MajicDiver
Solar Enthusiast
Would someone be willing to explain why you can’t put 2 EG4 48VDC batteries in series and what would/might happen if you did?
What I am considering is connecting them to the PV input of an inverter with a turn on voltage of 50VDC and rated to 600VDC. Looking for a way to use low voltage battery on an inverter that only has high voltage battery input, to reduce costs- HV batteries are expensiveWould someone be willing to explain why you can’t put 2 EG4 48VDC batteries in series and what would/might happen if you did?
I dont understand what that would achieve? The PV inputs are just that, an input. How would you charge this 100v battery?What I am considering is connecting them to the PV input of an inverter with a turn on voltage of 50VDC and rated to 600VDC. Looking for a way to use low voltage battery on an inverter that only has high voltage battery input, to reduce costs- HV batteries are expensive
I thought fuses were over current devices? I guess that is why you described it as “best case“? LOLBest case scenario is that a fuse would blow
A separate AC charger, charge manually during daytime then cut it into the inverter with a breaker when desired.I dont understand what that would achieve? The PV inputs are just that, an input. How would you charge this 100v battery?
CorrectI thought fuses were over current devices? I guess that is why you described it as “best case“? LOL
It would depend on what the voltage rating was for the BMS of the EG4 batteries. Doubtful that they could handle it.What I am considering is connecting them to the PV input of an inverter with a turn on voltage of 50VDC and rated to 600VDC. Looking for a way to use low voltage battery on an inverter that only has high voltage battery input, to reduce costs- HV batteries are expensive
I’m just trying to see if there is a issue that prevents doing it. To address max short circuit current rating of inverter input use a breaker that trips before that current level between the battery and inverter PV input.With respect to MajicDiver comment, I'm wondering what would happen. Example take a 39vdc (2ft by 4ft) solar panel and short circuit the leads and you get a ISC of 9 amps. (at least on my panels). So, in theory only 9 amps is available at the PV input terminals.
Now take any battery, 6v, 12v, 24v, 48v, any size, and short their terminals. you will get a massive surge of current and a spark you can't believe. So, then in theory, if you connect any of these batteries to the pv terminal of your controller, I would think that you would destroy the inverter. Again this is just in theory on my part as I have never tried it and can't afford to buy a new controller/inverter.
But then on the other hand, when you connect your solar panel to the input of your controller, only the current that would flow is dependent on the load the controller is controlling regardless of how much current is available from the panels.
So maybe, MajicDiver comment isn't so bad after all.
Yes, you are the professional one to reply the questions. Also have the 48V100AH battery in series type, but not this kind of structure.The BMS may not be able to shut off or interrupt current flow if series string voltage exceeds maximum MOSFET switch voltage of BMS. If BMS uses 100V rated MOSFETs then with 3 of 48V batteries in series they will enter avalanche mode and continue passing current even if BMS tries to shut them off. Then you end up without short circuit, under voltage and over voltage protection. Also if the battery or BMS data connection is negative terminal bonded to the metal case then you end up with a short circuit if you mount 2 rack batteries together or if you daisy chain the data lines. Don't do it unless the battery is designed to be connected in series.
Thanks, and the EG4 manuals clearly indicate you can only series the smaller voltage models up to 48 vdc and not the 48 volt model. Does anyone know of a brand that can go to 72 or perhaps 96 volts?The BMS may not be able to shut off or interrupt current flow if series string voltage exceeds maximum MOSFET switch voltage of BMS. If BMS uses 100V rated MOSFETs then with 3 of 48V batteries in series they will enter avalanche mode and continue passing current even if BMS tries to shut them off. Then you end up without short circuit, under voltage and over voltage protection. Also if the battery or BMS data connection is negative terminal bonded to the metal case then you end up with a short circuit if you mount 2 rack batteries together or if you daisy chain the data lines. Don't do it unless the battery is designed to be connected in series.
That’s what I might end up doing- but I am a mechanic by nature not an electrician and would prefer to achieve it with “off the shelf” components as opposed to actually building a complete battery.It would depend on what the voltage rating was for the BMS of the EG4 batteries. Doubtful that they could handle it.
You could build your own high voltage battery. With a high voltage BMS.
Good luckThat’s what I might end up doing- but I am a mechanic by nature not an electrician and would prefer to achieve it with “off the shelf” components as opposed to actually building a complete battery.
Why you need the high voltage system? The high voltage battery must match with high voltage inverter, you can check the Sofar, Growatt, Luxpower and some other inverter brand which have the small power but high voltage version for home energy storage system. At this situation, the battery pack also should be high voltage system, there isn't the BMS supplier willing to provide this to the individul clients.Thanks, and the EG4 manuals clearly indicate you can only series the smaller voltage models up to 48 vdc and not the 48 volt model. Does anyone know of a brand that can go to 72 or perhaps 96 volts?