AC doesn’t work after lithium/inverter install

StirCrazy wrote:

jkwilson wrote:

LittleBill wrote:

jkwilson wrote:
Going back to an earlier post you mention a toaster oven “ramping up” its power use. That doesn’t make sense. A resistive device will instantly go to full power and then actually fall just a bit as the elements heat. The ramping effect you are seeing may be a problem with your inverter or battery system limiting power on initial demand and could be the source of the air conditioner problem as well.

its not instant, at least not my testing. resistive and ptc type elements, ramp, its less then 2 seconds in my test, but motor's definitely surge harder in my testing.

It will be closer to instant than you can measure. If you are seeing a 2 second delay it’s in your measurement equipment or power source.

I believe him. the resistance of elements change as they heat up and ramp power as they warm up. they never start blasting and go to full power in an instant. the larger the element the longer it will take and it won't be at full power untill the temrature fo that element hits the point where the resistance stops changing with the power thats available.

You have it backwards. Resistance increases as the wire heats. A resistive load will draw peak power nearly instantly, then it will decline slightly and pretty well stabilize. No resistive device will exhibit anything close to a 2 second delay to full power. That would indicate a reactive load.

jkwilson wrote:

LittleBill wrote:

jkwilson wrote:
Going back to an earlier post you mention a toaster oven “ramping up” its power use. That doesn’t make sense. A resistive device will instantly go to full power and then actually fall just a bit as the elements heat. The ramping effect you are seeing may be a problem with your inverter or battery system limiting power on initial demand and could be the source of the air conditioner problem as well.

its not instant, at least not my testing. resistive and ptc type elements, ramp, its less then 2 seconds in my test, but motor's definitely surge harder in my testing.

It will be closer to instant than you can measure. If you are seeing a 2 second delay it’s in your measurement equipment or power source.

I believe him. the resistance of elements change as they heat up and ramp power as they warm up. they never start blasting and go to full power in an instant. the larger the element the longer it will take and it won't be at full power untill the temrature fo that element hits the point where the resistance stops changing with the power thats available.

LittleBill wrote:

jkwilson wrote:
Going back to an earlier post you mention a toaster oven “ramping up” its power use. That doesn’t make sense. A resistive device will instantly go to full power and then actually fall just a bit as the elements heat. The ramping effect you are seeing may be a problem with your inverter or battery system limiting power on initial demand and could be the source of the air conditioner problem as well.

its not instant, at least not my testing. resistive and ptc type elements, ramp, its less then 2 seconds in my test, but motor's definitely surge harder in my testing.

It will be closer to instant than you can measure. If you are seeing a 2 second delay it’s in your measurement equipment or power source.

jkwilson wrote:
Going back to an earlier post you mention a toaster oven “ramping up” its power use. That doesn’t make sense. A resistive device will instantly go to full power and then actually fall just a bit as the elements heat. The ramping effect you are seeing may be a problem with your inverter or battery system limiting power on initial demand and could be the source of the air conditioner problem as well.

its not instant, at least not my testing. resistive and ptc type elements, ramp, its less then 2 seconds in my test, but motor's definitely surge harder in my testing.

Going back to an earlier post you mention a toaster oven “ramping up” its power use. That doesn’t make sense. A resistive device will instantly go to full power and then actually fall just a bit as the elements heat. The ramping effect you are seeing may be a problem with your inverter or battery system limiting power on initial demand and could be the source of the air conditioner problem as well.

What does Renogy say about the flicker? It doesn't seem desirable and might be an indication of some issue.

Flicker suggests an electrical transient condition that can effect electronic equipment causing shut down, reboot etc.

"As for the flicker, presumably the lighting is operating directly from battery 12v and competing with the inverter, which is also drawing from the battery. As the inverter is stepping up it's amp draw, there will be a tiny drop in battery voltage, and the battery BMS may be doing something to adjust to the new & higher amp draw."

Xiaowudao wrote:
Thanks all for the replies. Here’s some more info…

The ac doesn’t work on shore power either. Right after I finished this install we did try to run the Ac for the first time on both inverter and shore power. During these tests the compressor would turn on and off like it wasn’t able to sustain itself. And now it will not work on either shore power or inverter. The fan on the ac runs but compressor does not. I feel like having the soft start should have been sufficient in running the ac off inverter.

