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What's The Best BMS? (Grrrr... ?)

HRTKD said:
I went to that website. I don't how how far out of date it is, but it is out of date. The first link I clicked on no longer exists. :( But, that's not quite the point of showing that website. It is a slick way to narrow down the list of BMS' that fit your need.
Click to expand...
Agreed. I really liked how the distinctions between them were based on aggregate function.
 
I'm a software developer by trade, dealing mostly with databases. The core of what we need is a "database", which can take many forms. When I deal with users, I often start with the end product and work my way backwards. That way I don't gather a bunch of data that doesn't solve what I'm trying to provide to the end user. I'm greatly simplifying the process, I don't want to get into sprints, scrums and agile.

I think we should first define the data points that are critical to the deciding which BMS is right for a user. List these items and let's agree on those first. Then put those items in a spreadsheet as columns and we can add rows to the spreadsheet for each brand/model of BMS. The set of data points isn't set in stone. As we come upon a BMS that has some gee-whiz feature, add a new column to the spreadsheet. Not every BMS will fill in all the columns. Once we have that data gathered we can decide if it's necessary to present the data in a different way. Most people can use a spreadsheet. Let's not make it any more complicated than necessary.
 
HRTKD said:
I think we should first define the data points that are critical to the deciding which BMS is right for a user. List these items and let's agree on those first. ...The set of data points isn't set in stone. As we come upon a BMS that has some gee-whiz feature, add a new column to the spreadsheet. Once we have that data gathered we can decide if it's necessary to present the data in a different way. Most people can use a spreadsheet. Let's not make it any more complicated than necessary.
Click to expand...

I agree with this approach, and think its worth pursuing. I would say start small with a select set of features and a select set of BMS'. Too much information can obscure whats important.

Though I will say, as I already mentioned, I don't think this format or focus is aimed at the beginners which were the initial focus of @tictag post. A spreadsheet is a good way to compare features for someone who already understands what matters, what the features mean, and knows what they are looking for. But most beginners come here barely understanding (or not understanding) what a BMS is, if they need one, what it does, what features are important, and how it differs from other products.

I think a spreadsheet of the most common BMS' and most relevant features is a highly useful project, worth pursuing, and I'm happy to contribute. But I think it may not be the concise and beginner friendly resource that would be most beneficial to newbies.

As to the specifics of the spreadsheet I'd say begin with:
  1. Daly
  2. JBD (the BMS sold by DYKB, Overkill Solar, Battery Hookup, and others)
  3. Ant
  4. Chargery
  5. SBMS0
Just based on forum posts/interest, I would guestimate that these 5 BMS' probably account for 80% or 90% of what forum members are using (unless I'm overlooking another popular FET based BMS), with the top 3 or 4 accounting for the lions share of that percentage.
Daly Smart BMS should be added but as far as I know, nobody has experience with this yet, so we should probably hold off on that for now. I'm guessing there will be a Will Prowse video on the Daly Smart coming soon.

And regarding what features are important here are some features that come to mind:
  1. Type (Inline FET based, relay based, remote control of other components, etc)
  2. Supported voltages
  3. Maximum current (nominal)
  4. Cost
  5. User friendliness / beginner friendliness (scale of 1 to 5 maybe?)
  6. High voltage protection
  7. Low voltage protection
  8. Cell Balancing
  9. Over current Protection
  10. Low Temperature Protection
  11. SOC monitoring
  12. User configurable settings
  13. BT / Wifi / connectivity options
  14. Self consumption (not sure how to define this)
  15. Level of support and/or documentation
  16. Link to the product page
  17. Link to the product manual
 
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Dzl said:
I have been perturbed by the same issue for a while now, and agree with pretty much everything you have articulated here, and have been pondering what would improve the situation. I had been considering putting together some sort of index of the 5 or so most common BMS with a quick reference of features, current limits, etc, but never got past the half-baked idea phase (and I'm in the same boat as you, spend some time researching BMS' but no real experience).

Really there are two issues that need addressing.
  1. People need help understanding what a BMS is and does
  2. People need help choosing the best BMS for them
  3. Actually, a third thing a lot of people are just seeking is confidence/reassurance/confirmation about a BMS they think might work for them
People really need help with the first question, but usually ask the second question. It seems almost everyday there is a new thread "what is the best BMS?" or "I bought 280Ah cells what BMS do I need?"

Its hard to answer the second question in a concise way regardless of the asker's knowledge, but its especially hard if they don't have a handle on what a BMS is conceptually. And I don't fault newbies for not understanding its a rather esoteric subject, with very few beginner friendly learning resources. Even most of us who have devoted some time to learning have pretty shaky understandings in my opinion.

I think two things would be very useful
  1. A thread, wiki entry, or @Will Prowse video (or all of the above) that is an introduction to BMS', what they are, what features matter, how to size them.
  2. A thread, wiki entry or @Will Prowse video comparing some of the most common BMS key features.
Honestly, I think this is perfect material for Will, there are a lot of people thirsty for this info, and he is quite good at explaining things in simple terms.
Click to expand...


