2015 Chevy Colorado won't charge our camper battery!

My husband and I have a purchased a Chevy Colorado to tow our Off-road Aliner Expedition camper that weighs under 3,000 pounds loaded. The truck accomplishes this just fine except for one major “hitch”. The Colorado’s charging system does not sufficiently charge our camper battery after a 3 - 4 hour tow, even though we bought the tow package which includes a 7-pin plug. The owners’ manual says the following:

“If charging a remote (non-vehicle) battery, press the Tow/Haul Mode button, if equipped, on the center stack. 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.”

Here’s the problem:
June 13, 2015 tests – battery charging logic seems to be inadequate for effectively recharging a camper battery. Readings made 6/13/2015:

  1. When the truck battery gets low, the alternator produces 14.45 volts and quickly (within a few minutes) recharges the battery. When the truck battery gets up to about 13.5 volts, alternator output drops to 12.87 volts.
  2. Unfortunately, this means that truck alternator output is only 12.87 volts for the vast majority of the time the truck is running. This is inadequate voltage to recharge the camper battery at other than a slow trickle rate. When dry camping and moving from one site to another in two hours or less, this is insufficient time to adequately recharge the camper battery for reliable use.
  3. The camper battery will last less than 24 hours when charged to 12.87 volts. The camper refrigerator stops cooling (even while running on propane) when the camper battery voltage drops below about 10.8 volts (it’s supposed to operate down to about 9.6 volts, but that’s a refrigerator issue we’re looking into separately). The control circuitry stops functioning at this voltage level and shuts down the refrigerator.
  4. When charged via 110 volts AC, the camper battery gets up to about 13.6 volts. It lasts nearly 72 hours when charged to this level.

We have taken our Colorado to two dealerships and both concluded that the truck is operating the way it is designed. One dealership, under the guidance of GM Chevy techs, built a device to test the battery charging capability of our truck, one other Colorado and one Canyon and all 3 trucks performed almost identically. The Chevy folks have given us a case number but refuse to return our calls or contact the dealership where we bought the truck. We want this problem resolved even if it means installing an after-market device. We are unable to utilize the truck for our “off the grid” camp trips, which was the whole idea for purchasing this truck. My question to you is how can we get this problem resolved?

While the engine is running the alternater voltage should be about 14.0v. With the engine off a fully charged battery should be about 12.8v. It sounds as though everything is just as should be expected but you expect more. Maybe you need a significantly larger battery. Or possibly 2 batteries. And the deep cycle variety would be your best bet.

Did you either press the tow/haul button or turn on the headlights as the work-a-round the manual says to do? It seems like that would help, as it should raise the alternator’s output voltage as you are driving down the road with the headlights on.

If you continue to have this difficulty, I think you’re going to have to talk to an RV specialty shop. This must be a common problem w/RV’s and they likely have an easy solution.

I came across this problem 15 years ago first with my fathers truck then my truck.
My father complained about the trailer batteries not charging while traveling. When he arrived after a 1,800 mile trip I found his house batteries to be at 25% charge. I measured 13.5 volts at the truck batteries while running but 12.2 volts at the trailer connector.

The problem is the refrigerator(s) operating on 12 volts while traveling draw more energy than the truck wiring can supply. On his truck 12 volts to the tow connector is supplied through a 12 gauge wire from the under hood fuse box. Because of the resistance in 20 feet of 12 gauge wire the voltage was pulled down to 12.2 volts while powering the refrigerators.

I ran a 10 gauge wire parallel to the factory wire from the fuse box to the hitch connector. No point in cutting the factory wire, two wires are better than one. 8 gauge wire may be preferred if available.

Five years later I had the same problem when I bought my tent trailer. Even thou the refrigerator is very small the battery discharges while driving. I installed the heavier gauge wire on the truck and I have no problem camping for three days on a single battery.

Your adaptive charging system complicates things but I believe you will see an difference by improving the truck wiring.

Another option is to get a 150 watt inverter ($25) which will convert your 12 volts from the car to 120 VAC, then a 10 amp battery charger ($40) from that output to the trailer battery.

Or 300 watt inverter and 20 amp charger.

The advantage is that you have a battery charger for other use, ditto an inverter.

It’s possible someone makes the two combined in one box, but I have not found any.

On my cheverolet trailblazer there is a post near the under hood fusebox, and a red wire with an eye on the end.
This connection has something to do with the trailer, but comes from the factory disconnected.

Check your manual, starting at 9-57, there is a reference to a plug behind the driver side kick panel.

Stop in at a camper place and make sure whatever pin should be chargeing your camper is getting juice.

I assume the camper battery wiring is fairly long and as @Nevada_545 stated there may be significant voltage drop in the wiring to the battery. Adding larger power and ground wires between the alternator output lead and the camper may overcome the issue. The difference between the voltages across the two battery systems, while the camper battery is charging will be the amount of voltage drop you have in the wiring. This mod may be your best and easiest solution to the problem.

You could also modify the battery voltage sense lead for the regulator circuit by adding a small resistance in the lead. This would make the regulator think that the battery voltage is low and make the alternator put out a higher charging voltage. The problem with doing that, it may overcharge the car battery. Other mods could be done to overcome that but it adds more complications.

