Choice of BMS

paulydee

New member
Joined
May 18, 2019
Messages
16
Hi Guys

Just seeking some advice for asecond hand home off grid systemi've recently acquired.
I'm running a SMA Sunny Island 6.0H with 16 x 3.2VSinopoly 200ah Lithium Ion batteries and looking for a compatible BMS.

The system was five years old when I bought it soI've had toreplace three dud batteries with newSinopoly 200ah ones
12 of the remainingbatteries have the same voltage 3.29 and the last one ishave 3.26V.

I've had a look a the Batrium and REC BMS systems which both seem to be compatible however due to my location (Australia) they cost around $1000 including software which is out of my budget, also not sure how I connect the cellMons to my battery terminals as they appear to be too small?

I also had a brief look at the Tiny BMS but cannot determine if it's compatible with my system.

I'm not good with electronics or code so could anyone offer advice on a more reasonably priced off the shelf or tried and tested DIYBMS ?

Thanks in advance.
 
Batrium system would be the best answer (they are Australian made, based in Newcastle).
Can you post pics of your batteries?

I have some similar prismatic cells & used right angle brackets (Bunnings) to attach the cellmons due to cell top construction & terminal spacing like this:

image_nhigzs.jpg


The cellmons were too long & would have touched the other sidesterminal link if I'd bolted them direct to the battery posts.
In hindsight I should probably have looped the cables differently but everything is working OK now & if it isn't broken....

There are other BMS systems but very few with the data monitoring like Batrium.

This one might be next best: https://secondlifestorage.com/t-Good-Chinese-BMS-review
 
Redpacket said:
Batrium system would be the best answer (they are Australian made, based in Newcastle).
Can you post pics of your batteries?

I have some similar prismatic cells & used right angle brackets (Bunnings) to attach the cellmons due to cell top construction & terminal spacing like this:

image_nhigzs.jpg


The cellmons were too long & would have touched the other sidesterminal link if I'd bolted them direct to the battery posts.
In hindsight I should probably have looped the cables differently but everything is working OK now & if it isn't broken....

There are other BMS systems but very few with the data monitoring like Batrium.

This one might be next best: https://secondlifestorage.com/t-Good-Chinese-BMS-review

Thanks for the reply Redpacket,

I've uploaded some pics of the battery setup before I bought it so now the EV cell monitors/balancers which may have lead to the destruction of the three batteries I had to replace have been removed !

Are you using blockmons for the cell monitors?
I like the Bunnings right angle solution makes sense to me !
I've also inherited this lithium battery charger but when I connect itthe led indicator flashes to signal it can't see the batteries. Not sure if i really need it as the Sunny Island should handle the charging side of things from what I can guess. Any ideas?


image_drocfk.jpg

image_twufkt.jpg

image_rujkgu.jpg

image_ikvjre.jpg

image_uhncie.jpg
 
Always nice to get free gear! :D



image_ikvjre.jpg


hahahah Make sure you ask it nicely if you want to get permission to open it :p
 
Yes, I'm using M8 blockmons for the cell monitors. they look like they'd suit your cells better than mine, yours are quite a bit larger.
I reckon they'd bolt straight on without brackets.
Suggest getting some plastic on that metal sheet cover - you really, really don't don't want any short circuits!

Look after the cells & they should last a long time
Set the full voltage on the Sunny Island to 3.45V/cell not more. Do not use the manufacturers 3.65V you'll seriously shorten the cells cycle life.
Also don't let them go flat - keep them above about 2.90V/cell ("=flat").
Above or below these voltages, there's very little capacity in a LiFePo4 cell & you just stress the chemistry & get swelling/gassing, etc.
I'm thinking with three new cells in the pack, you'll need to watch for cell balance more due to capacity differences.

Yeah, message on that charger's good fun right? :)
 
you might want to checkout the chargery bms16 (cost a little over 100) , I just got the chargery bms8t (86 dollars) to run on my solar system. So far its been running excellent and with the lcd display you can see all your cells voltage.

Its fully programmable so you can adjust the cutoff voltages during charge/discharge. The chargery uses contacters (you have to supply your own) to cutoff power, that means you can handle as many amps as your contactor can handle. The contactor to cutoff power you want to install between the solar panel and your solar controller, that way when it triggers the controller will still be getting power from thebattery. It also has audible/flashing alarms if the limits are reached.

