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Choice of BMS
#1
Hi Guys

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

The system was five years old when I bought it so I've had to replace three dud batteries with new Sinopoly 200ah ones
12 of the remaining batteries have the same voltage 3.29 and the last one is have 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 DIY BMS ?

Thanks in advance.
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#2
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:


The cellmons were too long & would have touched the other sides terminal 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
Running off solar, DIY & electronics fan :-)
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#3
(05-19-2019, 05:52 AM)Redpacket Wrote: 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:


The cellmons were too long & would have touched the other sides terminal 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?

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#4
Always nice to get free gear! Big Grin




hahahah Make sure you ask it nicely if you want to get permission to open it Tongue
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
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#5
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? :-)
Running off solar, DIY & electronics fan :-)
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#6
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 the battery. 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
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#7
(05-19-2019, 12:06 PM)Korishan Wrote: Always nice to get free gear! Big Grin




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

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:


Power and voltage monitoring wires out of charger:


Here are the other ends:


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


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


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



The wires from the charger go in this side:


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


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.
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#8
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-6-5-100V-...2500921464

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.
Running off solar, DIY & electronics fan :-)
Reply
#9
(05-19-2019, 02:48 PM)Redpacket Wrote: 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 the Sunny 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:

 

The system previously had these EV cell monitors attached 


but i'm not sure if there was a proper BMS or if they just relied on this charger and SI 6.0H to control everything:
 

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 ??

(05-19-2019, 05:48 PM)jonyjoe505 Wrote: 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 the battery. 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
Thanks JoneyJoe

I'll have a look at the Chargery bms16.
Could you recommend a contactor to handle my 200ah lifepo4 system please?

(05-19-2019, 11:56 PM)Redpacket Wrote: 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-6-5-100V-...2500921464

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?

The DC breaker in between the battery and SI 6.0 is rated at 160A, are you thinking this should be replaced with a 10A breaker or just add a 10A between it and the control electronics ? By control 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 : )
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#10
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".
Running off solar, DIY & electronics fan :-)
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