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Old 07-16-2016, 08:07 PM   #1
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Magnum Low Battery Fault Microwave

Hello

Ended up boondocking on brother-in-laws driveway for a month in 90 deg plus temps due to a family emergency. I am pushed into finally making the effort to fully understand the Magnum AGS system.

Not sure if I am expecting too much but I am trying to run the microwave using the PureSine inverter. I have the low battery cutoff set to 11.5v and meter is reading 12.8v. When microwave or other hi current appliance starts the low battery faults and we loose all ac.

Seems obvious to start by lowering the battery cutoff voltage but I am just not sure if is possible to power these appliances with our system. We have the Magnum and 6 -6v Discovery AGM's.
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Old 07-16-2016, 09:24 PM   #2
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I would look into the voltage settings for your AGM batteries. My understanding (and I am not an expert) is that depleting them below the 50% charged rate severely shortens their life. As a result, I start my generator at about 12.3 volts. I would get a learned opinion on what the start voltage should be - I suspect 11.5 is way too low unless you own a battery shop. Hopefully, you will find someone here who can provide the answer.
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Old 07-16-2016, 09:38 PM   #3
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It appears that your battery back is severely low on voltage to start with, you may have to take a voltage check at the battery with a good voltmeter.
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Old 07-16-2016, 09:45 PM   #4
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Is your AGS set to Auto GenSt Enab? This is the normal operating setting. Our manual says to set the start volts at 11VDC. Set one ac to start when the temp is reached that you set the thermostat at. Set the second to start 2 to 5 degrees higher. Have you tried the autogenst test? From the sound of it you are pulling more amps than the system can supply.
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Old 07-16-2016, 11:11 PM   #5
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See if this helps. Click on the yellow post it notes and they will pop up.
Attached Files
File Type: pdf Remote Control (ME-RC).pdf (1.25 MB, 47 views)
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Old 07-17-2016, 06:42 AM   #6
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If the cables to the inverter are not big enough, voltage will drop under load, and cause low voltage shutdown.
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Old 07-17-2016, 07:08 AM   #7
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Quote:
Originally Posted by mpierce View Post
If the cables to the inverter are not big enough, voltage will drop under load, and cause low voltage shutdown.
Ditto dirty battery connections, loose or dirty connections anywhere between the battery post and the Inverter input. You are sucking a lot of DC current to run the microwave. I hope you have several big batteries. If not add the internal resistance of the batteries to the list.

FWIW I would not try to run the microwave off the battery bank. I know some folks do and talk about it. It is still a bad idea because it sucks out a lot of current. That is not what deep cycle batteries are intended to supply.
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Old 07-17-2016, 08:05 AM   #8
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https://search.yahoo.com/search?p=yo...12&type=926458

Check this video out.
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Old 07-17-2016, 08:24 AM   #9
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You could do some troubleshooting by running MicroWave for 30 seconds and then feel the battery terminals.

Although you are pulling 150 to 200 amps, that current is divided between all 6 of your batteries. That works out to less the 30 amps each.

If any connections are warmer than the others, that could be your problem. It the main cables or any connections in between are hot, look for problems there.

One other test is to hold the boost switch, turn on the MicroWave and see if it shuts down due to low voltage. If it don't, I would suspect your batteries.
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Old 07-17-2016, 04:37 PM   #10
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Thank you Bob. I was trying to push the start v setting lower to account for a surge that might drop the voltage for more than a minute or so hoping that voltage would stabilize before the fault.
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Old 07-17-2016, 04:45 PM   #11
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Yes. Enabled. I have the Acs setup as you described and they work fine because the Gen Auto Starts as soon as the thermostat calls for power so dc is not required. I know I mentioned the heat here but that is what motivated me to start learning about the ags system.
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Old 07-17-2016, 04:54 PM   #12
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First time I have seen that PDF format. I noticed the one note re Low Battery Cut Out set to 10. I have mine set to 11 to protect the batteries.
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Old 07-17-2016, 05:02 PM   #13
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Generalizing probably won't give you the answer you want but "in general" running 800 to 1000 watt appliances is not a good practice for inverters and worse for the batteries they draw on. A quick call to the manufacturer tech folks will indicate that. You can do it but there is a fairly good chance you will not be satisfied in the end. I had a friend that had to do it to support a dialysis machine so he got 4 dedicated batteries just for that...it worked but he had to pay attention and it wasn't cheap.
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Old 07-17-2016, 05:23 PM   #14
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Quote:
Originally Posted by Oggi View Post
First time I have seen that PDF format. I noticed the one note re Low Battery Cut Out set to 10. I have mine set to 11 to protect the batteries.
The reason for 10 is because a sudden surge by turning on a microwave can take the voltage down at the inverter to that level. This does not mean the voltage right at the batteries goes quite that low but close and it is just momentarily. This keeps the generator from kicking on during the day boondocking and my Solar is trying to catch up.

No, 10 volts is not the place you want your batteries run down to. Not even 11 but temporary drops won't kill them.
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