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Choice of BMS
#11
(05-20-2019, 03:19 PM)Redpacket Wrote: 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 three replacement 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.
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#12
(05-21-2019, 09:03 AM)paulydee Wrote: Reckon I need to invest in a proper BMS as while I was charging using the SI 6.0H today one of the three replacement 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.
Proceed with caution. Knowledge is Power! Literally! Cool 
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#13
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.
Korishan likes this post
Running off solar, DIY & electronics fan :-)
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#14
(05-21-2019, 12:46 PM)Redpacket Wrote: 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
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#15
(05-21-2019, 08:37 PM)Korishan Wrote:
(05-21-2019, 12:46 PM)Redpacket Wrote: 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.
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset. MY'13 Vauxhall Ampera
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#16
(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

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!
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#17
(05-23-2019, 12:19 PM)HughF Wrote: 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 are trying 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.
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#18
(05-26-2019, 07:13 AM)Sean Wrote:
(05-23-2019, 12:19 PM)HughF Wrote: 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 are trying 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.
Sean likes this post
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset. MY'13 Vauxhall Ampera
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#19
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 !!
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#20
You don't need the expansion if you just want to drive just the AC 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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