New inverter failure - fixed was pre-charge

[Patricktxfl]

Fairly new to solar and inverter setup. My second rv trailer with single 100ah chins lithium and Portable solar adding a renogy 1000w inverter on this one, all equipment new. My issue is with inverter, when I have attempted to operate trailer without inverter pos/neg connected and everything is okay on 12v, no solar hooked up.
Simple system:
I have ANL on positive and off/on switch and Aili shunt on ground. Total length of 4 awg pre-made wiring is 4 1/2 feet between battery and inverter.
Positive 10ga jumper from fuse block to terminal block for solar and RV.
Negative 10ga jump from switch off side to terminal block for solar and RV.

When I connect inverter the battery bms seems to be seeing short and turning off before even turning on inverter. I originally had inverter mounted and grounded, and then tried isolated from frame ground.

When I first tried it seemed to test as positive grounded as I could switch off Negative side and use meter on dc test 13+ v between Negative battery terminal and frame, so seemed inverter was passing positive to frame.

I'm starting to think some type of DOA short, but thought I would ask before giving up. I've opened case with support, searched web and this forum for help. If you can help please feel free to give me your opinions.

Attached photo, Just FYI, the grey conduit and small black were existing trailer wiring and not part of system just crosses mounting board. I have not yet installed plug in fuse for solar or positive feed to shunt.


Thanks for your feedback

 

[HRTKD]

It's possible that your inverter is trying to charge its capacitors and your battery BMS can't keep up with the large amp draw. But a 1000 watt inverter shouldn't have capacitors that are that large such that they trip a BMS that is rated for 300 amps for 5 seconds.

 

[Patricktxfl]

It's possible that your inverter is trying to charge its capacitors and your battery BMS can't keep up with the large amp draw. But a 1000 watt inverter shouldn't have capacitors that are that large such that they trip a BMS that is rated for 300 amps for 5 seconds.

I thought about that possibility, since I tried originally using switch on negative to energize inverter. But that wouldn't cause it to short pos to ground would it?

On my ungrounded attempt I used an extra cable and tried sparking between two neg cables to energize capacitors, but that didn't seem to make any difference.

 

[HRTKD]

I put the cables to my inverter on backwards. The inverter didn't complain, but the BMS shutdown, complaining about a short circuit I believe. Once I stopped slapping myself on the forehead and switched the cables to the proper studs on the inverter it all worked fine (after I reset the BMS).

Does the inverter have the ability to use 110v AC as input? If so, connect that up and see if the inverter is active. At the very least, that confirms that the inverter is functional on AC.

 

[Supervstech]

I thought about that possibility, since I tried originally using switch on negative to energize inverter. But that wouldn't cause it to short pos to ground would it?

On my ungrounded attempt I used an extra cable and tried sparking between two neg cables to energize capacitors, but that didn't seem to make any difference.

You need a resistor to charge capacitors gently… sparking cables won’t help…

 

[Patricktxfl]

I put the cables to my inverter on backwards. The inverter didn't complain, but the BMS shutdown, complaining about a short circuit I believe. Once I stopped slapping myself on the forehead and switched the cables to the proper studs on the inverter it all worked fine (after I reset the BMS).

Does the inverter have the ability to use 110v AC as input? If so, connect that up and see if the inverter is active. At the very least, that confirms that the inverter is functional on AC.

No input just 12v. I have FLA battery to test with but kind of worried if its true that its shorted bad things might happen

 

[Patricktxfl]

You need a resistor to charge capacitors gently… sparking cables won’t help…

Thats what I saw Will did on 12v systems. I was just reading using a light bulb to charge.

The symptom that worries me was positive connected to inverter negative dis connected. I was testing with meter and was reading 12v between trailer frame and negative battery. The only way I can figure that would be positive short to inverter case. Have you seen this? Can capacitor cause that?

 

[Zwy]

Fairly new to solar and inverter setup. My second rv trailer with single 100ah chins lithium and Portable solar adding a renogy 1000w inverter on this one, all equipment new. My issue is with inverter, when I have attempted to operate trailer without inverter pos/neg connected and everything is okay on 12v, no solar hooked up.
Simple system:
I have ANL on positive and off/on switch and Aili shunt on ground. Total length of 4 awg pre-made wiring is 4 1/2 feet between battery and inverter.
Positive 10ga jumper from fuse block to terminal block for solar and RV.
Negative 10ga jump from switch off side to terminal block for solar and RV.

When I connect inverter the battery bms seems to be seeing short and turning off before even turning on inverter. I originally had inverter mounted and grounded, and then tried isolated from frame ground.

When I first tried it seemed to test as positive grounded as I could switch off Negative side and use meter on dc test 13+ v between Negative battery terminal and frame, so seemed inverter was passing positive to frame.

I'm starting to think some type of DOA short, but thought I would ask before giving up. I've opened case with support, searched web and this forum for help. If you can help please feel free to give me your opinions.

Attached photo, Just FYI, the grey conduit and small black were existing trailer wiring and not part of system just crosses mounting board. I have not yet installed plug in fuse for solar or positive feed to shunt.


Thanks for your feedback

I'd be double checking your polarity on everything.

