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Trailer battery charging with GM products.


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Learn new stuff everyday. I wonder if the GM professional who wrote the second paragraph knows GM discontinued generators 50 years ago.

 

Regulated Voltage Control (RVC) is GMs' platform for computer controlled charging systems. This system is designed to raise and lower the alternator's voltage set point based on vehicle electrical needs. This maximizes charging system efficiency by reducing voltage output when higher voltages are not required.
 

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. To keep the generator in the "Charge Mode", use either of the following two methods.

• The first method is to use the tow/haul mode when towing or hauling a camper or trailer. 

• The second method is to turn on the headlights, which will increase the generator's targeted output voltage to 13.9-14.5 volts.

Edited by Dean
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4 minutes ago, Dean said:

Learn new stuff everyday.

 

Regulated Voltage Control (RVC) is GMs' platform for computer controlled charging systems. This system is designed to raise and lower the alternator's voltage set point based on vehicle electrical needs. This maximizes charging system efficiency by reducing voltage output when higher voltages are not required.
 

Interesting . . . . . we have a 2013 F350.  I don't know if it has the RVC and we have not towed with it since trading our 5th-wheel for a camper van.  It does have towing mode.

How would one evaluate whether the tow vehicle is charging the house batteries?  Would idling while connected to the trailer (no battery load on tow vehicle) tell the charge voltage on the trailer battery by way of the onboard battery monitor.

This also brings up another subject I've not thought of:

How does the charging work when you have the solar system and are also towing where there would be two sources of incoming charge coming into the house batteries?  I'm sure there's a logical explanation, but I'm not savvy on the details of 12v systems.

Ray and Susan Huff

Elite II Twin "Pearl" - Hull#699; taking delivery December 7, 2020

2013 F350 3.2l diesel Super Duty 4x4 long bed crew cab

2017 Leisure Travel Van Unity Twin Bed (sold)

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I suspect the Zamp controller and the Progressive Dynamics AC/DC distribution panel are independently regulating charge to the batteries.  If the batteries are charged, neither is delivering current.

 

Your 2013 truck probably doesn’t have an RVC function.

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20 hours ago, Dean said:

I suspect the Zamp controller and the Progressive Dynamics AC/DC distribution panel are independently regulating charge to the batteries.  If the batteries are charged, neither is delivering current.

 

Your 2013 truck probably doesn’t have an RVC function.

Thanks, Dean.  You are probably right about our PU not having RVC.  One of the things we like about our "older" pickup is that it only has a few of the new, sophisticated features.

Edit: If the distribution panel and the solar controller independently regulate charge to the batteries, are both solar and TV battery both supplying power to the batteries concurrently or does one default over the other?

I think I'm setting myself up for the "accountant's response" - It depends 😀

Edited by Susan Huff
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Ray and Susan Huff

Elite II Twin "Pearl" - Hull#699; taking delivery December 7, 2020

2013 F350 3.2l diesel Super Duty 4x4 long bed crew cab

2017 Leisure Travel Van Unity Twin Bed (sold)

AZARCACOGAHIIDILKSLAMSMONENVNMOKORSCTNTX

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I've never used my 12v hot lead on my trailer harness because I've never towed a trailer with a battery (or any 12v winches, etc) before.  Do current owners tow with that lead hot by default or are there some that don't use it?  I'm not keen on putting more stress on my TV alternator and engine if I don't have to.  I was thinking with solar and big batteries I'd not have to worry about it.

John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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2 hours ago, NCeagle said:

I've never used my 12v hot lead on my trailer harness because I've never towed a trailer with a battery (or any 12v winches, etc) before.  Do current owners tow with that lead hot by default or are there some that don't use it?  I'm not keen on putting more stress on my TV alternator and engine if I don't have to.  I was thinking with solar and big batteries I'd not have to worry about it.

Following:

  • With Lithium option would solar top off the batteries while on the road?  If solar is adding charge, will the batteries still draw from the TV battery?
  • How do you "not use" the 12v hot lead when connected to the TV?  Isn't it integrated into the plug?

