New SOK Bluetooth BMS for DIY

Looks like I may have gotten lucky. I ordered 2x standard marine 206AH batteries, and they came with the new BMS with Bluetooth? ?

Yup. Or unlucky, depending on how you use your batteries. The non BT BMS is more capable than the BT one. I keep saying I am going to swap my non BT BMSs back in but I like the BT info too much to do it.

How more capable? Just not having the extra draw?

beckkl said:

How more capable? Just not having the extra draw?

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The extra draw and the non BT BMS is a LOT less sensitive to turning on my inverter. Now that I have the inverter inrush issue solved, I am going to put off swapping the BMSs out. I have the 15k BTU aircon and residential fridge running right now and with the solar it is pulling 96 amps from my 2x12V 206Ah SOK batteries. That's plenty of oomph for now.

Weird. I have the BT heated 100AH 12 V and can power up a hair dryer taking 100A with no issue. Maybe way less surge? I'd be lost without the BT info, really helped me understand the draw from different loads in my camper. I suppose I could have gotten this information in other ways, but just really convenient.

beckkl said:

Weird. I have the BT heated 100AH 12 V and can power up a hair dryer taking 100A with no issue. Maybe way less surge? I'd be lost without the BT info, really helped me understand the draw from different loads in my camper. I suppose I could have gotten this information in other ways, but just really convenient.

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The issue is the inrush current to the 3000W inverter caps trips the high current protection in the bms.

That makes sense. I know for a fact that the 12V 100AH heated version cannot handle "Peak Discharge Current: 200 A (7.5 s ±2.5 s)"

How did you get around this?

beckkl said:

That makes sense. I know for a fact that the 12V 100AH heated version cannot handle "Peak Discharge Current: 200 A (7.5 s ±2.5 s)"

How did you get around this?

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I have a precharge circuit for the inverter. As long as I use it I am fine but if I forget, both batteries will go into protect.

I’ve finished my system now and my pair of 206Ah with the BT BMS have no issues starting my 15k A/C(or running anything else) from a MultiPlus-II 3000 120x2. I don’t have a pre charge circuit. I do have an EasyStart installed in my A/C unit.

Th

jsalbre said:

I’ve finished my system now and my pair of 206Ah with the BT BMS have no issues starting my 15k A/C(or running anything else) from a MultiPlus-II 3000 120x2. I don’t have a pre charge circuit. I do have an EasyStart installed in my A/C unit.

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Yeah, the EasyStart is the key there.

beckkl said:

Th

Yeah, the EasyStart is the key there.

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Oh yeah. I consider an EasyStart to be a requirement for running an A/C unit on any inverter or generator.

Many people talk about needing precharge circuits just to turn on their inverter though. I’ve not needed that for mine.

I have an easy start on both 15k air conditioners. That doesn’t help with the inverter caps, though.

corn18 said:

I have an easy start on both 15k air conditioners. That doesn’t help with the inverter caps, though.

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I only run the A/C on the generator for now. Have a predator 3800 and it seems to run the 15KBTU fine. Would I still see some benefit to the easystart?

beckkl said:

I only run the A/C on the generator for now. Have a predator 3800 and it seems to run the 15KBTU fine. Would I still see some benefit to the easystart?

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Only if you want to try to run two air conditioners off the generator. That would be tight even with soft starts. If you only have the one ac then you shouldn’t need a soft start.

One thing I like about having a soft start on my 15k ac is I can run it off my little 2000W predator inverter genset. Nice not having to carry around a 100 lbs bigger genset.

corn18 said:

I have an easy start on both 15k air conditioners. That doesn’t help with the inverter caps, though.

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What inverter are you running?

jsalbre said:

What inverter are you running?

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Same as yours. If I turn the solar on and there is any sun at all, I don’t have to precharge. Or if the truck is running and hooked to the trailer. But without help, both of my batteries will go into protect if I don’t precharge the inverter caps.

corn18 said:

Same as yours. If I turn the solar on and there is any sun at all, I don’t have to precharge. Or if the truck is running and hooked to the trailer. But without help, both of my batteries will go into protect if I don’t precharge the inverter caps.

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Interesting. I don’t have any issue even with the solar controller breakers flipped off. I wonder if it’s a difference between BMSes or MultiPluses?

jsalbre said:

Interesting. I don’t have any issue even with the solar controller breakers flipped off. I wonder if it’s a difference between BMSes or MultiPluses?