 

[Hedges]

Does inverter have an on/off switch?
I have an old StatPower inverter. It will spark when connected to 12V. I just used a light bulb as resistor to precharge. Switched on, the inverter beeped for low voltage. Switched off, I watched voltage rise with a DMM, then bolted cable in place.

Even if you can't turn yours off, connecting in series with a light bulb (or other resistor) should let you see if some voltage develops across inverter vs. it being a dead short.

 

[Zwy]

Thats what I saw Will did on 12v systems. I was just reading using a light bulb to charge.

You can use a pencil too, cut off the eraser and touch the graphite on each end to complete the circuit.

The symptom that worries me was positive connected to inverter negative dis connected. I was testing with meter and was reading 12v between trailer frame and negative battery. The only way I can figure that would be positive short to inverter case. Have you seen this? Can capacitor cause that?

 

[Supervstech]

Thats what I saw Will did on 12v systems. I was just reading using a light bulb to charge.

The symptom that worries me was positive connected to inverter negative dis connected. I was testing with meter and was reading 12v between trailer frame and negative battery. The only way I can figure that would be positive short to inverter case. Have you seen this? Can capacitor cause that?

I don’t follow.
If you disconnected negative, and checked from positive to negative post there would be voltage. Checking from chassis to negative post would also show voltage… any continuity would show up as voltage.

 

[Patricktxfl]

I'd be double checking your polarity on everything.

I have and fairly easy to do, all positive red all negative black. Inverter is color coded and printed on case.

 

[Patricktxfl]

Does inverter have an on/off switch?
I have an old StatPower inverter. It will spark when connected to 12V. I just used a light bulb as resistor to precharge. Switched on, the inverter beeped for low voltage. Switched off, I watched voltage rise with a DMM, then bolted cable in place.

Even if you can't turn yours off, connecting in series with a light bulb (or other resistor) should let you see if some voltage develops across inverter vs. it being a dead short.

Yes inverter has off switch and have kept in off so far as it's shutting down bms when connected before even trying to power inverter

 

[Zwy]

I have and fairly easy to do, all positive red all negative black. Inverter is color coded and printed on case.

Is the polarity correct on the battery? I've seen members switch the leads on the mulimeter also.

 

[Patricktxfl]

I don’t follow.
If you disconnected negative, and checked from positive to negative post there would be voltage. Checking from chassis to negative post would also show voltage… any continuity would show up as voltage.

Negative cable removed from battery. Frame to Negative term showed 13+v. Didn't think there was a path between them unless positive was shorted to ground.

 

[Patricktxfl]

Is the polarity correct on the battery? I've seen members switch the leads on the mulimeter also.

Yes polarity at battery is correct, I even tested both ways with meter so I could tell internal of battery was correct. Meter black to pos and red to neg displays a negative value.
Thanks I appreciate you guys helping me walk through possible ideas.

 

[Hedges]

Yes inverter has off switch and have kept in off so far as it's shutting down bms when connected before even trying to power inverter

Some inverters have a breaker/switch which entirely disconnects them from battery.
Others have a tiny switch signaling the to turn on. In the case of my StatPower, switch off keeps it from drawing power, but capacitors are still connected to battery terminals so can precharge.

See how it behaves with precharge resistor or light bulb.

Negative cable removed from battery. Frame to Negative term showed 13+v. Didn't think there was a path between them unless positive was shorted to ground.

Sounds normal. "Path" may be through capacitors, looks like a connection to a DMM with 10 meg ohm input impedance.
But a short would look the same. That's where precharge comes in.

 

[foggysail]

I believe you are experiencing a common problem with vehicle inverters. NEITHER SIDE OF THE AC LINE FROM THE INVERTER CAN BE CONNECTED TO THE SAME GROUND THAT YOUR INVERTER SHARE!!!! KEEP TRYING AND YOU WILL BURN UP YOUR INVERTER. There are NO grounded conductors similar to house wiring

 

[Patricktxfl]

Hey all thanks for comments. So since so many suggested could be capacitor issue I went back out and found I could charge capacitor with a small ga jumper wire.
I was able to remove jumper and quickly install negative side and proper voltage across inverter terminals and was able to start inverter and it produced 118v AC.

So I think we're on the path to get me fixed.

I have a follow up question for you. Testing it appears you can't switch the negative side of inverter or I have to do redo the capacitor charge.

Is switching between battery and inverter an immediate fail in my design?

I read a post using a 4 position switch that allowed a capacitor charge path. So hit 1 path small wire then switch to 2 for large cable then turn on inverter inverter. Another idea was momentary switch path, then switch primary feed.

It being an occasional use RV was thinking switch everything which work previously without inverter.

Huge thanks again all.

 

[Patricktxfl]

Some inverters have a breaker/switch which entirely disconnects them from battery.
Others have a tiny switch signaling the to turn on. In the case of my StatPower, switch off keeps it from drawing power, but capacitors are still connected to battery terminals so can precharge.

See how it behaves with precharge resistor or light bulb.



Sounds normal. "Path" may be through capacitors, looks like a connection to a DMM with 10 meg ohm input impedance.
But a short would look the same. That's where precharge comes in.

Thanks. I think you were right. I posted a reply to all, can you answer if my design to have a switch in negative is a design failure. Seems like switching off discharges capacitors so bms turns off again, and requires doing capacitor charge again.