Charging while driving

[craigolsen]

Never had a trailer before and wondered if while I'm towing my trailer, is it charging the house battery for the trailer?
Thanks everyone, Craig

[dbailey]

yes...

[craigolsen]

Thanks Doug

[Brian B-P]

Yes, if your tow vehicle is supplying power to the appropriate pin of the electrical connector.

[rbryan4]

Solar too-- and you don't have to be driving.

[Ron in BC]

Originally Posted by Brian B-P

Yes, if your tow vehicle is supplying power to the appropriate pin of the electrical connector.

And if it isn't it's not a major deal to install a charging line to the 7 pin connector. There's been threads about it in the past.

In my case I ran a dedicated fused wire from TV battery to the 7 pin connector. It has a switch that I can turn off to avoid draining the battery. Others have done higher level installs using a solenoid.

Definitely worth having. No sense driving for several hours without recharging the trailer battery at the same time. Depends on the alternator you have and the wiring size whether you want to run the fridge on 12 volts at the same time.

Ron

[padlin]

If you leave the 7pin connected at night, does it drain the TV' s battery?

[kstock11]

In my GMC Acadia with the towing option, there is a towing button to push when towing to "boost" the electric going to the trailer. As to draining the battery when parked overnight - I always disconnect when parked as a friend ended up with a dead car battery when he forgot to disconnect.

[Jim Bennett]

Originally Posted by padlin

If you leave the 7pin connected at night, does it drain the TV' s battery?

Most newer vehicles have a solenoid that switches the power to the trailer off, when the ignition is off. Not something to take for granted though, and should be confirmed. In most cases, if you are stopping overnight only, and both batteries are fully charged, even if the drain from your use in the trailer is from both the trailer and the tow, you should not have a problem starting your car up in the morning (unless you leave the fridge on 12V ).

[J Mac]

When Cap-It installed my break controller they did NOT install a solenoid switch and my tow vehicles battery went dead. Later, it shorted out completely and would drain the tow's battery every night if I didn't unhook the neg. terminal. The short, somehow, eventually killed the break controller and the 7 pin. Replacement cost...lots!!

[dave macrae]

Originally Posted by kstock11

In my GMC Acadia with the towing option, there is a towing button to push when towing to "boost" the electric going to the trailer. As to draining the battery when parked overnight - I always disconnect when parked as a friend ended up with a dead car battery when he forgot to disconnect.

Are you talking about the Tow Haul switch ? I have never heard of a feature boosting the electrical output to the trailer. The tow haul switch simply alows the transmission to adjust things like shift points, line pressures, torque converter lock up and alow for engine braking while going down hills. I checked gm service info and can find nothing about boosting electrical output to the trailer.

[padlin]

Fwiw, while driving the last 2 days in sunny weather. Running fridge on battery, the battery monitor shows 14A draw for the 6.7 fridge, 10 from the truck and the balance from the solar.

[Brian B-P]

I did a quick Google search for "tow haul alternator" and found lots of references to the charging system output being increased (a higher voltage target) when tow/haul is engaged... but of course these are not authoritative. It would be easy to check: plug a voltmeter in, drive until the voltage settles at a steady level, and turn the tow/haul switch on and off. I'll try to remember to do this in our Ford-based motorhome sometime.

[dave macrae]

Originally Posted by Brian B-P

I did a quick Google search for "tow haul alternator" and found lots of references to the charging system output being increased (a higher voltage target) when tow/haul is engaged... but of course these are not authoritative. It would be easy to check: plug a voltmeter in, drive until the voltage settles at a steady level, and turn the tow/haul switch on and off. I'll try to remember to do this in our Ford-based motorhome sometime.