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That is a great question. I can live with the need to precharge. I would really like for the inverter not to buzz when on shore power. I have isolated it to the charger. I wish I could just turn the inverter off when on shore power, but the ATS doesn't work without the inverter turned on. I can mitigate it during the day and set the inverter to charge only with the solar on. I set the float voltage on the inverter/charger 0.1V lower than the float voltage on the SCC and that keeps the inverter/charger from turning on which eliminates the buzz. But the charger still comes on at night. Might have to set the inverter/charger float down to 13.8 when on shore power.

When on batteries, the inverter/charger always hums but I am ok with that. That means it's working. But I don't need it when on shore power.

Just to add what everyone else has said.

Just did a build with 2 SOK 12V 100Ah, Heated w/ Bluetooth batteries and a Victron 2K Multiplus, a Victron Orion TR Smart, and a Victron SmartSolar 100|30

1) I have stressed it to around 109A on each battery and the system continued to run for several minutes before I shut down the load. (This also exceeded the 2KW of the inverter) I also stressed it to shut off, but was not measuring the load so I do not know where the system shut off.

2) Both batteries will shut down (D-MOS turns off) if the Victron MultiPlus is connected to the DC without a precharge. The 330A, no delay Short-Circuit protection is far less forgiving than a lot of other BMSs. Many (most?) BMSs would be able to handle the surge of a 2K inverter.
This is the precharge circuit that is now on the build:

3) Both batteries have a cell that runs away at the end of the charge cycle. The Cell overvoltage is hit before the charge cycle completes and the C-MOS turns off. There are comments online that the balancer on the BMS will eventually take care of this. I have my doubts, but we will see. There may be a need to open the battery and manually balance the cells.

4) When the short circuit protection trips, or the cell under-voltage trips, the only indication in the app that something has happened is the D-MOS or C-MOS indicators grey out. There is nothing that tells you why it is greyed out. There is a battery status page in the app, but I have never seen that page provide any information. It would be nice if that page would display the reason the D-MOS and/ or C-MOS is off. (Or perhaps have a log of recent events)

5) To turn the D-Mos back on, you must put a sufficient charge voltage on the battery. The charge voltage must be a little bit higher than the internal battery voltage. (This confused me for a while when I had the charge voltage turned down a bit and it was not restarting the battery)

I prefer an auto reset.... but others prefer a manual intervention after a bad event. Note: An auto-reset would require a HW redesign of the BMS. I wonder if they could add a control to the app that lets you turn it back on?

6) The app indicates nothing about balancer settings or balancer activity. This would be a much-welcomed upgrade to the app

FilterGuy said:

Just did a build with 2 SOK 12V 100Ah, Heated w/ Bluetooth batteries and a Victron 2K Multiplus, a Victron Orion TR Smart, and a Victron SmartSolar 100|30

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An Additional thing I learned during the build:

7) When the batteries were first received, there was an indication in the app that the 'actual capacity' was something like 140Ah. This turns out to be a value that the battery calculates after a few cycles. In fact, SOK instructs users to do two full cycles to train the BMS on what the SOC is:


The following is from that page:

When you receive the SOK bluetooth battery, please search ABC-BMS on google or apple store and install on your phone, but the SOC and capacity incorrect, have to do 2 cycles.

Few steps to do this:

1. Check the voltage on the terminal, it should be 10V~14V
2. discharge it, using a 12v DC load connect with terminals directly, let it working till it stop, after fully discharge, the BMS should be cut off, the Voltage on the terminals should be 0V.
3. Wake up the battery: connect a lifepo4 battery charger on the terminals, it should be wake up back to work, BUT not all lifepo4 battery charger could wake up the battery, please check this video if wake up not successful: https://www.youtube.com/watch?v=TJ_Klwp-JyM
4. After you wake up the battery, connect with the lifepo4 battery charger, let it working till BMS cut off.
5. Repeat the step 2, still using a DC 12v load discharge it till cut off.
6. Repeat the step 3, wake up the battery.
7. Charge the Battery , check the app, the SOC and capacity should be correct.

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After the batteries were cycled a couple of times the "actual capacity" came way down and is more in line with what is expected.