One other thing that hasn’t been mentioned so far is adding a solar panel charger to the roof of the camper. This mod would help keep the battery charged even while you are camping and of course have enough light for the panel to operate.

"One other thing that hasn’t been mentioned so far is adding a solar charger panel to the roof of the camper. "

I like the way you’re thinking! Solar panels have dropped way down in price, so that this solution may well be cheaper than running heavy-gauge copper back to the trailer. You’re also NOT dependant on driving the truck to recharge, provided the sun shines where you camp. (“In the pines, in the pines/Where the sun never shines…”)

@CO, are you aware of the current demands of the accesories in your camper and the current capacity of your accesory battery? A battery(ies) with adequate capacity could be kept on float chargers at your home and be ready for the road. And certainly solar cells would be a convenient way to keep the batteries charged while camping.

I think your problem is that you probably have a light duty alternator. I had this problem while towing a travel trailer to Alaska about 12 years ago. I stopped and bought a heavy duty alternator and had no other issues with charging the battery on my truck or on the travel trailer. If you are using electric for your refrigerator…try using the propane to power the fridge if you have that option.

“When the truck battery gets up to about 13.5 volts, alternator output drops to 12.87 volts.”

As you add electrical load such as tow/haul mode/headlights/rear window defogger does the battery voltage not drop below 13.5v?

It’s not sensing the extra load from the trailer and it’s only sensing battey voltage. I personally like the solar cells charging the camper.

Thanks to everyone for your thoughtful comments! We’re considering what we should do next. Our dealer Service Manager had a call today with Chevy Customer Assistance and the GM District Manager for after-sales issues. Essentially, Chevy is sticking with their position that the truck is “operating as designed.” Unfortunately, they won’t tell us any of their design parameters for the charging circuit system nor how much driving time should be sufficient to adequately charge the camper battery. That response, however, still seems to us to be inconsistent with the text in the owners’ manual (p. 9-65), which states, “If charging a remote (non-vehicle) battery, press the Tow/Haul Mode button, if equipped, on the center stack. This will boost the vehicle system voltage and properly charge the battery.” Our truck is so equipped, but enabling Tow/Haul Mode does nothing to increase alternator output. We’ve tried driving with the headlights on as well, but couldn’t see any real improvement in charging capability. Perhaps some supplemental wiring would prove useful.

The following is from a General Motors bulletin from a few years ago, it explains the charging system strategy;

Voltmeter Fluctuation Condition

Some customers may comment that the voltmeter is fluctuating between 12 and 14 volts on their full size pickup or utility vehicle. Starting with the 2005 model year, light duty full size pickups and utilities are equipped with a Regulated Voltage Control (RVC) system. This system reduces the targeted output of the generator to 12.6-13.1 volts when in “Fuel Economy Mode” to improve fuel economy. The generator may exit “Fuel Economy Mode” if additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems that usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.

Camper/Trailer Battery Charging Concerns

Some customers may comment that when towing or hauling a camper/trailer, the auxiliary battery for the camper/trailer will not stay charged. In most cases, this concern is blamed on the new RVC system. While the RVC system does reduce the generator’s targeted output voltage to 12.6-13.1 volts when in “Fuel Economy Mode”, this feature is bypassed if the tow/haul feature is enabled. With the tow/haul feature enabled, the RVC system will stay in “Charge Mode” and the targeted generator output voltage will be 13.9-15.5 volts, depending on the battery state of charge and the estimated battery temperature.

Operating at 12.6 volts won’t charge your campers battery due to the resistance in the wiring and the number of connections. The system must be kept in “charge mode” and the wiring must be adequate to supply sufficient power to your trailer.

My father was a full time RVer after he retired and after I improved the wiring on his truck he had no complaints about the batteries. He spent the winter months camping near the Salton Sea (dry camping). His fifth wheel camper had four house batteries and could power the trailer for seven days before recharging while operating duel refrigerators and central heating. Running out of propane seemed to be a regular problem.

Did you check by the fuse box for the wire? looks like this. You can see the post on the bottom left of the fusebox, and the not yet connected wire to the left. This is not connected at the factory by default on my tb.

Swing by a reputable camper dealer and have them check it out.

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Good info @Nevada_545. From what the OP stated about the issue it seems that the RVC control is either not functioning, the wire losses back to the camper battery are too much to make it effective, or possibly both.

A DC-DC converter with 12V-16V input and 14V out would get the job done.
The charge voltage would be regulated against variations in the towing vehicles system as well as voltage drop in the wiring.
I couldn’t find a turnkey solution to buy on the googles.
This 15V 5A unit comes close.
It could be pretty compact. 10 amp charge is 140W.
I imagine a plastic case a bit smaller than a shoe.

A little more searching and I found this.

I don’t hold out much hope that GM will be able to address this. I’d be looking at the ‘use a float charger at home + a solar charger on the road’ combo.

Lots of good info here. If tow/haul mode doesn’t provide “charge mode” voltage then it’s faulty period. Easy to verify with a simple volt meter.

Chevy verifies that in tow/haul there is a constant 14v available to charge camper battery, correct?
If so then you have something to work with.
If not then they own you a fix or compensation.