New SOK Bluetooth BMS for DIY

[jharrell]

Looks like SOK finally has a Bluetooth version of their BMS and are selling separately as a DIY piece. Seems they have up its rating slightly to 70 amp charge / 120 amp discharge, but if its like their current BMS which looks identical its actually 150 / 150 continuous:

https://www.us.sokbattery.com/product-page/sok-bms-for-12vlifepo4-battery-diy

Might replace the BMS's in my 206ah SOK's if this one works well as having Bluetooth to keep an eye in the individual batteries would be nice, I would imagine their plug and play batteries will get these at some point.

 

[HighTechLab]

Unless I have old information the current SOK BMS is 50a charge rated and 100a continuous discharge rated.

 

[jharrell]

Unless I have old information the current SOK BMS is 50a charge rated and 100a continuous discharge rated.

My info is based on this post https://diysolarforum.com/threads/is-this-12v-battery-better-than-battle-born.10087/post-134056

"the BMS we rate: charge Current is 50A, discharge current is 100A, but we design it charge current is 140A~150A, discharge current is 140A~150A if the charge or discharge current over 150A, the BMS would be cut off in 10 or 15 minutes."

Subsequently my own testing confirmed with my own 206ah SOK battery which did not shutdown with nearly 140 amp continuous discharge and 110 amps continuous charge rate.

A single port BMS by design has the charge and discharge FETs in series and therefore would physically have the same capabilities charge or discharge if the BMS was limited to less of charge rate than discharge it would be a software setting only and in the case of SOK that software setting is 150 / 150 according to SOK.

 

[corn18]

Looks like SOK finally has a Bluetooth version of their BMS and are selling separately as a DIY piece. Seems they have up its rating slightly to 70 amp charge / 120 amp discharge, but if its like their current BMS which looks identical its actually 150 / 150 continuous:

https://www.us.sokbattery.com/product-page/sok-bms-for-12vlifepo4-battery-diy

Might replace the BMS's in my 206ah SOK's if this one works well as having Bluetooth to keep an eye in the individual batteries would be nice, I would imagine their plug and play batteries will get these at some point.

Well, that didn't last long. It isn't on the site anymore.

 

[jharrell]

Well, that didn't last long. It isn't on the site anymore.

Weird they made a announcement in their FB group and said it would ship in Feb. Here is a screenshot of the App from the iOS app store:

 

[corn18]

If they pop back up, let us know. I will buy 2.

 

[jharrell]

If they pop back up, let us know. I will buy 2.

Looks like its back on the site and someone already received a couple and posted them working in the FB group as a replacement in their 100ah SOK's. They reported the app working at least 30ft away even through the metal case.

 

[corn18]

Awesome sauce! Just ordered two.

 

[corn18]

Just installed the new BT BMS on both of my SOK 206Ah 12V batteries. Works great. App can see both batteries. Both batteries show up as 100Ah, so I am asking if I can get the password for the parameters menu to change that. Haven't heard back. May not even be possible.

 

[corn18]

Just a heads up for anyone thinking about upgrading. Wait until the new BMS with heat function comes out. BT is nice, but I would prefer to have built in heat as well. Guess that's the price I pay for being an early adopter.

I did reinstall the batteries today. Of note, I forgot to use my precharge circuit when I powered up the system the first time and one of the BMSs went into self protect. Didn't have that with the original BMS. Glad I have the precharge.

 

[jharrell]

Yes disappointing considering they advertised it would have heater function and install pictures show BMS with heater leads. Will be interesting to see how they handle the heater upgrade kit they say will be coming out in a few weeks. I did grab screen shot of video they posted showing password to setting of BMS for future reference, which seems to be 200810:

 

[corn18]

Yes disappointing considering they advertised it would have heater function and install pictures show BMS with heater leads. Will be interesting to see how they handle the heater upgrade kit they say will be coming out in a few weeks. I did grab screen shot of video they posted showing password to setting of BMS for future reference, which seems to be 200810:

View attachment 84017

That's it. Nice to see what's going on inside but will be nicer to have the heater function. Patience is key, I guess.

 

[amartin]

Just took another look at their website, seems like they are updating. However it does show the new product with Bluetooth and heater being restocked on March 10th. Price of $650 with free shipping. Unless someone tells me the app is hot garbage compared to the Overkill/JBD then I'll probably order this one. Wonder if the app will have a way to turn off the heater or set temperature parameters for when it triggers...

SOK 12V100Ah LiFePO4 Battery Bluetooth&Built-in heater | SOK Battery

In stock now, ready to ship! Latest V8 version Bluetooth BMS, top battery cells balance function. SK12V100H designed for cold weather using! Can safely charge at temperatures down to -20°C (-4°F) by a standard charger or solar charger. The heater pads which draws power from the charger...

www.us.sokbattery.com

 

[joshwalee]

I just picked up one of the 100ah and built it into a power bank with a Victron 100|30 MPPT, Victron BMV-712, and Renogy 1000w inverter. Today is day one and I'll see how it holds up overall. This is replacing a Bluetti EB55 that is being RMA'd under warranty for a PV input failure. I used Milwaukee Packouts so I can stack and roll it with other packed items when out and about.

