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Open Roads Forum  >  Tech Issues

 > Tow Vehicle Battery and Alternator

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grizzzman

salt lake city, Utah

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Posted: 11/07/19 12:56pm Link  |  Quote  |  Print  |  Notify Moderator

I'm going to purchase and install the 40 amp DC to DC charger. Couple questions though.

A signal control (ignition line) is required to activate this device. Considering the application is a tow behind trailer, can I use the 7 pin trailer harness to tap into for a 12 volt source instead of running a separate line all the way back to the TV's ignition circuit? It would either be the #4 pin (aux) or #3 pin (tail/running lights). I think the tail lights would be a better option as I could control the unit's power via the headlight switch. Thoughts?

Most newer trucks switch off power to the plug with key off. With that said you would need to disconnect or install a diode to keep the trailer from back feeding and causing the charger to stay on. Any 12 volt circuit that would turn off when you want it to will work.


Also, the Renogy wiring diagram shows both positive and negative lines running from the starter battery to the DCDC charger. Is it possible to just wire in a negative line to the chassis of the TV (near the hitch) and run that along side the positive line from the starter battery? I would use a dual pole plug & socket like the Tectran recommended earlier in the thread.


I would not have an issue with using the frame as a ground.(just make sure battery to frame cable is adequate.)
Also, I would wire in a fuse or breaker on the positive feed near the starter battery. Is a 60 amp ok for 6 AWG wire? What is preferred, breaker or fuse?

If you used a breaker, you would not need to carry a spare. Either will work.

Finally, there are dip switches on the charger that customize the charging profile of the battery bank. Considering I'm using flooded GC2 6 volt batteries, what is the recommended absorption and float "end-of-charge" voltages for my configuration?

If it were me 14.7 and 13.2(you could bump up to 13.5 or 13.8 if you are using a lot of power.


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CJM1973

Trenton, MI

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Posted: 11/07/19 01:38pm Link  |  Quote  |  Print  |  Notify Moderator

grizzzman wrote:

I'm going to purchase and install the 40 amp DC to DC charger. Couple questions though.

A signal control (ignition line) is required to activate this device. Considering the application is a tow behind trailer, can I use the 7 pin trailer harness to tap into for a 12 volt source instead of running a separate line all the way back to the TV's ignition circuit? It would either be the #4 pin (aux) or #3 pin (tail/running lights). I think the tail lights would be a better option as I could control the unit's power via the headlight switch. Thoughts?

Most newer trucks switch off power to the plug with key off. With that said you would need to disconnect or install a diode to keep the trailer from back feeding and causing the charger to stay on. Any 12 volt circuit that would turn off when you want it to will work.


Also, the Renogy wiring diagram shows both positive and negative lines running from the starter battery to the DCDC charger. Is it possible to just wire in a negative line to the chassis of the TV (near the hitch) and run that along side the positive line from the starter battery? I would use a dual pole plug & socket like the Tectran recommended earlier in the thread.


I would not have an issue with using the frame as a ground.(just make sure battery to frame cable is adequate.)
Also, I would wire in a fuse or breaker on the positive feed near the starter battery. Is a 60 amp ok for 6 AWG wire? What is preferred, breaker or fuse?

If you used a breaker, you would not need to carry a spare. Either will work.

Finally, there are dip switches on the charger that customize the charging profile of the battery bank. Considering I'm using flooded GC2 6 volt batteries, what is the recommended absorption and float "end-of-charge" voltages for my configuration?

If it were me 14.7 and 13.2(you could bump up to 13.5 or 13.8 if you are using a lot of power.


Thanks a bunch. AWG cable, breaker, plug ends, and DCDC charger are on their way. Hopefully, the weather holds out so I can get this project behind me before thanksgiving.

mapguy

Puget Sound

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Posted: 11/07/19 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

Sorry - late to the party....

Personally, I prefer external regulation/control on non ecu controlled vehicles. Check the link for info...this is one source.
https://alternatorparts.com/quicktifier-external-bridge-rectifier.html

details of how this works has been detailed by Mexicowanderer here many times.