on the google search all I could find was couple of people on different forums, certainly nothing conclusive. Here is the description and operation out of gm service info.
2013 GMC Truck Acadia - AWD | Acadia, Enclave, Traverse VIN R/V Service Manual 3206 | Document ID: 2169193
Tow/Haul Mode Description and Operation
2013 GMC Truck Acadia - AWD | Acadia, Enclave, Traverse VIN R/V Service Manual 3206 | Document ID: 2169193
Tow/Haul Mode Description and Operation
Tow/haul mode is a function within the vehicle's software/calibration that optimizes transmission gear selection for operation during towing or with heavy loads. This optimization includes improving acceleration performance during launches, reducing shift busyness, assisting brake performance and speed control during engine braking situations, and improving vehicle speed control while requiring less throttle pedal activity.
In general, tow/haul mode maintains lower gears longer and increases shift pressures. It is designed to be most effective when the vehicle and trailer combined weight is at least 75% of the vehicle's Gross Combined Weight Rating (GCWR). Operation of tow/haul in a lightly loaded or non-loaded vehicle will not cause damage. However, there is no benefit to the selection of tow/haul when the vehicle is unloaded, and use of tow/haul mode during unloaded driving conditions will decrease fuel economy and may generate shift feel concerns.

[dave macrae]

I just read through the charging system description and operation as well, nothing is mentioned about tow haul


Charging System OperationThe purpose of the charging system is to maintain the battery charge and vehicle loads. There are 6 modes of operation and they include:

• Battery Sulfation Mode
• Charge Mode
• Fuel Economy Mode
• Headlamp Mode
• Start Up Mode
• Voltage Reduction Mode

The engine control module (ECM) controls the generator through the generator turn ON signal circuit. The ECM monitors the generator performance though the generator field duty cycle signal circuit. The signal is a pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0–100 percent. Normal duty cycle is between 5–95 percent. Between 0–5 percent and 95–100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generatord increased power output,

[dave macrae]

This sounds like something that a car salesperson would spout off about in a attempt to sell something, sadly this happens a lot. Its possible it exists I just can not find any proof.

[Brian B-P]

I didn't see anything similar in the Acadia owner's manual, but the 2014 GMC Sierra Denali (Canada) owner's manual includes (on page 9-84):

If charging a remote (non-vehicle) battery, press the Tow/Haul Mode button, if equipped, located at the end of the shift lever. This will boost the vehicle system voltage and properly charge the battery. If the trailer is too light for Tow/Haul Mode, or the vehicle is not equipped with Tow/Haul, turn on the headlamps as a second way to boost the vehicle system and charge the battery.

I assume the ECM selects the target charging system voltage based on various factors... including the state of the tow/haul mode, just as it responds to the headlight operation.

It may apply to the Acadia as well, or that may just be a misunderstanding.

[dave macrae]

That's interesting Brian . I will look at the service info for a truck . I was looking at the Acadia info before . Perhaps the trucks are different.

[MyronL]

Here’s my battery charging - fridge notes while driving. These stats compiled on recent 420 mile trip to Lake Powel, AZ.

ET-19 with twin 6 V. batteries, filled Dometic 4.3 fridge, tow vehicle is 2014 Silverado, 5.3L.

Starting time, voltage & temperatures:
7 am, 14.5v. fridge 35° @ 4 dots, trailer 51°

Drive-Time check. voltage/temp., and Distance

10 am, 12.9v fridge 33° trailer 65° ..............109 miles
12 noon. 12.9v fridge 35° trailer 63° ...........118 miles
3:30 pm. 12.7v fridge 36° trailer 70°............100 miles
6:30 pm. Arrive Lake Powel. ......................113 miles
...Forgot to note the temperatures but, I remember being so happy....
Switched fridge to propane, drop it to 3 dots.
6 am next day. Fridge 33° and trailer 47°

2:30 PM. fridge rose to 46° and it was 76° in the trailer. So I bumped it up to 4 dots/propane.. I had opened it at 2 PM to get food.

Conclusion: when driving and fridge is on battery power my tow does an excellent job of maintaining trailer battery voltage.

[cpaharley2008]

Do you have solar Myron?