Ray and Susan Huff

Elite II Twin "Pearl" - Hull#699; taking delivery December 7, 2020

2013 F350 3.2l diesel Super Duty 4x4 long bed crew cab

2017 Leisure Travel Van Unity Twin Bed (sold)

AZARCACOGAHIIDILKSLAMSMONENVNMOKORSCTNTX

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32 minutes ago, Susan Huff said:

Following:

  • With Lithium option would solar top off the batteries while on the road?  If solar is adding charge, will the batteries still draw from the TV battery?
  • How do you "not use" the 12v hot lead when connected to the TV?  Isn't it integrated into the plug?

I know solar will top off any batteries (Lithium included) during a day trip.  I'm hoping there isn't a problem with just a fan or a few small things running in the Ollie while towing at night without the hot lead from the TV.

My understanding is that the configuration of the trailer harness lead does vary from vehicle to vehicle, so your mileage may vary with this answer.  With my TV (older Silverado), I have a standard "always hot" lead on my trailer harness - nothing fancy - it's a 12v x 40amp circuit on my truck.  I removed the 40 amp fuse to kill that power just about the day I brought the truck home 14 years ago to "not use" the lead.  I didn't like the idea of having to worry about disconnecting the trailer every time I parked the truck to protect against phantom power draw or whatever else might lead to a dead battery - and at 40 amps it could happen very quickly if not careful.  Some trucks are wired so that the lead is only hot when the ignition is on and many come with a dummy fuse in place of a real one so an owner can enable the lead only if needed.  I'd prefer that but I've never bothered rewiring my truck.

I am going to wait and see what other owners do here because of my inexperience with travel trailer batteries in general, but if I have to put my fuse back in to make that lead hot I'll look into a heavy duty alternator and rewire to have it only hot when the ignition is running.  As it stands now, I'm running a small data center in my truck already so power is more limited there than it will be with the Ollie.  When on a roadtrip, we typically have 2 iphones, an ipad mini, my truck performance monitor, my backup camera, our cellular hot-spot/wifi router, our cell phone signal booster, my wife's laptop for work and a 12v powered dometic cooler running and being powered simultaneously!  

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John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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28 minutes ago, Dean said:

40 amp  is a rather large fuse for a circuit delivering <9 amps through a 10 ga wire.

Seems to be since typically you use 8 gauge with a 40 amp circuit.  It's what was in it when I bought it, so it's probably for something like a winch that takes a lot of start up amps but doesn't have a constant pull over 30 amps.  It's one of those large maxi fuses that GM uses and I double checked it - still in my center console after all these years - definitely 40 amp.  Like this one:  Bussmann (BP/FMX-40-RP) Green 40 Amp Female Maxi Fuse

John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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5 hours ago, NCeagle said:

I know solar will top off any batteries (Lithium included) during a day trip.  I'm hoping there isn't a problem with just a fan or a few small things running in the Ollie while towing at night without the hot lead from the TV.

We have had driving days when there was not enough sun to charge our batteries.  Last year while driving from Glacier to Bozeman we had heavy clouds and rain, it was dark.  That same trip while camping at Grand Teton we had several similar days when our batteries were not charged late in the afternoon.  Running the furnace at night took more from our batteries than the gray clouds and rain allowed back in.  I had to pull out the generator for several hours.  My trucks have been Rams and a Toyota and we’ve not had any issues charging while towing.  Some days we were glad we did because the sun was nowhere to be found.  Solar works great in the sun.  

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Mike and Carol | Fair Oaks Ranch, TX | 2016 Elite II #135 | 2020 Ram 2500 Laramie 6.7L Cummins Diesel

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Posted (edited)

Solar does work great, in the sun. If you travel camp, changing spots every couple days, you'll probably be fine with just fixed solar. On sunny days, the open highway gives plenty of opportunity for charging.

Suitcase solar can help a lot in shaded spots. Sometimes. Not always. Have to find your place in the sun for the suitcase.

My 05 Silverado with tow package  had the fake fuse , or no fuse, can't remember which, 13 years ago. After looking up the manual instructions,  adding the proper fuse, the inline charging worked fine with the 7 pin connector. 

The solar charger and charger/converter work together. Solar gives us the best full charge. The truck only charges when we actually need it, which is mostly never.

When we hit a string of crappy, rainy days, camping, we break out the honda 1000.  It's all good, 13 seasons in, with a handful of days plugged in.

