Bluetooth Mighty Mouse Power Save Hack

bluetooth mighty mouse

[Ram Sripracha] thought it was mighty odd that his new bluetooth Mighty Mouse had an LED that was constantly on when the mouse wasn’t moving. He decided to pop the case open and see what the current draw was. When the mouse is moving the LED is off and the current draw is ~.0285 amps; when the mouse has stopped the LED is on and the current draw is ~.0450 amps. He removed the LED to create a lower power bluetooth Mighty Mouse that only uses .0017 amps when not moving. So, 3.8% of the power that was originally consumed while sitting still.

30 thoughts on “Bluetooth Mighty Mouse Power Save Hack

  1. Hmm, those numbers indicate that the LED got > 40 mA, thats a lot of current to feed a LED.

    Wonder what function the LED had in the first place, it seems very stupid to waste power like this? Say the batteries were good for 1000 mAh, with 45 mA idle current it would give about 20 hours of lifetime… the LED is not lit when the mouse is completely idle, is it…

  2. @dangel and elliot

    ok so basically what you want is more hacks per day. I can totally understand you and support that but as far as I can recall elliot made clear a long time ago that he will stick to the one hack one day scheme, because it was better/easyer(don

  3. >> David, you seem to have a knack for spotting me around the net.

    It’s funny that you remeber that because I was thinking about it too. Now I feel like a stalker :P

  4. I just got my mouse an hour ago, and I don’t think this hack is necessary. The LED only turns on when the laser isn’t focused on anything. So, if you pick up the mouse to look at it, the light will come on. But put it on a surface & the led will turn off. I know it’s complicated — a bit like a fridge door — but trust me, the LED is off most of the time. You can put your thumb on the laser (at the right focus distance) and watch the LED turn off.

    Great disassembly guide, thanks.

  5. I doubt that little surface-mount green LED draws 40ma! Here’s my theory – it’s tied to another function. My Bluetooth mouse has a red LED in the sensor, which gets very bright when it’s not focused on a surface. I see no light being emitted from the Mighty Mouse’s sensor on the video, so it must be infrared. I’m guessing that the IR LED is also getting brighter when the sensor is defocused, accounting for most of the 40ma. The green LED is probably there to let the user know “yes, the mouse is powered and working” when you pick it up, since you can’t see the infrared LED. But removing the green LED may have broken a circuit and disabled the “bright mode” of the IR LED, accounting for the large drop in current the author observed. It would be interesting for the author to follow up on this by testing with an IR-sensitive camera. Even if I’m correct, this hack may not be completely useless – you could toss the modified mouse in a bag for travel without removing the batteries, and not worry about excessive drain.

  6. mentor: if i remember correctly, elliot changed the format to one hack per day due to the fact that he was not getting enough submissions. i personally liked the multiple hack posts, as the hacks were usually less involved than the fully written up hacks, and each hack could be browsed over in a few minutes. in other words, the hacks in the multiple hack posts were similar to lots of the things that one sees on the make blog, and were perfect for browsing at work. i liked this aspect of the site, and was sad to see it go. the more in depth hacks that you see on hackaday now have always been here, its just that now they are the *only* content that the site provides. while i still enjoy the hacks, i enjoied the more simple ones displayed in the multiple hack posts as well. due to the fact that half of the reason why i read this website has gone away, i feel as if it has gone “downhill”. with that being said, i still read the site daily, i would just like to see it return to the way it was.

  7. …also, while some may disagree with me on this, i believe the writing on hackaday, on a whole, is not as good as it used to be. before vince left the website, he used to write introductions to most of the hacks which often had little to do with the hack at hand. this, in my opinion, gave the site a more personal, community oriented feeling. you know, like the site was actually someones blog, rather than a website owned by a larger corporate entity (and yes, i know had is independent now, but it feels less so than it used to). since his leaving, the posts on the site have become little more than dry descriptions of the hack, and i find myself skipping them and clikcing directly on the link off the page.

  8. darkcobra – I used my isight to try to look at the laser, but no success. I can see normal IR remotes with it, so this is either a further-away wavelength, or too collimated (and my aim was bad). Hmm… more experiments needed in a dark room.

