree. My email to them focused on their exceptional build quality. It seems the new BMS may be a missed opportunity, but hopefully their support can match their build quality. I'm not shopping BMS yet.

 

[joshwalee]

Update 2: SOK was prompt to respond and there has been an update pushed out to the Play Store for the BMS app. Functionality has been restored and there is also protection mode visibility included now (see attached). Big thanks to the developer for the contact and resolution!

According to my response from SOK the battery has a max discharge current of 120A, rather than 200A, and this aligns with user experience reported here. I wish this was published correctly in the spec sheet to prevent a situation like mine where a second smaller inverter was purchased, but I can live with it.

I will give full credit to the brand and developer for timely action and communication. It is very much appreciated and nice to have function restored.

 

[jharrell]

According to my response from SOK the battery has a max discharge current of 120A, rather than 200A, and this aligns with user experience reported here.

Nice addition to show the the protection mode, should help with troubleshooting.

Would be a huge downgrade to only have 120 amps peak discharge, not only does my older one do above 140 continuous it will surge up to 200 for 3 seconds and 330 amps for a few ms. Then you look at Battleborn who does 200 amps for 30 seconds and unlimited for 500ms which is much more forgiving and it auto restarts.

Starting to realize that what really makes a good BMS is the surge ratings less than the continuous and how it handles restarts after. Most of the issues reported and I am sure results in returns of perfectly good batteries is plugging into an inverter and having it shutdown with no easy way to restart or even know it needs to be restarted with a external voltage source.

 

[joshwalee]

Nice addition to show the the protection mode, should help with troubleshooting.

Would be a huge downgrade to only have 120 amps peak discharge, not only does my older one do above 140 continuous it will surge up to 200 for 3 seconds and 330 amps for a few ms. Then you look at Battleborn who does 200 amps for 30 seconds and unlimited for 500ms which is much more forgiving and it auto restarts.

Starting to realize that what really makes a good BMS is the surge ratings less than the continuous and how it handles restarts after. Most of the issues reported and I am sure results in returns a perfect good batteries is plugging into an inverter and having it shutdown with no easy way to restart or even know it needs to be restarted with a external voltage source.

Yes, 120A is a far stretch from the published 200A for 3s and cut-off of 330A. The product sheet should certainly be updated to provide correct expectations. With my current setup it is usable, but falls well below what I had planned for. Maybe room for continued improvement...

I will still stand behind this product and SOK's level of support. I hope to see more great things from the brand as they mature.

 

[joshwalee]

I just went through a discharge cycle from 13.8V-10.6V (my BMS voltage cut-off). My BMV shows 110Ah while monitoring draw with an external amp clamp as well. I'm satisfied with capacity. It appears the protection state function is still a WIP since it does not highlight any items even though my D MOS is off. Hopefully it will be working in the next release.

 

[beckkl]

Just got the heated version of this in the mail. I am super annoyed that the app requests location access. I cannot figure out why this should be required to connect to battery via bluetooth. Not super excited to give my location to some cut rate app developer in China.

Edit:Typo

 

[kinyoubi]

Just got the heated version of this in the mail. I am super annoyed that the app requests location access. I cannot figure out why this should be required to connect to battery via bluetooth. Not super excited to give my location to some cut rate app developer in China.

Edit:Typo

Unfortunately, this seems to be a symptom of Android apps that use Bluetooth requiring location access. See this thread:

Why do I need to turn on location services to pair with a Bluetooth device?

Whenever I try to connect my Samsung Galaxy S6 with Android 6.0.1 to a Bluetooth enabled device, it tells me to enable "location services". When I complained about this, the software vendor replie...

android.stackexchange.com

 

[B-ManFX4]

Any idea if SOK is planning to address the BMS going to sleep issue? I hate to think I will have to pull a generator out and "kickstart" the BMS via the Victron chargers before I can use my RV. Unless someone has another way to wake the BMS up ?