I am using a 7" tablet on a motorbike as "moving map". Because MFN shows almost no roads when beeing in overview-zoom-level I am using Osmand for map viewing (plus AFTrack for nmea-logging). Battery level in this case decreases about 10 % per hour with the device connected to board power (that's bad enough but I dindn't find a way to feed the tablet with more power). Short time ago hvdwolf mentioned something about "more roads visible in map mode" and therefore I decided to give it a new try. Besides the fact that i didn't see more roads than before I noticed that the battery level decreased about 18 % per hour, only displaying the map and logging nmea, without navigating. This means that after about 5 and a half hour the tablet went down and I had to switch to paper mode. Has anyone of you compared power consumption of MFN vs. some other navigation software?
p.s.: When using a normal phone navigating with MFN the device stays on 100 %, so here it is no problem.
HW renderer has multiply higher consuption than SW renderer. HW renderer consumes battery even when screen is off or navigator is active on background.
I notice also that while navigating the battery capacity decreases gradually, so that after a trip of about 5 hours the battery is empty in spite of the device (a Samsung Galaxy S3) being connected to the board power network. Formerly (months ago) this didn't happen.
On sunny summer days, my car charger stops charging if the phone is too hot (to prevent explosion...) and it seems like the phone is consuming more power than the charger supplies, but indeed it blocks the charger's current..
Some devices (like galaxy s2 9.7'') require a stronger current. This used to be 500 mA. Some now require 2 A or 2.4 A. You car USB should be able to deliver a 2 A / 2.4 A current on one USB port, if the device requires this.
Most car USB ports definitely do not deliver this 2-2.4A. I do drive a lot of rental cars and have already driven at least 50+ car models/versions. When I connect my phone on the usb port it most of the times is not charged but simply slower drained.
I almost always use a 12V plug with USB connect (with a strong enough power supply) as the 12V connections in a car most of the time deliver a much higher amperage than the usb port(s). And that's already for a phone, I can image that the difference is even greater for a tablet.
Not all 12v to USB connectors deliver a high current. With some the current is intentionally limited, as it is with USB ports. You should check the spec.