Mastervolt MassCombi Issue

[twistedtree]

I'm seeing some strange behavior from my MasterVolt MassCombi inverter/charger. I have it set up to automatically start charging anytime there is AC present from shore power or the generator. At the same time, the passthrough relay passes the AC through to the loads.

I'm finding that sometimes when I apply AC the device does not power on. Normally when AC is applied all the LEDs on the remote panel light up, then it flashes a sequence to tell you what firmware rev it's running, then the charger starts. The passthrough relay goes active right away. When it's not working properly, no LEDs come on at all on the remote display, and I get a slow blink on the AC Present LED. If I wait long enough sometimes it will eventually come on after a minute or two.

The manual only describes the AC Present LED flashing in conjunction with other LEDs, and I don't have any others active.

My first assumption was that the AC was out of range, but my panel meter reads 116V and 60hz, so I think it's OK.

Anyone have any ideas?

[Mardav]

Check all the grounds, AC and DC. Check for loose connections or corrosion (at the isolator too).

[CharlieJ]

My first assumption was that the AC was out of range, but my panel meter reads 116V and 60hz, so I think it's OK.

You may be on the right track by ensuring the incoming power is qualified. Check the programming of the I/C and see what the spec is for incoming power. Than check your incoming power (shore and genset) with a good quality DMM for both voltage and frequency. If it will work on mains but not on genset power and voltage and frequency are within the allowable band, you will need to check the waveform with an o'scope to ensure your genset is not flat-topping the sine wave.

Hope this helps.
Charlie

[donradcliffe]

I suspect the same as Charlie that it doesn't want to work on the genset, but works fine with dockpower. If you put some resistive load on the genset like the water heater, it may smooth out the waveform so the battery charger is happy.

[twistedtree]

I first observed the issue with dock power. I tried with the genset today and got the same results. After some number of tries, it comes on then works fine if I cycle AC.

I checked the wiring at the inverter today and everything was tight and clean. I also tried switching the manual bypass switch a few times thinking I might have crudded up contact on that, but it made no difference.

By the way, I checked more closely and when it does this, there are no LEDs on at all either on the remote or the inverter itself.

Tomorrow I'll try measuring the voltage right at the inverter input when I turn on dock power. That will tell me a lot.

[twistedtree]

I measured the voltage on the terminals of the inverter this morning when I powered it up. The voltage was good, but as expected it didn't power up. To me this was the final indictment of the MassCombi as the culprit. After little while on the phone with MasterVolt they agreed that it appeared to be an inverter issue.

I've purchased an advanced replacement for which they will credit me once I return the failing unit.

[donradcliffe]

You're lucky--my stuff usually works fine as long as I have the voltmeter out.

[twistedtree]

Originally Posted by donradcliffe

You're lucky--my stuff usually works fine as long as I have the voltmeter out.

Yes, I know how that goes....

I was able to reproduce the problem by shutting off the input breaker to the inverter for 5 minutes or so.

[twistedtree]

Here's a quick follow up on this. The replacement inverter arrived today and I made the swap. The new one appears to work fine, and I'll ship out the broken one tomorrow. Assuming the problem is reproducible by the manufacturer, they will credit me back for the cost of the replacement.