Microwave drawing significant power, or batteries low?

[littlec]

Hi all,

Last weekend, I heated up some coffee in the microwave and *bam*, my AGS kicked in. I had thought my batteries were fully charged (as indicated by lights on control panel, not known for their accuracy). However, I thought that a full bank of charged batteries could have heated at least one cup of joe without crying uncle. Any thoughts?


Thanks,
littlec

[Mekanic]

how many and how old are these batteries? some times a old and dying battery can have 12 volts at rest and then when you apply a load it all of a sudden it turns into a 7 volt battery.

[BryanL]

Check connections and make sure they are tight between the battery and inverter. The wiring should be 2g or larger and very short.

Make sure your battery gets a full and complete charge.

Consider bank size. a 1 kw microwave load needs at least 100 pounds of battery. (usually no problem with a Newmar, I'd think).

Then, see Mekanic's advice. As batteries age they get weak and internal resistance builds. That will show as a voltage drop under load. You should expect 4 or 5 years from the batteries if they've been treated right.

[YC1]

Check your programming for the generator start voltage setting. You can set it for 10.5 dc and have a bit more leg room.

[Perry White]

If you watch the amp draw on your microwave you will be surprised. My AGS kicks in at 11.4 volts. It doesn't take much to load the batteries. Turn AGS off when using your heavy appliances. The bats will dip and go back up when done with micro.

[HoRotica]

I just fixed our house microwave last week. I had it plugged into a Kill-A-Watt to verify that it was working correctly. Drawing nearly 15 amps while it was running...

Chris

[WheelingIt]

I agree with the others. Battery voltage will dip quite a bit when you run a heavy appliance, so if your AGS is preset that may be the issue.

[Perry White]

I found out my GE only cooks about half the heat when on modified inverter. Sounds funny too.

[Iron Man]

Quote:

Originally Posted by Perry White I found out my GE only cooks about half the heat when on modified inverter. Sounds funny too.

I have heard of microwaves being damaged by modified sine wave inverter. What brought it to Newmars attention was the first all electric Essex 2005 or 2006 was having issues with the refrigerators. The circuit boards could not handle the modified sine wave inverter power output and Newmar would replace the inverter with a true sine wave inverter. The modified sine wave inverter also caused issue with electric blankets and other electrical items.

[Mr_D]

Quote:

Originally Posted by Perry White I found out my GE only cooks about half the heat when on modified inverter. Sounds funny too.

Our GE Advantium does the same. I have to start the gen if the campgrounds has low voltage too.

[Mr_D]

Quote:

Originally Posted by Iron Man I have heard of microwaves being damaged by modified sine wave inverter. What brought it to Newmars attention was the first all electric Essex 2005 or 2006 was having issues with the refrigerators. The circuit boards could not handle the modified sine wave inverter power output and Newmar would replace the inverter with a true sine wave inverter. The modified sine wave inverter also caused issue with electric blankets and other electrical items.

Newmar didn't like to use the full wave inverters when they had a three year warranty on the rig as the inverters only carried a one year warranty.

[littlec]

Quote:

Originally Posted by Mekanic how many and how old are these batteries? some times a old and dying battery can have 12 volts at rest and then when you apply a load it all of a sudden it turns into a 7 volt battery.

Hi Mekanic,

For coach batteries, I've got 4 12V, about a year-and-a-half old. I would think they should still hold a charge. I've had them checked at Autozone, where they've assured me that they are still okay. Should I be skeptical, given my microwave experience?

littlec

[wa8yxm]

Quote:

Originally Posted by Perry White I found out my GE only cooks about half the heat when on modified inverter. Sounds funny too.

Microwaves are high on the list of things that do not work properly on MSW, EXCEPTION is made by Panasonic, they have a line of Inverter Microwaves.. These puppies basically start by doing an AC to DC conversion then they do a DC to AC inversion and that runs the microwave.. They are very simply the best made. But expensive.. I've seen one of them.

Other things that do not always work well on MSW include all manner of radio hardware (Includes televisions and sat receivers) Audio amps, electric blankets (of all things) and "Fancy" coffee pots with electronic controls. Simple coffee makers work great.

[tvman44]

A microwave oven will draw 100 to 150 amps from the battery bank. That is a lot of power for a battery bank.