Not a Fan of USB, or Batter Tenders... they look clean but not practical in my world.
I am a huge fan of 12v POWER SOCKET Adapters!!!
You can use a OG GPS, Cellphone cables with em.
BUT the bonus is SOLAR PANEL Chargers can be plugged into em when your GROM is not in use. (East Coast Winter Peeps)
SOLAR rocks!!! Got a stable of 10 scoots soooooo can't ride em all.
Hence the Solar Trickle Chargers keep my stable nice and Charge!!! Especially my Scoots with no kick starts!
My rides are stored in a Shed so again Solar is KING! Got the Panels on the Roof of the shed.
Oya make sure to put an inline Fuse in it to be safe.
MY FAVORITE 12v POWER SOCKET Adapter can be found at PEPBOYS.
Bell Automotive Products All Weather 12V Power Socket/ | Product Details | Pep Boys
They look clean, they keep out the elements if/when raining and/or not in use.
Just Word of WARNING!!!
If/When you buy one... OPEN IT UP RIGHT IN FRONT OF THE CASHIER WHEN YOU BUY IT!!!
(Look at Link) that Spring setup & the Plastic tabs CAN/Will sometimes Break if assembled wrong (Kid in China don't give one ounce of F#cks)
I have bought these a couple times, came hope and SNAP when using it for the 1st time. Never had a problem returning it on the same day.
But to save yourself a trip, do it there... right on the spot in case it does break.
-Honest™