KEEP BATTERY CHARGED WHILE USING THE NORCOLD 3-WAY ON 12V

ScottG

Good info and graphics, MuttonChops. It's consistent with my observations that simply turning on the headlights won't necessarily kick the alternator up to its maximum output--even with the fridge running on DC.

Unfortunately, I don't have a tow-haul setting on my manual transmission Frontier, so I mostly rely on ice jugs to keep the fridge cold in transit so as not to deplete the T@B battery (as noted above).

dsatwork

MuttonChops said:

Great forum thread.

As noted most newer vehicles have some type of Variable Alternator Output Control to help boost overall MPG. The chart below shows this working in different tow vehicle electrical load configurations. For those of us with more visual minds.

Chevy Colorado. Recording voltmeter at 7-pin reading every 20 seconds, no trailer.
Vehicle first driven to nearly fully charge battery and force lower voltage output mode.  Since 13.6 is below a battery charging voltage I did not drive long enough to force the worse case low range voltage below 13.1.

Vehicle Reference Information:

In GMC Canyon/Colorado mid-size trucks if the vehicle battery is sensed to be fully charged than Fuel Economy Mode turns-on with Battery Charge / Alternator output controlled at 12.5 to 13.1 VDC. Well below the level needed to charge a trailer battery via the 7-Pin connector V+Battery circuit.

GMC overrides the Fuel Economy Mode if headlights are turned on or the Tow/Haul Mode feature is turned on. Tow/Haul changes transmission shift points, default maximum gear in 'L' transmission mode, and alternator output. Tow/Haul voltage output range is 13.9 to 14.5 VDC.

+12V wire to 7-pin is 10 AWG and directly connected to Battery via a 30 Amp fuse. +12V stays on when vehicle is not running.

In my limited load test it seems Tow/Haul does a better job of stepping up the voltage than just having the headlight on. Having an actual trailer battery load may cause the vehicle computer to increase the voltage more.

@MuttonChops this is great stuff.....So my 2016 Sorento has a sport mode, I wander if I can use it like a haul mode to force the alternator to work at maximum capacity. @jason330i have your done any testing with sport mode in regards to the alternator? I've noticed that having the lights on help keep it at 13.8. Occasionally, it will be at 14+. But I also have the ARB pulling pulling on the system and as miserly as it is, it's still drawing off the system. I really need the alternator running at maximum output when I'm running the fridge on 12v. The batteries must to stay at 12.5 or better for the fridge to keep up on 12v.  We pack a lot of food on our trips and taking any space up with ice jugs in a 2 CF fridge, just seems to be counter productive. 

MuttonChops

@dsatwork

While your question is directed to jason330i and I don't have experience with the Sorento vehicle . . . . . my slightly educated Guess would be that placing the transmission in Sport Mode does not change the alternator output.

Owners manual indicates Sport Mode semi-locks the transmission into the gear you select. Sport Mode changes the transmission shift points and will hold a gear however if you abuse it the ECM will force an up/down shift to protect the drive train. Since a Sorento's primary use is not towing changing the alternator output as well is unlikely.

The basic (on-line) Kia Sorento Service Manual only references the Battery Sensor as the element that causes changes to the alternator output. Alternator troubleshooting instructions state “turn on headlights” and “turn on blower” (cabin fan) to increase electrical load to cause higher alternator output.

Sorento Service Manual Remarks:

Alternator Management System

Alternator management system controls the charging voltage set point in order to improve fuel economy, manage alternator load under various operating conditions, keep the battery charged, and protect the battery from over-charging.

ECM controls generating voltage by duty cycle (charging control, discharging control, normal control) based on the battery conditions and vehicle operating conditions. The system conducts discharging control when accelerating a vehicle. Vehicle reduces an alternator load and consumes an electric power form a battery.

The system conducts charging control when decelerating a vehicle. Vehicle increases an alternator load and charges a battery.

SteveK

A point to remember is that the alternator charge is designed and controlled in order to properly charge and maintain your vehicle battery.  The tow vehicle charge system knows and cares nothing about the trailer battery.  When you ask the voltage to be higher in order to charge the trailer battery, you are stressing your vehicle battery as it is then being over charged.

The exception to this is turning on the vehicle lights which increases the vehicle amp draw causing the electrical system to increase voltage to maintain the vehicle battery at it's desired voltage.  The only certain way to fully charge and condition a trailer battery from a tow vehicle is to use an external boost system as described in the very first post.

Ratkity

Thanks @MuttonChops! It just so happens that I have a 2015 GMC Canyon with built in tow package. I love the visual. Perfect for me.