 

[joshwalee]

I just picked up one of the 100ah and built it into a power bank with a Victron 100|30 MPPT, Victron BMV-712, and Renogy 1000w inverter. Today is day one and I'll see how it holds up overall. This is replacing a Bluetti EB55 that is being RMA'd under warranty for a PV input failure. I used Milwaukee Packouts so I can stack and roll it with other packed items when out and about.View attachment 90518View attachment 90519View attachment 90520View attachment 90521View attachment 90522

I've made some final adjustments and performed stress tests. Everything is good except the SOK battery goes to sleep after a while when no charge or load is detected. I have to reconnect the BMS with a 12V input when this happens. I'm experimenting with a small parasitic load to keep the unit awake on PV disconnect and transport. If anyone has any input or feedback for this condition it would be much appreciated!

 

[jharrell]

I've made some final adjustments and performed stress tests. Everything is good except the SOK battery goes to sleep after a while when no charge or load is detected. I have to reconnect the BMS with a 12V input when this happens. I'm experimenting with a small parasitic load to keep the unit awake on PV disconnect and transport. If anyone has any input or feedback for this condition it would be much appreciated!

Whats the bluetooth app say when asleep? Whats the internal voltage and is the discharge FET turned off? Would be odd behavior to sleep like just because of no load unless some internal parasitic load drains the batteries to LVCO. Also inverter cap inrush can do this if your physically disconnecting inverter then reconnecting.

 

[joshwalee]

Whats the bluetooth app say when asleep? Whats the internal voltage and is the discharge FET turned off? Would be odd behavior to sleep like just because of no load unless some internal parasitic load drains the batteries to LVCO. Also inverter cap inrush can do this if your physically disconnecting inverter then reconnecting.

Thanks for the response! BMS app reads 0.000V even though cell voltage is adequate (example: 3.275V per cell). My MPPT and BMV are not available through the Victron app since they are not powered on. I can upload my BMS/MPPT/BMV values and a schematic in a bit if that helps. (working now)

 

[joshwalee]

Whats the bluetooth app say when asleep? Whats the internal voltage and is the discharge FET turned off? Would be odd behavior to sleep like just because of no load unless some internal parasitic load drains the batteries to LVCO. Also inverter cap inrush can do this if your physically disconnecting inverter then reconnecting.

Internal voltage at 13.1V last time it happened with D MOS off (FET).

SOK BMS:
Design Capacity: 100Ah
Full Capacity: 100Ah
BAT over charge: 14.8V
BAT over charge release: 14.4V
COV: 3.7V
COVC: 3.65V
OCT: 60C
OCTC: 50C
CTC: 0C
CTCC: 5C
BAT over discharge: 11V
BAT over discharge release: 11.2V
CUV: 2.5V
CUVC: 2.6V
OTD: 75C
OTDC: 70C
UTD: -20C
UTDC: -15C
Taper Current: 10A
Design Voltage: 12.8V
Full Voltage: 13.4V
Pack low voltage: 10.4V

MPPT 100/30:
Battery Voltage: 12V
Max charge current: 30A
Absorption voltage: 14.6V
Float voltage: 13.8V
Equalization voltage: 14.6V
Automatic equalization: Disabled
Temperature compensation: -16.20mV/C
Low temperature cut-off: Disabled

BMV-712:
Battery capacity: 100Ah
Charged voltage: 13.4V
Discharge floor: 10%
Tail current: 2.00%
Charged detection time: 3m
Peukert exponent: 1.05
Charge efficiency factor: 98%
Current threshold: 0.10A
Time-to-go averaging period: 3m
Relay mode: Default (no relays set)
Invert relay: off
Battery mode: Battery Monitor
Shunt current: 500A
Shunt voltage: 50mV
Aux input: Temperature

 

[joshwalee]

Additional schematic added (shunt shows battery monitor, but I have a 2 wire temp sensor connected). I ran my fridge on ECO at 50 degrees past night and the BMS did not disconnect the battery. I'll be disconnecting at 100% SOC to test function with BMV backlight off vs always on at minimum brightness to see if it makes a difference. When the condition occurs I can wake it using a power supply like shown in the video below, but I would like to prevent it entirely.

 

[jharrell]

Normally to have the discharge FET off with a voltage above LVCO would mean an overcurrent event. Usually this is because something with a large capacitance is connected like a large inverter causing a temporary high in rush current.

I can't think of a reason why the BMS would disconnect discharge FET simply due to no load, makes no sense. I do wish they would put a event log on these BMS's that told you reasons why the BMS did what it did. Even just recording last 10 events would be immensely valuable in troubleshooting.

Maybe HighTechLab from CurrentConnected will see this and have some more insight.