  9. Big time screw up by the guy!!!

    Totally unnecessary as he got his observations all wrong. The disproportional increase in power consumption was probably related to the fact that the laser was being up-powered or more actively scanning when it can’t find a surface to reflect the beam.

    Bad hack!!!

  10. I could be slightly wrong about the hack. I didn’t think about the led being lit because it was out-of-focus. I will do some more testing on a unmodified one to see how much power it’ll draw when it is stationary.

    One thing for sure is that without the led, there is some power saving. The question is how much is it really saving. (=

  11. Mike, did you just call me a large corporation? ;-) , but seriously Vince was a douche and got fired for it nearly a year ago:

    As the title says, Hack-A-Day was one hack every day from the beginning. Sometimes we’ve had more, but never less. I personally have posted a hack every day for the last 15 months. That’s not to say we don’t care about the site. This weekend I’ll be handing out over 500 free Hack-A-Day shirts at Defcon.

    If your looking for some interesting links, I’m in Boston right now at SIGGRAPH posting about cool projects. Have a look:

  12. Ram: Sure, if you flip the cover over the laser, you’ll save even more power!!! :P The question is, how much power do you want to save before you have a half functional rodent.

    Definitely a one of a kind hack that gave me a big laugh.

  13. wow! i’m really impressed at how quickly the comments section has turned around. no flames! it is actually pleasant to read the comments again.

    You would honestly think that the led would work the opposite way; light up when in motion, amd dim when not in use… at least, thats what my optical mouse does, (note, not a mighty mouse).

  14. elliot: i have (or had rather) no idea why vince got fired. i merely enjoied his sometimes pointless ramblings. with that being said, if he was an ass (and it seems that he was) i dont wish him back. my suggestion for more interaction with the readers still stands though. the fact that you took the time to actually respond to my (more or less uninformed it seems) previous comment I think is the sort of thing that causes me to read hackaday when my boss isnt looking.

    in response to other things:

    -no i was not refering to you as a corporate entity :p
    -since i am not going to defcon, would it be possible for me to score a shirt (even for unfree?…please?). if not, are you planning on dispensing shirts around silicon valley anytime soon.
    -that mobile phone tennis is badass. it would be nice to see, every once in a while (perhaps weekly?) a list of links to cool shit like that that perhaps isnt fully written up, but still cool to read about. thats more or less what I was trying to suggest.
    -i have a hack of sorts that i would love to get on hackaday, however, i have no place to host it. it involves a junkyard, a 1960s bridgeport cnc mill, punch tape, very outdated and obscure code standards, a homebrew mill controller, and a custom g-code parser written in visual basic. is there a way you could help me out here?
    -and lastly, do keep up the good work, no matter how much it sounds like it, i am not planning on leaving hackaday anytime soon.

  15. “-that mobile phone tennis is badass. it would be nice to see, every once in a while (perhaps weekly?) a list of links to cool shit like that that perhaps isnt fully written up, but still cool to read about. thats more or less what I was trying to suggest.”

    We had that: hackaday extra. Haven’t seen one in a while.

  16. mike

    I live in the Bay Area and do some hobby stuff with CNC mills. I can also help you host your hack if you’re willing to share in the fun. I currently don’t know anyone that even knows what a Bridgeport is.

    scottyg at csua dot berkeley dot edu

  17. @elliot
    Would it be possible to open up volunteer positions for the site? I’m sure that there are more than a few willing people who would like to have their hands in making this site grow to new levels of awesomeness. I’m pretty sure they’d work for free too.

  18. Sorry but i have to say that the LED is only on when you pick the mouse up and leave it in the air… try this move the mouse to the edge of your desk, so the light just hangs over the edge…. LED does not turn on. this hack is what i believe is a waste of time, and voids the warrenty, for noo need(only when you hold the mouse in the air… when do we do this???)

  19. If keeping up with more than a hack a day is a hassle, going back to two or more writers may not be a horrible idea. I wouldn’t mind posting a hack every other day as long as I can work from home, pay or not..

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