Travel Trailer Battery Charging from the Tow Vehicle 7-Way

Updated 04/26/2019 | Published 04/25/2019

Products Featured in This Question

Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End

(111)

$11.69

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

(87)

$535.00

40-Amp MIDI Fuse Kit for Redarc In-Vehicle 25-Amp BCDC Battery Charger

(18)

$90.00

Question:

Will the tow vehicle charge the battery using pin 4 of a seven pin connector and if so, what limits the rate of charge?

asked by: Dale L

Expert Reply:

When your trailer is connected to a 7-way like the Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End # PK12703 the pin at the 1 o'clock position is the 12V power that will charge your trailer battery when it is connected to the corresponding pin on your trailer side connector. This will give your trailer battery a slight maintenance charge that is about 2-4 amps depending on what your alternator can put out that isn't being used by your tow vehicle. This will be like a trickle charger but will slowly charge a drained but not depleted battery. This really isn't for charging as much as maintaining as it would take pretty much all day to charge most batteries depending on how depleted.

If you want a stronger charge to your trailer so that it can restore lost function, then you will want to use a DC to DC charger like the Redarc 25 amp # 331-BCDC1225D with fuse kit # 331-FK40. This will charge a drained or depleted battery much faster. The battery bank size will determine how long to charge. Normally a couple of hours max.

expert reply by: Jason S