Heltec BMS' (up to 350A) with Active Balancing & Independent Active Balancers

[Steve_S]

Another Case in Point. ElectricCarPartsCompany sells, BMS, they also sell the Chargery BMS BUT it is labeled as "Choice BMS", they aren't the only ones who did that BTW, but they ARE Chargery which is a small specialised operation that does their own stuff. Some parts are contracted out.

LOL that is what I meant with the tire analogy.

I suppose the only way to know, would be to buy a bunch of these "similars" tear into them and look at the PCB's and components such as the chips themselves but even that may be off-target unless or compare the firmware code itself (not gonna happen).

I feel with a certain confidence that DALY is made by DALY along with their other products. we have to go with the reviews & writeups of peoples experiences with the different ones.

Of course Electrodacus, Batrium, TinyBMS and that tier are known entities @ $ entity pricing too.

 

[ArthurEld]

I would definitely prefer to buy from the manufacturer. Though some manufacturers don't provide good support.
But like you say, at least you should be able to search for the manufacturers name and part name or model # to find info.

I saw Deligreen's Daly BMS's

 

[Dzl]

Another Case in Point. ElectricCarPartsCompany sells, BMS, they also sell the Chargery BMS BUT it is labeled as "Choice BMS", they aren't the only ones who did that BTW, but they ARE Chargery which is a small specialised operation that does their own stuff. Some parts are contracted out.

Yeah I've noticed ECPC is a fan of rebranding/renaming products.

Chargery --> "Choice"
ETC Cells --> "Xcell Cells"
Frey Cells --> "Fortune Cells" (Looks like they aren't the only ones rebranding Frey as Fortune so they may actually be buying from a company that sells them already branded as fortune cells)

LOL that is what I meant with the tire analogy.

Sorry, may have misinterpreted your meaning there.

I feel with a certain confidence that DALY is made by DALY along with their other products.

Agreed Daly is one of the only companies that I feel moderately confident that they are the manufacturer or at least intimately involved in the design/manufacturing process. (side note: did you notice Daly recently added active cooling to most of their high current BMS', or at least they added it to the pictures on their official aliexpress store)

 

[ArthurEld]

(1) none of this as best I can tell applies to the black aluminum cased BMS from Heltec, I'm still interested in it, and I haven't seen it or anything similar to it sold elsewhere (and if I discovered that it were, I would still be intererested)

The black one you are talking about has no identification on it in the pictures. None of them have model names or numbers.
I'm looking at the 200a version
Upnorthandpersonal's link has if for $241 - https://www.aliexpress.com/item/4000776885236.html
Another one on Aliexpress for $199 - https://www.aliexpress.com/item/4001296672548.html
And Alibaba has it for $195 - https://www.alibaba.com/product-detail/14-24S-200A-Smart-BMS-with_62544207027.html

 

[Dzl]

Strangely the first link and the second link take you to the same store and what look to be the same BMS with the same spec sheet in the photos, but with a price discrepancy of $40 and slight differences in the wording of the title. Might want to look at the finer details between the two before choosing. Or maybe the sales rep can shed some light on the differences.

I wonder what the big QR code on the front is all about. Maybe a link to the app, or manual, maybe just serial number or something. Tried to scan it but no luck.

 

[upnorthandpersonal]

I wonder what the big QR code on the front is all about. Maybe a link to the app

Yes, it's a link to the app.

 

[ArthurEld]

I ordered the 200A with 2A active balance from Heltec on Alibaba. I asked for the latest version. I told them I'd buy a few more if I like it and that people here are interested. I paid $213. I know it is available cheaper but I was afraid there might be older versions.

 

[Haugen]

And Alibaba has it for $195 - https://www.alibaba.com/product-detail/14-24S-200A-Smart-BMS-with_62544207027.html

That's the one I bought.
2A Active balance with a CAN bus were the important specs for me.
Trying to interface it with a SolArk. I think I'm breaking ground on this. If anyone is ahead of me on the CAN bus path, I would appreciate an assist.

 

[GXMnow]

As it turns out, my JK BMS is a re-badged Heltec. It has been up and running on my battery bank for over 2 months now. The active balancing is working great and it has been handling up to 80 amps on the 200 amp rated version and only getting a barely warm to the touch. So Far, So Good.

I have not tried digging into the RS-485 or CAN bus ports yet. I just monitor it once in a while on the phone app. Over this weekend, I finally got my battery bank moved into its new steel rack enclosure, and I started wiring up my aux DC power panel. And I ran into something very odd.

