Truck to camper wiring questions

[jonwegs]

I am new to the forum and owning a 2003 Lance 815. Vehicle is 1992 F-250 7.3 IDI. Also inexperienced with electrical systems.

My plan for the setup is almost always dry camping. So I am really wanting to get the battery charging system dialed in. I have already bought Lance's unique truck side male plug which I quickly learned I needed. My model does not have a built in battery isolator/separator.

I hoped I could wire the lance plug directly into my 7 pin in the bed of my truck, but the trailer wiring has smaller than 8 gauge wire for the power wire and ground wire. I tried this and the running lights work, but I now know the smaller gauge hot wire and ground won't charge the camper battery.

What do I need to do to successfully and safely wire my camper to the power generated when the engine is running?

Some say wire 8 gauge or bigger directly from the truck battery via an isolator, some say from the alternator via an isolator. While others say just wire it directly to the windshield wiper motor.

I will also have a solar panel (being shipped now), so ideally this will not be the only way my camper battery gets charged.

Any advice, links, or previous posts I didn't find would be greatly appreciated. And apologies for my ignorance on what seems like such common knowledge info for experienced folks.

[KKELLER14K]

Wow..lol. I still believe that isolating the charge wire makes good sense and go big.Thanks for the revisit and shout out AnEv942. I can't believe some of my how to's are still out there but pictures are worth a thousand words and these subjects will always come up. Happy trails!!

[bb_94401]

For those who want to learn way more than they ever knew existed about VRLA (Valve Regulated Lead Acid) batteries, a company called C&D Technologies has a "Resources Page" on their website where they have the following Technical Bulletins as PDF files.


By extension you'll also learn a lot about agm, gel and regular flooded batteries. For the most authoritative source for your particular battery, the "good" manufacturers have technical bulletins and technical people you can talk to if you have questions or need to put technical information in perspective.


VRLA Batteries

• 41-2128 Charging Regulated VRLA Batteries
• 41-2129 Constant Voltage Charger Selection for VRLA Batteries
• 41-2130 Recharging Time Determination for VRLA Batteries
• 41-2131 Charger Output AC Ripple and the affect on VRLA Batteries
• 41-6739 Gassing and Ventilation
• 41-7135 Capacity Testing VRLA Batteries (20 to 200 Ah Capacity)
• 41-7264 Integrity Testing
• 41-7271 Impedance and Conductance Test
• 41-7272 Self Discharge and Inventory Control
• 41-7327 VRLA Battery and their Application
• 41-7329 Life Expectancy and Temperature
• 41-7334 UPS Applications and VRLA Battery Sizing
• 41-7471 Operational Qualification and Warranty Registration Checklist
• 41-7546 10 Year VRLA Periodic Maintenance Instructions
• 41-7745 Lead Acid Battery Terminology Glossary
• 41-7944 Thermal Runaway In VRLA Batteries - Its Causes and Prevention
• 41-7952 Parallel Operations Lead Acid Batteries
• 41-7953 VRLA Batteries Electrolyte Freeze Protection
• 41-7954 VRLA Batteries Extended Run Time
• 41-7955 VRLA Batteries Engine Starting Applications

For those concerned with the causes and how to prevent thermal run away (aka blow the battery) you might find bulletin 41-7944 interesting.

[cewillis]

Kayteg1 wrote:

cewillis wrote:
Those that want to learn -- will.

Not that easy. There is a lot in electricity that even professional electricians don't understand.
Like household wiring where 2 hot wires use single common.
Some houses had fire after electrician did some additional wiring.
With TC battery charging you have several factors, who interact and you can't judge one without considering the other.
- truck charging voltage (that on older trucks changed with rpm)
-voltage drop on long wire (that is changing depends on the amperage)
-max amp output the truck alternator can send
- max amp charge the battery will take without exploding
-time you have to charge the TC battery
- your choice of faster charge and shorter battery life, or the other way around?
Those are the issues I learned the hard way, even I never had intention to become electrician. I bet real pro will have more to add.

And those that don't -- won't.

[Kayteg1]

Grit dog wrote:
You’re blowing the whole exploding battery thing out of proportion. What makes you think the alternator will send more amps to the camper battery than it does to the truck batteries?

See, that is where subject knowledge apply.
And take it from the guy who did manage to blow the battery with high charge 😉
Coming to the point, truck batteries are always well charged, or they will not turn the engine over. So when alternator delivers ca 14V, the batteries being at 12.5 + V don't take high amperage.
Now when you run thick cable to TC battery discharged down to 10V, the full alternator power will go straight to it.
High amp = lot of heat and lot of potential something will blow.

[Grit_dog]

You’re blowing the whole exploding battery thing out of proportion. What makes you think the alternator will send more amps to the camper battery than it does to the truck batteries?

[Kayteg1]

cewillis wrote:
Those that want to learn -- will.

Not that easy. There is a lot in electricity that even professional electricians don't understand.
Like household wiring where 2 hot wires use single common.
Some houses had fire after electrician did some additional wiring.
With TC battery charging you have several factors, who interact and you can't judge one without considering the other.
- truck charging voltage (that on older trucks changed with rpm)
-voltage drop on long wire (that is changing depends on the amperage)
-max amp output the truck alternator can send
- max amp charge the battery will take without exploding
-time you have to charge the TC battery
- your choice of faster charge and shorter battery life, or the other way around?
Those are the issues I learned the hard way, even I never had intention to become electrician. I bet real pro will have more to add.

