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 > charging of 2 camper batteries with truck alternator?

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Kayteg1

California > Nevada

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Posted: 09/30/18 09:09pm Link  |  Quote  |  Print  |  Notify Moderator

From what I observed on my trucks is that trailer wire is usually 10 ga, what theoretically is good for about 40 amp, but on other side, when you follow the wire from the alternator via truck bumper plug, back to camper cord and then to camper battery - you will find 30 to 40 ft of wiring, what will create quite a resistance and with resulting voltage drop, the charging current will be greatly reduced.
I consider that a good thing as charging 100 am-h battery with 40 amp can overheat it and will shorten its life.
Meaning in natural way you will get you battery charged maybe in longer period, but without much danger.
This has been working in RV for well over 50 years, so why change it?





time2roll

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Posted: 09/30/18 10:42pm Link  |  Quote  |  Print  |  Notify Moderator

Frank Mehaffey wrote:

5. The Old Wizard 1's recommendation from the DC-DC battery charging past forum entry about using a
CTEK D250SA or D250S to charge a drained battery, sends more 12v power back to the camper batteries while driving or fast idling. This is my leading candidate for a solution at this time of my "education". If I am traveling with full batteries in the camper, would there be a way to disable that system or is it built to do that when the camper batteries are full? Will the smart charging system that the old wizard mentioned in new trucks interfere with a CTEK unit?

Thank you for all your help.
The CTEK system would be in the camper and would generally be installed in the existing charge line. This system would boost voltage so as to pull the extra power you need from the alternator and put the correct charging voltage on the camper battery. Multiple charging sources do not present an issue so no issues with the existing converter. Even the 20 amp max will do well charging the two batteries. You may still want some solar but that can come later.


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Frank Mehaffey

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Posted: 10/01/18 05:01am Link  |  Quote  |  Print  |  Notify Moderator

Thanks to everyone to explaining my concerns. I am going to leave things alone for now, and install a solar charging system when I have the $ to help keep the batteries charged.

theoldwizard1

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Posted: 10/01/18 06:17am Link  |  Quote  |  Print  |  Notify Moderator

Frank Mehaffey wrote:


If I am traveling with full batteries in the camper, would there be a way to disable that system or is it built to do that when the camper batteries are full? Will the smart charging system that the old wizard mentioned in new trucks interfere with a CTEK unit?

These are "smart" chargers and will not over charge.

mkirsch

Rochester, NY

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Posted: 10/01/18 08:55am Link  |  Quote  |  Print  |  Notify Moderator

Regarding "jumper cables," many TC owners will install "jumper cables" permanently in their truck, running directly from under the hood, to their camper batteries, underneath, out of sight, to maximize the charge rate. Minimum 6ga wire, preferably heavier.

It's not 100% but it is better than the factory charging system and will help you extend your batteries on longer trips.

The "smart" charging system in your truck will only ramp down voltage when it senses that the battery is charged. Your camper batteries will keep the system thinking that it is not charged, and will keep the alternator running at the required output to charge the batteries.


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DWeikert

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Posted: 10/01/18 11:10am Link  |  Quote  |  Print  |  Notify Moderator

mkirsch wrote:

Regarding "jumper cables," many TC owners will install "jumper cables" permanently in their truck, running directly from under the hood, to their camper batteries, underneath, out of sight, to maximize the charge rate. Minimum 6ga wire, preferably heavier.

It's not 100% but it is better than the factory charging system and will help you extend your batteries on longer trips.

On longer trips the heavier gauge wire isn't really needed since you'll have plenty of time to get the batteries up to charge. It's getting the batteries topped off on short trips that calls for the heavy wiring.


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burningman

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Posted: 10/01/18 11:59am Link  |  Quote  |  Print  |  Notify Moderator

Here’s what works:
Buy a 25 foot 2-gauge set of jumper cables.
Cut the clamps off.
Buy one of these: Quick disconnect
Put that on one end. Run the cables to one of your batteries. Put some battery cable lugs on the other end of the cables and bolt them to the battery.
Do the same on your camper, run some 2-gauge from the batteries to the other half of the quick-disconnect.
If you want to be a little fancier about it, it wouldn’t hurt to install a 150-amp breaker near the truck battery, like this one: 150-amp breaker
Now you’ll have full current to your camper batteries to charge as quickly as possible. You can just unplug the connector when parked and using the camper, simple and free, or be as fancy as you wish with a shut-off switch or a solenoid wired to the truck that’s “hot” only when the ignition is on.

This is how I do it, and it works great.


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Kayteg1

California > Nevada

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Posted: 10/01/18 12:37pm Link  |  Quote  |  Print  |  Notify Moderator

burningman wrote:

Here’s what works:
Buy a 25 foot 2-gauge set of jumper cables.
Cut the clamps off.
Buy one of these: Quick disconnect
Put that on one end. Run the cables to one of your batteries. Put some battery cable lugs on the other end of the cables and bolt them to the battery.
Do the same on your camper, run some 2-gauge from the batteries to the other half of the quick-disconnect.
If you want to be a little fancier about it, it wouldn’t hurt to install a 150-amp breaker near the truck battery, like this one: 150-amp breaker
Now you’ll have full current to your camper batteries to charge as quickly as possible. You can just unplug the connector when parked and using the camper, simple and free, or be as fancy as you wish with a shut-off switch or a solenoid wired to the truck that’s “hot” only when the ignition is on.

This is how I do it, and it works great.


I've been thinking about such setup, so would you mind to show details, that still bother me?
1. How do you protect the jump cables from rubbing insulation around the truck frame?
2. with tall sides on new truck, I have no access to put plugs inside the truck bed. How did you do it?

theoldwizard1

SE MI

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Posted: 10/01/18 02:56pm Link  |  Quote  |  Print  |  Notify Moderator

mkirsch wrote:

The "smart" charging system in your truck will only ramp down voltage when it senses that the battery is charged. Your camper batteries will keep the system thinking that it is not charged, and will keep the alternator running at the required output to charge the batteries.

Not completely correct. The smart charging systems in vehicle today provide the absolute minimum voltage to prevent the vehicle battery from going dead after the energy used to start the car has been replaced.

This is typically NOT enough to recharge an auxiliary battery in the RV. It might keep it from going dead, but you will never get it 100% recharged.

burningman

Seattle, WA USA

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Posted: 10/01/18 04:35pm Link  |  Quote  |  Print  |  Notify Moderator

I drilled a hole on the inside of my bed big enough for the cables and put a rubber grommet in the hole, then fed the cable through. I used a set of jumper cables because it was the cheapest way to get 25 feet of heavy gauge two conductor cables.
Protecting from chafing is mostly a matter of securing the cable really well so none of it moves, but there were a couple places I put some large rubber hose around the cables.
A circuit breaker really is a good idea, these are big cables connected straight to the batteries running most of the length of the truck. A short would rain on the party.

The truck will charge the camper batteries. Once they are connected to the truck batteries, the alternator doesn’t know or care where the batteries are. The low batteries will put a load on the alternator and it will accommodate it.

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