Ive been googling this for weeks now. And still no real understanding of what i need. Unless just spend $1300 on a bms.
48 cells, 3 strings 48 volt system, 280 AH cells.
 
I took Dzl's list and pasted it into a public editable google sheet. It has no special formatting - just trying to keep it very basic and friendly. Maybe can be a starting point.

Public - Google Drive

drive.google.com drive.google.com

I will back this up locally occasionally in case of "accidents".
 
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JoeHam said:
I agree with everything said and would approach it from the other end, as in what features do you need. Obviously every use case is different and I use my BMS only to monitor and passively balance my cells. I also only balance during charging.

Here are some features/specs to determine before you go shopping what to look for:

What voltage?



(Im on 48, 3 strings of 16, 280 AH)




What amperage? In my case zero amps since I don’t run my system through the BMS. Others may want high amp FETs or to run external relays.


(No clue why i would or would not run it through a bms? If i dont got to why would I?)






Is low temp disconnect needed? For many this is a complete non issue if their cells live inside the home. For others it’s a deal breaker to save cells from certain destruction out in the wild.




(Id like to have a low or high temp disconnect. Guess im going to build an insulated box with heat mat and thermostat, fan for summer)




What level of cell monitoring? Voltage only, internal resistance etc.



(What do I need? All i want is it to work without any trouble, dont want to babysit it)





What level of charge control? I leave that up to my SCC but others want it in the BMS.




(Dont understand this)




What amount of whiz bang wow features? Bluetooth, data logging etc to name a couple. Again, some couldn’t care less and for some it’s a deal breaker.



(Care less about any of that, no internet here anyways)




So I guess what I’m suggesting is a detailed feature list so people can decide what they want/need and then narrow their search greatly.



(Yes id like a narrow search with a dependable bms)




I spent a ton of time figuring out my need/want list. Getting the correct BMS was simple after that ground work was done.



(What do I need, need 1 bms or 3?)




I also propose spending an unlimited amount of Wills time to produce a video on this subject ? as no one does it better.



(Ya no videos on the matter.)
Click to expand...


My questions and answers in parenthesis up above
 
Bleedingblue said:
My questions and answers in parenthesis up above
Click to expand...

I think this thread is not the best place for these questions, but if you have a thread on the topic already, or start one, I (and hopefully others) can help you think through some of these questions.
 
HRTKD said:
JoeHam covered it but danphillips didn't: high/low temperature

Number of cells monitored: 4s, 8s, 16s, etc.

I don't know if it matters, or if it's possible, but if you use an 8s BMS on a setup with only four cells, will the BMS still work?
Click to expand...


Why do so many offer a 14s or 15s but not a 16s
 
Whoever posted the DYKBHUANG Store entry in the spreadsheet, I think its probable that is a duplicate of the 'ANT BMS' entry.

This is the image of the Ant BMS from the link provided in WIll's video

Screenshot_20200619_192619.png


Here is the image of the BMS added to the spreadsheet as DYKBHUANG Store BMS

Screenshot_20200619_192507.png

As an aside, I dont know where the name Ant BMS came from, I've never seen any ad or description call it that.
 
Dzl said:
I think this thread is not the best place for these questions, but if you have a thread on the topic already, or start one, I (and hopefully others) can help you think through some of these questions.
Click to expand...


I thought that is what the whole point of the thread is about. BMS for beginners and that is a beginners questions.

Like for example I just got this email response from a BMS manufacturer/sellier etc.


"Hi,

I do not have any 48V 16s BMS mine is limited to 8s 24V
Also no matter what BMS you decide to get the only correct configuration is to have groups of 3 cells in parallel (any number of parallel cells are not different in any way from a single higher capacity cell) then 16 of those connected in series for 48V.
You are not allowed to directly parallel lithium batteries, just lithium cells (I know there is a lot of bad information available and you probably have seen DIY installations with parallel batteries it is just not allowed or a good idea)."




Now with this answer it doesnt make sense to me.
 
Ha, yes that was me because I just received it, after two months. It is on ebay too, as "unbranded"
www.ebay.com

Rechargeable Batteries for Sale - eBay

Cheap Rechargeable Batteries for sale - Free shipping on many items - Browse rechargeable AA batteries, AAA rechargeable batteries, Eneloop batteries, AA battery chargers & 9v rechargeable batteries on eBay
www.ebay.com

I'll make a note.
Edit: Yes, the APK file has "ant bms" in the name.
 
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Fred S said:
Ha, yes that was me because I just received it after two months. It is on ebay too, as "unbranded"
www.ebay.com

Rechargeable Batteries for Sale - eBay

Cheap Rechargeable Batteries for sale - Free shipping on many items - Browse rechargeable AA batteries, AAA rechargeable batteries, Eneloop batteries, AA battery chargers & 9v rechargeable batteries on eBay
www.ebay.com

I'll make a note.
Click to expand...

Part of what makes this topic difficult. So many sellers selling the same, or very similar generic looking products without a clear manufacturer or brand.

