Replacement BMS for a SOK battery

[Doug4096]

I just received my SOK that I ordered about a month ago. Unfortunately the BMS is dead. Have 3.26 on each cell and 0 volts at the battery terminals. Waiting for a RMA from SOK to return it, however they require that you pay shipping back to China, which might be expensive.

Does anybody know of a compatible decent bms that would fit? I know the cells are good, but if the cost of shipping is about the same as a new BMS, I would rather go that route and avoid all the hassle of shipping it back and wait even longer for a working battery.

Also due to the bad experience with SOK, I would not buy from them again. Thinking would like to get a couple of Chins or Ampere Time and giving the SOK (once repaired) to my brother for his trolling motor on his boat.

Thanks in advance.

 

[fratermus]

Some discussion here: https://diysolarforum.com/threads/upgrade-lifepo4-bms-to-manageable.24151/

Hopefully a peer with esoteric SOK knowledge will step in and save the day.

 

[SOK-MIN]

we never request you ship back to China... in fact, we take care of Warranty , why not to get refund or replacement ?

 

[Doug4096]

we never request you ship back to China... in fact, we take care of Warranty , why not to get refund or replacement ?

SOK-MIN, you warranty requires that I ship the battery back to you at my cost. There is no mention of a US based address to send it back to on your website. Matter of fact, though out our email conversation, which BTW, I am willing to post here you repeatedly ask me to post to your facebook group, even though I already told you that I had. It was like you were not even listening to me. You even admitted you had no clue why the bms stopped working, but you assured me it was fine. Only after the battery started working after setting unattached overnight, did you express any interest in me returning the battery calling what happen as wired, which I assumed you meant as wierd. As for you your first message here, which you deleted perhaps you never considered the internet is forever "
SOK-MIN replied to a thread you are watching at DIY Solar Power Forum.

Replacement BMS for a SOK battery​

Lies , we never request you ship back to CHINA !!!

View this thread

Watched threads​

Please do not reply to this message. You must visit the forum to reply.


This message was sent to you because you opted to watch the thread Replacement BMS for a SOK battery at DIY Solar Power Forum with email notification of new replies. You will not receive any further emails about this thread until you have read the new messages.


If you no longer wish to receive these emails, you may disable emails from this thread or disable all emails.",

It is true that you never requested me to ship it back anywhere, you were not interested in providing me an RMA at all instead declaring you only had 2 returns out of 220,000 shipped for bad bms, until the BMS unexpectedly woke up after several unsuccessful attempts. It was only after the battery was working did you actually asked me if I wanted to send the battery back after calling what happened wierd., which I can only take that you were more interested in getting the battery back to see what actually happened more than providing a customer with warranty service.

To be honest I was always going to order another one as I already made the compartment to mount two of them side by side in my class b RV. I am retired and on a fixed income and did not want to risk another $570 dollars on something that might not work. Since the battery is working even though it had some hiccups (We have a saying that sometimes shit happens, meaning sometimes things get wierd), I was all set to order another one, but after your response , I will give the battery to my brother for his small boat (after all he can row back to shore if it goes stops working again) and go with a couple of Ampere Time / Chins from Amazon.

edited to correct mispellings only.

 

[Notech]

SOK-MIN, you warranty requires that I ship the battery back to you at my cost. There is no mention of a US based address to send it back to on your website. Matter of fact, though out our email conversation, which BTW, I am willing to post here you repeatedly ask me to post to your facebook group, even though I already told you that I had. It was like you were not even listening to me. You even admitted you had no clue why the bms stopped working, but you assured me it was fine. Only after the battery started working after setting unattached overnight, did you express any interest in me returning the battery calling what happen as wired, which I assumed you meant as wierd. As for you your first message here, which you deleted perhaps you never considered the internet is forever "
SOK-MIN replied to a thread you are watching at DIY Solar Power Forum.

Replacement BMS for a SOK battery​

Lies , we never request you ship back to CHINA !!!

View this thread

Watched threads​

Please do not reply to this message. You must visit the forum to reply.


This message was sent to you because you opted to watch the thread Replacement BMS for a SOK battery at DIY Solar Power Forum with email notification of new replies. You will not receive any further emails about this thread until you have read the new messages.


If you no longer wish to receive these emails, you may disable emails from this thread or disable all emails.",

It is true that you never requested me to ship it back anywhere, you were not interested in providing me an RMA at all instead declaring you only had 2 returns out of 220,000 shipped for bad bms, until the BMS unexpectedly woke up after several unsuccessful attempts. It was only after the battery was working did you actually asked me if I wanted to send the battery back after calling what happened wierd., which I can only take that you were more interested in getting the battery back to see what actually happened more than providing a customer with warranty service.

To be honest I was always going to order another one as I already made the compartment to mount two of them side by side in my class b RV. I am retired and on a fixed income and did not want to risk another $570 dollars on something that might not work. Since the battery is working even though it had some hiccups (We have a saying that sometimes shit happens, meaning sometimes things get wierd), I was all set to order another one, but after your response , I will give the battery to my brother for his small boat (after all he can row back to shore if it goes stops working again) and go with a couple of Ampere Time / Chins from Amazon.

edited to correct mispellings only.

