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RV 4 2 · 01-03-2012, 10:45 PM

Sorry this is kind of long.
I have an 08 - 36' Dolphin on a W24 chassis. I thas the 2000w inverter and the 4 batteries in the compartment forward of the door.
I have had to replace the chassis battery in Sept 2010 and the 4 Trojan house batteries have not been replaced yet.
So here go my questions.
1. I think I was told that this is how National wired the coaches and I think it is wrong but when the coach is plugged into ground power, I cannot turn on any lights or appliances when the battery switch is not engaged. I can understand this when not connected to ground power but not when it is plugged in. Can someone explain this one to me as it makes no sense.
2. Whenever I plug into ground power, I hear a solenoid sound in the power bay (I figure it is the power transfer switch) but it is never immediate. It can take anywhere between 1 and at times up to 5+ minutes before I hear it. Anyone care to guess why it is not consistent?
3. As said above, I replaced my original chassis battery in Sept 2010. I am already having issues with the charge on the battery. As near as I can tell, there must be a decent draw on the chassis somewhere as I am finding that if I do not plug in the coach, my chassis battery drops down below 11V in a couple of weeks. Anyone have suggestions on how I can go about testing and trying to figure out what is causing such a drastic drain. I am a EE but right now basic testing and troubleshooting with a multimeter is escaping me and I don't have access to the instructions right now.
4. when I test my house batteries, I see voltage levels anywhere above 12.3V but when I plug in my coach to ground power, my inverter hums loud enough to hear inside the coach and the charge indicator shows red for a while before going to yellow and then green. I recently checked my house batteries while the inverter was humming and I could hear bubbling in the batteries. I think the charge at the time was a little over 13V. Is this normal for the inverter to hum like this while charging the batteries and what about the bubbling? Is that normal? I did notice that the inverter fan was not running and the area around the inverter was not any warmer than anywhere else in the bay. It has done this as far back as I can remember since purchasing the coach new. Any insights would be helpful.

Thanks to anyone who reads through this novel and can offer any insights, answers, or suggestions.

M&EM · 01-03-2012, 11:21 PM

Mike and Linda,

"I have had to replace the chassis battery in Sept 2010 and the 4 Trojan house batteries have not been replaced yet.
So here go my questions. "
1. I think I was told that this is how National wired the coaches and I think it is wrong but when the coach is plugged into ground power, I cannot turn on any lights or appliances when the battery switch is not engaged. I can understand this when not connected to ground power but not when it is plugged in. Can someone explain this one to me as it makes no sense." The battery switch disconnects 12 volts supply to the coach. The coach lights work on 12 volts. Thus no lights when switch is off. The refrig, furnace and other appliances requiring 12 volts will also will not work.
2. Whenever I plug into ground power, I hear a solenoid sound in the power bay (I figure it is the power transfer switch) but it is never immediate. It can take anywhere between 1 and at times up to 5+ minutes before I hear it. Anyone care to guess why it is not consistent? What you may be hearing is the isolation relay being activated that connects coach and chassis battery system together to share the charging source provided by the inverter. This action depends on the state of charge of the coach batteries which may vary from time to time. The system allows the coach batteries to attain about 13 volts before sharing with the chassis battery.
3. As said above, I replaced my original chassis battery in Sept 2010. I am already having issues with the charge on the battery. As near as I can tell, there must be a decent draw on the chassis somewhere as I am finding that if I do not plug in the coach, my chassis battery drops down below 11V in a couple of weeks. Anyone have suggestions on how I can go about testing and trying to figure out what is causing such a drastic drain. I am a EE but right now basic testing and troubleshooting with a multimeter is escaping me and I don't have access to the instructions right now. Check to see if the radio has a switch on the dash that allows it to operate 1 as a radio or 2 provide sound from the TV. This switch will allow the radio to draw power if not in the center off position. There are other phantom loads that will run down battery charge in 3 weeks time. Battery disconnects may be a way to prevent this.
4. when I test my house batteries, I see voltage levels anywhere above 12.3V but when I plug in my coach to ground power, my inverter hums loud enough to hear inside the coach and the charge indicator shows red for a while before going to yellow and then green. I recently checked my house batteries while the inverter was humming and I could hear bubbling in the batteries. I think the charge at the time was a little over 13V. Is this normal for the inverter to hum like this while charging the batteries and what about the bubbling? Is that normal? I did notice that the inverter fan was not running and the area around the inverter was not any warmer than anywhere else in the bay. It has done this as far back as I can remember since purchasing the coach new. Any insights would be helpful. I think some humming is normal. Out gassing during charging is normal. More vigorously bubbling occurs around 14.4 volts. If this happening at 13 volts, I would suspect a battery issue. The inverter fan may only need to run as the inverter internals requires extra cooling as on a hot ambient or very heavy charging rate.

wa8yxm · 01-04-2012, 12:36 AM

The dropping voltage on the chassis battery if not charged is.... normal

There are two ways to wire the converter,, House or battery side of the disconnect switch. appears they choose battery. Rare but not improper.

As for the solenoid sound.. I can't tell. too many options there.

RV 4 2 · 01-05-2012, 09:56 PM

Guys, thanks for the input. Now I don't feel too bad and maybe some of these problems are normal. In some cases, kind of stupid but normal.
on #1, it didn't occur to me that some of the other appliances needed 12v, duh. BUT by plugging in the coach to ground power and turning on the inverter, shouldn't many of the 12V dependent devices be able to run without connecting the house batteries?
To me they should but maybe that is how the coach is wired. Kind of like what wa8yxm was stating. Again, kind of dumb in my opinion but I will accept it.
#2 That makes a lot of sense, thanks.
#3 as for the radio switch, I remember there being one for TV audio through the stereo system but not the radio. I will have to take a look at that switch but I think it was just a two position switch.
#4, that makes sense also but I can't say I have ever heard that with some of my friends coaches but then I think their inverter/house batteries are in a different location that may not be as easily heard as my coach. I will have to try to remember to ask them.

Thanks again,
Mike