On a recent trip to Florida my microwave called it quits! It will run for a few seconds then seems to short out losing all power. The power will return after a few minutes. This was while running on the generator. Haven't tried with shore power yet. Does anyone know the where to look for a replacement microwave?
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Quote:
Originally Posted by Jeff64
On a recent trip to Florida my microwave called it quits! It will run for a few seconds then seems to short out losing all power. The power will return after a few minutes. This was while running on the generator. Haven't tried with shore power yet. Does anyone know the where to look for a replacement microwave?
That may not be a problem with your microwave. Your on-board Onan generator only provides 20-amp service. The Energy Management System (EMS) has a preconfigured load-shedding routine so that if your draw exceeds 20 amps on generator power, it shuts down appliances in a specific sequence to get the total load below 20 amps. The A/C is the first to cut out— if it's running— and the microwave I believe is the second to cut out.
Try the microwave while you're on 30-amp shore power. Chances are it won't cut out, because there will be enough amperage to run everything you have turned on.
Also, while on generator power you might try turning off other high-draw electrical appliances when you need the microwave.
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I thought getting old would take longer!
I'm currently getting my 4th microwave installed.
My 1st microwave had exactly that problem - it would run for about 90 seconds and then quit. Made no difference whether I was on generator or shore power.
My 2nd microwave had something loose inside the motor area and rattled very badly.
My 3rd microwave would only run on microwave power, not convection, bake, roast, etc.
The quality is abysmal.
Hat's off to the first person who cites the make and model of these things that are failing, because I would like to know what to avoid in the future.
Knock wood, no problems with the one we currently have, which is either a Dometic CDMW07W, or CDMW07B, or CDMW07S (says the owner's manual; I can't check the oven itself as the Interstate is in its storage locker).
Upon Protag's suggestion I tried with shore power and it works fine! I've had the van for over two years and not had this issue. I believe what has happened is I've installed two GLP 6ct batteries a few months back and haven't used the van since. I seem to remember the guy at Centex batteries (the Lifeline dealer had be turn up the charge rate a bit for the bigger batteries. When you first start the generator the EMS system applies bulk charging immediately regardless of whether or not the batteries are charged until it evaluates the battery status and backs the charge rate down after a couple min if they are fully charged. I started the generator and tried the micro. It went off immediately. After the charger dropped to absorb the micro worked fine. I guess I have the option of placing the charging system on standby should the batteries need bulk charging, at least long enough to warm up the coffee! Nice to know I don't need to replace the Microwave.
Thank you for your responses.
Upon Protag's suggestion I tried with shore power and it works fine! ... I seem to remember the guy at Centex batteries (the Lifeline dealer had be turn up the charge rate a bit for the bigger batteries. When you first start the generator the EMS system applies bulk charging immediately regardless of whether or not the batteries are charged until it evaluates the battery status and backs the charge rate down after a couple min if they are fully charged. I started the generator and tried the micro. It went off immediately. After the charger dropped to absorb the micro worked fine. I guess I have the option of placing the charging system on standby should the batteries need bulk charging, at least long enough to warm up the coffee! ...
Thanks for the update - glad your microwave is OK. For clarity your batteries are not charged by the EMS. They are charged by the Magnum inverter/charger. The Centex tech would have changed the Magnum settings.
What Airstream calls the EMS is know as a MINI POWER CONTROL SYSTEM (Mini-PCS) by the vendor Precision Circuits Inc. I've attached an image of the control panel. When running the generator the green "GEN" should be lit. Then as Protag mentioned you only have 20A service. You can monitor the AC Amps on the PCS/EMS panel as it measures current through the Main Circuit Breaker. I've attached a pdf file showing the PCS wiring.
You may have had something else turned on when you tried to use the microwave, since the Magnum MMS1012 maximum charging rate is 50A DC, which equates to 5-6A AC. The microwave draws 12-13A AC, of course it could be a little higher on start. So the total load would be 17-19A AC, pretty close to the max of 20A. Anything else turned on like the TVs would push the current over 20A and then the PCS/EMS would turn off the microwave.
You don't have the option of turning the battery charging system to standby, unless you have added a total battery cut-off switch when you upgraded the batteries. The charger will always charge the batteries as first priority when either plugged into shore power or running the generator.
I easily reach the 30A limit whenever plugged in and using the water heater plus AC and then try to use the microwave. It's a good system that prevents tripping circuit breakers. I also use the PCS/EMS AC Amps display to tell how much I'm loading the generator when running it for use or just to routinely exercise the generator.
Hope this helps,
- - Mike
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2013 Lounge EXT on 2012 Sprinter
Thanks for the update - glad your microwave is OK. For clarity your batteries are not charged by the EMS. They are charged by the Magnum inverter/charger. The Centex tech would have changed the Magnum settings.
What Airstream calls the EMS is know as a MINI POWER CONTROL SYSTEM (Mini-PCS) by the vendor Precision Circuits Inc. I've attached an image of the control panel. When running the generator the green "GEN" should be lit. Then as Protag mentioned you only have 20A service. You can monitor the AC Amps on the PCS/EMS panel as it measures current through the Main Circuit Breaker. I've attached a pdf file showing the PCS wiring.
You may have had something else turned on when you tried to use the microwave, since the Magnum MMS1012 maximum charging rate is 50A DC, which equates to 5-6A AC. The microwave draws 12-13A AC, of course it could be a little higher on start. So the total load would be 17-19A AC, pretty close to the max of 20A. Anything else turned on like the TVs would push the current over 20A and then the PCS/EMS would turn off the microwave.
You don't have the option of turning the battery charging system to standby, unless you have added a total battery cut-off switch when you upgraded the batteries. The charger will always charge the batteries as first priority when either plugged into shore power or running the generator.
I easily reach the 30A limit whenever plugged in and using the water heater plus AC and then try to use the microwave. It's a good system that prevents tripping circuit breakers. I also use the PCS/EMS AC Amps display to tell how much I'm loading the generator when running it for use or just to routinely exercise the generator.
Hope this helps,
- - Mike
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2013 Lounge EXT on 2012 Sprinter
Thank you for clarifying. I did make sure there was nothing else turned on except the overhead lighting. That is why I suspect the change to charging rate is the culprit considering I've never experienced this prior to the battery upgrade. In the menu of the Magnum control panel there's an option to place the battery charger on standby. I've not added a total battery cutoff switch. Are you suggesting that option is only displayed and not actually functional?
Thank you for clarifying. I did make sure there was nothing else turned on except the overhead lighting. That is why I suspect the change to charging rate is the culprit considering I've never experienced this prior to the battery upgrade. In the menu of the Magnum control panel there's an option to place the battery charger on standby. I've not added a total battery cutoff switch. Are you suggesting that option is only displayed and not actually functional?
Jeff - my error, you can indeed turn charging on and off via the control panel.
- - Mike
2013 Lounge EXT on 2012 Sprinter
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- - Mike
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