The Electrodacus SBMS thread (SBMS0, DSSR50, etc)

[childcarepro]

I'd be curious to hear more about that 24vdc heat pump you mentioned earlier

Ah, that's something being developed by Hotspot Energy. They're developing a 24VDC 7000-9000 BTU mini-split air conditioner for RVs with a cassette-style indoor unit that is a drop-in replacement for noisy, inefficient RV A/C. I envied people who use traditional mini split units in RVs but I literally have no wall space for the indoor unit in my 25' Sprinter Class A motorhome. It was supposed to come out this quarter.

Hotspot Energy is a company that makes a bunch of interesting products like the Free Pool Heater, a titanium heat exchanger that lets you replace your condenser unit and use your pool water kind of as a geothermal heat pump to pump heat into rather than an air exchange.

 

[Cal]

Hey guys, so I took a break from this project to set up equities investments. Looks like everyone else has been doing the same thing? It's been quiet in here!

I always want maximum features, but what I'm really looking for simplicity over power. I'm sticking with my Victron ecosystem because it's slick and polished and does just about everything I need including remote monitoring and control, so the SBMS0 would just be a BMS. Is Electrodacus's SBMS0 compatible with my goals?

Yep, been investing in wm.

I think SBMS0 is a great choice. You might right now be looking for simplicity over power, but once you become more familiar with the system you want options. If you can read and follow directions then Electrodacus will fit nicely in your system.

 

[childcarepro]

One BMS that may meet your needs (as written) is the Heltec BMS, I don't recall if it is available for 24v or just 48v but it is a true active balancing FET based BMS and I believe is rated at 200A maybe higher. There is a thread on the forum dedicated to it. But only a few people from the forum have purchased it and most have been recent purchases.

How did I miss this?!? I totally moved past your Heltec suggestion and on to your high end options. I just stumbled onto Heltec again from an eBay seller who sells Daly BMS's who suggested the Heltec because it has BT and his Daly 8S 200A doesn't. That's when I found the video from this forum (https://diysolarforum.com/threads/h...balancing-independent-active-balancers.11453/) showing active cell balancing actually working. WHAT?!? Stop the presses. How is one of the only active cell balancers one of the cheapest BMSes?!?

I think this is the simple, powerful solution I'm looking for. WDYT? And I'll probably order two just to have as a backup, though it does require soldering so it's quite not a drop-in replacement.

Having the wiring harness like in the video is a good idea, to be able to disconnect the battery from the balancer and vice versa. If I pre-wire the backup balancer with a harness, it should be a quick replacement. Maybe the BattGo is a good idea for monitoring; I don't know how good the Heltec's app is.

 

[childcarepro]

Yep, been investing in wm.

I think SBMS0 is a great choice. You might right now be looking for simplicity over power, but once you become more familiar with the system you want options. If you can read and follow directions then Electrodacus will fit nicely in your system.

@Cal, I agree the SBMS0 sounds amazing, and has a very mature interface. The up front work is rough; I skimmed the manual; it's dense, and I'm not sure I'm up to the task re: electronic know-how, with opto-couplers and all.

At this point I am intrigued by the Heltec's true active balancing and the 5.5A balancing current and low cost. I imagine it works well during charge and discharge, not just just equalizing voltages across cells with no charge and discharge current.

 

[sremick]

A lot of people misunderstand what active balancing means (the terms are slightly misleading). Active balancing means the BMS or Balancer transfers energy from one cell to another whereas passive balancing bleeds energy from high cells--Almost all BMSes are passive balancing. If you truly need active balancing, you rule out 90% of the BMSes (including SBMS, Charger, Daly, JBD Smart BMS (overkill solar) and Ant BMS).

If you just need a BMS that balances, than all of the above BMSes will work (passive (resistive) balancing)

Does the SBMS40 also not do the "active" balancing in the sense of your definition? I'm not sure I fully understand the degree that my SBMS does "balancing".... I'd like to understand my product better.

