Community Forums

tanner.p · 03-20-2020, 03:31 PM

I recently purchased a 2017 Fleetwood Discovery LXE (40G). I started the generator and tried running the microwave. About 40 seconds into cooking the inverter cut out and the firefly panel showed low house battery voltage. Do I have to do something to switch from battery/inverter power to generator power? I was under the impression that this was automatic.

twinboat · 03-20-2020, 03:34 PM

Go out to the generator and check the circuit breakers on it. If they are off, no power gets to the RV.

With the generator running and outputting power, the inverter should be in charge mode.

96 Wideglide · 03-20-2020, 03:35 PM

Should be

!!

tanner.p · 03-20-2020, 03:43 PM

The reported battery voltage increased after the generator ran for 30 minutes following the cut out, so from that it seems like the batteries are charging. I wasn't able to enable the inverter again until I went out and manually cut/reset the inverter's power switch.

I did recently clean a fair bit of corrosion off the battery cables. Could corrosion be a way to explain this? I've seen much worse corrosion on car batteries, so I wasn't alarmed. I'm new to most of these electrical components and trying to better understand what is going wrong.

twinboat · 03-20-2020, 04:28 PM

Is the inverter/charger panel showing a charge light ?

Was the volts up around 13 volts or more ?

So you have an amp display, showing high charging amps ?

Did you physically check the breakers on the generator ?
Some generators have small alternators that charge the batteries. Doesn't mean its outputting 120 volts.

tanner.p · 03-23-2020, 03:34 PM

Thank you for the responses!

I can now better describe what was happening. I had turned on the generator and thought it was working as expected. I wasn't getting microwave power until I also turned on the inverter. It turns out the breaker at the generator was off and I was powering the microwave purely off the inverter. Being hours new to all the switches at the time, I assumed the inverter needed to be on along with the generator.

If curious, I posted another thread regarding the generator powering my cooktop.

What should be able to expect in terms of running the microwave off a 2,000 watt inverter. Like I described, the microwave ran for about 40 seconds before the batteries were drained. Is this a sign of bad batteries, or should no one ever run a microwave off the inverter?

And on that note, maybe someone can chime in on the visual condition of these batteries? Is this a bad bulge? Kinda looks like it. (white streaks are from my baking soda cleaning)

Bigd9 · 03-23-2020, 03:58 PM

My take is someone has tightened the hold down too much and that has cocked and raised the top of the battery. I don't know if that has damaged the batteries or not. Check to make sure the water level in each cell is at the correct level. Also you can carefully use a hydrometer to check the acid to see if the batteries are charged or not. The batteries should all read the same.

See if you can check the voltage on each battery. They should all be the same.

I sent you a PM(private message)

tanner.p · 03-23-2020, 05:21 PM

Quote:

Originally Posted by Bigd9

See if you can check the voltage on each battery. They should all be the same.

I fully charged all 6 batteries overnight (shore power). Then I turned off the inverter and the main/aux switches and let everything sit for a week. I measured the voltage on each battery with the cables removed. The 6 house batteries measured as follows:

6.75
6.75
6.76
6.71
6.78
6.77

A hydrometer would be my next step. I guess you could say at this point I'm trying to determine what to expect from the batteries.

Bigd9 · 03-23-2020, 05:36 PM

They look good. Check out this website for Trojan battery voltages at various charge states. see table 1.
https://www.trojanbattery.com/tech-s...y-maintenance/

Side note, I usually leave the inverter on 24/7. That way the residential refrigerator will keep on running as we travel down the road.

Gary RVRoamer · 03-24-2020, 10:21 AM

Your voltages are fine, but that's not the entire picture. If you have 4 (or more) 6v house batteries, you should have adequate of DC power (amp-hours) to run most anything for awhile. However, the inverter is sensitive to the DC voltage and batteries that can keep the all lights going for a dozen hours may drop below the inverter's minimum voltage threshold rather quickly when the amp load is high. This can be caused by a poor quality connection at one or more places, or by batteries that have lost capacity due to frequent deep discharging.

