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Gladrags1 04-18-2011 12:29 PM

AC Power - microwave problem
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I have a Freedom Charger / inverter connected to my Heart Interface 2000 electrical system on my boat and I have some problems with it supplying ac electric power to my microwave when I am plugged in to shore power. I am NOT referring to any problems with power from the inverter.

I have a microwave installed on board. The microwave was old and was not working on the boat. I removed it and found that it worked just fine when connected ashore. What happen when installed aboard is that it would not turn on when you pressed "start." Once removed, I noticed that there was corrosion at the back so I removed the cover and sanded and painted the cover. Now it would not work at all. Success, huh? However, that is not what I am writing about. It's only provided to provide backdrop.

I bought a new compact microwave and ran a new 12 guage cable to its own 15 amp breaker on the electrical panel. I turned the microwave on and immediately the main breaker (30 amp) on the inverter/charger popped off and then reset itself. I turned off the charger and then turned on the microwave. Success! It ran. OK, the charger and the microwave use too much electricity when used together. I later installed the microwave in the cabinatery and then tried to turn it on. Remembering that I needed to turn the charger off first. Now the darned circuit breaker on the inverter/charger pops off even when I have the charger off. BTW, the micro is a 700 watt unit that runs on a 15 amp circuit.

As I am writing this, I am thinking I should have tried to run it on the inverter but I didn't think of it then. However, I should be able to run it as connected, shouldn't I? Anything I missed? Could I have a problem with the charger/inverter? Any ideas?

btrayfors 04-18-2011 05:56 PM

My guess is that it's high inrush current to the microwave that's causing you problems.

Microwaves, and most other modern appliances and electronic devices, often have very high inrush current demands. These can be 5, 10, 50, or even 100 times the average rated current, though only for a few milliseconds.

Breakers are usually designed to take inrush current as much as maybe 6 to 8 times their rating before tripping.

It could be also that your breaker(s) has/have deteriorated, as they do over time, i.e., they are unable to carry rated loads.

About the only thing you can do, IMHO, is to only start up the microwave when EVERYTHING else is turned off.



Gladrags1 04-19-2011 04:11 AM

4 Attachment(s)
Any idea why it would work one weekend and not the other? I believe there weren't any other breakers turned on. I had the lights on the boat on but they are on the dc side of things. I have a small window airconditioner which worked last year. Will try to see if that works this year. That plugs in to a different circuit.


mitiempo 04-19-2011 10:38 AM

Was the inverter/charger charging at the time? If so there would be less power available to pass through for other uses depending which inverter you have and how it was wired.

Stu Jackson 04-19-2011 01:22 PM

MacGyverRI 04-19-2011 11:10 PM

It could be the shore power/plug or other boats causing it all.

Can you get a volt meter on a plug, check volts, then turn the charger on and see what the running volts are? Avg. will be 90-110, a low of 85 or lower volts wont really cut it and is usually caused by other boats w/ high current draw.

Gladrags1 04-20-2011 06:25 AM

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Originally Posted by Stu Jackson (Post 721858)

That's an interesting concept! You mean that the inverter might be set to trip at a lower amperage by the Link 2000 and I can reset that. Am I understanding this correctly?

Mitiempo: I have turned off charging before turning the micro on so there is nothing else using the voltage. It's a good idea to check the voltage on the boat to make sure there is no voltage drop. There wouldn't be any other boats pulling down the voltage since I'm the only boat on my pier (private pier).

Thanks for the ideas, it's given me some things to try.


Stu Jackson 04-20-2011 11:57 AM


Originally Posted by Gladrags1 (Post 722066)
That's an interesting concept! You mean that the inverter might be set to trip at a lower amperage by the Link 2000 and I can reset that. Am I understanding this correctly?

Tod, it means what it says. It won't use all the power for charging and gives you more to work with for AC loads when your charger is working. If you have a Link 1000 or 2000, you can also turn the charger OFF and have all AC available for your microwave.

Stu Jackson 04-20-2011 12:21 PM

Also, the 12 gauge wire seems small, I'd use 10 gauge.

mitiempo 04-20-2011 10:33 PM

12 gauge is fine for an individual AC circuit, in this case the microwave's 15 amp circuit. 10 gauge should be used for the main input to the panel from the shorepower inlet.

I use 14 gauge for individual AC circuits of 15 amps.

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