Stupid noobie question...

Discussion in 'General Electronics Chat' started by Tifa, May 20, 2016.

  1. Tifa

    Thread Starter Member

    Nov 5, 2009
    I have a Garmin motorcycle satnav that uses an external cable transformer like the one in the pic.
    (sorry pic is so big)
    I have the transformer wired to directly to the motorcycle battery.
    It appears to have failed as there is now no voltage at the satnav connection.
    Out of curiosity, how much current is it likely to draw with the satnav unit taken OFF the motorcycle?
    i.e with no load .
    I'm aware that the winding ( the primary?) will take a little current, but surely, not enough to cook it within a few weeks?
    I can't get a muli meter to it just yet.
    Any help/info would be great.
    Thanks guys.


    Mods Note:
    Please compress the resolution to a clear and appropreate size as 800x600 or 1024x768, the photo already compressed to 800x600.
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    very little
  3. dl324

    Distinguished Member

    Mar 30, 2015
    The input to the adapter is DC, so it likely doesn't have a transformer. Some/most adapters consume power with no load, but it's typically small. Since the adapter in question is designed for direct wire, one would think that it was designed to be connected continuously without damage.

    The black thing on the power lead might be a fuse. Have you checked it?
  4. SLK001

    Active Member

    Nov 29, 2011
    It's too big to be just a linear voltage regulator. I would imagine that it is a DC-DC converter, which in idle, would consume very little power. If the fuse is okay, then you're going to have to cut open the converter.
  5. crutschow


    Mar 14, 2008
    I agree that it must be a switching regulator, since a linear regulator would need a large heatsink to dissipate the 14W or more dissipated for a 2A, 5V output (so it's actually too small, not too large).
  6. wayneh


    Sep 9, 2010
    I use a 12V-5V converter to charge my iPhone in the car when I need to. It draws so little current that I just leave it plugged in all the time. Even in cold weather and after several days, the car starts fine.

    However, I would NOT leave such a thing attached to a battery over an off-season without a trickle charger.
  7. ian field

    Distinguished Member

    Oct 27, 2012
    Its worth a trudge round the discount stores - some have cigar socket adaptors to 5V. Not all handle 2A, but some do.

    It near certain to be cheaper than replacing that, and adding a cigar socket to plug it into would make it easy to disconnect when standing.
  8. wayneh


    Sep 9, 2010
    Yeah, I have a 12V-5V converter that plugs into the cigarette lighter....errrr... I mean "accessory port". It's rated to 3A and cost well under $10.
    Last edited: May 21, 2016
  9. hp1729

    Well-Known Member

    Nov 23, 2015
    I can't even find that part number on the Garmin web site (320-00322-70)

    (to OP) Is it sealed or screwed together. Can you take it apart and attempt repairs?
    Last edited: May 21, 2016