RV car charging problem

[Emile]

Hello

I pull my RV 24 ft Mallard Trailer with my Jeep Grand Sherokee 2002

My Jeep does not charge my battery compleetely but it is charge full when connected to AC Power

I have measure de voltage on my Jeep battery and it measure OK 13.5 V but if i measure the battery of my trailer when my Jeep running i only measure 12.7 V, so i have 0.8 V difference which tells me that there is a diode drop between the 2 batteries and thats why the battrey of my trailer never charge compleetely.

Is someone can tell me if that is the problem or something else before i start working on it

I know verry well all kind of inverters since i work most of my life of designing these type of inverters for military applications

Is someone can tell me where i could find the skematic of my inverter ? which is an :
Intelli Power PD9130

Is that a problem of my inverter charger ?
Is there a way i can solve my problem ?

Also is that normal that problem or i have a problem somewhere in the inverter ?
Is someone else has that problem ?

Thanks for your answers
Émile

[Roy in TO]

Are you using a battery isolator or solenoid on your Jeep?
What guage wire to the rear?

[Emile]

Thanks Roy for your answer

My Jeep has not been modify to add any parts
My wiring gage is a #8

Since I am just coming from vacation i will be doing more test to day and come back to you after

Thanks again
Émile

[john warren]

did it ever charge it fully?
your alternator may not be a heavy duty one. your putting out plenty of voltage,,,but its amperage you need,not sure what stock is on a jeep, but part of the tow pack is a high output alternator i think.

[DMAC1]

make sure to check for poor connections, escpecialy at the tow vehicle receptacle. what you have is a voltage drop accros the circuit. the charge from the vehicle to the rv battery doesn't really use the rv converter. .8 of a voltage drop is huge and almost always from a poor connection. the wires going into the back of the tow vehicle receptacle very often corrode

[cpaharley2008]

Most Jeeps need a separate power wire as the factory wire is too small for any volts to charge your trailer. That said, most auto's alternators are adequate for lights and your propane detector on your trailer bit little is left to charge your battery, unless you drive in day with no lights then there is more reserve available to charge your trailer battery, if the wire is up to size.

[DMAC1]

Using the vehicles altenator to charge the battery doesn't always work that well unless you are running down the road at speed so the altenator is turning fast enough to produce enough amperage, that said the run of wire to the rv battery is long and ushaually incorporates many connections/ junction points to restrict the flow of the juice. the voltage should still be close between the two batteries while hooked up and running though.

[Raz]

13.5 --> 12.7 as others have said is due to I squared R losses, corrosion, or a diode to isolate and prevent discharge of the Jeep battery. I have not been able to find a schematic for any of the newer (switching) Progressive Dynamic converters. If your battery charges fully when you are connected to AC. your converter is probably fine. The converter is not part of the charging system when you are driving. Raz

[Emile]

Thans everybody for your answers

I beleave your are all very close to my problem

I just come to make few tests and i found a 27 ohms both directions between the Jeep connector and the converter and that would cause my problem i beleave

My RV manual shows a 40 amps breaker in that line as you can see in the picture and that could be the cause of my bug But i cannot find that breaker since the wirer is going under the floor of my RV.

Is that possible that they would have put a breaker under the floor ?



Thanks again for your help
Émile

[cpaharley2008]

There is a main breaker, around 30-50 amps on the trailer that can blow. It is a little square box with 2 copper lugs. This may be somewhere in your system. It is shown above as a 40 amp breaker. That will prevent you being able to charge while towing if it is blown or defective.

[Ron in BC]

It looks to me that the circuit breaker only protects the converter circuit, not the car charging circuit. It appears that the wire from the trailer plug only uses a terminal of the circuit breaker as a connector and the car charging current doesn't actually pass through the circuit breaker.

When you find the circuit breaker check for corrosion on the terminal. I'd remove it, wire brush it and re-install it. I'd also check the voltage at that terminal as compared to the plug voltage and also for voltage drop between the circuit breaker terminal and the battery terminal.

Good luck locating the circuit breaker.