Wow, I have gotten the same response this week from him. I found this thread by search and it took 3 emails to repeat myself, and then a cryptic reply and hand scribbled connections that had nothing to do with my question.

I was like, woah. Did I just make a mistake in ordering a 2nd one? According to him, I can only connect 2 same capacity Sok batteries in parallel, and when I asked if in series, he said if same AH batteries I can connect together, and different capacity stand alone.

Huh? I went to the FB group and in the file section was useless. Very mickey mouse. Shocked me. Should have saved up for Battleborns and avoided this lack of communication. Not to mention, before I bought the 2nd battery, I searched their site, searched this forum, websites, authorized distributor sites, and the lack of info was there too. I thought at the very least I could connect a 100ah and 206 in series. Still haven't been able to get acknowledgement that he heard or understood my question ?

As far as parallel, this is what I got. Not the 2nd question about series ?

 

[jharrell]

I was like, woah. Did I just make a mistake in ordering a 2nd one? According to him, I can only connect 2 same capacity Sok batteries in parallel, and when I asked if in series, he said if same AH batteries I can connect together, and different capacity stand alon

Lot of conflicting information on the mixing capacities from all parties. Normally you can mix batteries of the same chemistry with different capacities in parallel no problem, they self balance so it is impossible for one to be at a different state of charge than the other, they will accept and give current at a rate proportional to their capacity. Series is a different matter you cannot mix capacities in series. Laptops and phones mix multiple internal batteries with different capacities all the time for physical space constraints.

There is no doubt Battleborn will have better customer support, this is why you pay nearly twice cost per kWh, SOK batteries are constructed well and the BMS is one of the largest I have seen and they actually make it themselves, Min seems to be one person in China handling US support, they could definitely use help. I tested my 206ah BMS to 130 amps discharge and 108 amps charge with no cutouts, word is the BMS is actually 150 amp continuous.

 

[Notech]

Yes support is severely lacking. It's actually a joke. According to the Min update this morning, they can not mixed *period*.

A little detail that should be disclosed, ya think?

"No, don't connect 100Ah and 206Ah in parallel or in series.
NOT using mix."

Well the 100AH is useless to me now. You get what u pay for, and buyers need details from the dealers and need full disclosure, BEFORE they purchase.

That will never happen with China customer service ?

I know their specs have new updates on actual amps lately, so they don't even know what they have.

How do I run two separate banks as I build them?

 

[jharrell]

Yes support is severely lacking. It's actually a joke. According to the Min update this morning, they can not mixed *period*.

A little detail that should be disclosed, ya think?

"No, don't connect 100Ah and 206Ah in parallel or in series.
NOT using mix."

Well you could pay a lot more for Battleborn to tell you the same thing: https://battlebornbatteries.com/100ah-batteries-in-line-with-my-270ah-batteries/

Normally Battleborn is a great source of info but I don't agree with them on this, so long as they are they same chemistry and same voltage (12v with 12v) there should be no issue. Battleborn gives the same charging voltage specs between different sizes so there can't really be a large voltage difference, any small difference will simply balance as they said the higher battery charging the other, just like two of the same size would.

Someone needs a better explanation as to why you can't mix capacities of the same chemistry, since its done all the time, goes against my understanding of electricity, and even Will seems to think its fine and made a Frankenstein battery of all different makes and sizes: https://diysolarforum.com/threads/mixing-different-lifepo4-batteries.9066/post-97640

I think in the end if the manufacturer won't honor warranty if mixing capacities in parallel like Battleborn and probably SOK then its better to retain the warranty regardless of who's right. SOK can definitely be more clear in general, they have conflicting info on battery case size, and BMS capacities, at least Battleborn make their position clear with extensive documentation, blogs post and videos and there is nothing wrong paying much more money for the same Wh to compensate them for that.

 

[monks-cat]

Sorry to intrude, but what ended up happening with the warranty? I'm currently dealing with a similar problem. My BMS on my SOK battery is tripping when it shouldn't.

 

[williamsk913]

Well you could pay a lot more for Battleborn to tell you the same thing: https://battlebornbatteries.com/100ah-batteries-in-line-with-my-270ah-batteries/

Normally Battleborn is a great source of info but I don't agree with them on this, so long as they are they same chemistry and same voltage (12v with 12v) there should be no issue. Battleborn gives the same charging voltage specs between different sizes so there can't really be a large voltage difference, any small difference will simply balance as they said the higher battery charging the other, just like two of the same size would.

Someone needs a better explanation as to why you can't mix capacities of the same chemistry, since its done all the time, goes against my understanding of electricity, and even Will seems to think its fine and made a Frankenstein battery of all different makes and sizes: https://diysolarforum.com/threads/mixing-different-lifepo4-batteries.9066/post-97640

I think in the end if the manufacturer won't honor warranty if mixing capacities in parallel like Battleborn and probably SOK then its better to retain the warranty regardless of who's right. SOK can definitely be more clear in general, they have conflicting info on battery case size, and BMS capacities, at least Battleborn make their position clear with extensive documentation, blogs post and videos and there is nothing wrong paying much more money for the same Wh to compensate them for that.