You still need a coulombmeter to determine battery condition, the chargery can monitor amps in/out with the shunt included but from my use so far,the SOC readings are its weak points. It also monitors battery temperature (Celsius or Fahrenheit)with 2 probes and balances at 1.2 amps per cell which might not be enough in a battery with balance problems. Its not wireless like some of the other smart bms, but you can set the lcd display up to 6 feet away from the battery with the cord provided. Its definitely a major upgrade from the 4 dollar bms I was using on my 220ah lifepo4.


screenshot of 16s lcd

image_waubqx.jpg
 
Korishan said:
Always nice to get free gear! :D



image_ikvjre.jpg


hahahah Make sure you ask it nicely if you want to get permission to open it :p

Ha ha, yes always be polite to avoid a nasty shock !

Not exactly sure how this was wired up to charge the batteries but have included some pics with my best guess.
Here's the overall set up:

image_qtbtmg.jpg


Power and voltage monitoring wires out of charger:

image_qoptad.jpg


Here are the other ends:

image_sjlqxy.jpg

image_afllfv.jpg


Power endplugs into +ve & -ve cables that are connected tothe DC breaker and flows through to the batteries:

image_ucwick.jpg


Voltage monitoring wires connect to+ve & -ve terminals on Sunny Island 6.0H (inverter/charger).

image_ccxima.jpg


The bit i'm not exactly sure about is what happens inthis white box (that I didn't ask permission before opening !!):

image_vokgjp.jpg


image_yniyde.jpg


The wires from the charger go in this side:

image_oiheeb.jpg


and come out this side and then into theSunny Island 6.0H(inverter/charger):

image_joxqdv.jpg


I'm pretty sure i've joined the+ve & -ve wires from the white box to the SI 6.0H correctly but the charger doesn't seem to acknowledge that batteries are there to be charged.

Any advice from anyone would be appreciated as this is all new to me.
 
So the white box is basically a crude voltmeter - the 3914 chip (top right) is a bar graph led driver.....
They have used antenna coax cable there which is an "interesting" choice! That's got to go!
I'd toss that white box & use something like one of these as a "master" meter (ie 100A version, simple backup for BMS monitoring):
https://www.ebay.com.au/itm/DC-6-5-...isplay-Volt-Amp-Power-Watt-Meter/182500921464

At least it looks like there's some fuses. There should be smaller rated breakers/fuses on the control electronics. I've got a 10A DC breaker between the battery & all the smaller electronics.
 
Redpacket said:
Yes, I'm using M8 blockmons for the cell monitors. they look like they'd suit your cells better than mine, yours are quite a bit larger.
I reckon they'd bolt straight on without brackets.
Suggest getting some plastic on that metal sheet cover - you really, really don't don't want any short circuits!

Look after the cells & they should last a long time
Set the full voltage on the Sunny Island to 3.45V/cell not more. Do not use the manufacturers 3.65V you'll seriously shorten the cells cycle life.
Also don't let them go flat - keep them above about 2.90V/cell ("=flat").
Above or below these voltages, there's very little capacity in a LiFePo4 cell & you just stress the chemistry & get swelling/gassing, etc.
I'm thinking with three new cells in the pack, you'll need to watch for cell balance more due to capacity differences.

Yeah, message on that charger's good fun right? :)
Thanks Redpacket
Yeah charger message was good fun and i'm definitely going to insulate the metal cover sheet !
I've checked theSunny Island and it's been set to 3.45V/cell but set up as a VRLA battery bank instead of Lithium Ion, not sure why or how this affects charge/discharge. I'm not going to use the system until i'm sure i won't cause any further damage as some of the batteries are showing signs of swelling and one of gassing:


image_xifyyf.jpg

image_mqwfqy.jpg


The system previously had these EV cell monitors attached

image_hvqyqk.jpg


but i'm not sure if there was a proper BMSor if theyjust relied onthis charger and SI 6.0Hto control everything:

image_oellqh.jpg


Anyway something didn't work properly so after 5 years use i've bought this system cheap and am trying to get it running properly again so any advice would be appreciated ; )
I don't have any electronic test gear except a multi-meter so not sure if the old EV cell monitors work or not so thinking I need to replace these ??


jonyjoe505 said:
you might want to checkout the chargery bms16 (cost a little over 100) , I just got the chargery bms8t (86 dollars) to run on my solar system. So far its been running excellent and with the lcd display you can see all your cells voltage.

