Power cables

Assuming the cradle has a mini-USB port, then yes, you can use the 255's power adapter. But, if you have free traffic, why wouldn't you want to use it?

In the Philadelphia area the traffic feature doesn't work all that good, half the time by the time I hear "traffic ahead" I've been sitting in it for a couple minutes.

Another is the annoying ad pop-ups when you stop.

Then he can send it to me.

I can think of one reason, at least for my 3790LMT the provided power cord with embedded traffic receiver burns a noticeable amount of power even when the GPS receiver is turned off. I forget the exact numbers I measured and I'm too lazy to look them up but it's on the order of thirty milliamps coming straight off the car's 12 V system. As in retirement I don't use my car every day, that is just enough that I feel the need to pull the cord out of the accessory socket when I park the car in my garage.

If I had a compatible straight through cord I would swap it and just leave the thing plugged in all the time, since my hometown (Albuquerque) does not have traffic reception. Then I would just take the traffic cord on trips.

That is 10 hours for .300 ma 30 hours for not even 1 amp, hardly a worthwhile consideration especially given the fact that most car radios also draw power from the battery while the ignition is turned off. This is to keep the memory alive. Following your reasoning you should remove your car radio when not using the car.

I also pull the 12 volt connector out but not for that reason. If parked where the GPS can be seen then I remove the GPS for security reasons.

I've done this using a power cable from an old nuvi 205
with my 1350LMT. The only drawback I've experienced in not having the traffic feature which you say is not a concern.

I first became aware of the issue of Garmin GPS receivers draining car batteries when I came back from a two week trip to find that my Audi would not start. By fortunate coincidence my daughter had first tried packing the bags into our Prius, so that was the car that went to the airport. Had we taken the Audi we would've needed to jumpstart.

The GPS in that case was an 855, infamous for not really turning off even when it looks like it is off. I subsequently fashioned cables and procured meters that allow me to measure the actual power consumption of the 855 and of the car as a whole. I have forgotten the exact numbers, but believe that the 855 by itself added about 120 mA to the overall car 12V drain when everything was "turned off". I measured the total car "off" power without the 855 at a time average of about 25 mA.

So leaving the 3790 LMT plugged into its power cord plugged into my car when the car is off more than doubles the off state power consumption. As I'm retired (from a career as an electrical engineer), and don't drive the car every day, I choose to lower the cycling of my car's 12 V battery by pulling the Garmin plug.

I cannot easily segregate the car radio but I seriously doubt it is pulling anywhere near as much as my Garmin GPS power cord. In any case it is nowhere near so easy to segregate so, no, my reasoning would not call for disconnecting it.

Lead-acid batteries, as do most other types, age when you cycle them. Why incur the aging imposed by my traffic receiver power cord, which is, by the way, receiving no traffic data?

Archae86, you are not really serious with this "GPS killing car battery" story? Do you have alarm in your car? It will be drawing power all the time when you engage it. Did you had alarm turn on when you were checking power drain? On the other hand, isn't your utility power socket cut off from power when you turn off ignition? I mean remove key, not leaving it in "accessory" position?
Same with on-board computer. If you have remote to open door what do you think is powering computer that is responsible for this function?

And about recharging car battery. I don't wanna burst your happiness, but every time you turn on engine in your car the battery is being recharged. So even disconnecting battery every time you park will do no difference to its longevity. After a few years you will have to buy new one anyway.

Yes, I'm quite sure that he is.

All of those things may draw power from the battery, but it's a question of how much?

My RV has both a carbon monoxide detector and an LP gas detector; together they draw about 250 mA. I have to remember to pull their fuses if I am going to be leaving the rig parked for several weeks without an AC hookup, otherwise I will have a very depleted house battery when I return, and lead-acid batteries do NOT fare well if left sitting in a depleted state for significant periods of time.

On the other hand I can leave my car parked for several months at a time with the battery keeping my radio and entry/alarm system alive and upon my return the battery may not be fully charged but it is certainly not depleted to the point where it has any difficulty turning over the engine. The current drawn by those circuits is negligible.

They also just don't really like to cycle.

In case I was too detailed before, let me be simpler: my 855 "off" consumption raised the turned-off power in my Audi by something like a factor of six. My 3790LMT with traffic power cord raises the turned-off power consumption by well over a factor of two. And, of course for this to be true, a 2002 Audi A4 powers the cigarette lighter and accessory sockets when it is turned off.