You can't use them in parallel because the battery will attempt to supply power proportional to its size relative to the total ahs. The 200ah SOK batteries have the same BMS as the 100ah batteries, which means with a super heavy draw that BMS will kick in and dump it all on small battery before that BMS kicks on in turn. You need a BMS capable of supplying 1c of its amps to make unequal size lifepo4 batteries *potentially* work. The other complicating issue is that they obviously use different cells, may have different resistance (I would think this would be less of an issue but who knows)?

 

[jharrell]

You can't use them in parallel because the battery will attempt to supply power proportional to its size relative to the total ahs. The 200ah SOK batteries have the same BMS as the 100ah batteries, which means with a super heavy draw that BMS will kick in and dump it all on small battery before that BMS kicks on in turn. You need a BMS capable of supplying 1c of its amps to make unequal size lifepo4 batteries *potentially* work. The other complicating issue is that they obviously use different cells, may have different resistance (I would think this would be less of an issue but who knows)?

This is no different than any parallel battery configuration other than the proportions. So long as your load does not exceed the BMS capabilities there is no issue. Just like parallel batteries of equal size split the load and you can size your load according to an equal split, with different capacities you must size based on the unequal proportions. There is no rule that says a BMS must supply 1C, the BMS need only be sized for the load not the cells C rating. Yes different size cells have different internal resistance, this is how the current get distributed proportionally! The smaller cells have higher IR than larger cells therefore more current will flow to larger cells, thats how the whole things works!

If you want more details watch this excellent two part series that show an extreme capacity difference in parallel:

 

[williamsk913]

This is no different than any parallel battery configuration other than the proportions. So long as your load does not exceed the BMS capabilities there is no issue. Just like parallel batteries of equal size split the load and you can size your load according to an equal split, with different capacities you must size based on the unequal proportions. There is no rule that says a BMS must supply 1C, the BMS need only be sized for the load not the cells C rating. Yes different size cells have different internal resistance, this is how the current get distributed proportionally! The smaller cells have higher IR than larger cells therefore more current will flow to larger cells, thats how the whole things works!

If you want more details watch this excellent two part series that show an extreme capacity difference in parallel:

And that does nothing to disprove what I have said? The problem is, with household/ RV electrical systems, there is never really a set load. You can't guarantee that one more appliance isn't going to be plugged in. Should you design a system using dissemilar batteries without BMSes capable of a 1c discharge, you must design protection into the system so the total draw is unable to exceed the limit of the BMS that is the weakest link.

 

[jharrell]

You can't use them in parallel because the battery will attempt to supply power proportional to its size relative to the total ahs.

This is what I am disproving, it is false, YES YOU CAN PARALLEL THEM. There is no difference between two batteries of equal capacity in parallel or of different capacities other than the proportion of current. 1C has no more to do with it than it does with batteries of equal capacity. The cells are C rated, the BMS is amp rated they don't have to match up, both the cell and BMS must be able to support the load, the load is split based on the IR of the cells which is determined by their capacity, so long as the load is under both the cell and BMS rating there is no issue, period. There are many batteries where the BMS has a lower rating than the cell 1C rating.

Let me ask this, if you have two equal capacity batteries, can they support 2 times the load or not? If one shuts down the remaining will not support the load which could easily exceed the single batteries BMS or cell rating in many supported configurations, so that situation is not unique to parallel batteries of different capacities.

Maybe you can argue with Will about it, here is his take on different capacities in parallel:

 

[Danzig]

Wow, I was just getting ready to pull the trigger on 6 of the 48v 100ah SOK server rack batteries. But now I'm hesitant... it seems there are potential problems with both brands... SOK and EG4. Is the percentage of people having these kinds of problems just a small minority? I'd be interested in seeing the return rates of these products.

 

[MIFARMS]

Well, I have 6 of the 12V 206Ah batteries (configured for 24 Volt), and I'm happy with them. I purchased mine thru Current Connected, and they are an SOK service center, but, but I think they will only warranty batteries purchased thru them (don't quote me on that, but I believe that's what I read on their site). But I have had excellent communication, and service from CC. I ran across this thread looking for a spare BMS for my SOK's just in case for a spare. Realize this thread is kinda stale now, and maybe there were problems back in the day. But I think (hope) that's all history at this point.

 

[Tommy74]

Well, I have 6 of the 12V 206Ah batteries (configured for 24 Volt), and I'm happy with them. I purchased mine thru Current Connected, and they are an SOK service center, but, but I think they will only warranty batteries purchased thru them (don't quote me on that, but I believe that's what I read on their site). But I have had excellent communication, and service from CC. I ran across this thread looking for a spare BMS for my SOK's just in case for a spare. Realize this thread is kinda stale now, and maybe there were problems back in the day. But I think (hope) that's all history at this point.

I have some version 8. The latest version. Had some miscommunication and was sent too many under warranty. Where are you located?