Ron

[Raz]

I'm unclear if this is the actual wiring diagram for the trailer from the trailer manufacturer or a suggested wiring from the converter manufacturer. The phrase "Electrical system wiring diagram (typical)" in the lower left leads me to think the latter. Raz

[Emile]

Raz the picture of the skematic has been taken from my RV Mallard manual

[Raz]

I agree with Ron, your issue is between pin 4 on the plug or where ever you are measuring beyond that and the terminal on the breaker. Since the converter charges the battery, the breaker should be ok. Since the distribution section is shown separate but is probably part of the converter, the breaker might also be. Raz

[Emile]

Thanks to help me

I made a good look at it and i found than all the wires from the inverter and the fuses box are going and coming through the floor.
And all the wires from the front are going through the plastic water protection via a hole in a square plate held with 8 screws and water seal all around.
To me i beleave the breaker is beahind that plate and i will remouve it today to check behind.

I took some picture to show wou watt i saw

#1 = On the drawers compartment. The inverter box whih the 2 disconnected ouput wire, one goes to the battery and the other to the main RV connector which has 27 ohms both directions.




#2 = The inverter wires cross the wall to under the stove compartment




3 = Under the stove compartment The fuses boxe




#4 = All wiring under the stove goes through a floor hole




#5 = All wires from the front are going through a plate under the front of the RV



That is the plate i have to remouve today
I hope the seal can be remouved easely so i can put it back with good sealing.

I will tell you if the breaker is there

Thanks
Émile

[Emile]

I have remouved that plate and found 2 breakers assemble to the wooden floor frame of the RV.
One for the brake-away switch
And one for the RV connector power to jeep

Both of them are very rusted and one i had to break since the screw was too rusted. A 22 ohms resistor is connected bettween the 2 lugs across the thermal swich.

My RV parts store has probably some in stock if not they can order it for me i beleave.

I will give you a final feedback when charging system is working properly

Thanks to all for your help it is very appreciated

Émile

[streetvan1]

I think you're overcomplicating/overthinking this issue.

I have to ask.... when you measure across the terminals of the trailer battery with the jeep running, it's 12.7 volts? What is the voltage there with the car shut off? I suspect it'll be 12.7.

Here's a quick test that I'd do : just quickly unplug the trailer from the car, and test the voltage at the trailer charge pin of your car end connector. Put your positive voltmeter lead on the charge wire, and the negative lead to the ground pin.

Based on what you're saying in your initial post, I'm guessing that there's no power being supplied at the back of our jeep, and that you need to trace the circuit for an open, blown fuse, etc in the car, not the trailer.

I suspect this because your convertor works when youp lug in to 120. The convertor isn't used when charging from the car, just a simple wire.

Some of the other guys have suggested a bigger wire, which is a good idea, but you should still have about 13.5 volts to the back, even with a small wire. It just might take all day to charge!

The 27 ohms from the trailer connector to the inverter sounds odd, but should only affect the use of the inverter, not the charging of the battery. What's important is the resistance from the trailer connector charge pin to the positive battery terminal. If that's at 0 ohms, then that reinforces that the fault is in your jeep.

Good luck!

[Emile]

Thanks everubody for helping me

I have change the 2 breakers and my jeep is now charging my RV battery properly

I can consider that proplem solve

One more question :
What do you think about putting 2 X 12 volts batteries in parallel instead of using 2 X 6 Volts batteries in series
I know there is a small problem due to specific gravity but it is very important for a trailer operation ?
I dont want to bye 2 X 6 Volts batteries since i have already 2 X 12 vols batteries.
Is that two 12 volts in parallel is gone to help very mutch ?

Thanks very much
Émile

[Ron in BC]

Excellent, always nice to see a problem worked through to a successful solution

Re batteries; Using 6 volt batteries to build large capacity battery banks is sometimes done. But for trailer and boat use I've always found two 12V batteries in parallel to be the best solution for me. However, I should point out that I always use a battery switch to keep the two batteries separate from each other which prevents me from draining two batteries at once.

Ron

[Emile]

Thanks Ron

I will use two 12 vols batteries

I am plannig to go for a trip of 2 weaks this automne and camps site are close in mid september
So i might be only 3 days in the same place without mooving but it is better to play safe in case i decide to stay longer.

Émile