 

[ArthurEld]

How did I miss this?!? I totally moved past your Heltec suggestion and on to your high end options. I just stumbled onto Heltec again from an eBay seller who sells Daly BMS's who suggested the Heltec because it has BT and his Daly 8S 200A doesn't. That's when I found the video from this forum (https://diysolarforum.com/threads/h...balancing-independent-active-balancers.11453/) showing active cell balancing actually working. WHAT?!? Stop the presses. How is one of the only active cell balancers one of the cheapest BMSes?!?

I think this is the simple, powerful solution I'm looking for. WDYT? And I'll probably order two just to have as a backup, though it does require soldering so it's quite not a drop-in replacement.

Having the wiring harness like in the video is a good idea, to be able to disconnect the battery from the balancer and vice versa. If I pre-wire the backup balancer with a harness, it should be a quick replacement. Maybe the BattGo is a good idea for monitoring; I don't know how good the Heltec's app is.

I have a Heltec 200A with 2A active balance.
This BMS is completely different than all of the other Heltec BMSs.
It isn't clear who actually makes it. Another company JK sells it too.
I haven't tried this BMS yet. There are a couple good reviews around here and a couple bad.
I agree that it looks like the best one for the price. I'm not recommending it yet.

 

[childcarepro]

I have a Heltec 200A with 2A active balance.
This BMS is completely different than all of the other Heltec BMSs.
It isn't clear who actually makes it. Another company JK sells it too.
I haven't tried this BMS yet. There are a couple good reviews around here and a couple bad.
I agree that it looks like the best one for the price. I'm not recommending it yet.

Did you see this one: https://heltec-bms.com/product/3s-21s-5a-capacitive-active-equalization-active-balancer/

It claims 5.5A active balancing using capacitive balancing; 1A at 0.1V differential, higher at higher voltage differentials.

 

[ArthurEld]

Did you see this one: https://heltec-bms.com/product/3s-21s-5a-capacitive-active-equalization-active-balancer/

It claims 5.5A active balancing using capacitive balancing; 1A at 0.1V differential, higher at higher voltage differentials.

Yes, I saw them.
I am sure you could use it with any BMS. I think you are supposed to turn off the passive balancer.

 

[childcarepro]

Yes, I saw them.
I am sure you could use it with any BMS. I think you are supposed to turn off the passive balancer.

Wait, are you saying that one ONLY equalizes between cells, but does not maintain balance during charge or discharge? That seems like a very narrow use case.

 

[Dzl]

Does the SBMS40 also not do the "active" balancing in the sense of your definition? I'm not sure I fully understand the degree that my SBMS does "balancing".... I'd like to understand my product better.

Just to clarify, its not my definition, it is the definition.
I actually prefer to call passive "dissipative" or "resistive" balancing but these terms are less understood/common outside of technical spaces but I think they better convey the concept. Active is also sometimes called "non-dissipative"

I'm not positive about the SBMS40, but I suspect like the SBMS0, it is a passive balancing BMS (as mentioned above, almost every BMS is).

Just to reiterate the distinction one more time, Active balancing transfers energy from high to low cells (using capacitors or inductors) whereas passive balancing simply bleeds off energy (using resistors) from the high cells. An advantage of active balancing is it only wastes about 30% of the energy as opposed to 100% with a dissipative (passive) balancer, and active balancers usually have higher current ratings. There are trade-offs though. I am not informed enough to write about them here, but I recommend these links (click the links there is a lot more info than the short excerpts I pulled out as quotes:

Dissipative vs Non-Dissipative (aka Active vs Passive) cell balancing -- LiionBMS

Dissipative: energy is removed from the most charged cell and is wasted in heat
Nondissipative: energy is transferred between cells and therefore it is not wasted

Traditionally, dissipative balancing is known as "passive balancing", and non-dissipative balancing is known as "active balancing". Unfortunately, the meaning of "active" and "passive" balancing has been confusing and interpreted in other ways. The terms "dissipative" and "nondissipative" are not open to misinterpretation. Therefore, we would like to take the lead in attempting to change the usage of these terms in the industry.

Battery Cell Balancing -- Wikipedia

Balancing can be active or passive. The term battery regulator typically refers only to devices that perform passive balancing.
In passive balancing, energy is drawn from the most charged cell and dissipated as heat, usually through resistors.
In active balancing, energy is drawn from the most charged cell and transferred to the least charged cells, usually through capacitor-based, inductor-based or DC-DC converters.

