Quote:
Originally Posted by PopBeavers
I have both a 2002 Chevy 1500HD and 2008 GMC 2500HD, both factory equipped with the towing package.
If I leave home with the pair of group 24 RV/Marine batteries charged and the TM fridge already cold and running on 12 volts on setting 5, when I arrive in camp 3 hours later the fridge is still very cold and my batteries are both fully charged.
I have no idea what the wire size is on the trucks, nor how many connectors there are. I do know that there is a 40 amp fuse under the hood for the charge line to the trailer.
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That has been essentially what I have seen with my 2004 Chev Suburban 1500 and the 3326 until I installed a Tri-metric battery monitor. We have always started with a loaded, cold refrig set on 5 and always arrived with the refrig still cold and the TM monitor saying the battery is "good".
Now (with the Tri-metric) I see the battery (a single Group 27) has lost about 6% after a 2 hour tow but I have never noticed the loss because we always connect shore power as soon as we arrive at campsite or back home.
Looking into it last week(just to see what was actually happening) I set up the TM so I could measure current and voltage at various points in the charge circuit with the TM on battery only and then with the TV connected and running.
I have the factory trailer wiring package on the Suburban with the standard 40 amp fuse, the standard 7 wire Bargman connectors and a 12 ft long Bargman cable into the 3326. That cable terminates in the the refrig cabinet (outside, bottom vent space).
I started with a fully charged Group 27 (rated at 160 volt-amp capacity when loaded at 15 amps). With the refrig and the fan on, the Tri-metric display said battery at 100%, 12.65 volts and -10.7 amps (leaving the TM battery). I then connected the Bargman cable to the TV with the engine running.
At this point the Tri-metric read 99%, 12.60 volts and -5.6 amps indicating that some of the refrig current was being supplied by the TV. I measured the TV battery voltage as 13.73 and using a DC clamp-on ammeter, I read 5.1 amps in the TV wiring harness near the hitch.
Exploring the wiring further I found the Bargman cable termination in the TM refrig cabinet was easy to get to and also provided easy access to the refrig terminals, the wires feeding the TM battery and the wires coming back to the refrig from the TM battery buss fuse panel. Measuring voltages and currents at this location I found 13.3 volts at 5.1 amps on the Bargman cable (#10 wires) and 11.6 volts at 10 amps on the refrig DC supply terminals. Here I also confirmed the TM battery was supplying 5.6 amps.
The 13.73 volts at the TV battery minus the 13.3 volts in the TM meant I was losing 0.43 volts in the total wiring from the TV battery to the TM cable termination in the refrig cabinet. The current in this wiring was 5.1 amps. About normal for a two wire #10 circuit running 15 ft.
I also noticed the TM battery charging and refrig supply wires were #12 and ran at least 18 ft back to the battery in the rear storage and at least another 15 feet from the DC fuse panel forward to the refrig.
Left in this condition, the TM battery was slowly discharging at a rate of approximately 5 amps-hours/hour or over 3%/hour. On an eight hour trip the battery would be down to about 75%. Since I never checked it before, I would never have noticed it be cause it would recharge over night when I plugged into shore power.
For me and this particular TM (2010 3326) it's an easy fix. Since I have the Bargman cable right next to the refrig DC terminals I will connect it directly to the refrig as well as leave the existing connections. That will remove the refrig load from the TM battery, supply the refrig from the TV (when towing) and provide an additional set of #12 wires for charging the TM battery. All of the wires are already fused properly.
I'll be trying this idea out on our trip to Pismo Beach so will let you know how it works out.
Jerry