CJM1973

Trenton, MI

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Posted: 11/07/19 03:09pm Link  |  Quote  |  Print  |  Notify Moderator

mapguy wrote:

Sorry - late to the party....

Personally, I prefer external regulation/control on non ecu controlled vehicles. Check the link for info...this is one source.
https://alternatorparts.com/quicktifier-external-bridge-rectifier.html

details of how this works has been detailed by Mexicowanderer here many times.


Interesting. I will investigate.

Rbertalotto

Massachusetts

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Posted: 11/10/19 05:19pm Link  |  Quote  |  Print  |  Notify Moderator

Looks like there is loads of miss information on this thread....About hooking a DC to DC directly to the Alternator....NO

About mounting the DC to DC at the trailer... I don't think so

Check out this excellent video of realtime testing of Renogy DC to DC

https://youtu.be/EcVjPap9dkY

https://youtu.be/EcVjPap9dkY


RoyB
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CJM1973

Trenton, MI

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Posted: 11/10/19 07:32pm Link  |  Quote  |  Print  |  Notify Moderator

Rbertalotto wrote:

Looks like there is loads of miss information on this thread....About hooking a DC to DC directly to the Alternator....NO

About mounting the DC to DC at the trailer... I don't think so

Check out this excellent video of realtime testing of Renogy DC to DC

https://youtu.be/EcVjPap9dkY

https://youtu.be/EcVjPap9dkY


Thanks. Seen the video. Everywhere I've read says to mount the dcdc charger closest to the house batteries. Haven't read otherwise.

Rbertalotto

Massachusetts

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Posted: 11/10/19 07:50pm Link  |  Quote  |  Print  |  Notify Moderator

Well...Learn something new every day.....Looking at Renogy Install Manual

"When selecting a location for the DCDC, make sure that the unit is as close as possible to the battery you will be charging (auxiliary battery). "

I had read on a few other sites to put it close to the main battery.....Don't trust everything you read on the internet.. :-)

CJM1973

Trenton, MI

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Posted: 11/10/19 08:13pm Link  |  Quote  |  Print  |  Notify Moderator

Rbertalotto wrote:

Well...Learn something new every day.....Looking at Renogy Install Manual

"When selecting a location for the DCDC, make sure that the unit is as close as possible to the battery you will be charging (auxiliary battery). "

I had read on a few other sites to put it close to the main battery.....Don't trust everything you read on the internet.. :-)

Yeah, I learned early on that there are a bunch of liars on it...except for maybe RV .net. [emoticon]

I bought a water proof tongue box that I will install it in along with my 3 AGM 100 AH batteries. Between the new battery bank and this new DCDC charger, I our Alaska trip will be less reliant on firing up the old inverter generator. I'm bringing one just to be safe.

Rbertalotto

Massachusetts

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Posted: 11/10/19 08:17pm Link  |  Quote  |  Print  |  Notify Moderator

I ordered the Renogy 40A version to charge my portable battery box I just built for my Roof Top Tent....and to charge the trailer batteries when I'm pulling that unit.

These DC to DC chargers are really neat...Lots more control and safety for your alternator and your batteries that a simple solenoid like we used to do.

With my 2018 RAM I understand that a simple solenoid setup will confuse the computer controlled alternator but these DC to DC chargers are fine....

We shall see!

You can see my Portable Battery and RTT solar here:

www.rvbprecision.com

time2roll

Southern California

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Posted: 11/10/19 09:03pm Link  |  Quote  |  Print  |  Notify Moderator

Rbertalotto wrote:

Well...Learn something new every day.....Looking at Renogy Install Manual

"When selecting a location for the DCDC, make sure that the unit is as close as possible to the battery you will be charging (auxiliary battery). "

I had read on a few other sites to put it close to the main battery.....Don't trust everything you read on the internet.. :-)
All charging systems work better when close to the battery getting charged.
Solar, converter, alternator, and this Renogy dc/dc charger.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

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