Active Battery Cell Balancing -- Analog.com

 

[Dzl]

Wait, are you saying that one ONLY equalizes between cells, but does not maintain balance during charge or discharge? That seems like a very narrow use case.

I believe you have found the wrong product. Heltec makes active balancers, as well as an active balancing BMS (balancer vs BMS is another often misunderstood topic). The balancer is just a single purpose tool, not a replacement for a BMS. The BMS is more expensive than the balancer and obviously more fully featured. Search for the BMS @upnorthandpersonal is using, IIRC, it is in the ballpark of ~$200.

edit: I believe this is the correct link and this is a relevant thread (if you get past the first page or two where the conversation is a bit muddled).

 

[Cal]

@Cal, I agree the SBMS0 sounds amazing, and has a very mature interface. The up front work is rough; I skimmed the manual; it's dense, and I'm not sure I'm up to the task re: electronic know-how, with opto-couplers and all.

At this point I am intrigued by the Heltec's true active balancing and the 5.5A balancing current and low cost. I imagine it works well during charge and discharge, not just just equalizing voltages across cells with no charge and discharge current.

Back in the day, Bell motorcycle helmets had an ad:

If you got a $10 head, wear a $10 helmet.

Or:

How much is your head worth?

If you're considering Heltic, then I'd say do more research.

This link states balancing current is 0.083 A.

 

[Dzl]

If you're considering Heltic, then I'd say do more research.


This link states balancing current is 0.083 A.

While I agree more research is a good idea-- particularly for a BMS that is rather new here, I think you also may need to do more research before forming or stating an opinion.

You linked to one of their passive balancing BMSes, not the active balancing BMS being discussed. They make (if they are in fact the true manufacturer) dozens of BMSes and balancers. Some dissipative (passive) some non-dissipative (active), some 'smart' some not, some cheap some moderately expensive.

I'm not positive, but I believe this is the correct link to the Active Balancing BMS. Balance currents range from 0.6A to 2A, price ranges from $90-500 depending on model.

73.0US $ |Heltec 1A/2A Active Balance BMS Battery Protection Board 13S ~24S 100A 200A CAN RS485 APP Lifepo4 li ion LTO 48V 16S 20S 60V 72V|Battery Accessories| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Cal]

Sorry dude, opinions require no research.

 

[ArthurEld]

Sorry dude, opinions require no research.

You sound like our politicians.

 

[childcarepro]

I believe you have found the wrong product. Heltec makes active balancers, as well as an active balancing BMS (balancer vs BMS is another often misunderstood topic). The balancer is just a single purpose tool, not a replacement for a BMS. The BMS is more expensive than the balancer and obviously more fully featured. Search for the BMS @upnorthandpersonal is using, IIRC, it is in the ballpark of ~$200.

edit: I believe this is the correct link and this is a relevant thread (if you get past the first page or two where the conversation is a bit muddled).

Rookie mistake. Looks like I got a little too excited at finding an active balancing [not] BMS for so cheap and from a US seller. Let me look at the active balancing BMS instead of the active balancer. Thanks! Looks like the link you gave is for an 8S-24S passive balancing BMS w/ 200 mA balance current. This one appears to be an active balancing BMS that supports 1.5A balance current: https://www.aliexpress.com/item/1005001412712740.html?spm=2114.12010612.8148356.16.628c4df41Hrmw8

I'm still waiting to hear back from 123electric.de about pricing on their 123\SmartBMS gen3. They did confirm their BMS can activate the SmartBattery Protects and turn off the MultiPlus and SmartSolar, but no pricing was offered.

Back in the day, Bell motorcycle helmets had an ad:

If you got a $10 head, wear a $10 helmet.

I agree that you often get what you pay for, which is why I have a 90% Victron setup. But don't worry, I was not going with Heltec just to save money! I just want a simple, plug-and-play, capable solution. I was really excited about true active balancing, though it turns out I was barking up the wrong tree anyway.

