Aims Inverter problem

bergger

So I have no idea what is happening with our inverter.  We have the original Aims 1200 watt pure sign inverter in our 2021 400.  It has always worked flawlessly.  We really do not use it very often when boondocking.  Only to power our DVD player, very low watts, or to brew coffee in our small 5 cup Mr. Coffee, which pulls between 750-800 watts for a few minutes as it brews.  It will use 4% of the battery for a pot of coffee. 

On our latest trip which was this past Wed-Sunday, the inverter was fine brewing coffee on Thurs, Friday and Saturday.  After I brew a pot I turn it off to save power since it has a hot plate that will come on and off.  Saturday I decided to brew a 2nd pot after the the coffee maker had been off for at least 30 minutes.  About 2/3rds of the way through the brew we noticed a faint beeping coming from under the bed.  It was the inverter.  The light was still green but the inverter was beeping.  A short time later, still as it was brewing, the inverter started to kick off power and immediately back on.  It would go from green light to red fault light back to green and repeat.  It finished the brew but kept turning power on and off.  After this pot was complete I heard the fan turn on the inverter.  I kept the inverter powered on until the fan turned off.  I then turned off the inverter.

I assumed it just overheated but thought it odd that the power was kicking on and off and the fan never came on until after the brew was finally finished.  If it overheated the fan should have come on earlier then it should have killed power while it cooled itself down.  At least that's how I understand it to work.  We still have the original 6v AGM batteries but the smart shunt showed them fully charged.  The volts being 13.8.  I don't think the inverter will shut off unless batteries are near dead with very low volts coming in.  

This morning on our last day I turned on the inverter and the coffee pot.  It brewed just under half the 5 cup pot and then consistently kicked on and off then finally kicked off.  A few seconds later I could turn the inverter back on but as soon as I turned on the coffee pot it kicked off power and stayed off.   It will kill the power but the inverter still stays on with a green light. Stove top coffee was had this morning!

I got home and opened it all up.  Everything seems normal as far as looking at an inverter goes!  I plugged in our Jackery 1000 to charge and the inverter does fine pulling 150 watts.  I plugged in my heat gun since I can adjust the power on it.  The inverter seems to do fine up until about 300 watts then just kills power, but it stays powered on.  The red light kicks on, power is killed, then it immediately goes back to green light.  I've not heard the fan come back on since Saturday but during my tests the inverter is cool, not having enough time to warm up before it kills power. 

Any ideas why all of a sudden our inverter is not working properly and any suggestions?  I hate to spend close to $500 for a new one if it may be something else.  

MuttonChops

Gosh, sounds like it has died.
Nothing in the limited troubleshooting fault modes information on-line that addresses the power cycling.

You might consider calling AIMS Support before ordering a replacement.

As for fan operation . . . manual notes it is unit case temperature controlled, turns on around 104°F case temp

bergger

I’ll call Aims tomorrow. I just got done charging my jackery off the inverter. Took about 1.5 hours and the inverter fan was coming on and off as it should. It just seems to stop working at loads over 300 watts. 

webers3

So you are assuming the inverter is the problem but what about your batteries? You don't indicate what is the capacity of your batteries, maybe they do not have enough capacity to drive the inverter at the loads your coffee maker requires, especially boon docking for extended period. You say: "We still have the original 6v AGM batteries but the smart shunt showed them fully charged.  The volts being 13.8" The SmartShunt should show you the percentage left on the batteries, not voltage, which at 13.8v is not a resting voltage for AGM batteries, it does not mean the batteries are fully charged, do you have solar? 13.8v would indicate your solar controller supplying to the batteries, not state of charge of the batteries. Assuming your SmartShunt is calibrated correctly you need to take a close look at what happens when you put a load on the batteries. I think you need to charge your batteries and try Mr Coffee again

bergger

I've got the factory 163 watt solar panel and the victron 15 amp charge controller.  Smart shunt showed batteries at 100% when I tested them at home and when the issue happened when camping they were at 96 and 94%. 

I just now turned off the batteries with the disconnect switch, and turned off my solar charge controller.  The smart shunt showed 100% charge with 13.41 volts.  I used my multimeter and it showed 13.57 volts on the batteries.  Possibly the batteries but the numbers seemed to indicate it's not the batteries.   Do I need to let the batteries sit a bit before I put the multimeter on them?  And maybe the 800  watt load is just pulling too much off the batteries causing the inverter to shut down, then the batteries are bouncing back up after the load is cut off? But electrical is not my strong point so I'm not sure.  Honestly if it were something I'd rather it be the batteries since they are 4 years old and I'd rather replace them vs. the inverter.  If I can't seem to find a solution I may end up just replacing the batteries anyway next year and see if that fixes it.  They will be 5 years old at that point.  I can easily do without an inverter when camping.  I also plan on trying the coffee maker again tomorrow to see what happens.  Fingers crossed and thanks for the input.  

webers3

Yes you need to let the batteries sit for 10-15 minutes after charging to get to “resting” voltage, which for fully charged AGM is about 12.8v. You still didn’t indicate to capacity of your battery bank. I would suspect your 4 year old battery before your inverter. Put the multimeter on the battery when you have a load on them, such as your coffee maker, I bet the voltage goes well below 12v when the inverter cuts out. The other factor with old batteries is how well do they recover after a substantial load, they may have been ok brewing 2-3 coffee pots at 800watts but then they didn’t recover well, even with a bit of solar, and fell well below 12v on subsequent load. BTW the SmartShunt history page will show you how much energy you used vs how much you put in and the lowest battery voltage.

bergger

224ah, the standard factory T@b 400 battery bank.  I'll put the multimeter on it tomorrow when I test it again with a higher load. 

rh5555

This sounds like the typical failure mode of one of your AGM batteries.  When they fail, they develop a high resistance which causes the terminal voltage to sag when current is drawn.  The odd behavior of the inverter is entirely consistent with a low voltage shutdown.  I'd suggest repeating the coffee-brewing experiment, but this time watch the battery voltage using your smart shunt.  I think you'll see the battery voltage drooping.  If so, it's time to look at Lithium replacements.  If the battery voltage doesn't droop, I'd check the heavy-duty 12V wiring that goes to the inverter, maybe you've developed a loose connection (probably at the AIMS input).