Sherry

 

 

 

 

Edited by SeaDawg

2008 Ram 1500 4 × 4

2008 Oliver Elite, Hull #12
 

 

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On 8/13/2020 at 11:55 AM, Susan Huff said:

Interesting . . . . . we have a 2013 F350.  I don't know if it has the RVC and we have not towed with it since trading our 5th-wheel for a camper van.  It does have towing mode...

Our 2014 Sierra 1500 had it. I panicked on a trip when I glanced down at the Alternator gauge and saw it was not putting out anything. I stopped at a GMC dealer in some little town and was informed about what was going on. Turning on the lights or tow/haul mode will initiate it, but it is not instantaneous. It took about 10-15 minutes for the needle on the gauge to register an increased output. I suppose the Silverado 2500 has it also, but I've never noticed.

I would be remiss to recommend not using your vehicle to add to your trailer battery charging and just relying on solar. Like Mike stated, the sun does not always shine and a few continuous dark, cloudy, rainy days will necessitate turning to other means of charging such as putting the generator out in the rain and getting it running or (horrors) driving somewhere you can pay for a hookup. Or, you could always just go home.

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Steve, Tali and the dogs: Reacher, Lucy and Rocky plus our beloved Storm and Maggie (both waiting at the Rainbow Bridge) 2008 Legacy Elite I - Outlaw Oliver, HULL NUMBER: 0026 2014 Legacy Elite II - Outlaw Oliver, HULL NUMBER: 0050 2017 Silverado High Country 2500HD Diesel 4x4 

 

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Thanks for the insight on this topic!  I'm convinced that I want/will need the ability to charge my Ollie batteries while towing now, but the engineer in me wants to understand how the connections are made within the Ollie and what technology is being used.  I need to figure out if an upgrade my alternator and/or an increase in the wire gauge is required for me to actually take advantage of this charging method.

Using some real world estimates, electrical properties dictate that a 14 volt current over a 10 gauge wire from a typical TV alternator (that's the average voltage from a properly running stock alternator) will experience a 3.85% voltage drop over 30 feet (my truck is 20 feet long and then there's an estimated 10 more feet to get to the battery bank in the Oliver).  That means that I'll have about 13.46 volts on the charge wire at termination.  13.46 volts would only be enough to trickle charge a 12V battery on it's own, so if I go this route and there's no magic going on with the electrical components in the Oliver, I may need to beef up my alternator and/or wire gauge.

Unless someone knows off-hand how Oliver wires all this together, I'll ask them directly.  The owners manual doesn't have the detail to figure this out.

Sorry if this is getting too deep into the weeds.  Oliver probably has a simple answer for this.  I'm assuming the moderators will let me know if I'm going way off base here and inadvertently hijacking the original intent of this thread.  😐 

John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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On 8/14/2020 at 7:21 AM, NCeagle said:

I know solar will top off any batteries (Lithium included) during a day trip.  I'm hoping there isn't a problem with just a fan or a few small things running in the Ollie while towing at night without the hot lead from the TV.

My understanding is that the configuration of the trailer harness lead does vary from vehicle to vehicle, so your mileage may vary with this answer.  With my TV (older Silverado), I have a standard "always hot" lead on my trailer harness - nothing fancy - it's a 12v x 40amp circuit on my truck.  I removed the 40 amp fuse to kill that power just about the day I brought the truck home 14 years ago to "not use" the lead.  I didn't like the idea of having to worry about disconnecting the trailer every time I parked the truck to protect against phantom power draw or whatever else might lead to a dead battery - and at 40 amps it could happen very quickly if not careful.  Some trucks are wired so that the lead is only hot when the ignition is on and many come with a dummy fuse in place of a real one so an owner can enable the lead only if needed.  I'd prefer that but I've never bothered rewiring my truck.

I am going to wait and see what other owners do here because of my inexperience with travel trailer batteries in general, but if I have to put my fuse back in to make that lead hot I'll look into a heavy duty alternator and rewire to have it only hot when the ignition is running.  As it stands now, I'm running a small data center in my truck already so power is more limited there than it will be with the Ollie.  When on a roadtrip, we typically have 2 iphones, an ipad mini, my truck performance monitor, my backup camera, our cellular hot-spot/wifi router, our cell phone signal booster, my wife's laptop for work and a 12v powered dometic cooler running and being powered simultaneously!  

