Battery fan won't run on battery bank USB, but will on 'puter USB... Any Ideas for lite bike elec?

PhotowhitPhotowhit Solar Expert Posts: 4,335 ✭✭✭✭
I've been contemplating setting up a bicycle travel, small solar system, using a lithium battery bank as the battery bank.

I've picked up a few odds and ends to this end, and last night I wired a small 5" battery fan with a USB cords and plugged it into my computer and it worked fine. Later I tried my battery bank and it won't run...

I had used red and the bare ground wire. 

After checking a color wiring pinout I went ahead and attached the black to the bare ground and it worked.

Curios why this happened? I guess the outside metal is wired on the computer, but not the battery bank? Just seems odd.

Can I leave it this way, or should I disconnect the bare ground?

Guess I should say, Mine was a thrift store find and didn't come with the usb cord, I just hard wired to the 4 - AA battery slot.

Open to other interesting electronic devices to add to the bicycle dashboard. maybe a small TV, I'll use a Sandisk sport for radio and mp3 player and a raspberry Pi zero for a computer. Looking for a small computer screen or a hack for a small high res picture display or some other monitor. Glad to hear ideas.

Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.


  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    Maybe it's just me, but I find the labelling on the pic a bit confusing. It seems to me a serial (uSb) cable minimally has receive-rx, transmit-tx, and signal ground. The signal ground is the reference for high/low signal voltage.

    It can/should be at about the same potential as the DC negative, but as it's important as the signal reference, generally a separate wire AFAIK. The bare ground is apparently the DC negative?

    There are small screens available for rPi, but I'm not sure about the zero. Maybe use a phone ssh app for kb/display?
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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