National Dolphin 05 battery drain

[JJH3rd]

We returned from a two week trip a couple of weeks ago and set up the MH in the back yard with shore power from a 50A circuit off my shop. We had to be away from home for the weekend and when we got back I found the following:


1 – the A/C wasn’t working – I left it set at 88F so that the insides don’t roast in the GA summer
2 – the house batteries (two) were reading 8.8v on the panel (chassis battery at 12.2v)
3 – the 12v lights were barely flickering
4 – the inverter was inadvertently left on


Applying Occam’s razor and not being able to get anyone to work on the MH on a Sunday (without $$$) I put the house batteries on a charger. What a difference a few volts make! As soon as the house batteries read 11v, I started the A/C and bingo its works as per usual. Also I can use the 12v lights to read the panel – they are working fine as well.
I blame all this on leaving the inverter in the “on” position while connected to shore power for a long period of time. I read in one of the posts in this forum that for my model, the inverter/converter actually trickle charges the batteries when it is “off” and connected to shore power. I deduced that by having it on all that time it kept sucking power out of the batteries to provide 120vac that the A/C didn’t need because it was connected to a 50A shore supply. Somehow, when the voltage dropped low enough the A/C stopped using the full compressor (it will work from a 120V/30A line – but at about half power).

Am I just thinking wishfully or are my logic and deductions sound?

JJ

[donhoward49]

Not being a mechanic, i think you are correct. When my inverter was "on" it tried to operate the fridg. I have a wall switch for the inverter by the entry door, and also a switch on the inverter, both switches must be "off". Donn't know why two switches but with only the wall switch off it still tried to operate the TV.. I see using the inverter only for boondocking, and have no plans for that.
Also be sure your cable/antenna switch box up next to the TV is off, as it will draw some 12 volt.

[JJH3rd]

Thanks for reminding me of phantom loads. I'll go on a hunter-killer run.

JJ

[hdossett]

Your A/C and fridge do not run on the inverter. (or at least I have never seen a setup that did). They do use 12VDC for control voltage. The inverter would have shut its self off @ the battery low voltage point, maybe 10.5V.

So, why did the batteries go flat? Charger not charging and phantom loads draining them? A 2005 model should have an inverter/charger with an auto-transfer switch which would put all loads on shore power when you plug in.

Back to why no charging. Did you notice if the charger was in fact on while you were away?

That would be my first guess!

good luck and let us know what you find.

H
P.S., what inverter/charger do you have?

[Richard S.]

My 07 Seabreeze fridge was pluged into an outlet that was powered off the inverter, this was from the factory that way. I changed to the other outlet in the fridge compartment that is only hot on shore power.

[JJH3rd]

The MH has a Xantrex Freedom 458 inverter/charger. (Pic #1) As I worte, now that the house batteries are charged, all is well.

In the process of taking the picture of the Xantrex I came across this red toggle switch on the left rear) wall of the compartment with the other DC control circuits. What does it control? (pic #2)

[Bill WA6YBD]

I have the same make and year as your coach. Mine does not have that switch. Its hard to tell but it kinda looks like a battery disconnect switch that may have been added and not factory. What does it do when you flip it??

~Bill

[JJH3rd]

In our Dolphin the 6V house batteries were replaces with two 12V batteries and apparently at that time a DC cut-out switch (the red-handled one in pic #2) was installed between the Coach and the starting battery.
When that switch is "off" nothing lights up when you turn the ignition key. With it on - every thing works. I suppose it is an anti-theft device.

JJ

[Bill WA6YBD]

So the disconnect switch is on the chassis (motor) battery. One time I had a dead coach battery. I never fully understood why. I suspected something to do with the electric steps as they are connected to the chassis battery I think or they are connected ahead of the battery disconnect for the house batteries. The dead battery only happened once and I was able to start the engine using the battery boost switch. The battery recovered even though it was stone cold dead. Every time I go to get the MH from storage I have a cold feeling the battery will be dead again but so for so good.