RV Electrical question

[lenray]

Lady friend has a 50 amp RV. Her battery is reading 9.6. Some inside electrical things work others don't. Do you need a fully charged battery even if hooked up to shore power>>>>??? Across the two hots is 220. Each hot to a ground is 120.

 

[504]

Almost nothing will work without a good battery in an RV. Most stuff runs through the inverter.

 

[DannyE]

On my 18 cedar creek everything in the camper that runs on 12 V will run great without the battery connected Dan

 

[KCTractors]

It is possible that the convertor is not working. Unhook the 12 volt battery and plug the 120 volt cord back in in to the RV. The 12 volt lights should work, if they don't the convertor may be done for.

 

[leroy in ne]

Circuit breaker or fuse to converter, reset on internal breaker on converter. Has any one checked these possibilities of being present and tripped?

 

[buickanddeere]

. Three prong 50 amp RV plug and receptacles have a ground , neutral and one live line that is 120V to neutral .
Probably burned the battery charger to a crisp .
Time to find the fool that wired the receptacle with 240V and give them a thrashing .

 

[MarkB_MI]

Power converter is probably bad. After being discharged to less than ten volts, there's a good chance the battery isn't any good, either.

There are a pair of big fuses on the power converter (probably 40 or 50 amps) whose purpose is to protect against reversed battery polarity. That's the first place I'd look. And if one of those is blown, make sure the battery is hooked up properly (negative to ground) before replacing it.

A very common power converter is the WFCO WF-8955. These can be replaced with a Progressive Dynamics PD4655 which is a much better unit.

 

[MarkB_MI]

> Three prong 50 amp RV plug and receptacles have a ground , neutral and one live line that is 120V to neutral . Probably burned the battery charger to a crisp . Time to find the fool that wired the receptacle with 240V and give them a thrashing .

You may be thinking of the three prong 30 amp plug. A 50 amp RV plug has four prongs. 50 amp RV service is normally hooked up so you have 240 volts from hot to hot, but it will still work if it's wired so both hots are wired to the same leg (assuming the RV has no 240V appliances).

 

[MarkB_MI]

Correction: With 50 amp service, your friend's RV probably doesn't have an 8900 series WFCO converter. I don't know if there's an upgraded replacement converter available for the 50 amp WFCO converters.

 

[MarkB_MI]

A bit more information for you: Most of the stuff in an RV runs off 12 volt power, or at least requires 12V power to operate. This includes the lighting, refrigerator, furnace and water pump. The refrigerator will switch from propane to 120 VAC when you have shore power.

There are just a few appliances that require shore power to operate, including air conditioners, TV set and microwave oven. If your shore power is good, these will all work. If not, they won't.

If all the 115 volt appliances are working, and the 12 volt appliances are not working or are barely working, the power converter isn't putting out any DC power.

 

[Tony in SD]

X2 what mark said

 

[Geo-TH,In]

Mark,
I don't own an RV so I know very little about the converter.

I'm guessing they are nothing more than a large 12v battery charger. Do they have large capacitors?

I have the mother of all diodes.
The phone company used large DC power supplies and these came out of the power supply. I've been saving the diodes in case I find a DC welder that needs huge diodes.

 

[MarkB_MI]

> I'm guessing they are nothing more than a large 12v battery charger.

Well, yes. They're typically three or four stage chargers. They also handle both AC and DC power distribution. I'm only familiar with the low-end converters; I'm sure the big rigs have much more sophisticated converters, probably with inverter capability.

> Do they have large capacitors?

No, not really. I think they mostly rely on the battery to filter their output. I'm pretty sure they use switching rather than linear regulators for higher efficiency. Switching regulators rely on inductors rather than capacitors for filtering.

 

[John T]

Good Morning Lenray, good questions:

Do you need a fully charged battery even if hooked up to shore power>>>>???


YES AND NO to properly operate typical 12 volt RV appliances like water pump, vent fans, many furnaces, lights, many RV fridge control circuits YOU NEED 12 VDC suppled from EITHER a good charged battery orrrrrrrrr a working 120 VAC to 12 VDC converter/charger that's properly configured.........

To operate 120 VAC appliances THAT DONT RERQUIRE ANY 12 VDC CONTROLS good supplied shore power is all you need

If the batteries are that low lights vent fans water pumps furnaces etc wont work WELL DUH

If the batteries are that low the converter/charger may be bad,,,,,,,, or mis wired to batteries,,,,,,,,,or the breaker to converter/charger is tripped,,,,,,,,,,,,or batteries are totally shot or discharged,,,,,,,,,,or the power cord or pedestal or RV panel isnt getting good voltage......


Across the two hots is 220. Each hot to a ground is 120.

CORRECT 240 Line to Line,,,,,,,120 VAC from EITHER Hot to Neutral orrrr Ground is most common and correct ...

John T 50 year RV owner

 

[sotxbill]

My 96 rv has a heart 3000 watt converter/charger. If the house batteries are allowed to get too low, the converter will go into safety mode and NOT try to charge the batteries. Its a safety feature to prevent generating explosive gases i closed spaces. SO>>>>>>

I have to disconnnect the batteries charge them back up to around 12 volts... reconnect them and and power cycle the the converter.. then it will see good safe batteries and go into the the 3 stage charging mode. This only happens when your disconnected from power too long and allow the house batteries to go too low. On the other hand, if the house batteries will not come up to a decent charge, the house batteries must be replaced for the rv to try to maintain them. This means new house batteries. If they are over 3 years old, they are probably bad.. If they are over 5 years old, they are very very very bad. And your converter/charger is doing what it is designed to do... not start a fire or explosion.

On other rvs I see cheap converter that have failed and no longer produce 12 volts for the rv or the batteries. Some new ones DONT charge the batteries at all and rely on vehicle power to charge them up.. The converter only provide rv power and it was low on dc voltage. ymmv

 

[buickanddeere]

. Poster only mentioned three prongs . If the system has two live lines , there also needs to be a neutral and a ground . That adds up to four prongs.

 

[MarkB_MI]

> Poster only mentioned three prongs . If the system has two live lines , there also needs to be a neutral and a ground . That adds up to four prongs.

Nope. He said he had a '50 amp RV'. 50 RV plugs have four prongs. He also said he measured 'to <b style=color:red>A</b> ground', which probably means he thought the two grounded prongs are both called 'ground'.

 

[Mule Meat]

Could it be wired Split Phase (220 volts) when it should be wired Single Phase (120 volt)?

Either one can be wired using a NEMA 14-50R outlet.

 

[buickanddeere]

(quoted from post at 05:47:17 09/09/23) &gt; Poster only mentioned three prongs . If the system has two live lines , there also needs to be a neutral and a ground . That adds up to four prongs.

Nope. He said he had a '50 amp RV'. 50 RV plugs have four prongs. He also said he measured 'to &lt;b style=color:red&gt;A&lt;/b&gt; ground', which probably means he thought the two grounded prongs are both called 'ground'.

Poster should have been clearer and still should tell us three or four .

 

[John T]

Unless its been modified ???? what are called 50 Amp RV's (4 Conducor power cord) plug into a power pedestals NEMA 14-50 R Receptacle which is a FOUR terminal device, Line 1 Line 2 Neutral Ground... If wired as most (not all) it would be 240 L1 to L2, or 120 L1 or L2 to Neutral or Ground. In 50 yeas of RV use I have seen a few with 208 L1 to L2. Of course some are even wired different/incorrect where its ZERO Volts L1 to L2 yet still 120 L1 or L2 to Neutral or Ground !!!!!!!!

John T