Power/Charging Port Issue:

[Walstw01]

When my boys built my truck, they added an under-dash phone charging port, wired through a switch to the accessory pin in the fuse block.  When I plug in my charger and connect it to my phone, it does not charge it.  It will charge their phones just fine, but my phone is one of the newer ones that requires the 3-amp charger.  I also have an ”Otto the Automatic Wireless Phone Charging Holder”  (has sensors to automatically open and close the arms that grip the phone, along with built-in wireless charging).  The charging port doesn’t supply enough power to operated the wireless charging phone holder either.  I thought there was a possibility of the port they installed being the limiting factor, so I bought one that was rated to 7-amps and replaced the cigarette lighter power port in the ashtray spare change storage bin.  Still no luck.  Any ideas on what I should look for?  Possibility of corrosion in fuse block limiting power?  I’m at a loss …

[bd]

First, what year/model truck is it so I can look at the correct wiring and fuse box diagram?

The ACC power tap in the fuse box is only energized when the ignition key is in the Accessory and Run positions and should be powered through a 20-amp fuse, typically.  Make sure the phone charger is properly grounded to clean bare metal that, in turn, is properly grounded to B-.  Corrosion of fuse contacts is more common in the older glass fuse type boxes, but the newer blade type boxes are not immune if exposed to moisture and dust.  Scrape glass fuse contacts to clean them then apply some antioxidant paste to inhibit subsequent corrosion.  Blade type contacts are best scoured using some fine-grit valve grinding compound slathered onto a sacrificial fuse that is then inserted and withdrawn from the fuse socket repeatedly.  Be sure to rinse all of the abrasive off of the contacts using some aerosol electronics cleaner before inserting a new correctly rated fuse.

[Walstw01]

Sorry, my mind has been elsewhere ...
1979 GMC K25

[bd]

Is the charger plugged into the cavity located between the PWR ACC fuse (above) and the turn signal flasher (below)?  That cavity supplies constant battery power through the PWR ACC fuse, which should be rated 20 amps.  That is more than ample power for any phone charger, assuming no voltage losses across poor connections.  Verify that the fuse isn't blown, then try connecting your charger(s) directly to the vehicle battery, temporarily, to verify that it (they) work correctly.  Do the chargers have their own internal fuses that might be compromised?

[Walstw01]

I would have replied earlier, but I work retail ever other weekend (and this was my weekend) ...
I do not think my "phone charging holder" has any compromised fuses, as I switched it to my daily driver impala, and it worked fine.  When I get a chance I'll try the port between the PWE ACC fuse and flasher.  It did occur to me to test it right from the battery, but, had no time.
Thanks for the options!

[Walstw01]

I FINALLY had time to dig into this, problem was solved by running a wire from the (hot) firewall junction block, to a switch, then a 5-amp fuse, then to the port.

I really need a shop to work in.  Everything I do is outside, so I have to plan to "tear-down" and button back up in one session ... no "well, let's hang it up for the night & pick back up were we left off on Saturday ..."