Magic Mouse (A1296) 14500 Rechargeable 3.7v Li-ion Conversion

UPDATE March 30: My Li-ion mouse lasted 29 full-time work days before (as expected) suddenly stopping due to protected li-ion cut-off. My net search WRT Eneloop MM users finds them reporting about 14 days of run-time (please add comment if that's off the mark). This still may not make this a rational, logical instructable to perform, especially if its preconditions (having li-ions & charger, "extra" MM, acceptance of risk) are not met.

Like these mice except for their consumption of AA (alkaline) batteries. No biggie for casually used machines but annoying for Macs used 40 hrs a week or more. Seems every 3 - 4 weeks, at inopportune times, I get low battery warning and have to grab new AAs & toss the old ones.

Researched Magic Mouse (MM) rechargeable battery solutions none seemed optimal usage-wise. They (all?) relied on NiMH batteries having nominal charge of 1.2v, so 2.4v combined. Seems fully charged NiMHs, even the excellent Eneloops, show 75% - 80% charge on mouse and only last a week [Edit: reports indicate closer to 2 weeks] of (heavy) use before needing recharge. Though the Mobee Inductive Charger looked like an interesting solution, it has the NiMH limitations & mixed reviews.

Having several spare good quality protected 14500 3.7v Li-ions, and a reliable charger for them, thought I could make better use of the spares. 14500s are nominally AA size (but protected ones are longer - see last step). If I could only somehow modify the MM to use them.

DISCLAIMER: THIS IS A DELICATE, TRICKY MOD. IT'S POSSIBLE YOU'LL END UP RUINING YOUR MOUSE IN THE PROCESS, RENDERING IT BROKEN. The tricky parts are mechanical ones (flexing plastic retainer hoops, re-attaching bottom metal + gliders), not electrical ones.

Notes:

• Don't yet know the long-term effects of running the mouse at higher voltages than it expects. But the one I modded has been working perfectly for days now.
• You'll be loosing the low battery warning since the protected Li-ion cell cut-off voltage is above that of the MM's warning voltage

Step 1: The Goal & Items Needed

Goal was to convert a MM to use two 3.7v 14500s in parallel. An unknown was whether MM circuitry would tolerate the higher Li-ion voltage (3.7v, 4v unloaded) than the series AA alkalines it was designed for (3v, 3.4v unloaded). It turns out it does, I've been using the modded mouse for days now & its working perfectly.

DISCLAIMER Redux: Think some skill, patience, luck and a crazy desire to pull it off are required. Helps if you've an "extra" or secondary Magic Mouse to try this on. And if you've protected 14500s & charger lying around so that they are not really part of the expense of this project.

What you'll need:

• Desire for long-lasting rechargeable MM has to outweigh the possibility that you won't succeed & will be sacrificing the MM to the cause.
• little prying devices (e.g. small flat-head screwdrivers),
• soldering iron w/somewhat fine tip, solder.
• slender tip needle-nose pliers,
• a couple short pieces of solid-core wire.
• any DMM to check connectivity.
• Dremel or small grinding tool + bit (to provide clearance for protected 14500 top/positive nubs).
• 4 high-quality, tested/reviewed protected 14500 Li-ion cells (2 for spares) and a reliable charger for them*. Need to be protected cells because mouse's low-battery cutoff is about 2.2v, too low / unsafe for 3.7v cells (protected cells cutoff @ about 2.7v or so).

* Do not buy or use any old/cheap/no-name cells or charger, only ones that are tested/reviewed - best reviews I've found are from "HKJ" on BudgetLightForum whose reviews are usually available here

Step 2: Modification Plan and Initial Mouse Disassembly

The MM uses 3 volts by strapping its AAs in series - with a connection from left battery negative (lower left contact) to right battery positive (upper right contact) when viewed from bottom. You should confirm this with your DMM on ohms setting - should be at or near 0 ohms.

