Electrical problem

[awhalen]

Hi
Our coach electric is acting weird. When plugged in the electric won’t work but when engine is started then power comes on and stays on after engine shut down for 10 minutes to three hours before shutting off again.
Any ideas?
Thanks!

[javelin]

So just to be clear, when you are on shore power (AC cord plugged in) you get no DC lights and fans working.......is the use/store switch “on”; are any AC breakers tripped on the converter input? Do your AC appliances work OK?


What happens when you start the Generator.....do you get DC lights and fans working then?


When you start the “engine”......(do you mean the vehicle engine as opposed to Generator?).....the DC lights and fans start working as long as the engine is running and for anywhere from 10 min to 3 hours after you shut off the engine. This sounds like the alternator is charging your coach batteries OK and your use/store latching relay is closed (operated OK) and the converter output/DC fuse panel is being fed 12vdc OK. So depending on how long you charge the coach batteries for, when you shut off the vehicle engine your batteries start discharging to keep DC loads working. Depending on how much load you have on the DC batteries, will determine how long they will operate. Do the DC loads just quit, or do they slowly get dimmer? Also when no DC loads are working and you start the vehicle engine again, do you have to re-operate the use/store latching relay?


By the way it is always valuable to provide coach model and year details, which may allow forum folks to help you faster.

[awhalen]

Thanks-
It’s a Thor windsport 29M 2017.
The a/c power doesn’t work until the RV drive engine starts... so having the RV plugged into a wall 115 volt outlet will work only one the RV is physically started... a minute later the A/C kicks on... I can then kill the engine and the RV will run exclusively on wall 115 outlet current. It will run for ten minutes or 3 hours and then stop. The Olan generator works fine.. it’s as though the engine kicks on the A/C but it won’t last when engine is turned off.. checked every fuse.. no reserve polarity , I lent my RV to a nurse for a month who got the Covid-19 and had to quarantine outside her house away from her kids... she said her house breakers would trip allot with air conditioning on during the day, we are in south FL.. just got it back a few days ago,, thanks for any suggestions or help.

[javelin]

Hi, firstly you should be congratulated for loaning your coach to a nurse working to save people during this pandemic, but afraid to go home to “potentially” infect his/her own family. Cudos to you and him/her for risking your situations in life to help.


So I am not sure how familiar you are with AC and DC power systems in RV’s, and don’t want to be insulting with my questions. I don’t know your coach at all, but a quick look up on net seems to indicate no factory stand alone inverter or inverter/charger (is this correct?)
......so I assume you have the basic stand alone converter (converts 115vac to 12vdc to charge coach batteries and power DC fuses, lights fans etc)?


I am just trying to understand how running the vehicle engine (alternator providing 12vdc) to charge chassis and coach batteries would enable your shore power (AC circuits not on an inverter output– like a blow dryer etc) to function. If we assume your use/store is latched on, then the 12vdc from the alternator would reach the coach batteries and DC fuse panel as well to operate your DC circuits OK. You are saying though that 12vdc is required to operate AC circuits. So are the AC circuits fed from the output of an inverter (12vdc converter to 115vac output?). Sometimes clarifying the problem specifics helps with the solution.

[javelin]

Sorry, been a long day here.....I have AC power on the brain and re-read your post about A/C as in "air conditioner". I think your coach has the 13.5 roof A/C unit and probably is a hard start on just 115VAC from your house shore power. It should be running on the 30 amp shore as a start. The thermostat requires 12vdc to operate and control furnace and A/C unit....so perhaps check the voltage on your chassis batteries.....fully charged wet cell batteries are 12.6VDC. If the coach batteries are discharged 12vdc or below then running the engine charges them up and will enable thermostat operation again.......but if you are on shore power your converter should also be charging batteries and powering DC fuse panel via the converter.

[16ACE27]

Your house batteries are dead and your converter is not working is my best guess.

By starting the RV the alternator will attempt to charge the chassis and then the house batteries.
Until you have 12 VDC on the house DC buss you have no internal DC lights, No control power to operate the fridge, furnace, water heater, or Air Conditioner.

Once you turn off the RV engine the residual charge on the house batteries will continue to provide the needed control power until they are exhausted again. Then everything is off again.

Check your converter 120 VAC breaker
Check your converter output/reverse polarity fuses.

Don't touch your USE/STORE switch as it would have to be in the USE position already for this problem to cause these symptoms.