Re: GPS Power

I have found a couple of places that have simple plans for 12vac to 12vdc
rectifiers. I have built one to run a strobe light on a work sled that
required 12 vdc from a lighting coil that produces only 12vac.

http://www.allaboutcircuits.com/vol_6/chpt_5/6.html

If you attach a "12 volt power outlet" (aka cigarette lighter socket) to the
rectifier output, you can use the original GPS power cord to reduce the
voltage to the correct level.

Another possibility would be to take along a smallish 12 volt dc battery and
power the GPS as a "dead loss" system. Some of the small cheap booster
battery/cable packs sold by Wal-mart and Sears have a 12 volt power outlet
included. My snowmobile has a weak battery charging system, so I power
accessories off a removable jump starter battery pack which I charge in the
house between uses.

"Sunny" <sunny@xxxxxxxxxx> wrote in message
news:LZmpf.988$1Y4.45285@xxxxxxxxxxxxxxxxxxxxxxxx
>
>
> Dennis Mayer wrote:
>
>>
>> Sunny wrote:
>>
>>>Bought myself a Christmas present today - a Garmin Quest GPS.
>>>
>>>I got it because I often use lakes as 'transport sections' to reach
>>>trail systems that are otherwise too far away for day trips, but I
>>>sometimes get lost on the ice.
>>>
>>>I've been playing with the software, plotted my favorite lake routes on
>>>the map and transferred them to the GPS unit - looks like it will do
>>>what I want, i.e. show me the route I plotted vs where I am right now.
>>>
>>>My question is ... do I have to run it on battery while riding, or can I
>>>power it from the sled?
>>>
>>>The GPS came with a cigarette lighter adapter, but the speaker for
>>>announcing route directions is part of the adapter and doesn't look like
>>>it was designed for outdoor use - and my sled doesn't have a battery,
>>>let alone a cigarette lighter socket.
>>>
>>>Can I power the GPS off the lighting coil on the sled? If so, what's the
>>>best way to hook it up?
>>>
>>>Thanks,
>>>
>>>Sunny
>>
>>
>>
>> Generally speaking about Garmin units.... the cigar plugs takes in
>> 12V DC...
>>
>> but the Garmin Cigar Power cord reduces the voltage to 3 V DC.....
>
> Thanks for pointing that out!
>
> The manual says 13.8v, but that didn't seem right for the GPS unit itself.
>
> It turns out both the AC adapter and car adapter output is 5v DC, and the
> GPS 'threshold' voltage (the voltage at which it detects external power
> and turns itself on) is 4.5v.
>
>> You should not hot wire 12V DC from the sled to the Garmin GPS.......
>
> Definitely not!
>
> There was a dead TV on the curb today - so I hauled it in, pulled a
> suitable power transistor and zener diode, and built a DC-DC converter. My
> converter's output is 4.9v, and it runs the GPS just fine from a car
> battery.
>
> Next step is to find out if my sled has a rectifier (sled is at the
> cottage, I'm stuck in the city this weekend), if not I'll need to add a
> bridge rectifier and filter capacitor ahead of the DC-DC converter -
> already pulled those from the TV in case I need them.
>
> However, I guess I'll still have to buy a second car adapter ($$) since I
> don't see a way to get a reliable connection to the power buttons on the
> GPS unit without using Garmin's cradle - unless someone has a cheaper
> idea...
>
> Sunny


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