I ran a 30 amp fused feed from the battery bank out to the panel. The panel has four 15 amp breakers. The first breaker is feeding a DROK 12 volt 25 amp DC-DC buck converter. I have tested it on a few small loads and the output is pretty clean. I have not pulled enough power to get it warm at all. But as I was closing things up, I wanted to test it before I screwed down all the panels. The 12 volt out is working, I plugged in a car power adapter that has lighter sockets, and four USB charge ports. I plugged in my phone, and it's charging, yeah! but I opened the BMS app just to see how much current it was pulling, and the current goes from 0.2 amps to 0.4 amps when I plug in my phone. At 55 volts, that is 11 watts, so it is about dead on for 2.1 amp charging at 5 volts. All looks good, but then I notice the balancing is going nuts. Last I checked, all my cells were within 0.003 volts. Now it is reporting a spread of 0.022 and it is trying to shuffle some power to balance it out. But the high cell keep changing to any cell on the left side. The low cell seems to be sticking to cell 12 of 14. The high cells do seem to dip a tick as it pulls the 2 amps, the the low cell is not budging. They are all well in a safe range, within 0.02 of 3.75 volts, so I am not worried about anything bad happening. It is reporting the pack at 70% charged. I was about to just let it balance overnight, but out of curiosity, I checked a few cells with my meter, and they were all fine, right at 3.758 volts. Even #12, being reported at 3.738 was actually at 3.758 volts. So I figured my balance lead may have lost connection or something. Since I am going to turn the rack to start checking the leads, and my 30 fuses on the balance wires, I turn off my 12 volt output and unplug my phone. What do you know.... All the cells show perfect balance again. ?????? The highest to lowest voltage delta is showing 0.002 to 0.003 as I stare at it. I put on some load from the XW-Pro inverter, and the voltage dipped a little, but all the cells held balance. I wiggled and tugged on my balance wire harness, no issues at all. I turn on my 12 volt buck converter....... OOPS Cell 12 drops to 3.74 volts, a few on the cell one to cell eight side start bouncing up a few millivolts again.

The wires are not very close. The DC-DC converter is 8 inches from the BMS board, but on the opposite side of a 1/8 inch aluminum panel, and below a 1/16 inch steel shelf. The DROK converter is drawing from the BMS output, but it is hard to think it could be putting more noise into the current path than the XW-Pro inverter. But it is obvious something odd is going on. It is 2AM, so I have it set to charge again when the sun comes up, and I am going to bed. I will try adding a noise filter on the power line to the buck converter and see if it helps out. I was hoping to use the 12 and a 24 volt converter to power my PLC and the Conext Gateway, but I don't want them freaking ut the BMS balancing like that. It will drive it to unbalance the cells.

At this point, I can't blame this on the Heltec (Ki Kong) BMS as no other load on it has cause anything like this. It has to be the switching noise of the buck converter.

 

[Haugen]

@GMXnow, That is an interesting problem.
I'm a little suspicious that #12 is always the low cell. Maybe swap it with another cell and see if the issue follows the cell?

If you are using the prismatic cells with the blue wrappers, the outer case is tied to the positive terminal. Make sure that you haven't compromised that. It could be an opening to allow the EMI to get to that cell via the metal stand.

 

[Steve_S]

@GMXnow, That is an interesting problem.
I'm a little suspicious that #12 is always the low cell. Maybe swap it with another cell and see if the issue follows the cell?

If you are using the prismatic cells with the blue wrappers, the outer case is tied to the positive terminal. Make sure that you haven't compromised that. It could be an opening to allow the EMI to get to that cell via the metal stand.

I have yet to see a casing that is either {Pos or Neg} or bound to a terminal in any way.
I just rechecked out of curiosity on EVE's & AyouPower cells and nope.

GXMnow I don't know about the cheap buck converters, especially the adjustable ones but it is unlikely an "isolated" transformer / converter and therein may be the cause of the issues. BMS' can be quite sensitive as you've discovered. Typically, an isolated converter will cost more.

 

[Haugen]

I have yet to see a casing that is either {Pos or Neg} or bound to a terminal in any way.
I just rechecked out of curiosity on EVE's & AyouPower cells and nope.

I didn't believe it when I first read it. Sounds preposterous, right!
I used a probe to poke through the blue wrappers on mine and they measured 0V to the positive terminal and 3.2V to the negative.

 

[GXMnow]

I will look into it more today. It is certainly not a cell issue as my Fluke meter shows all the cells at the correct voltage within 0.002 of what the BMS is showing when the buck converter is off. When I turn on the buck converter, the cell voltage readings all start to bounce a bit, but just the cell 12 dropped the 20 mv. I can't explain why just that one went more goofy than all of the 13 others.

These are LG Chem Chevy Bolt cells. They are pouch cells in proper cell holders. The outsides of the pouches are a type of plastic film. There is an aluminum sheet between ever second cell for cooling when used in the electric car. I do not measure any leakage current to the aluminum sheets. I did pull a 20 amps load and checked for any voltage drops at the buss bars. Most of the connections are still the factory spot welds. Everything measures fine. The pack is currently charging at 20.9 amps. About 1,200 watts, out of the 1,900 watts that are coming from my solar panels.