The AC is a 13500btu roof air conditioner by dometic (dometic brisk air 2). The inverter has a surge rating of 6000w and 3000w constant so I feel with the easy start it should be ok?

I have the following parts:

3000w renogy pure sine wave inverter
https://ca.renogy.com/3000w-12v-pure-sine-wave-inverter/

3 x 170ah renogy lithium batteries
https://ca.renogy.com/renogy-lithium-iron-phosphate-battery-12-volt-170ah/

Go power 30 amp automatic transfer switch
https://gpelectric.com/products/30-amp-transfer-switch/

Progressive dynamics lithium charger
https://www.etrailer.com/RV-Converters/Progressive-Dynamics/PD9130LV.html

Micro air easy start
https://www.microair.net/products/easystart-364-3-ton-single-phase-soft-starter-for-air-conditioners

Have figured the issue with micro-air and air conditioner yet? I have a Carrier A/C unit which is different than yours but when originally installing the micro-air I thought I followed the directions but I missed one wire connection. The "ptc" gets disconnected from the run capacitor and it had a spliced wire on that connected the terminal block to the run capacitor, I didn't realize I needed to make a wire to reconnect the terminal block back to the run capacitor. After doing so it worked as it should.

Symptoms before this wire reconnected was the a/c fan would run but the compressor never turned on and the micro-air unit never had the light light up.

Are you sure you have everything wired properly and if so are the lights on the micro-air unit on?

Just throwing it out there incase you haven't figured it out yet. ;)

I would test the A/C on utility power only until you get it figured out.
No sense and complicating the diagnosis with possibilities of the battery-inverter.

Hi all thanks a lot for all the replies and suggestions on how to tackle all this. To answer some questions...

This trailer is less than 1 year old, bought brand new in feb 2021.

The way I tested the compressor and start run capacitor on the AC was via the tips in this video: ***Link Removed***https://www.youtube.com/watch?v=3VckFAXg1CY&feature=emb_title
However I've been told on another forum that this is not a complete test and doesn't necessarily mean that the capacitor and/or compressor are problem free.

My main reason for installing this system is to be able to camp off grid as we primarily boondock, and are planning on going fulltime soon. we work remotely so we need to be able to plug in devices such as laptops etc quite often. We have a generator as backup but don't want to always lug it out and the noise etc.
The AC working with the system is just a nice bonus. I didn't specifically install the system because my primary goal was to run the AC off it. Reports from others that have the same battery/AC setup report that they get approx 5 hours of runtime for their AC which sounds plenty to me.
I have 550 watts of solar on the roof and an additional 200 watts via a foldout style panel that sits on the ground. I also have a DC to DC charger so it can charge better while towing since just using the 7 pin connection will not charge lithiums all the way.

I will try some of the suggestions in this thread and report back! I feel like the system should be working okay as I ran a 1500w toaster oven for 30 minutes as a test and it works except for the intermittent flicker when the oven ramps up usage. I posted this issue on another forum and a user there suggested "As for the flicker, presumably the lighting is operating directly from battery 12v and competing with the inverter, which is also drawing from the battery. As the inverter is stepping up it's amp draw, there will be a tiny drop in battery voltage, and the battery BMS may be doing something to adjust to the new & higher amp draw."

Thank you all again for the troubleshooting suggestions.

Itinerant1 wrote:
. . . I'm running my 15k air conditioner right now off the batteries/ solar drawing 75a from the batteries to cool the inside down a little. Started it at 15:30 77f inside, just turned off 72f inside after 40 minutes. Nice not having to drag a generator out.

Nice to be able to do that. You obviously have a fair bit of solar.

IMO, powering an RV a/c via battery is not a viable, practical option except in a few niche situations. We found one that works well for us. Our a/c only needs 5 min to make our truck camper feel noticeably cooler. During the summer we always power the a/c with batteries when we take breaks on the road. Instant, silent power---no generator noise or setup. Once back on the road the dc to dc charger preps everything for our next stop. With few exceptions, our lifepo4 is fully charged when we make our final stop for the day. Prior to this upgrade we never turned on the a/c---just too much trouble dragging out the generator. Not the case anymore.