Sounds like you need all the power you can get in your pickup - good reason to not have its battery connected to the trailer.

Someone else, please chime in . . . . . it's my understanding that the pickup engine must be running for the trailer to draw power from the vehicle battery.  Maybe I'm wrong . . . . . or maybe it depends on your specific vehicle.  Needless to say, power management can sometimes be a mystery.

Ray and Susan Huff

Elite II Twin "Pearl" - Hull#699; taking delivery December 7, 2020

2013 F350 3.2l diesel Super Duty 4x4 long bed crew cab

2017 Leisure Travel Van Unity Twin Bed (sold)

AZARCACOGAHIIDILKSLAMSMONENVNMOKORSCTNTX

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18 hours ago, ScubaRx said:

Our 2014 Sierra 1500 had it. I panicked on a trip when I glanced down at the Alternator gauge and saw it was not putting out anything. I stopped at a GMC dealer in some little town and was informed about what was going on. Turning on the lights or tow/haul mode will initiate it, but it is not instantaneous. It took about 10-15 minutes for the needle on the gauge to register an increased output. I suppose the Silverado 2500 has it also, but I've never noticed.

I would be remiss to recommend not using your vehicle to add to your trailer battery charging and just relying on solar. Like Mike stated, the sun does not always shine and a few continuous dark, cloudy, rainy days will necessitate turning to other means of charging such as putting the generator out in the rain and getting it running or (horrors) driving somewhere you can pay for a hookup. Or, you could always just go home.

More reason to keep our Ford.  Living where we do, in the Pacific Northwest, sun is not always abundant.  I can live with paying for a hookup, but staying home is not an option . . . . . been doing that too much, lately, thanks to Covid 😊

Ray and Susan Huff

Elite II Twin "Pearl" - Hull#699; taking delivery December 7, 2020

2013 F350 3.2l diesel Super Duty 4x4 long bed crew cab

2017 Leisure Travel Van Unity Twin Bed (sold)

AZARCACOGAHIIDILKSLAMSMONENVNMOKORSCTNTX

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Just to close on this topic, I'm going to post what I've learned through some additional research. 

1.  With my current "stock" alternator and wiring setup, I have more voltage at my alternator (14.1) than I have at the trailer harness hot lead (13.9 volts).  The drop in voltage is explained by Ohm's law.  Basically, the wire used in the trailer harness is nowhere near a heavy enough gauge to preserve the voltage over the 20' run to the back of the truck.  It's going to drop even more going from my harness back to the Oliver battery bank.  A reasonable estimate is down to 13.8 volts.

2.  Lead acid batteries accept charge when the voltage is between 13.8 - 14.7 and maintain via a float charge when the voltage is between 3.5 and 3.8.  The LifeBlue lithiums absorb a charge when the voltage is between 14.1 - 14.6 and maintain via float when voltage is between 13.6 and 13.8.

3.  Given these facts, I would only be borderline float/charge with lead acid and only able to float charge the lithiums.  So really no charging capability at all - just maintaining / floating.

4.  I sent and email to LifeBlue since I'm getting the Lithium package and I asked them for guidance on setting up a TV to charge the LifeBlue lithiums.  See attached file.

5.  From the provided diagram, one can see the tow vehicle needs a solenoid to protect the TV battery when the ignition is off and only charge the lithium house batteries when the ignition is on.  The solenoid is connected to the TV battery and alternator through a heavy duty MRBF fuse and 2 gauge or larger  wire.  The solenoid is then connected through a wire and high amp Anderson plug.  I specifically asked about the recommended gauge of wire between the Solenoid and Anderson plug if the run is 20' and was told 0 gauge minimum, 00 gauge optimal if I include 10 more feet for the Ollie.  That's some THICK wire!

6.  From there the current goes into the Oliver and the wire thickness of 00  would have to be maintained to the batteries.  They also recommend a cutoff switch.

7.  I've asked Jason in Oliver service for the electrical diagram of the Oliver Elite II (specifically this connection) to see what kind (if any) of upgrades would be required on the Ollie side.  I'll share what I get back from him in case anyone is interested.

