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there is no way PowerJack has any way to correctly monitor the individual cells, and if a problem develops due to incorrect connection or just a plain old bad cell, then i need to be able to cut off the discharging or turn the inverter off...automatically..
That is a major problem with LiFePO4 cells . I monitor my ev car lithium ion with a voltmeter connected to every battery and I have 13 string of battery . You can not monitor your battery like this because you have too many battery and if voltage of LiFePO4 cells go below 2.5 volts that will destroy your LiFePO4 cells I know because I have many worthless LiFePO4 cells when this happen 3 years ago . Sid use an active balancer that will fix the undervoltage problem of using LiFePO4 cells and should ask him how it works as it monitor every cells .
I did have one 16 cell LiFEPO4 battery (2P8S 24-volt 272AH LiFePO4 Lishen cells build so effectively a 544Ah battery) discharge low enough that the inverter low voltage audible warning was making noise and the red warning light was on....so i shut it down the inverter until i could charge the battery up some...
PowerJack inverters will not protect your battery sufficiently from over-discharge as far as I can tell....🤔
the SBMS0 does monitor every individual cell in the 8S LiFePO4 battery builds and can shut off the inverter discharge when any cell gets too low but I need to be able to control the inverter on/off switch via the SBMS0 and i have not cured that issue yet.....
the Electrodacus SBMS0 balances the cells as it charges... it is a passive cell balancer....
not super with electronic diagnosis circuit type things....definitely a weak space in my knowledge...🤣🤣
thinking of getting some more pieces and parts to test out on breadboard type circuits...
the LiFePO4 batteries are too expensive to make big dumb mistakes...🤔🤔🤔
i keep studying but so many details to understand...
120/240 house wiring is easy for me....
not so easy the BMS etc. with lifepo4,,, lead acid was easy but short life span and heavy....but high maintenance also...
I like the LiFePO4 over lead acid though.....
i bought heavy bus bars to make a bigger battery....still in acquisition stage a bit....😎
thanks for all the replies and guidance😎
You can program one of the GPIO lines on the SBMS to turn your inverter on and off. You can buy a cheapie 'arduino relay module' from all the usual cheap places. Exactly what is on the board varies. Some have an opto-coupler driving a transistor which in turn controls a relay and with correct jumper setting can provide DC isolation from the SBMS and relay board power if need be. So far I've not seen one of these modules without a protection diode, but I'm sure they are out there. The switched contacts on the relay module can be used to turn the PJ on / off by wiring relay contacts inline with or across the PJ power switch. I'm sure @dickson could offer you guidance on wiring it in.
the SBMS0 does monitor every individual cell in the 8S LiFePO4 battery builds and can shut off the inverter discharge when any cell gets too low but I need to be able to control the inverter on/off switch via the SBMS0 and i have not cured that issue
Now I know that you want the SBMS0 to automatically shut down the inverter . I just monitor the voltage of my battery and disconnect the one low voltage battery string from the busbar and recharge one string at a time which is a lot of work . I thought about auto shut down also when one string of battery get low but have not try because Powerjack is too sensitive to blowing the FETs .
So far I've not seen one of these modules without a protection diode, but I'm sure they are out there. A diode is use with relay to protect the FETs from back emf when the relay shut down the inverter if running a large inductive load . I am afraid of the back emf so have not try .
Plenty there to buy, most show a diode on the PCB. Of course that's no guarantee the received product is the same but if it doesn't raise a claim on the selected 'cheap place to buy cheap crap web site' and try again.
So far I've not seen one of these modules without a protection diode, but I'm sure they are out there. A diode is use with relay to protect the FETs from back emf when the relay shut down the inverter if running a large inductive load . I am afraid of the back emf so have not try .
The reason for a diode across the relay is to prevent destruction of the transistor/FET by overvoltage.
<img alt="Using an NPN Transistor as a Relay - YouTube" data-ratio="75.00" style="width:349.333px;height:262px;" width="480" data-src=" 
&f=1&nofb=1" src="/applications/core/interface/js/spacer.png">In short, when the transistor is ON, it pulls the relay DOWN to ground. When the transistor turns OFF, the relay will kick back UPWARDS. It will happily swing right past the +12v rail here--and easily exceed a 40v (or even 100v) FET / transistor, damaging it.
The blocking diode shorts out this "flyback", preventing it from exceeding the +12v rail--and by deduction, preventing it from exceeding the voltage rating of the FET/transistor.
but have not try because Powerjack is too sensitive to blowing the FETs .
This is a result of poor FET drive and signal handling.
there are 3 wires connected to the switch with spade type connectors. on the other side of the switch there are 3 more places to connect spade type connectors. i would have to look again but i believe it is a red wire on top and 2 black wires on the spade connectors below it...
are all the PowerJack switches the same type toggle switch?? power sav on; off; power sav off orientation???
i only use the power sav off, and the off positions..... no use for the power sav on position as i always have some sort of load running....
power sav off is actually the inverter in on all the time.... the center position is off.... I don't use the power sav on position as it does not function for my purposes...
what is the voltage going through the switch wire? etc??
