Camper Battery doesnt charge while going down the road

[desertratt1]

Just curious why my house battery would not charge while driving. I have 2001 Dodge Cummins. Anyone know anything about this and is there a way to have it charging. I just assumed it would charge thru the 7 pin. Also we had check light on our frig i ordered a new dinosaur board put it in didnt change a thing. Would only give check light while driving down the road we constantly have to recent frig would be fine than do it again.

Appreciate any input.

Thanks

[covered_wagon]

desertratt1 wrote:
I thank everyone for all the impute. Looks like i need to do some checking. I looked under the hood pulled the fuse/relay cover i have a trailer relay. Not sure how all that works. Camper is off truck i will hook it up start checking things out. I just assumed the truck would charge the battery period. My Dodge is a camper special. I plan on installing a 200 watt solar setup at some point but i considered the truck charging the battery in the camper a given. Like i said will look at all the suggestions to resolve this over weekend. Than will get back and post.

Thanks
Rick

My 02 is a camper special as well. I have my continious duty relay switched so I can let the alternater replenish the starting batts from using the starter, grid heaters and finally seat heaters. Once warmed up and time allowed to charge the truck batts, I switch that on to take care of the two camper batteries. 5 hrs run time brings it up to near full charge on 2 deep cycle 12 volt batts. It works great and run furnace whenever I need, sometimes all night.

That was a good suggestion to make sure your fridge is not set to run 12 volts. I never use the automated setting.

[desertratt1]

I thank everyone for all the impute. Looks like i need to do some checking. I looked under the hood pulled the fuse/relay cover i have a trailer relay. Not sure how all that works. Camper is off truck i will hook it up start checking things out. I just assumed the truck would charge the battery period. My Dodge is a camper special. I plan on installing a 200 watt solar setup at some point but i considered the truck charging the battery in the camper a given. Like i said will look at all the suggestions to resolve this over weekend. Than will get back and post.

Thanks
Rick

[ScottG]

cewillis wrote:

theoldwizard1 wrote:

Much simpler and probably more effective is a DC-DC charger.

Modern vehicles vehicles drop the voltage from the alternator to <13.5V shortly after starting. This has is not adequate to charge a house battery. The DC-DC charger boosts that up to the proper charging voltage.

Adequate current transfer is still required in any case -- thus heavy gauge wire.

My alternator - and I suspect all functioning alternators - charges at a voltage determined by the load voltage. While the load voltage is below ~14.3 to 14.4v, the alternator charges at ~14.4 volts. When the load voltage comes up, the alternator drops to the maintenance voltage of ~13.5v. Otherwise, the load (batteries - truck + camper) would never reach full charge.

The OP's truck stays in the 14.X range.

[cewillis]

theoldwizard1 wrote:

Much simpler and probably more effective is a DC-DC charger.

Modern vehicles vehicles drop the voltage from the alternator to <13.5V shortly after starting. This has is not adequate to charge a house battery. The DC-DC charger boosts that up to the proper charging voltage.

Adequate current transfer is still required in any case -- thus heavy gauge wire.

My alternator - and I suspect all functioning alternators - charges at a voltage determined by the load voltage. While the load voltage is below ~14.3 to 14.4v, the alternator charges at ~14.4 volts. When the load voltage comes up, the alternator drops to the maintenance voltage of ~13.5v. Otherwise, the load (batteries - truck + camper) would never reach full charge.

[ScottG]

mkirsch wrote:

ScottG wrote:

covered wagon wrote:

srschang wrote:
You're not going to get much charging through the factory 7 pin plug. The wire from the alternator to the 7 pin plug is too small.

My 02 Dodge Cummins does great no mods except it has the trailer plug in the rear and that's what it's hooked to. I know it's too far but, it does great.

When checking you need to take apart the male part of the 7 pin adapter that's mounted on the camper. The guys building these things get piece rate and so that wire doesn't often get stripped... they just try driving the set screw in tight enough to break thru the wire insulation and that's what I have found twice now. Both times fixing these have had good results.

My 03 does great as well.
I don't know about newer RAM's but older ones had a 10 awg wire feeding the 7 pin charging circuit and it passes plenty of power.

What's "great?"

If you don't run the battery down much, it does not need much charging.

Mine have had no problem supplying 20~25+ amps continuously when called upon over the last 30+ years. The 10 awg wire trucks of this era used is the key.