What I call the JBD Bms (this one) (based on the serial number JBD-SP04S020) has been referred to by 3 different names (not including JBD) and sold by 3 different sellers in the 5 or 6 months its been known to us.
 
Fred S said:
Edit: Yes, the APK file has "ant bms" in the name.
Click to expand...

In that case, I think you should consolidate it with the entry for Ant BMS, and use that name since DYKBHUANG is the name of a store that sells multiple BMS' including others on our list.
 
Sounds good. Couldn't find the actual manufacturer in a brief search.
These are good examples for which a consolidated sheet of info like this may help folks out.
 
Dzl said:
Though I will say, as I already mentioned, I don't think this format or focus is aimed at the beginners which were the initial focus of @tictag post. A spreadsheet is a good way to compare features for someone who already understands what matters, what the features mean, and knows what they are looking for.
Click to expand...
I agree, though there is nothing stopping us having both ... a newbie-friendly article, with some kind of 'For advanced users only' database attached to it e.g. spreadsheet?
Bleedingblue said:
Why do so many offer a 14s or 15s but not a 16s
Click to expand...
When you 'think' of a 8S or a 16S battery, you're 'thinking' of LFP cells where 4S is 12.8V, 8S is 25.6V etc, that is, lead-acid drop-in replacements. Not all Lithium-ion cells are 3.2V (nominal). NMC, for example, is 3.7V (nominal) meaning that a lead-acid drop-in replacement would be 3S for a 12V (11.1V) battery, 7S for a 24V (25.9V) battery etc. These BMS's cater for all Lithium-ion battery technology.
Bleedingblue said:
I thought that is what the whole point of the thread is about. BMS for beginners and that is a beginners questions.
Click to expand...
No, this thread is very specifically NOT about a general BMS discussion, it is actually about avoiding multiple threads about general BMS discussion, by consolidating BMS information into one place - that place likely to be a wiki article. But, similar to most other threads that mention BMS's on this forum, it has unfortunately become that. Inevitable, I guess, but let's not lose sight of its principle purpose i.e. the OP's original query.
Dzl said:
and sold by 3 different sellers in the 5 or 6 months its been known to us.
Click to expand...
Just a quick point to all (not a response to @Dzl): do we agree that this wiki article, or however we end up with this consolidated article, should not consider where the described product can be purchased? I know that sounds like we would lose out on valuable information but such sales-oriented product links would very quickly become stale, leading to 404's or 'product no longer sold' etc .... increased confusion.
 
tictag said:
I agree, though there is nothing stopping us having both ... a newbie-friendly article, with some kind of 'For advanced users only' database attached to it e.g. spreadsheet?
Click to expand...

My thoughts exactly. Both have value.

Just a quick point to all (not a response to @Dzl): do we agree that this wiki article, or however we end up with this consolidated article, should not consider where the described product can be purchased? I know that sounds like we would lose out on valuable information but such sales-oriented product links would very quickly become stale, leading to 404's or 'product no longer sold' etc .... increased confusion.
Click to expand...

We are in agreement that the wiki should not focus on where things can be purchased. And BMS' should not be identified or named by where they are sold. However in practice, since a lot of the common FET based BMS' are unlabeled, unbranded, generics, people have defaulted to referencing them based on who sells them. Its unideal, but hard to avoid. Taking the JBD-SP04S020 for instance, to my knowledge I'm the only person on this site who has ever referred to it as the JBD BMS or the JBD-SP04S020 (based on its serial number), its a shitty name but its the only universally identifying name or feature, everyone else refers to it by where they bought it (Overkill Solar, DYKB, or Battery Hookup), it wasn't until this week or last that I confirmed these names all referred to the same BMS.

If we don't reference those sellers or people won't have any idea what the JBD BMS (or whatever other name we use) is. But I suppose making mention of other names/sellers, is different than your concern about sales links. To further complicate things, the generics and semi-generics often seem to not have brand websites, product pages, or documentation outside of aliexpress or wherever they are sold. I do think its important in a market flooded with similar looking unbranded options and knockoffs, to give people some sort of reference point. Ideally this could just be the model and brand, or a link to the product website, in cases where there isn't one I don't know what the next best thing is, what do you think? I don't have a solution, just minor problems :oops: :)
 
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Dzl said:
Ideally this could just be the model and brand, or a link to the product website, in cases where there isn't one I don't know what the next best thing is, what do you think? I don't have a solution, just minor problems
Click to expand...
Totally agree, if a product manufacturer's product page is available, then this should be used, if not, then there is still value linking to a sales-oriented page (e.g. Amazon, Aliexpress etc) - we might just have to call out that this is a generic sales link (and therefore, might contain out-of-date specs etc).
 
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Use the manufacturers page, Amazon, Ebay, Aliexpress or what ever page/store they have, or were it can be purchased.

This alone will solve the clone, unbranded problem ANT bms/JBD/DYKB has !

I Would be perfectly happy with a simple BMS that does Balancing, LVD, HVD and is able to show me what its doing! Active balancing would be prefered...

In other words a 200amp Daly BMS with an LCD or Phone app.
 
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