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Any parasitic power draw with a Garmin GPS?

khittner

New member
Just got a new Garmin Zumo 396LMT-S GPS, and I’m attaching its mounting hardware, cradle, and power cable to my ‘84 R100RT. Is there going to be a parasitic draw from my battery by the cradle or GPS that I should be cognizant of when I’m not using the GPS? I don’t need a GPS often to navigate, and if it’s going to be a significant power suck on the bike’s modest OE charging capabilities and battery, I could leave it un-wired, and just run it when needed off its internal battery. Any advice from the experienced farkle-adders out there would be helpful. Thanks.
 
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When in the cradle there will be a little draw. My 660 cradle draws nothing when the GPS is not in the cradle.
 
My zumo 590 goes dark when I turn off the ignition, but it is in sort of a "sleep" mode that draws a small amount of power. To turn it off completely, I need to press and hold the power button on the back until the display asks if I want to shut down the unit. I've never bothered to measure the power draw in either case.
 
Short answer is YES there definitely is. I studied this 7 years ago when I got my Zumo 660 and put in on my 1100RT. I have cradles on my RS and G/S now too. Back then there seemed to be a lot of assumptions and even more misinformation on what the power deal was with Garmin units.
So here are my results. Note that your unit may draw less or more power; you have to test that to know for sure.

1996 R1100RT - Garmin Zumo 660 Current Test Notes:
**All results are in milli Amps (mA) or .XXX of an amp for you math nuts.

1) Motorcycle only: The motorcycle itself draws 2.33mA with the ignition turned off. Most of this is the quartz clock in the fairing and the rest would just be leakage current through the ECU and all the other electronics on board.

2) Motorcycle, Garmin Zumo 660 Cradle only: Once you connect the cradle to power the current draw is 2.43mA. This is 0.1mA more than the above Motorcycle only test.

3) Motorcycle, Garmin Zumo 660 Cradle, and Zumo 660 unit locked into cradle: At start up there is a short but significant inrush current of around 2.5 AMPS to 3.0 AMPS but almost immediately the readings drop to 250mA and bounce from 250mA to 305mA as the firmware loads maps etc. Once the unit is up and running it continues to bounce from around 250mA to 312mA which is likely because it is searching for a satellite.

4) The debate over wiring to switched vs un-switched power comes down to choice and early onset dementia. If you are forgetful, then wire it to switched power. All my cradles are on unswitched power as I like to be able to use the GPS in the cradle when the bike is not running and the key is not turned on. Sometimes you just want to check something, find something, review your route... and I don't want to need to have the key on to do that so that is my choice.
I guesstimate the average current draw is around 280mA when the unit is just running and doing it's thing. Actually that is a fair bit of juice IMO. Switching bluetooth on and off with no devices connected (would draw more power obviously since transmitting is power consumptive) shows a mere 2mA to 3mA increase (ON) and decrease (OFF).
5) Turn GPS off but leave it in the Cradle: This results in a current draw of 3.17mA. So this means the GPS is pulling 84mA even when it is OFF but in the cradle. I have to admit this surprised me.
6) Finally, I removed the GPS from the cradle and the current draw once again fell to 2.33mA as in test 1.

CONCLUSION:
1) 0.1 mA is bugger all. So having the cradle connected to power all the time is 1/233rd worse than just leaving your battery connected to your bike (clock) all the time. NO BIG DEAL.
2) Leaving the GPS in the cradle but turned off still adds just under 1mA to the power draw from your battery. NO BIG DEAL but take it out anyway to keep the pin springs in good shape and prevent theft.
3) Removing your GPS from it's cradle will save you 1mA but better yet, it will help you _keep_ your unit!
***Your application may vary, all standard disclaimers apply!
 
Thanks to all for your experiences and data. Mine is wired unswitched directly to the battery, but I'll probably be running an empty cradle most of the time, so the unit will be as secure as anything else on the bike, and power losses minimized to the "no sweat" level when the bike is parked.
 
Thanks to all for your experiences and data. Mine is wired unswitched directly to the battery, but I'll probably be running an empty cradle most of the time, so the unit will be as secure as anything else on the bike, and power losses minimized to the "no sweat" level when the bike is parked.

That is more or less what I do but I don't leave the GPS alone in the cradle in public places as it is so easy to grab and go. Also don't leave in in the cradle over winter or long periods because the spring tension on those tiny gold plated pins goes soft and you start having contact issues. If you run empty cradle put the protective cover on it whenever the GPS is not there. The pins also get mild corrosion pretty quickly. They can be cleaned up with one of those soft white erasers but you must be really gentle. You don't want to rub the gold off.
 
Is there any lube/corrosion protectant that would be prudent to put/spray on the cradle contacts? I just got a new can of Boeshield T-9 the other day . . .
 
Is there any lube/corrosion protectant that would be prudent to put/spray on the cradle contacts? I just got a new can of Boeshield T-9 the other day . . .

I would ask Garmin about that but given the design I have not ever used anything on the pins other than some rubbing alcohol on a lint free wipe to clean them and then a soft white eraser to gently clean the pin heads of any corrosion. The pins are very delicate and the spring tension is as well so I wouldn't risk gumming up the works with any chemicals although Garmin may recommend something they use but I doubt it.

The weather cover is your best friend. I always put it on whenever the GPS is no in the cradle. Since it seals really well that helps to prevent crud and corrosion starting.
 
Years ago I had a R1150GSA and a 478. With the 478 off in 2 or 3 weeks it would draw the mc battery down to where it would not start.
 
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