Here are the cell voltages with the system charging. The charge current does bounce from about 19 to 24 amps, the average charge current is 20.97 amps right now. That bouncing is caused by the XW-Pro charge current being a full wave rectified sine wave. This picture shows all of the cell voltages are between 3.825 and 3.828, just a 0.003 difference from top to bottom.

Now I turn on the DROK 12 volt Buck converter with a small load.

The total voltage reading dropped 0.16 volts. That is not real. I see no change in voltage at all with this small load. The battery is still chargin at over 20 amps. But now the cell balance is all over the place. The Cell 2 dropped to 3.814 an 11 mv change, but then look at cell 12 3.753 a drop of 73 mv, from a 0.4 amp change in current. Nope, this is not real. Cell voltage on the Fluke meter is still 3.825 volts at the balance leads. The reading at cell 10 actually went up to 3.829, but that is only 1 mv, well within the margin of error. It has to be something to do with the balance wires picking up the switching noise of the buck converter. It is just odd that it is hitting Cell 12 so much more than the rest.

When I shut the converter back off, it all returns to normal. All of the cels have climbed about 2 or 3 mv due to the 21 amp charge current.

Cell 10 is still highest and Cell 1 is the lowest, just like in the before picture.

I also have a 24 volt converter. Obviously from the same original manufacturer as the heat sink case is identical. These are the water tight sealed units they sell on Amazon for golf carts to step the voltage from the main battery down to run the lights and a radio etc. Here is the one causing the issue.

Amazon.com: DROK Waterproof DC-DC 30-60V 36V 48V to 12V 25A 300W Non-Isolated Synchronous Buck Power Converter Voltage Regulator Volt Power Supply Transformer Module for Automotive Electric Fan : Electronics

Buy DROK Waterproof DC-DC 30-60V 36V 48V to 12V 25A 300W Non-Isolated Synchronous Buck Power Converter Voltage Regulator Volt Power Supply Transformer Module for Automotive Electric Fan: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Here is the 24 volt one.

Amazon.com

I have not put a load on the 24 volt one yet. At no load it does not seem to cause an issue, but the 12 volt one does, even at no load. My first step will be adding a large filter cap on the input lines to the converter and see if it makes a difference.

 

[Gazoo]

I have yet to see a casing that is either {Pos or Neg} or bound to a terminal in any way.
I just rechecked out of curiosity on EVE's & AyouPower cells and nope.

I had read a couple posts that claimed differently. Thanks for clearing that up. I will check one of my cells when they arrive.

I still think it's best to keep the cells isolated from any metal...just in case.

 

[Dzl]

I didn't believe it when I first read it. Sounds preposterous, right!
I used a probe to poke through the blue wrappers on mine and they measured 0V to the positive terminal and 3.2V to the negative.

Anyone else with Blue Aluminums be willing to replicate this and report back?

 

[upnorthandpersonal]

Just checked my 280Ah EVE cell, the metal case is definitely connected to the positive.

 

[Gazoo]

I used a probe to poke through the blue wrappers on mine and they measured 0V to the positive terminal and 3.2V to the negative.

Just checked my 280Ah EVE cell, the metal case is definitely connected to the positive.

I have yet to see a casing that is either {Pos or Neg} or bound to a terminal in any way.
I just rechecked out of curiosity on EVE's & AyouPower cells and nope.

I wonder what is going on here as these statements are conflicting.

Anyone else with Blue Aluminums be willing to replicate this and report back?

I hope others will report back.....please. There are many that have purchased aluminum cased cells and it will only take a minute to check is the aluminum case is isolated.

 

[Dzl]

I have yet to see a casing that is either {Pos or Neg} or bound to a terminal in any way.
I just rechecked out of curiosity on EVE's & AyouPower cells and nope.

Steve, when you say you rechecked, are you referring to checking the datasheet, or physically testing the cells?

If the former, could you verify with a multimeter, if the latter, is it possible your probe did not fully penetrate the wrap?

 

[Steve_S]

Verified with multimeters, the cells are in front of me as I am now reconfiguring packs. I have cells from Ayoupower which do not even have a cover, raw exposed aluminium casing (from that Shunbin disaster). The 280 packs, I'll have to check in a couple of days when I am installing the Active Balancing subsystem.

@Will Prowse SUGGESTION - Video ?
Will you have a wide assortment of LFP cells from a myriad of suppliers. Could you maybe take a sampling of different cells and see if any have polarized cases ? Something a tad fishy and this needs to be put to bed.

 

[GXMnow]

Maybe check with a light bulb and see if it is just a tiny leakage current, or if it can actually pull current to the case. Some meters are very sensitive and a tiny bit of moisture can carry enough current to show full voltage. But if it won't light a small bulb, it is likely not a concern in actual use. Some meters even have a Low Z input mode to check if a voltage source can supply a few milliamps or if that will bleed it down to nothing.