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🆘 Relay specifically tripping inverter!!! 🆘

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Psi:

--- Quote from: mendip_discovery on July 27, 2023, 01:07:44 pm ---Measure the voltage at the battery. Could you be hitting a low voltage issue with the battery supply just enough for the inverter to go into shut down. The number of times I have had cars do this is annoyingly high.

--- End quote ---

Good use for a supercap across your battery.

Ian.M:
The place to initially check if the inverter's input voltage is dipping is right at its screw terminals, not at the battery, as its far more likely to be a high resistance connection somewhere than a bad battery.   If you find a significant voltage dip, re-check working back towards the battery to locate the problem.

bdunham7:

--- Quote from: bigjoncoop on July 27, 2023, 10:28:02 am ---I am open to any ideas and I appreciate any help.

--- End quote ---

First, ease up on the formatting!

I think we need to know the specifics on the AC unit.  What model, etc?  Is there a data plate that has information like LRA, voltage, etc?  Post a photo if there is.  Then you need to have a way of measuring some things--what equipment might you have?  Current clamp, DMM, oscilloscope, ?

Two 6R resistors in series gives you a current of 10A and that tripped the inverter?  That doesn't make sense.

Gregg:
From the Amazon listing for the inverter in question:

--- Quote --- FAQ FOR WZRELB PURE SINE WAVE INVERTER

Q: What kind of the inverter is suitable for your appliances?

A: Pls know that load is divided into resistive load and inductive load .If you need the inverter to run the resistive load (like laptop, TV, electric cooker,LED light), please choose the inverter with continuous power higher than the appliance's rated power. And it is best to use 80% of the rated power. If you use microwaves,water pumps, air conditioners and other appliances with motors or compressors ,please choose the inverter whose continuous power is 3-7 times higher than your appliances.If you want to power up a refrigerator, we suggest you use 10 times higher power inverter
--- End quote ---
It appears that the manufacturer is well aware of the device's limitations for high inductive loads and recommends sizing their inverters 10x the rated capacity for refrigeration systems.
While I applaud your efforts to put lipstick on the pig, the best solution is to replace the inverter with something that will reliably function as necessary.

bigjoncoop:
I am aware of the manufacturers note about inductive loads.

But it obvious that the inverter is capable of starting and running this air conditioner, as long as the compressor starts immediately upon power up...

@Ian.M I think hit the head on the nail with his last comment...

--- Quote from: Ian.M on July 27, 2023, 12:39:39 pm ---The test with the manual switch proves that the inverter simply doesn't have enough safe overload capacity to handle the motor's starting surge.  Why does it work when you hard-wire the compressor and startup the inverter?  Well, the inverter has probably got relaxed overload detection during inverter startup, and also it may well start outputting AC before its internal DC bus reaches 170V so reducing the compressor's inrush current.

--- End quote ---


So I think at this point since I've spent so much time and aggravation on this, I'm just going to bypass the main board and just direct wire the entire thing.

I'll use a normally closed contactor between the battery and the inverter and wire the float switches to the contacts on the contractor in order to cut the power if the condensation tank is full. I'll also make sure to power up the high and low side pressure switches.

I know I could also control the contact with the thermostat, but temperature control is not needed for my application. I just need this thing to keep running until I turn it off.

Trust me I completely understand the the best thing to do is purchase a larger inverter but it s not in the budget rite now...

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