 

[Dzl]

While I agree more research is a good idea-- particularly for a BMS that is rather new here, I think you also may need to do more research before forming or stating an opinion.

Sorry dude, opinions require no research.

My intention was not to offend, only clarify. Setting aside opinions on the validity of the statement above-- in this instance you are drawing inaccurate conclusions based on the wrong product (beyond that, its not even for the right battery chemistry), so in this instance I don't think its a stretch to conclude a bit more investigation wouldn't hurt, and I think we have an obligation to make an effort to give correct info or state our uncertainty. Happens to all of us from time to time, I feel like I misspeak or misread, or misunderstand something almost daily, its no biggie (I have interacted with you enough to know you share some great info), I only wish to clarify.

Rookie mistake. Looks like I got a little too excited at finding an active balancing [not] BMS for so cheap and from a US seller. Let me look at the active balancing BMS instead of the active balancer. Thanks! Looks like the link you gave is for an 8S-24S passive balancing BMS w/ 200 mA balance current. This one appears to be an active balancing BMS that supports 1.5A balance current: https://diysolarforum.com/threads/the-solar-bms-thread-sbms0-sbms40-sbms120-dssr20-and-so-on.4194/

I'm not sure this is the correct link. When I click it, it just takes me to the first post in this thread.

I'm still waiting to hear back from 123electric.de about pricing on their 123\SmartBMS gen3. They did confirm their BMS can activate the SmartBattery Protects and turn off the MultiPlus and SmartSolar, but no pricing was offered.

If you want ballpark pricing, here is an EU distributor with a-la-carte prices given in USD. They may ship to the US, not sure.

 

[childcarepro]

I'm not sure this is the correct link. When I click it, it just takes me to the first post in this thread.

If you want ballpark pricing, here is an EU distributor with a-la-carte prices given in USD. They may ship to the US, not sure.

Oops, I've edited my post with the correct link.

Thanks for the link; the prices seem reasonable.

Wondering if 123Smart may not be ideal. It seems like a monitoring and safety shut-off system with top balancing feature rather than continuous cell balancing? I watched their intro video and read their manual. I've reached out to them for confirmation.

In 123electric's intro video their app shows voltages for 16 cells, between 3.225V and 3.335V, a 0.10V delta, and they say they're "within safe limit." This delta seems a lot higher than inter-cell differentials with other BMS’s which shoot for 10-20 mV. The manual states: “V balance: This is the balancing voltage where you want all the cells to end up. Above this voltage the cell modules start to dissipate 1 ampere to balance the cells.”

The video also mentions your relays either shut off charging or discharging when any cell falls outside the voltage range. So it appears balancing only happens at the top, at low voltage if any cell falls below Vmin, it shuts off the loads rather than attempting to bypass the low cell.

Am I making a mountain out of a molehill?

Pros:
- 1 amp balancing current
- clean look w/o spaghetti wires everywhere
- integration with Victron ecosystem
- reasonably priced for an elegant system

Cons:
- no continuous intercell balancing, only top balancing
- appears to require soldering
- possible to damage the modules when working with the bank/cells?

 

[childcarepro]

I was looking at the specs of the Heltec active balancer w/ BMS for <16S (I'm shopping for one 4S and one 8S). I was going to oversize it, so the 360A for my 8S even though I never anticipate more than 125A so I get beefier components.

Am I reading this correctly? The photo is labeled, "50 mA passive balance, single string voltage reaches 3.65V to turn on" AND "1.5A active balance, single string pressure difference 0.1V open equalization." Does this mean it top balances at 3.65V using 50 mA resistance on the fully charged cells, vs up to 1.5A to actively balance between cells when >0.1V differential?

 

[childcarepro]

Or... what if I used the 123SmartBMS as my monitoring/top balancing/Victron connected system (1A is better than 50 mA for top balance) AND used the Heltec 5A active balancer (not BMS) to keep the cells in balance during charge/discharge? It seems to me they wouldn't interfere with each other, since the 123Smart only turns on its 1A resistor at the high voltage limit, while the active balancer only kicks on when cell voltage differential goes over 0.1V.

The other question is whether the active balancer would interfere with charge/discharge from the battery.