(((( I ordered the PowerJack 48-volt LiFePO4 battery in a SS box that is advertised as a 5KW battery, it should be here in 60 to 120 days via the slow boat ride....i estimate it will have 16 100Ah LiFePO4 cells in series to get the 5k rating....with a built in BMS))))
but i am still working thru the automated inverter shut down circuit wiring issue... for the 32 cell or 16 cell larger battery builds i am currently running....
as i say PowerJack can not or does not adequately monitor the battery individual cells to shut the inverters down in sufficient time,,,, so working to understand how to wire the switch into an automated shut down that the BMS controls...
it could be a moot point if the cells all stayed in perfect discharge unison,,,,but that is a perfect set of cells....not likely...
96 large 272ah and 280Ah
liFePO4 cells are a bit more than 8000 dollars investment so hoping to monitor them to get the 10 -13 year lifespan.... the inverter must be shut off when battery cell gets too low....
thanks for all your replies.... i am still trying to get it figured out....some electrical concepts are a bit difficult to pound thru this thick skull, so i study more before doing really dumb dumb things hopefully...🤣🤣
thanks and have a great day! 😎 i have to go feed the bottle lambs.
what is the voltage going through the switch wire? etc??
The switch simply cuts battery power to the main power supply IC.
It happens to be battery positive through a diode. Current is not very high. But it is battery voltage (i.e. 55v), which complicates switching requirements.
There's voltage dividers off either side of the switch that provides the "power switch state" to the CPU (to set the mode).
if i manually turn the PowerJack to off, then it still has a standby current draw from the battery....of about 50-60 watts i think more or less...
that is small enough that even during cloudy days the solar panels can charge the LiFePO4 batteries enough.
so i still need to automatically flip that switch off automatically to ensure the batteries do not get into the too deep discharge state of charge...
the SOC (State of charge) that PowerJack shows or utilizes is not adequate for a LifePO4 battery as the usable battery is a very flat curve and when it gets to the point of too much discharge , then it is a very rapid drop off.... i am sure a lot of people have read of this... so 20 to 90 percent SOC is a comfortable spot but the SOC must be monitored and controlled at the cell level...that is the purpose of the BMS is to not let the cells get overcharged.... the SBMS0 does this very well...but i still need to stop the discharge from the PowerJack as needed. so must still get the SBMS0 to be able to shut off the power switch...
PowerJack goes by the SOC of the battery as a whole and may or may not be sufficient way to safe-guard the expensive LIFePO4 battery bank....my understanding with using the LIFePO4 battery banks is that PowerJack's control it is not!!!(adequate)
but i could be wrong....
thanks for the help...
the SBMS0 monitors each cell or each set of 4 cells that i have connected in parallel...(4P8S)....i also have 2 in a 2P8S configuration...
the sbms0 has the ability to cut discharge with some types of inverters but powerjack does not fit the easy way...???
the small wires going through the power switch can not be carrying very much amperage or a very high voltage as they are too small...but what is the amount???
<img alt="20220323_035541_HDR.jpg" data-ratio="46.00" width="1000" data-src=" 
" src="/applications/core/interface/js/spacer.png" />
50-watts when off? That can't be right. That's closer to the actual idle current.
Off should be close to 0. I know my 12K U-Power uses <3W (<0.1A margin of error) when switched off.
Why do you want to integrate the BMS directly with the inverter? Why not just have it cut power to the inverter all together?
When my batteries reach 1%, the BMS has a transistor that disconnects the terminals - you don't have to do anything special - it cares for itself.
PowerJack goes by the SOC of the battery as a whole and may or may not be sufficient way to safe-guard the expensive LIFePO4 battery bank....my understanding with using the LIFePO4 battery banks is that PowerJack's control it is not!!!(adequate)
but i could be wrong....
You are NOT wrong . I lost over one thousand dollars of LIFePO4 battery bank and have not use LIFePO4 battery bank
since it is very difficult to know the SOC and every cell has a different voltage under inductive load . It could NOT run my washer 3 years ago as the voltage drop too fast when not 90 percent SOC . I think active balance will work for LIFePO4 battery bank but never try .
that is the switch on the PowerJack 48-volt 16000 watt psw sp lf amg version above...red wire on top two black wires below, then there are 3 un-used spade type connector posts or the right side in that photo...
i can't measure any voltage or amps right now as it is not hooked up to any battery. but still trying to be able to automatically shut it down in case of over- discharge of the expensive LiFePO4 battery...
thanks all, windy but sunny out today....😎😎
4 minutes ago, NotMario said:50-watts when off? That can't be right. That's closer to the actual idle current.
Off should be close to 0. I know my 12K U-Power uses <3W (<0.1A margin of error) when switched off.Why do you want to integrate the BMS directly with the inverter? Why not just have it cut power to the inverter all together?
When my batteries reach 1%, the BMS has a transistor that disconnects the terminals - you don't have to do anything special - it cares for itself.
i could be wrong on the Powerjack stand by watt draw... the SBMSO must shut it down a slightly different way than BMS which have the high current going thru the BMS... the SBMS0 has no large current going thru it... all is controlled by 23 to 26 AWG sense wires...i use cat 6 solid wire 23Awg i think...
i usually never turn them off. they always have a load of some sort on them....i would have to do some other measurements to get a better number...maybe it is 50-60 watts when it is turned on with nothing pulling a load what-so-ever...???
maybe i have the wording wrong????
thanks for your reply...🤔🤔😎