Mastervolt Inverter Issue

[brockfromwa]

I have a Mastervolt 12/2000 (120v) Mass Sine inverter that works with a modest load ~1000W but resets if the load is anything more than that. The fans turn on for a second when turning the inverter on, and then nothing even with a load on it. Seems like the inverter isn't fully operating the way it should to take the higher end of loads. What are your thoughts?
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-No error lights illuminate.
-"On" light slightly blinks here and there
-1200ah AGM house battery bank (6x 210ah Full river AGM)
-Eco mode and standby mode not turned on
-Inverter is 10 years old, but in great visual condition and no corrosion
-12v supply cables in great condition
-200a breaker functional

 

[Davidasailor26]

What gauge and length are the supply cables? My guess is the voltage is sagging below some threshold at the inverter. That could be because either the cables are too small and causing a voltage drop, or the batteries are worn and can’t put out that amperage anymore. To check you could put a load just below the problem level on the inverter and measure the voltage at both the battery posts and the inverter terminals.

 

[Project_Mayhem]

Has it ever been subjected to heavy or inductive loads? I've seen audio amplifiers clip or go into protect mode early due to a partially fried output transistor

 

[brockfromwa]

What gauge and length are the supply cables? My guess is the voltage is sagging below some threshold at the inverter. That could be because either the cables are too small and causing a voltage drop, or the batteries are worn and can’t put out that amperage anymore. To check you could put a load just below the problem level on the inverter and measure the voltage at both the battery posts and the inverter terminals.

Hi David,
Thank you for the quick reply!
The 12v supply cables are 3/0awg or 95mm^2 and are 4' in length from the 200a breaker to inverter. There is a 6' run from the battery bank to the disconnect switch/battery bus bars. The house bank smart shunt shows the voltage dropping to 12.1v. But good call on measuring the voltage at the inverter terminals. You can't trust the low voltage error light on the inverter! Hahaha

 

[brockfromwa]

Has it ever been subjected to heavy or inductive loads? I've seen audio amplifiers clip or go into protect mode early due to a partially fried output transistor

It may have, I've only owned the boat for 2 years of it's 10 year life. From other inverters I've used, typically if there's any kind of load the inverter fans fire up and the inverter makes some noise when it's doing it's thing. This Mastervolt is making some humming but the fans don't engage even with the microwave running and pulling 1100w.

 

[Davidasailor26]

Doesn’t sound like the cabling should be too bad. That’s 0.17V of drop at 1800 watts if the calculator I’m using is right. I presume it’s not a far run from the batteries to the breaker? Still probably worth checking voltage at the terminals in case there’s a bad crimp or connection.

 

[brockfromwa]

Update: Inverter does not operate at all when there's no solar/wind to stabilize the battery bank. It constantly turns on and off cycling every 2 seconds.
-Still no error lights.
-House bank voltage steady at 12.3v and SOC at 96%
-12.2v read at the inverter lugs
-Output voltage ramps up to 120v then falls off back to 0v

#Anyone else have intermittent functioning inverters?
#Is 10 years a good lifespan for Mastervolt inverters? This thing is apparently $2200 and significantly more expensive than even the Victron equivalent.

I'm in research mode for a new inverter, leaning towards the Victron 3000W inverter due to cheaper cost than the Mastervolt. (I'm slowly adding Victron components to my electrical system and will eventually tie them all together with the Cerbo)

 

[jssailem]

-House bank voltage steady at 12.3v and SOC at 96%
-12.2v read at the inverter lugs

The symptoms also suggest that the health of the battery bank may not be what you think.
Before opening my wallet for a new inverter (as fun as that may seem) I would look hard at the battery bank and do a 20 Amp Hour capacity test of the system.

Here is a link Under-Load Battery Voltage vs. SoC - Marine How To
and a chart image... Though the chart is more of an indicator that your batteries may be on borrowed time.