Summary.  Now I know why Mike and Carol also had to use a generator along with the TV alternator on that "cloudy" trip they described...  if the stock trailer harness lead is all that is being used, you won't really be able to add any significant charge to any house batteries while driving.  This is especially true for Lithiums.  Looks like a lot of upgrades / money to actually enable meaningful charging from the TV alternator - with the payoff being not having to carry a generator.  I'm still thinking this over.  I already have a generator I could use.  🙂

Alternator Charge Circuit copy.pdf

John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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21 minutes ago, NCeagle said:

Summary.  Now I know why Mike and Carol also had to use a generator along with the TV alternator on that "cloudy" trip they described...  if the stock trailer harness lead is all that is being used, you won't really be able to add any significant charge to any house batteries while driving.  This is especially true for Lithiums.  Looks like a lot of upgrades / money to actually enable meaningful charging from the TV alternator - with the payoff being not having to carry a generator.  I'm still thinking this over.  I already have a generator I could use.Alternator Charge Circuit copy.pdf🙂

Actually, the trip from Glacier NP to Bozeman ended in a park with 30a, so we didn’t use the generator.  The generator use was while we were static in Gros Ventre campground at Grand Teton NP with no hood ups.  I have the larger alternator and trailer tow package and my impression is that I’ve been charging my 4 AGMs while driving, although I haven’t done any specific measurements.

Mike and Carol | Fair Oaks Ranch, TX | 2016 Elite II #135 | 2020 Ram 2500 Laramie 6.7L Cummins Diesel

ALAZARCACOFLGAIDILKSKYLAMDMSMOMTNENVNMNYNCNDOHOKSCSDTNTXUTVAWVWYsm.jpg

 

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3 minutes ago, Mike and Carol said:

Actually, the trip from Glacier NP to Bozeman ended in a park with 30a, so we didn’t use the generator.  The generator use was while we were static in Gros Ventre campground at Grand Teton NP with no hood ups.  I have the larger alternator and trailer tow package and my impression is that I’ve been charging my 4 AGMs while driving, although I haven’t done any specific measurements.

You are most likely above 13.8 volts and charging your AGMs with your set up - you would know if you weren't.  I was not impressed when I measured my voltages because I have the towing package and expected better.  I suspect I have a problem somewhere. 

I think one important point is that for new owners that are getting the Lithium package (like me), there are increased voltage / amp requirements coupled with more stringent charging requirements that are really going to push the limits of some of the alternators in our TVs, and it looks like LifeBlue is recommending some significant upgrades to charge from the TV.  Hopefully Oliver engineering is aware and will advise / adjust accordingly.

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John and Anita

2020 Oliver Elite II, Hull 688

Tow Vehicle:  2006 Silverado 2500HD Crew Cab.  6.6L Duramax

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I’ll be watching this as Oliver starts putting in Lithium.  I don’t know how long my AGM’s will last but when replacement time comes I’ll be using everyone’s lessons learned.  Mike

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Mike and Carol | Fair Oaks Ranch, TX | 2016 Elite II #135 | 2020 Ram 2500 Laramie 6.7L Cummins Diesel

ALAZARCACOFLGAIDILKSKYLAMDMSMOMTNENVNMNYNCNDOHOKSCSDTNTXUTVAWVWYsm.jpg

 

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Posted (edited)
2 hours ago, Dean said:

That’s a good (excellent) setup. I’m surprised at the 6awg wires on the truck side but considering the short distance it probably makes little difference. 

I tried using the Sterling charger that they recommend, for the house battery in my truck, but found it to be a bit finicky - it didn’t play well with the smart relay on the starter battery. I talked to Lifeline about it at the time and they echoed my experience and recommended that I remove it and just let the truck’s regulator take care of things. So far, that’s worked fine but I can tell from my battery monitor that the truck really doesn’t see the battery and only charges when it feels like it. So I think some patience with figuring out the Sterling would pay off. Actually I think the right solution would be to remove the relay rather than the Sterling.

My first lesson in charging house batteries contained dire warnings about GM voltage regulators. That was six years ago I think, and it seems like the other manufacturers have followed suit. At least my Ford does what it wants, and doesn’t seem to believe that any other battery exists except it’s own. 

Edited by Overland
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Snowball • 256 • 2018 Ford Raptor

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