Luke Porter
Not on the road :(
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Joined: 10/03/2000
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Read in my Chevrolet owners manual that in tow/haul mode the vehicle system voltage is increased to charge the trailer batteries---I didn't know that.
It also suggests turning on the headlights, to increase voltage, when towing a tailer not heavy enough to use tow/haul mode.
Yep, actually drove to all of these places---in the last eight years. Missed Rhode Island and New Jersey.
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ScottG
Bothell Wa.
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Joined: 02/25/2005
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Something just isn't sounding right about all that. Could you re-read and post exactly what it says?
Scott, Grace and Wesly
2003 Dodge 3500 4x4, 6 speed Cummins (lightly bombed),
2004 Forest River 25RKS many, many mods.
H0NDA eu2000i
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Luke Porter
Not on the road :(
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Joined: 10/03/2000
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If charging a remote (non-vehicle) battery, press the Tow/Haul Mode button, if equipped, loacted 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.
What didn't sound right?
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ScottG
Bothell Wa.
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The part about raising the voltage. I've never heard of a vehicle doing this and I don't understand the need since the RV battery is just connected to the TV and will charge perfectly fine. Also, turning on the headlights has never changed the battery voltage as long as the voltage regulator is working correctly.
I'm curious if anybody else can shine some light on this - it's all news to me!
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Luke Porter
Not on the road :(
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ScottG wrote:- it's all news to me!
That's why I posted.
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buzzard616
Medicine Hat, Ab, Canada
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It's true. My 08 Silverado book says the same thing. I did some reading elsewhere and apparently alternator output is intentionally reduced under normal circumstances to unload it and save a few drops of gas. Going to Tow/Haul or turning on the headlights overrides this feature and resets the alternator to full output.
Seems like another idea that sounded great in the engineer's coffee lounge but ends up being another gadget to fail down the road.
Stu & Jackie Metcalfe
2000 Salem 27FKSS
2008 Sierra 2500 HD gasser
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ScottG
Bothell Wa.
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Wow, that really shows how far they're willing to go to save a drop of fuel but by lowering the system voltage the gain will be at the cost of overall battery life I suspect.
* This post was
edited 03/02/12 08:05pm by ScottG *
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Cedarhill
Deep South
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Alternator output voltage is dependent on load and current draw. This phenomenon is not unique to GM products. If you have a near dead starting battery, the voltage regulator will raise the output voltage in response for rapid charging. When you apply some other load, such as the headlamps, the voltage regulator can't distinguish between that load and a dead battery and will raise the voltage in response. It just so happens that this higher voltage will charge the RV battery faster at the same time.
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ScottG
Bothell Wa.
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Kinda but it doesn't sound like thats whats going on here. Besides, when you turn on the headlights in a normal modern vehicle the voltage does not change much if any (depending on how good the voltage regulator is), the current supplied by the alt increases. Also, in a normal vehicle, if you turn on a load like headlights, there is less current available to charge a battery since there's only so much power available.
Again this is on a modern vehicle, I realize the old cars of yesterday had fairly drastic voltage swings because of relatively weak charging systems and mechanical regulators.
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ScottG
Bothell Wa.
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The other thing that supports something very different going on from normal cars is that engaging the T/H alters the charging. Normally it just remaps trans performance which of course does nothing to alter system voltage.
* This post was
edited 03/02/12 09:38pm by ScottG *
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