[Kayteg1]

The cigarette pack-sized jump battery alone will start my Honda 3000 generator.
Good flashlight too and saved my photo session when I run low on android charge.

[Hemi_Joel]

mellow wrote:

Hemi Joel wrote:
I have never ran the batteries down enuff that the truck did not start, but I figure if I did, it should still start the generator to charge it back up.

I thought this myself, surprisingly the Onan generator takes a bit of juice to turn over. Ended up Having to get a jump start from a friend as I didn't feel like waiting for the solar to charge it.

After that I installed a Low voltage disconnect switch to my truck battery so it won't happen again.

I also carry one of those remote jumper packs that has a built in air compressor, 12v and 110 volt outlets as well. Just in case. I don't know how well it would do starting the cummins, but it should at least start the generator.

[mellow]

Hemi Joel wrote:
I have never ran the batteries down enuff that the truck did not start, but I figure if I did, it should still start the generator to charge it back up.

I thought this myself, surprisingly the Onan generator takes a bit of juice to turn over. Ended up Having to get a jump start from a friend as I didn't feel like waiting for the solar to charge it.

After that I installed a Low voltage disconnect switch to my truck battery so it won't happen again.

[cewillis]

Those that want to learn -- will.

[Hemi_Joel]

You do not want to use a small wire size to regulate the charge rate of the batteries. Because there will be consequenses. Like your camper batteries not charging. It is the job of the voltage regulator to limit the charge voltage. The right voltage regulator won't force the battery to take anymore than it can handle.

[Kayteg1]

cewillis wrote:

Why would you want to use a smaller wire over a longer distance to charge TC battery(s)?

Modern trucks beside powering glow plugs and other truck accessories also have ca 2000W electric cabin heater.
I doubt anybody has that stuff in his TC.
When you use heavy gauge TC cable and have deeply discharged camper battery, you'll be sending 100+ amp to it.
Very good way to fry the battery and potentially start a fire.

[cewillis]

Here's a simple way to look at the issue.
1) open truck hood
2) look at the wire from the alternator to the battery(s)
3) how long is it?
4) how big is it?
5) why did they do that?
Why would you want to use a smaller wire over a longer distance to charge TC battery(s)?

[bb_94401]

Recharging from the truck is convenient when you are traveling between sites. The size of the wire needed depends on

• Distance to and from the alternator and the TC
• Distance to and from the connector to the batteries inside the TC
• The type of Battery
• The size of your battery bank

The amphere rating of the connector at the TC also depends on the size of the battery bank as well. Anderson Power Products Powerpole and PowerMod HP lines make quality connectors. Others have used Liftgate connectors from autopart stores.

If you are going to be boondocking a lot, strongly condsider getting quality AGM batteries (Lifeline or Trojan. For all the pluses vs. regular flooded or cheap AGM batteries read the Lifeline Technical manual PDF.

While the resistance / impedence of flooded batteries usually limits charging to 0.1 x 20hr Ah capacity, quality AGM batteries can take up to 5 x 20hr Ah capacity during bulk charging. Faster overall charging. My alternator easily pushed 80A into two 6VDC Lifeline GPL-4ct batteries (220 Ah @ 20hr) through my 2AWG wiring. The converter in my TC typically charges at 0.35 x 20hr Ah Capacity. Think about the future when sizing your wiring. My battery bank is now 440 Ah to deal with boondocking during the winter.

If you are just running devices inside your TC while driving, then voltage drop due to wire resistance isn't as much an issue. If you want to have charging of the batteries while driving, minimizing voltage drop is very important. Lots of online wire size calculators.

Once you've connected your truck batteries (via alternator connection) to your TC batteries. You need to have a disconnect between the two so that you don't discharge your truck battery, while discharging your TC batteries, and stranding you.

Manual switches from online / local marine stores work well, but if you forget it is connected, you can end up with a dead truck battery.

Continuous duty solenoids, "ON" only when the ignition is on, work well most of the time. Although some on this forum have reported being stranded due to arcing of the contacts during connection, causing them to to weld together, fail closed and discharge the truck battery even with the ignition off.

Solid state electronics give the advantage of being automatic, yet avoiding the arcing issue. Traditional, inexpensive silicon diode based "isolators" isolated the batteries, however they had the downside of a 0.6 VDC voltage drop across the device, so not good for efficient charging. Devices from Power-gate from Perfect Switch and Blue Sea Systems have ultra low voltage drop MOSFET isolater, as well as voltage dependent relays that solve most charging / isolating issues (determines which batteries the ECU senses the voltage from to control the alternator output).

Remember to have fuses / circuit breakers near the batteries in both system to protect against shorts and enclose the wiring in split loom sleeving. Blue Sea Systems has fuse holders that connect directly to the battery. Mega fuses and other larger capacity fuses / breakers can be found online at VTE Warehouse

If the 12VDC power in your 7 pin connector is always on vs. ignition controlled, then you might consider pulling the fuse for this line, as parasitic draws of your TC you can still drain your truck battery, even though you have your TC batteries off during storage on the truck.

Finally, while you are rewiring the 12VDC supply inside your TC, if you don't have one already condsider adding a shunt and battery monitor (Trimetric, Xantrex, and others )to get the most lifetime out of your expensive batteries. A good monitor will also let you know when you will need to recharge your batteries to avoid waking up in the middle of the night with the heater just blowing cold air or the LP gas detector sounding due to low voltage.