GPSrChive Discussion Forum

Is anyone else finding their 66i is very sensitive to a bit of sun when on a windscreen mount?

A couple of times now, we have been driving on sunny days (30+ degrees C, 80-90 degrees F) and it has popped-up the warning message about being too hot to charge. While it was getting significant heat exposure through the windscreen, the aircon was keeping the inside of the car comfortable.

I think I'm going to have to ponder ways to build a sunshield onto my RAM mount.

Yes, the windshield acts like a huge magnifying glass and really heats things up!

Have you tried placing a thermometer in the windshield, I did it a few years ago and was surprised how hot it actually gets.

I don't know how it is with the 66i, but the montana 7xx uses power from the usb cable, so even if the battery is not charged at too high a temperature, the gps does not use anything from the battery.

As soon as the temperature drops, the battery will continue to charge again.
A little shade from something makes a big difference.


This too hot message can be a bit annoying but it shows that garmin has good protection for batteries against overheating and possibly fire.

FWIW, I have measured dash panels with temperatures in excess of 200°F during the summer using a FLIR.

I wasn't keeping a very close eye on it yesterday, but the yellow battery symbol would disappear after a period of time (5 or 10 minutes??) and it would start charging again. We were on a southbound trip (in the southern hemisphere), so the sum was minimised. The GPS was not hot to touch - warm yes, but not what you would call hot. I guess the charging process itself generates internal heat which would contribute to the warming. However, it was fully charged anyway, so there wasn't much charging to do.

Yes, you may be right Lost - even though it's not charging, it might not be draining the battery.

I had a close look at options for a sun shield, and it's too difficult - particularly as the unit has to raise up significantly to be extracted from the holder - so that limits what you can do for shielding on the upper surfaces. I think my best option (if I bother doing anything at all) is to extend the windscreen mount to get the unit to sit in the outlet of an air vent and get extra cooling.

It will be interesting to see how it goes on our northbound trip tomorrow.