Its fully programmable so you can adjust the cutoff voltages during charge/discharge. The chargery uses contacters (you have to supply your own) to cutoff power, that means you can handle as many amps as your contactor can handle. The contactor to cutoff power you want to install between the solar panel and your solar controller, that way when it triggers the controller will still be getting power from thebattery. It also has audible/flashing alarms if the limits are reached.

You still need a coulombmeter to determine battery condition, the chargery can monitor amps in/out with the shunt included but from my use so far,the SOC readings are its weak points. It also monitors battery temperature (Celsius or Fahrenheit)with 2 probes and balances at 1.2 amps per cell which might not be enough in a battery with balance problems. Its not wireless like some of the other smart bms, but you can set the lcd display up to 6 feet away from the battery with the cord provided. Its definitely a major upgrade from the 4 dollar bms I was using on my 220ah lifepo4.


screenshot of 16s lcd

image_waubqx.jpg
Thanks JoneyJoe

I'll have a look at the Chargery bms16.
Could you recommend a contactor to handle my200ah lifepo4 system please?


Redpacket said:
So the white box is basically a crude voltmeter - the 3914 chip (top right) is a bar graph led driver.....
They have used antenna coax cable there which is an "interesting" choice! That's got to go!
I'd toss that white box & use something like one of these as a "master" meter (ie 100A version, simple backup for BMS monitoring):
https://www.ebay.com.au/itm/DC-6-5-...isplay-Volt-Amp-Power-Watt-Meter/182500921464

At least it looks like there's some fuses. There should be smaller rated breakers/fuses on the control electronics. I've got a 10A DC breaker between the battery & all the smaller electronics.

Thanks Redpacket
If I toss the white box then do I need the"master" meter connected to the black box (charger)instead to get it to charge the batteries?

TheDC breaker in between the battery and SI 6.0 is rated at160A, are you thinking this should be replaced with a 10A breaker or just add a 10A between it and thecontrol electronics ? Bycontrol electronics do you mean the SI and black box charger and any BMS etc that I might add?
I noticed you are in NSW. I'm near Lismore NSW but off grid in the hills so trying to set up this system as a back up to my existing set-up : )
 
The white box probably needs to provide relay closure to the PSU to make it charge.

The previous cell monitors are only simple & only give a go/no-go indication as far as I remember with those.
I recall they make a continuous loop connection through all the modules if every thing is OK.
So the white box probably got the loop closed (OK) signal from the BMS modules & enabled the charger via the relay output.

You need much more the watch & balance the battery bank properly.

Re the breakers, the 160A "fuse disconnect" (blue & white thing) you have there should stay between the inverter & the battery.
The charger should have it's own fuse or breaker rated for the chargers max current.
You should have another separate breaker to the "control electronics" incl things like BMS, metering, step downs to 12V monitoring gear, etc.
I run my WiFi link of this feed & a few small DC lights over the gear only, no "house loads".
 
Redpacket said:
The white box probably needs to provide relay closure to the PSU to make it charge.

The previous cell monitors are only simple & only give a go/no-go indication as far as I remember with those.
I recall they make a continuous loop connection through all the modules if every thing is OK.
So the white box probably got the loop closed (OK) signal from the BMS modules & enabled the charger via the relay output.

You need much more the watch & balance the battery bank properly.

Re the breakers, the 160A "fuse disconnect" (blue & white thing) you have there should stay between the inverter & the battery.
The charger should have it's own fuse or breaker rated for the chargers max current.
You should have another separate breaker to the "control electronics" incl things like BMS, metering, step downs to 12V monitoring gear, etc.
I run my WiFi link of this feed & a few small DC lights over the gear only, no "house loads".
Thanks Redpacket

Reckon I need to invest in a proper BMS as while I was charging using the SI 6.0H today one of the threereplacement batteries that started as 3.37v (while the others were at 3.29v) reched 4.2v expanded, off gassed and sent up a small green flame !

