Our first boon dock night in our new to us MH and the 12V DC went dead. When I bought the coach they told me the batteries were fairly new I need to see if they have dates on them. Now for the use maybe I am expecting too much.The coach was plugged in for several weeks before we left on the trip so the batteries should have been fully charged. We drove around 2 hours to our destination. While driving we had the inverter on to play the stereo system. When we arrived we left the inverter on plus a few lights all LED. We watched a couple movies and it was fairly cold with the heater coming on and off very frequently. I also sleep with a CPAP machine so I need the inverter on for that machine. At 3 AM I woke up to an alarm beeping. I checked the battery voltage and it was down to around 9 volts. I had to start the coach and let it run for a couple minutes to start the generator. I let the generator run until about 6 AM. I can run my CPAP machine off 12 volts but I would need to wire a 12 volt receptacle next to my bed. Do the inverters draw a lot of power if they don't have a large load on them?Had I run the generator before going to bed we would have probably been OK but it seems it should have lasted longer than it did.I have a large solar panel on top and I know that does nothing at night but I am just giving all the particulars of my system. My battery bank for the house is 4 - 6 volt golf cart type batteries.This is our first RV with an inverter so I don't know what to expect.

The heater probably killed the batteries the fastest. That fan motor pulls a lot of amps.

Inverters do pull some power but first, how large is your battery pack? (amperage wise) then, what was your voltage prior to going to bed? (how fast did it discharge)How fast dit it charge? on the generator? How fast the battery pack will charge or discharge will give you an idea the condition of the batteries.

I wonder if a fuse has popped, had that happen withour FW. With the coach running check voltage at the batteries, should be around 13.5VDC

First off, you have 12 volt wires running all over the coach so it should be fairly easy to get a 12 volt outlet for your CPAP machine wired in. This will take care of the most important thing. If you have the original electronic equipment in your coach, like the TV and VCR, then I am sure that those items drained a lot from your batteries in a few hours. The newer electronics are much more efficient and they do have some TV's that run off of 12 volts. The inverter does draw some current if it is turned on, and especially if the battery charger portion is also turned on. The LED light are a good idea but I assume that they are all 12 volt lights and do not need the inverter. The 12 volt heater fan does draw some amps and does not need the inverter to operate.

I have seen some inverters that pull 4 amps at idle, no output load. That being said, 4, 6 volt batteries should last at least overnight. Have you checked the battery connections and the level in the batteries. A swelling I the cable usually means there is corrosion under the insulation.

Ran out of 12 DC @ 3 AM 1st night. | Good Sam Community

57 Replies

midnightsadie
Explorer II
Nov 12, 2018
you need your batteries tested, first place I,d start.
JimMooreGain
Explorer
Nov 12, 2018
With all the stuff you mentioned running, I'm not surprised the batteries ran down overnight, based on years of full timing and reading on forums like this one. Tonight make sure you run the generator before bed. When you get home, best to get that 12V adapter installed in the bedroom. But for now, you might just get a looooonnng extension cord so you can plug into the nearest 12V outlet.

Yes, an inverter does draw a relatively large amount of power at idle. Newer models are better then older models of course. Most manufactures finagle the ratings and state 80% to 90% efficiency but that's a pipe dream. Most can't reach 75% in practice, some poorly designed units only reach 50%.

Of course this all goes back to the batteries and if the batteries were cheap to begin with, that 9 volts you saw might mean they're not going to last long. You let them get that low too often and they'll be ruined.
wildmanbaker
Explorer
Nov 12, 2018
I have seen some inverters that pull 4 amps at idle, no output load. That being said, 4, 6 volt batteries should last at least overnight. Have you checked the battery connections and the level in the batteries. A swelling I the cable usually means there is corrosion under the insulation.
rgatijnet1
Explorer III
Nov 12, 2018
First off, you have 12 volt wires running all over the coach so it should be fairly easy to get a 12 volt outlet for your CPAP machine wired in. This will take care of the most important thing.
If you have the original electronic equipment in your coach, like the TV and VCR, then I am sure that those items drained a lot from your batteries in a few hours. The newer electronics are much more efficient and they do have some TV's that run off of 12 volts. The inverter does draw some current if it is turned on, and especially if the battery charger portion is also turned on. The LED light are a good idea but I assume that they are all 12 volt lights and do not need the inverter.
The 12 volt heater fan does draw some amps and does not need the inverter to operate.
romore
Explorer II
Nov 12, 2018
I wonder if a fuse has popped, had that happen withour FW. With the coach running check voltage at the batteries, should be around 13.5VDC
Tom_Barb
Explorer
Nov 12, 2018
Inverters do pull some power but first, how large is your battery pack? (amperage wise) then, what was your voltage prior to going to bed? (how fast did it discharge)
How fast dit it charge? on the generator?
How fast the battery pack will charge or discharge will give you an idea the condition of the batteries.
D_J_Wade
Explorer
Nov 12, 2018
The heater probably killed the batteries the fastest. That fan motor pulls a lot of amps.

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Ran out of 12 DC @ 3 AM 1st night.

57 Replies

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