A microwave is a high power consuming device, so is likely driving that 2000W inverter to near its max capacity. 2000W requires that the inverter pull a steady 170 amps from those batteries. That's a lot, so 40 seconds isn't out of the question. But if you have 6 x 6v batteries for the house (not including engine starting), then it should be enough to handle the microwave for 5+ minutes if the batteries are all good.

TonyMac · 03-24-2020, 10:37 AM

So, why is your generator not powering your microwave, and every other 120vac thing in your rig? On mine, I don't use the INVERTER for anything when the generator is running, or when connected to shore power. Seems like your batteries are fine, and not part of the problem anyway.

sibe · 03-24-2020, 10:38 AM

Quote:

Originally Posted by Gary RVRoamer

Your voltages are fine, but that's not the entire picture. If you have 4 (or more) 6v house batteries, you should have adequate of DC power (amp-hours) to run most anything for awhile. However, the inverter is sensitive to the DC voltage and batteries that can keep the all lights going for a dozen hours may drop below the inverter's minimum voltage threshold rather quickly when the amp load is high. This can be caused by a poor quality connection at one or more places, or by batteries that have lost capacity due to frequent deep discharging.

A microwave is a high power consuming device, so is likely driving that 2000W inverter to near its max capacity. 2000W requires that the inverter pull a steady 170 amps from those batteries. That's a lot, so 40 seconds isn't out of the question. But if you have 6 x 6v batteries for the house (not including engine starting), then it should be enough to handle the microwave for 5+ minutes if the batteries are all good.

you should have about 600+ AH in theory depends on micro wave 140-170 amp draw will be typical so even at a 50% dischare of lead acid 300+ amp hours will let that mikeywave run for atleast an hour if not 90-100 minutes..

Have proper volts is only part of the equation on a batter, it a cell is week....it aint gonna hold amps.. I have a genny battery that holds perfect volts. but put a small load on it, it drops like a prom dress.. sorry ..

tanner.p · 03-24-2020, 11:02 AM

Quote:

Originally Posted by TonyMac

So, why is your generator not powering your microwave, and every other 120vac thing in your rig? On mine, I don't use the INVERTER for anything when the generator is running, or when connected to shore power. Seems like your batteries are fine, and not part of the problem anyway.

The answer to the generator not powering the microwave was an issue with the breaker on the generator being off. If only everything was as simple as flipping a switch! In my case I just had to find the switch!

Quote:

Originally Posted by sibe

you should have about 600+ AH in theory depends on micro wave 140-170 amp draw will be typical so even at a 50% dischare of lead acid 300+ amp hours will let that mikeywave run for atleast an hour if not 90-100 minutes..

Have proper volts is only part of the equation on a batter, it a cell is week....it aint gonna hold amps.. I have a genny battery that holds perfect volts. but put a small load on it, it drops like a prom dress.. sorry ..

Makes sense. I don't know for sure how well the batteries were maintained over the last few years. It's possible they were abused. Either way, it makes sense that the microwave would push the inverter near its limits and could lead to short run times if the batteries or connections aren't in great shape.

creativepart · 03-24-2020, 11:24 AM

Since you solved the generator issue, let’s deal with the inverter cutting off with microwave usage. Assuming that your batteries are fully charged and from your description it sounds like they are, then the issue is likely caused by a momentary voltage drop and the voltage drop settings you have on the inverter.

When the microwave cranks up the heating power it puts a big load on the inverter which causes a big momentary voltage drop at your batteries. Most inverters have a setting that cuts out the inverter at a specific voltage. The default setting is pretty conservative to prevent battery damage.

It’s likely this is why your inverter shut off after 40 seconds.

I have 400ah of batteries and had my Magnum MS-2012 inverter do the exact same thing, with fully charged batteries. My inverter was set to turn off at a voltage of 12.2v. That seems like a good number for low voltage cutoff but it fails to recognize momentary voltage drops like you’re likely seeing from the microwave.