There have been a lot of blanket statements made in this thread that simply don't apply to the OP's 2002 Dodge.

[Geewizard]

cewillis wrote:

Right -- need a dedicated high capacity wire from an engine charge point to the camper battery(s), protected with fuses, and solenoid (or equiv) activated.
My simple circuit .

I agree. My setup is the same and has worked for years.

[mkirsch]

ScottG wrote:

covered wagon wrote:

srschang wrote:
You're not going to get much charging through the factory 7 pin plug. The wire from the alternator to the 7 pin plug is too small.

My 02 Dodge Cummins does great no mods except it has the trailer plug in the rear and that's what it's hooked to. I know it's too far but, it does great.

When checking you need to take apart the male part of the 7 pin adapter that's mounted on the camper. The guys building these things get piece rate and so that wire doesn't often get stripped... they just try driving the set screw in tight enough to break thru the wire insulation and that's what I have found twice now. Both times fixing these have had good results.

My 03 does great as well.
I don't know about newer RAM's but older ones had a 10 awg wire feeding the 7 pin charging circuit and it passes plenty of power.

What's "great?"

If you don't run the battery down much, it does not need much charging.

[bighatnohorse]

The fridge could be switching to DC power - the vehicle charge is not enough to keep up with the power drain from the fridge is running on DC power.
That's the first thing that you should check.

Second, after the truck is warmed up and running for a few minutes, check the camper battery (with a VOM) to see if it actually is getting charged from the truck.

After that, you can do all that other stuff that was recommended.

[ScottG]

covered wagon wrote:

srschang wrote:
You're not going to get much charging through the factory 7 pin plug. The wire from the alternator to the 7 pin plug is too small.

My 02 Dodge Cummins does great no mods except it has the trailer plug in the rear and that's what it's hooked to. I know it's too far but, it does great.

When checking you need to take apart the male part of the 7 pin adapter that's mounted on the camper. The guys building these things get piece rate and so that wire doesn't often get stripped... they just try driving the set screw in tight enough to break thru the wire insulation and that's what I have found twice now. Both times fixing these have had good results.

My 03 does great as well.
I don't know about newer RAM's but older ones had a 10 awg wire feeding the 7 pin charging circuit and it passes plenty of power.

[ticki2]

theoldwizard1 wrote:

CA Traveler wrote:
Buy a test light or voltmeter and check the charge line at the plug. Once it is charging you may need to use larger wire for faster charging.

You need to test the voltage AT THE HOUSE BATTERY after the engine has been running for 5-10 minutes. You will be surprised how low t s.

Low voltage is one thing , no voltage is a different problem

[covered_wagon]

srschang wrote:
You're not going to get much charging through the factory 7 pin plug. The wire from the alternator to the 7 pin plug is too small.

My 02 Dodge Cummins does great no mods except it has the trailer plug in the rear and that's what it's hooked to. I know it's too far but, it does great.

When checking you need to take apart the male part of the 7 pin adapter that's mounted on the camper. The guys building these things get piece rate and so that wire doesn't often get stripped... they just try driving the set screw in tight enough to break thru the wire insulation and that's what I have found twice now. Both times fixing these have had good results.

[bgum]

As said above the rate of energy flow is very little from the alternator to the RV Battery.

[theoldwizard1]

CA Traveler wrote:
Buy a test light or voltmeter and check the charge line at the plug. Once it is charging you may need to use larger wire for faster charging.

You need to test the voltage AT THE HOUSE BATTERY after the engine has been running for 5-10 minutes. You will be surprised how low t s.

[theoldwizard1]

cewillis wrote:

srschang wrote:
You're not going to get much charging through the factory 7 pin plug. The wire from the alternator to the 7 pin plug is too small.

Right -- need a dedicated high capacity wire from an engine charge point to the camper battery(s), protected with fuses, and solenoid (or equiv) activated.
My simple circuit .

Much simpler and probably more effective is a DC-DC charger.

Modern vehicles vehicles drop the voltage from the alternator to <13.5V shortly after starting. This has is not adequate to charge a house battery. The DC-DC charger boosts that up to the proper charging voltage.

[CA_Traveler]

Buy a test light or voltmeter and check the charge line at the plug. Once it is charging you may need to use larger wire for faster charging.