My BMW R1150 GSAA at Deals' Gap

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The Comms Box - Catching Waaaaay Up

Wow, it's already mid-August and I failed big time in documenting my efforts from much earlier in the year when I built the comms box for the KLX250S. I won't go into great detail on the construction steps in this posting, but following the mounting of the Pelican case to the rear rack, I

  1. Completed wiring up the radio, intercom and power distribution inside the case
  2. Completed connecting everything up wiring and wiring it to the bike
  3. Was hugely disappointed about the amount of alternator noise on the radio's transmit and receive audio(!)

Here are some pictures showing the construction efforts that went into the comms box.

Autocom and Yaesu radio mounted

Underside wiring - What you don't see

Where the wires will come out

Looks pretty clean

NMO-style antenna mount

Modified commercial PTT switch for the radio

I'd previously tamed some alternator noise on the GS by adding a 20 Amp DC Line Noise Filter from PowerWerx, so I ordered one up for this application and tried it out. It DID tame the noise on the receive audio through the intercom, but it didn't help at all on the noise that impacted the clarity of my transmit audio. So, after a brief period of head-scratching, I decided that I was simply asking too much of the little KLX250S's electrical system. I decided to go "off the grid" and go to a solar-charged, battery-only electrical system for the comms box.

Out came the DC relay that I'd use to switch electrical goodies on and off with the bike's ignition. That in itself didn't free up enough room for a battery inside the Pelican case, so I created a bracket to secure the battery to the top of the case. The battery is a 12 Volt, 5.1 Amp-Hr. sealed unit purchased from Batteries Plus

An Instapark All Black 5 Watt Mono-Crystalline Solar Panel was ordered up from Amazon. After a protection diode (1N5817) was added to the panel, a pair of aluminum brackets were fabricated to mount the panel above the battery and to the top of the case.

Simple brackets holding the solar panel and battery

Wiring details - no place to hide!

Another view of the 5 Watt solar panel

The Garmin and Yaesu head unit up front!

With everything mounted securely and wired, I'm able to say that the "off-the-grid" solution works as expected, with no electrical interference from the KLX250S. I decent sun, the solar panel extends the use of the radio, GPS and intercom well past the typical day of riding. An auxiliary power connector makes it simple to plug in for an overnight boost charge, too.