I've disconnected everything and removed the damaged cell but lesson learnt that I can't rely on the Sunny Island to stop this sort of thing happening as the overall voltage was still below 57.7v which is what I think it should have stopped charging at.
 
paulydee said:
Reckon I need to invest in a proper BMS as while I was charging using the SI 6.0H today one of the threereplacement batteries that started as 3.37v (while the others were at 3.29v) reched 4.2v expanded, off gassed and sent up a small green flame !

I've disconnected everything and removed the damaged cell but lesson learnt that I can't rely on the Sunny Island to stop this sort of thing happening as the overall voltage was still below 57.7v which is what I think it should have stopped charging at.

Wow! Fortunately you were around to notice it and take immediate action. And yes, this is "exactly" why we say to use a bms and not rely on the charger to handle series based batteries.
 
You're going to have to watch that pack like a hawk for a while until you get it stabilized & the SoC's on the cells evened out.
57.7 for the pack is too high, that's 3.60v/cell. LiFePo4 will not last at those voltages, you will halve the life of the pack.
54.4 is the max for my pack = ~3.4V/cell.
Yes this is fully charged SoC wise but not hammering the chemistry.
Be sure to switch off any "absorbtion" or "equalise" in the sunny boy &/or any charger. Lithiums are wrecked by this.
 
Redpacket said:
You're going to have to watch that pack like a hawk for a while until you get it stabilized & the SoC's on the cells evened out.
57.7 for the pack is too high, that's 3.60v/cell. LiFePo4 will not last at those voltages, you will halve the life of the pack.
54.4 is the max for my pack = ~3.4V/cell.
Yes this is fully charged SoC wise but not hammering the chemistry.
Be sure to switch off any "absorbtion" or "equalise" in the sunny boy &/or any charger. Lithiums are wrecked by this.

Agreed. And if you can't turn "off" the absorption or equalize or float options, set them as close as possible to the max voltage. Some controllers/chargers won't allow max voltage and float to be the same, but could be off by about .5V or so
 
Korishan said:
Redpacket said:
You're going to have to watch that pack like a hawk for a while until you get it stabilized & the SoC's on the cells evened out.
57.7 for the pack is too high, that's 3.60v/cell. LiFePo4 will not last at those voltages, you will halve the life of the pack.
54.4 is the max for my pack = ~3.4V/cell.
Yes this is fully charged SoC wise but not hammering the chemistry.
Be sure to switch off any "absorbtion" or "equalise" in the sunny boy &/or any charger. Lithiums are wrecked by this.

Agreed. And if you can't turn "off" the absorption or equalize or float options, set them as close as possible to the max voltage. Some controllers/chargers won't allow max voltage and float to be the same, but could be off by about .5V or so
Be aware that if you are charging off solar, and you hit 100%SOC by midday for example, you need to set the solar charge controller float voltage to the resting voltage of the pack, so that the solar can carry your loads until the sun drops to the point it can't carry them anymore. If you simply turn off the input to the MPPT charge controller when you have reached 100%SOC, and you have loads running for the rest of the day, you'll pull your pack down unnecessarily.

Not usually an issue in winter in northern europe where I struggle to get above 80%SOC most winter days, but in Australia where you have lots of sunshine and requirement for AC, I would want my solar to power my AC for as long as possible once the batteries were full.

I'm also of the opinion that you do need to run an absorption phase, albeit a short one. It's during the CV/absorption phase that the balancing occurs and allows the weak cells to come up. You definitely want to disable any EQ cycle though.
 
jonyjoe505 said:
you might want to checkout the chargery bms16 (cost a little over 100) , I just got the chargery bms8t (86 dollars) to run on my solar system. So far its been running excellent and with the lcd display you can see all your cells voltage.

Its fully programmable so you can adjust the cutoff voltages during charge/discharge. The chargery uses contacters (you have to supply your own) to cutoff power, that means you can handle as many amps as your contactor can handle. The contactor to cutoff power you want to install between the solar panel and your solar controller, that way when it triggers the controller will still be getting power from thebattery. It also has audible/flashing alarms if the limits are reached.

