12 Volt 5th Wheel Trailer Battery Charge While Towing

Updated 04/27/2018 | Published 04/26/2018

Products Featured in This Question

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp

(88)

$484.59

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

(88)

$620.00

Question:

I have a F-250 with a factory installed tow-command package. I have talked to RV owners and they state they are able to charge their RV battery from the truck if they are connected. I stopped once at a truck stop and used my 5th wheel and my battery was drained. I later found out that my truck did not charge the once plugged and on the road. which of the 7 pins is used to charge my RV battery

asked by: Greg

Expert Reply:

The pin at the 1 o'clock position is the 12V power used to provide the "maintenance" charge to your battery. The issue you found with your F-250 is the same as what you will find with all vehicles. The charge provided to your trailer battery is minimal when driving because even though it is 12V, it is only about 2-4 amps. This is because your vehicle alternator is generating around 14 amps when your truck is running and only the extra not being used to maintain your truck's electrical components is sent to that 12V pin. That amperage is not enough to charge a dead battery or charge a battery past about 80%.

If you want to be able to really charge a battery while towing, I recommend the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D which will boost that small charge to 25 amps when towing. This will allow you to use your refrigerator when towing if you have a 75-200 amp hour battery. If you have a larger than 200 amp hour battery, then you will want the 40 amp version # 331-BCDC1240D to run those extra options and charge and maintain your battery to 100%.

expert reply by: Jason S