+dfx Posted October 21, 2010 Share Posted October 21, 2010 In an attempt to further(?) dispel the myth that having WAAS enabled or having the magnetic compass enabled has any significant impact on battery life, I decided to repeat the excellent tests that tomc61 has performed on his Vista HCx and has posted here. However, I'm not as professionally equipped as he is and only have a cheapo digital multimeter, which has a few limitations. Most importantly, it isn't able to give proper min/max/average readings, and since naturally there's some constant fluctuations in the readings, all numbers given below are averages simply estimated by me. Furthermore, it only has options of measuring currents up to either 200 mA or up to 10 A. The problem with the 200 mA setting is that the Oregon occasionally draws more current than that. I tried replacing the 200-mA fuse with a piece of tinfoil, and while that worked for a while, eventually the multimeter got confused by high currents and started to give nonsense readings. So i had to use the 10 A setting, which unfortunately only gives me two digits after the comma, in other words is accurate to +-10 mA only. I think it's still meaningful enough to get the big picture though. Test setup I was using a stable 3 V power source (AC adapter) instead of batteries. Tests were performed on our balcony, where I had the Oregon sit for a while so it gets a somewhat decent signal. Test subject was my Oregon 450 with the latest firmware. Pictures of the highly professional setup are here and here (yeah, I only had two croc cables available, so I had to improvise). Booting During booting, the unit pretty much constantly draws 200-210 mA until it's done booting. For a second or two it drops to about 100 mA, but then goes right back up. WAAS enabled, compass enabled This is how I usually use the Oregon, so after I got a decent signal I started looking at various screens to see how much power it consumes. Backlight was turned off completely. Note that the unit was never able to get a WAAS lock throughout the whole test (it was, after all, our balcony), but the satellite status page showed that it was trying. Again, all numbers are rough estimates made by me due to the limitations of my multimeter. Main menu: 90 mA Satellite status screen: 100 mA Compass screen: 180 mA (which came as a surprise) Map screen: idle (not redrawing): 90 mA, redrawing: 200 mA until it's done. In other words, it was drawing 90 mA until i turned the unit slightly (compass was enabled) which caused it to redraw the map. Current went up to 200 mA for a few seconds until the redrawn map appeared on the screen. I have Birdseye loaded, so that makes the map redraws a bit slower. Menu movement, i.e. any kind of scrolling around or opening/closing screens: estimated 150-180 mA but only momentarily (for less than a second or so). Blanked map screen (blanked by the "power save" option): 90 mA, even when the unit is being turned. The map redraw is delayed until the screen comes back on. Backlight: Turning it up to 50% adds an estimated 10-20 mA to the power usage, 75% backlight about +30 mA and 100% backlight about 70-80 mA additional current. WAAS disabled I disabled WAAS (with compass still on) and looked at all the same screens as above again. All the numbers came out the same, there was no noticable difference at all. This means that WAAS additionally consumes less than 10 mA of power, and likely much less than that. WAAS enabled, compass disabled Again I looked at all the same screens as before and again the numbers came out the same. Even the compass screen still drew a constant 180 mA, even though it now had no reason at all to refresh or redraw anything, as I wasn't moving. I got curious to see if screen blanking ("power save") made any difference while on the compass screen, and even after several minutes of the screen being blank, power consumption was still 180 mA. My conclusion is the same as tomc61's, that neither WAAS nor compass has a significant impact on battery life. From my limited accuracy multimeter, I would estimate that the difference is less than 5% and probably much less than that. Additionally, the "power save" option only seems to make sense when you're sitting on the map screen, and the backlight seems to be less power hungry than I thought, at least when set below 50%. Quote Link to comment
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