POWER PROBLEM WITH NEWMAR, NEWBIE

[revrick3]

Help with new owner. Electical problem. I just got a 2003 Newmar Mountain Aire. 38 ft. gas. Chevy engine. Love it so far. Purchased 5 weeks ago and spent 3 weeks in backyard learning unit. Used generator 2 weeks with no problem. Kept it connected to normal 110 between times to keep batteries charged. 3rd weekend had 50 amp connection put in so we hooked to this and it was wonderful and quiet without generator. All working well. Gassed up and went to mountains this weekend with no issues. Had 50 amp hook up, no generator needed. Took all apart to leave today and no issues. Going down the road my wife went to restroom and no water pump. I had her try other switch and control panel over door is out. No inside power at all. Lights, pumps fridge all is out. Stopped and could not find anyting out of ordinary. Checked battery disconnect switch on panel over door and nothing. Still no lights. Cut on generator and in about 15 seconds power back on. Ran it awhile and cut it off and all went dead again. Went on home and hooked to shore power and it all worked again. Nothing was on including steps to get out door. If I ran generaror or hooked to shore it was fine but once I cut on engine only it all died. No issues running motor home or dash or generator, only cabin power. Help before I go broke as a shop please. I am not an electrician but somewhat handy so make your help simple please. Thanks for any help guys. Excited about first trip though it was great.

[msturtz]

There is a relay in most coaches that allows the house batteries to be charged by the alternator. It sounds like to me that that relay isn't closing when you are running the engine. This would cause the batteries to completely drain fairly quickly. Once lead acid batteries have been completely discharged they are damaged and while may come back up they would have greatly shortened life and be unable to hold a charge as long. Depending on how your battery bank is wired Series or parallel any single low or weak battery will bring down the entire bank. This is more of a problem for series wired batteries than parallel but this can still happen with parallel because more of the load is carried by the stronger battery. To test this theory with the vehicle running check the voltage at the house battery bank terminals. Check the voltage at the chassis battery and note it. Next check the voltage at the House battery bank it should be very close with only a few tenths of a volt drop. If it isn't then the relay isn't closing for some reason. A final test requires another person. With the engine running check the voltage at the chassis battery. Have another person press and hold the "emergency start" or "battery boost" button in the driver's area. Check the voltage at the House battery bank. It should be similar to the chassis battery bank. Keep in mind that this relay can be damaged by attempting to charge completely dead house batteries with the engine running. Typically they can't handle inverter loads for long and will either quit working or shut off for self protection.

[bsinmich]

I sent you a PM on the chassis but remembered another item If you need a new headlight for your Mountain Aire they are from a 1997-2002 Grand Marquis. I had one that was bad but never replaced it because I never used the headlights in all the time I had it. We were always parked when we needed headlights.

[enblethen]

I would suggest getting some electrical grease while you are out. Coat the clean conductor with it before crimping or installing new connector.
You could be a good bronze or copper set screw connector rather then a crimp.

[tommy_g]

Thanks Rick, for letting us know your potential problem and solution. This is as much help as anything for future problems of the same kind.

[revrick3]

Thanks for all of the advice. Checked battery power this am and 12.8 on both batteries connected to shore power as well as the same volt disconnected. Puzzled me then so I slid out my batteries and just started looking, did not see any loose connections then I noticed a large red cable laying down behind battery box. Pulled it up and it had corroded off the positive post in the back battery. Checked post and sure enough the end was still under the nut but not visible from front. Now that has to be my issue. Hopefully just get a new end put on this cable and reconnect to batteries and start it all up. You guys are great help. Thanks Rick

[bsinmich]

I just sold my '03 Mountain Aire in May after 11 years of owning it. I loved it and really miss it. There is no inverter to look for (unless added after market) The 2 6 V batteries are on the Right side and easily overlooked. The 2 batteries do last many years when taken care of. My guess is the batteries may have a shutoff or the cables could just need cleaning to get oxidation off of them. Those cables did corrode a lot on mine. When cleaning cables and battery posts only do one at a time to make sure they are all hooked up properly. I solved that problem by going with AGM golf cart batteries. No more corrosion and battery cleaning.

[msturtz]

There is a solenoid that connects the coach battery bank to the chassis battery bank when the engine is running and depending on the coach manufacturer when connected to shore power. It is very common for that part to fail which has the effect of no power while driving. If this is the case your coach battery bank is likely shot and will need to be replaced. It is easy to test to see if this part has failed. With the coach running connect a multi-meter to the coach or house battery bank. You should have about 13.6 VDC. If you have less then the relay isn't working.

[dougrainer]

revrick3 wrote:
Thanks, batteries are only 1 year old, both of them, System was working fine then it just stopped while driving. When I disconnected from shore power the lights worked and steps worked. Then about an hour later nothing worked. The inverter circuit breaker, where is this at. Can you walk me through how to trace this down. Remember guys, I am fairly familiar with 12 volt auto and 110 house current but this is a mix with inverters an converters and this is all new to me.

"Thanks, batteries are only 1 year old, both of them"

Batteries need constant vigil to make sure they are not boiled dry. Check the battery water. If left plugged in that will give a constant charge to the Coach Batteries and will boil them dry. Your Inverter/Converter circuit IS working or you would NOT have 12 volt power from Shore Or Genset. Doug

[enblethen]

He should still have 12 volts going down the road with main engine running.
The inverter if equipped should not effect the 12 volt systems.

[revrick3]

Thanks, batteries are only 1 year old, both of them, System was working fine then it just stopped while driving. When I disconnected from shore power the lights worked and steps worked. Then about an hour later nothing worked. The inverter circuit breaker, where is this at. Can you walk me through how to trace this down. Remember guys, I am fairly familiar with 12 volt auto and 110 house current but this is a mix with inverters an converters and this is all new to me.

[clinedinstjt]

reset your circuit breaker on your inverter. This may solve your problem

[Tom_Barb]

enblethen wrote:
Sounds like battery disconnect for coach is in the off position.

Or his main Battery fuse has blown, or possibility of the power transfer switch failed to transfer power and stayed in the external position.

[enblethen]

Sounds like battery disconnect for coach is in the off position.

[dougrainer]

You need to check the Coach battery water. Odds are the batteries have NO water and are dead. The reason you have power on 50 amp and Genset is the Converter is supplying the 12 volt power. With the Chassis engine running the Chassis engine Alternator is then supplying the 12 volt power. Doug