GordonThree wrote:
So you're increasing the voltage, to more efficiently transfer power from the tow to the trailer? Where does the voltage doubler get hooked up, hopefully someplace close to the alternator or starting battery?
There is an improvement in "Voltage Drop" power losses, but that's not the main purpose: The main purpose of all this stuff is presenting a sufficient Charging Voltage at batteries. First, we boost to more than the batteries can handle - then we let the Solar Controller adapt the high-power, 24V "fake Solar Panel" output into the correct profile (Volts and Amps) which the batteries should be given, according to SOC.
Per the linked picture (#2 of 4), the Boost occurs under the hood - reducing current on all the wires before the Solar Controller, including the "Trailer Battery Charge" wiring from under the dash back to the Bargman connector.
GordonThree wrote:
My thought: Bypass the bargman. Run 4ga or heavier off the alternator to the rear bumper and use a PowerPole connector to mate with similar wiring on the trailer side, leading to the battery box. Question is; would a factory alternator handle the extra load?
Yes, it would. (Unless your Trailer batteries are huge and discharged, e.g. 500Ah at 40% SOC.) "Brute Force" puts all the batteries into a single string, and the Trailer Batteries will drag down the Voltage of the Starting Battery by absorbing power until they are all equal. And at the same time, "Battery Voltage Sense" under the hood sees the reduced battery Voltage as well - invoking a higher "Battery Charge" Voltage within the TV (by drawing more Voltage and Power from the Alternator.)
IMO, having done a little bit of both jobs (rewiring the 4Runner "Battery Charge Wire" and installing my new gadgets) - installing the gadgets was
much easier, except for mounting the new dashboard "mode switch". And it avoids hanging an extra cable between TV and Trailer.
That durned "mode switch" took about 2 hours: I needed to trim the dash panel it in order to get into an "unused switch plug" which didn't really fit, and I also had to pull leads (12V, ground) from other wires under the dash. :M
The 4Runner's OEM "Battery Charge" wire was not bigger than 14-AWG, and actually looked closer to 16-AWG. I pulled a new #10, and the body panel disassembly/re-assembly was very time consuming (about 3 hours, total). In contrast, the "Relays-with-Booster Assembly" (at the TV) and the "Two Relays with a few wires coming out" were both assembled in the house (with beer and TV), plus about 1/2 hour installation in each vehicle.
