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MMP Solar PIP GK puts out 18A AC current to battery, JK BMS gets confused

Malmen

New Member
Joined
Oct 16, 2019
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22
Ok this is something really weird. I´m testing this new off grid system with grid assistanse. On battery and solar everyhing seems to work as expected but when PV is gone (dark) and battery is empty and the inverter switches to grid bypass (SBU mode) strange things happens. Inverter bypasses with the transfer switch and supply the load as expected but it makes a humming sound (maybe normal) but the JK BMS shows a discharge of 9 amps (24 volt system so about 200 watts) and at the same time the inverter shows about 9 amps charging amps the other way around. If you actually meassure the DC current flow with a clamp meter it shows a discharge of 2 amps DC but a AC amp reading of 18 amps AC!? Something is moving current back an forth very quickly. Too fast to see on one of my DMMs in AC mode but another DMM shows strange readings of 130 volt AC that flickers like it is high frequency or something. If I press the power button on inverter to cut the output, everything is back to normal. Inverter shows zero battery amps and JK BMS shows 1 amp discharge just like the clamp meter for powering inverter standby current. Any ideas what this is? I'll have to hook up my Tektronix scope and have a look at the signal. Could it be somekind of ground loop or other electrical loop of some kind? Im afraid of frying something if I keep running it like this.
 
I saw on a block diagram that an All in one inverter had a relay to bond neutral with ground and the AC output only had ground connected to Inverter chassie ground. I have both incomming AC ground and outgoing AC ground tied together. Can this be something related to my strange readings? Would it be better to have the ground only connected to inverter chassie?
 
Ok this is something really weird. I´m testing this new off grid system with grid assistanse. On battery and solar everyhing seems to work as expected but when PV is gone (dark) and battery is empty and the inverter switches to grid bypass (SBU mode) strange things happens. Inverter bypasses with the transfer switch and supply the load as expected but it makes a humming sound (maybe normal) but the JK BMS shows a discharge of 9 amps (24 volt system so about 200 watts) and at the same time the inverter shows about 9 amps charging amps the other way around. If you actually meassure the DC current flow with a clamp meter it shows a discharge of 2 amps DC but a AC amp reading of 18 amps AC!? Something is moving current back an forth very quickly. Too fast to see on one of my DMMs in AC mode but another DMM shows strange readings of 130 volt AC that flickers like it is high frequency or something. If I press the power button on inverter to cut the output, everything is back to normal. Inverter shows zero battery amps and JK BMS shows 1 amp discharge just like the clamp meter for powering inverter standby current. Any ideas what this is? I'll have to hook up my Tektronix scope and have a look at the signal. Could it be somekind of ground loop or other electrical loop of some kind? Im afraid of frying something if I keep running it like this.
Did you ever get this figured out? I have a SunGoldPower IP6048 that seems to be putting AC current on the DC battery line. I can literally feel the vibration of the current and if I put a metal screwdriver next to it, you can feel the AC vibration. It's also making the wires REALLY warm, so it's moving a LOT of current, but I can't figure out what, I literally have NO loads hooked up.
 
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