You still need a coulombmeter to determine battery condition, the chargery can monitor amps in/out with the shunt included but from my use so far,the SOC readings are its weak points. It also monitors battery temperature (Celsius or Fahrenheit)with 2 probes and balances at 1.2 amps per cell which might not be enough in a battery with balance problems. Its not wireless like some of the other smart bms, but you can set the lcd display up to 6 feet away from the battery with the cord provided. Its definitely a major upgrade from the 4 dollar bms I was using on my 220ah lifepo4.


screenshot of 16s lcd

image_waubqx.jpg

So I was hoping someone here would have some experience with the Chargery brand BMSs. I was really thinking they might be a less expensive option from the Batrium units but much more dependable than the cheap Chinese eBay BMSs. But it seems like they're designed for a lot of EV applications, which I'm not intending to use them at all for.

Since you seem to have some idea as to how the custom programming works, do you think I could use it to monitor and protect (don't really expect it to be actually effective at balancing in my application) the standard 18650 "DIY powerwall" packs that are so prevalent on YouTube and here? I'm not doing a full blown powerwall at 48V or anything but really more of a low voltage, high capacity battery for a mobile workstation (so 4S100P). Mainly I was worried that the voltages programmed in the BMS8T or BMS16 might specifically be for only LiFePo or other types of batteries.

Thanks in advance for any insight or help buddy!
 
HughF said:
I'm also of the opinion that you do need to run an absorption phase, albeit a short one. It's during the CV/absorption phase that the balancing occurs and allows the weak cells to come up. You definitely want to disable any EQ cycle though.

I suspect you aretrying to apply battery charging techniques gleaned during your use of other chemistry cells to Li cells ?

Idealy charging needs to be held in CV mode until all cells have a decaying tail current - using the WM4 we can use the bypass final setting to signal a charge complete when all cells are being bypassed by x amps - if you've got a reasonably sized pack you won't get all cells into bypass within a short period of time unless they are extremely well capacity matched. So the CV phase often take many hours and shouldn't really be a timed phase.
 
Sean said:
HughF said:
I'm also of the opinion that you do need to run an absorption phase, albeit a short one. It's during the CV/absorption phase that the balancing occurs and allows the weak cells to come up. You definitely want to disable any EQ cycle though.

I suspect you aretrying to apply battery charging techniques gleaned during your use of other chemistry cells to Li cells ?

Idealy charging needs to be held in CV mode until all cells have a decaying tail current - using the WM4 we can use the bypass final setting to signal a charge complete when all cells are being bypassed by x amps - if you've got a reasonably sized pack you won't get all cells into bypass within a short period of time unless they are extremely well capacity matched. So the CV phase often take many hours and shouldn't really be a timed phase.

My point was to counter those posts in this thread that say you should disable absorbtion and disable float settings and just charge till you hit a voltage setpoint then disable the charger. That isn't going to work in an off grid setup, as I'm sure you know (you're a smart guy with plenty of experience). You need a float setting...

Totally understood about the long absorbtion if your cells are out of balance. I wrote my post whilst drawing experience from my system which doesn't have the wm4 controlling charge current, and I don't have cooled mons, hence the short absorbtion time applied to my system.
 
Thanks Everyone for your help and advice.
I've ordered a Batrium WatchMon4 starter kit however I am unsure if I need the expansion kit to be able to use a shunt trip and circuit breaker which I need to protect my system properly.
I've emailed Maxine a few times but no word as yet and i'd like to get everything up and running ASAP.
Could someone advise if it's possible to control a shunt trip and circuit breaker without the expansion board please?
Also are there any alternatives (more reasonably priced) to the Schneider products Batrium have listed (ABB or NHP TERASKI) for my 48v system?
I'm running 16 x SinoPoly 200AH Lithium Ion batteries so not sure if I need the 125A breaker or if I can go smaller. Any advice would be appreciated as I'm new to all this and don't want to make anymore costly mistakes !!
 
You don't need the expansion if you just want to drive just theAC and DC breakers.

The Schneider trip needs to be fed with 48v +/- not much, so you'll need to use a DC - DC to ensure you don't over drive its coil at high states of charge - or use the ABB alternative which has a much wider coil voltage range, and is a fraction of the price.

The DC breaker, and compatable shunt is likely to be a very expensive item if purchased new - the Schneider or ABB breakers are intended for AC load shedding.

Regarding your mention of a 125A breaker, which I will assume will be your battery disconnect breaker - the rating of that breaker will be entirely dependent on your system design, specifically wire size, inverter rating, anticipated max current loading etc
 
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