WilliamA

Hey all,
This is proving to be an interesting thread with lots to unpack and think about.  The differences in vehicle design and battery management are an ongoing issue that will no doubt prove to be a subject of ongoing research.  
That said, I don't mean to add to the obfuscation here but there are some basics that need to be looked at as well.  First, assuming  there is a direct battery connection between the TV (tow vehicle) battery and the 7 way plug, that means that whenever the trailer plug is connected there is a parallel circuit connecting the two batteries, whether the engine is running or not.  It's possible that on some vehicles, when the ignition is off the trailer battery circuit is disconnected but for this discussion anyway, that's neither here nor there.  Assuming there's a parallel circuit connecting the two batteries, the batteries will work to even each other out.  The higher voltage battery will push to charge the lower voltage one until they are of matched voltage.  The closer they are voltage-wise, the longer that will take.  Nevertheless, they will push/pull until they match voltage.  As I said, this will happen regardless of whether the engine is running or not.  If the TV is running, the ecm will sense the (approximate) average voltage of both batteries.  In layman's terms, if the TV battery is 14 volts and the trailer battery is 12 volts the ecm will see about 13 volts and respond accordingly. Regardless of what kind of vehicle it is, the ecm is smart, but not THAT smart.  It (the ecm) cannot see separate voltages for the two batteries, only the average of both.  This, again, assumes they are wired in parallel and not run through a battery management system such as a smart controller.  
What I've not seen discussed here that needs to be is the very basics of circuitry.  If you have a 10 gauge wire going out to charge your trailer battery, then you need "at least" a 10 gauge ground wire coming back through the trailer connector.  Most trailer connectors (in my experience) have quite small 16 or maybe 14 gauge wires going out to the trailer.  This includes the ground wire.  Remember that all of the voltage out to the trailer for lights, refrigerators, charge lines etc, must run back through the same single ground wire to the TV.  If you have a 16 or even a 14 gauge ground wire in your trailer connector, then when the lights are on, that's about all the capacity that ground wire has.  There are a lot of lights on a trailer and it's a long way back there.  Now, in addition to the lights and other stuff, you add the current requirements of a 20 or 30 amp charging circuit and you're asking too much of the ground circuit.  You've got 6 wires going out hot to the trailer and all of that potential voltage (amperage) must return on 1 ground wire.  If your lights take a maximum of, say, 12 amps, then you add 20 amps from the charging line, you need a ground wire with a minimum capacity of 32 amps.  It stands to reason that the total potential capacity of the ground wire must be equal to the total capacity of all the hot wires combined.  If you limit the capacity of the ground circuit, you limit the amperage going out to the trailer.  The voltage, as seen with a meter or gauge, will be the same or nearly so between the TV and trailer but the amperage available will be drastically less.  It's the same as filling two 1 gallon jugs of water from the same pump, but one hose is 1/2" and the other is 1/8".  The pressure (voltage) will be the same in both hoses but the volume (amperage) will be very different.  The larger diameter hose will fill its jug first every time.  
It's safe to say that many folks are experiencing problems charging because the trailer ground is too small for the capacity of the combined load of lights and charging circuit. This is easy to check without doing a whole bunch of wiring.  Just add a jumper wire (10 gauge) that bolts from the trailer frame to the TV frame.  I suspect you'll see a dramatic reduction in charge time. 

I have run 10 gauge wire from the trailer plug to the battery for BOTH my charge line and my trailer ground (dedicated ground) on: My Toyota Rav4, my Jeep Cherokee and my Jeep Wrangler and have never experienced problems with my trailer battery draining while towing.  I leave my refrigerator on all the time, run electric brakes and have a full compliment of lights.  

WilliamA

MuttonChops

dsatwork said:

<DC-DC convertor> convert to higher Output Voltage, capable of charging batteries. Ctek makes (one the "D250S"), and Redarc devices from Australia are very popular for solving this problem.
. . .
Costs for Ctek and Redarc devices are much higher <than DIY>, but they can also support the use of Solar Panels.

Came Across a third brand/supplier for DC-DC Convertor Charger like the Ctek & Redarc units.
Sterling Power Ltd (has USA sales office)

http://www.sterling-power-usa.com/ProCharge-B-waterproof-dcinput-battery-charger-12volt-12volt.aspx
 

ChanW

Edit: Fixed. @MuttonChops, your link is goofy. The "http://" prefix is duplicated, I think. 

jkjenn

You have to be careful what vehicles you use these devices on. I have read in at least case, it also deactivated the vehicle's ESC system. You probably should not add this yourself unless you really understand the electronics of your vehichle.

ChanW

I have to ask, what's it for? 12v to 12v...?

ChanW

This thread is very interesting. Thanks for the detailed explanations from all you smart folks. I've always had a rudimentary understanding, or 'just enough to be dangerous', as they say.

I'll have to check our Tacoma for increased voltage with the headlights on.

It might explain why I couldn't seem to get a handle on keeping up with the three-way fridge. It seemed to keep up fine sometimes, and not keep up other times. Could be I simply didn't have the headlights on! (even though our 7-pin supply and ground are 10ga).

jkjenn

ChanW said:

This thread is very interesting. Thanks for the detailed explanations from all you smart folks. I've always had a rudimentary understanding, or 'just enough to be dangerous', as they say.

I'll have to check our Tacoma for increased voltage with the headlights on.

It might explain why I couldn't seem to get a handle on keeping up with the three-way fridge. It seemed to keep up fine sometimes, and not keep up other times. Could be I simply didn't have the headlights on! (even though our 7-pin supply and ground are 10ga).

Agreed. I am going to try with the headlights, on, too on my GC. Usually use the Automatic Lights feature but it might make a difference to turn on the lights.

Sharon_is_SAM

I need to see the difference.  I always have my lights on as a habit from parking in a dark employee garage.

ScottG

I always tow with my lights on anyway. I've heard it's actually a requirement in some places, but regardless, it seems like a good practice.

However, as noted previously, with my particular vehicle it does nothing to boost the alternator output or prevent the fridge from drawing down the T@B battery. YMMV