The plan is to break this series strap and make it parallel for your two 3.7v lithium ions by:

• desoldering / disconnecting right battery positive contact from PCB & attach the contact to left battery's positive terminal (when viewed from bottom - during the work this is reversed as you'll be viewing the PCB from its top!).
• strapping both batteries bottom / negative terminals together.

Disassembly: Others have documented MM disassembly fairly well here

and here

The key bits are:

DON'T ALLOW THE RIBBON CABLE AT MOUSE BOTTOM TO COME ALL THE WAY OUT OF ITS CONNECTOR. It's difficult to re-insert the cable. Always hold pressure to keep the lower portions of the mouse's upper & lower bodies close together. Check ribbon connector time to time during process & snug it back in using fine needle nose. And at end just prior to re-assembly.

DO YOUR BEST NOT TO BREAK THE FOUR PLASTIC HOOPS THAT HOLD THE MOUSE UPPER & LOWER PORTIONS TOGETHER. This is the most difficult part - flexing / prying 2 hoops on a side to free upper & lower mouse assemblies. If you break any you could try a bit of epoxy but don't get any within the loop holes or on the pins they engage.

Note: I did get minor splits in 2 of the 4 hoops yet the mouse still works perfectly. I think that as long as one upper & one lower hoop on opposing sides are somewhat sound the mouse should work properly.

Step 3: Once Separated But Still Attached by Ribbon Cable, Make Mods

You need not take out any screws from the mouse. Continually check that ribbon cable is still in its connector - use fine needle nose from time to time to snug it up & just before re-assembly.

1. De-solder / detach left side battery (as viewed from top) positive battery terminal from outer edge of PCB, its only attachment point.
2. Flatten the removed terminal, weave it behind the metal contact bar & solder jumper wire to right side battery positive terminal. Apply some epoxy / JB weld to center area under contact bar to secure relocated terminal, holding it close to battery compartment.
3. Run a jumper wire across lower / negative battery terminals.
4. Use your DMM to assure the bottom (negative) and top (positive) battery terminals are not shorted. They should read as open or some high resistance between them.
5. Assure that both bottom (negative) terminals are indeed shorted together & that both top (positive) terminals are as well.

You are ready for reassembly. Notes:

Use epoxy/JB weld to secure the new top/positive terminal, (glue) to re-attach the bottom metal portion of the mouse and to secure the 2 plastic gliders on each side of the battery compartment. The gliders have pins that I cut the tips off of to re-insert. This is an important tricky step - assure the gap around mouse top & bottom is fairly uniform, that the mouse pivots correctly (left- & right-button mouse presses work), and that the gliders are inserted such that mouse lies as flat as possible on a flat surface. I wrapped mouse in masking tape for a couple hours for epoxy to cure.

The mechanicals have to be fairly precise after re-assembly for the mouse to function properly. But even if your mouse ends up unusable you should at least come away with a greater appreciation of the engineering & assembly of the mouse.

Step 4: After Glue/epoxy Is Dry Dremel Down Mouse Top Terminal Plastic to Fit Cells

As we are using protected 14500s and they are bit longer than AAs you'll need to use a dremel/grinding tool with small round cutter to enable them to fit. You need more clearance for cell top / positive terminal nubs, much of the mouse's battery top terminal plastic may need to be removed to assure contact.

While doing this have the mouse switch on/up/green and assure that each 3.7v cell inserted individually make contact (e.g. mouse's green LED above switch comes on after a couple seconds). You want to use both cells in parallel to get good battery life.

The mouse I performed this surgery on has been working perfectly for days now and still reads 100% (due to 3.7v+ vs expected 3v+). I expect good life out of these batteries because of their higher nominal voltage & good mAh.

Again, because the mouse's low battery warning & cutout are below the protected cell's cutout (~ 2.7v) you may not get a low battery warning prior to the mouse losing connection. I mitigate this by using the widget "BatteryLevel" & occasionally hitting F12 to see battery status. There will be a target % of battery life that represents about 2.9v and this is the time I'd choose to swap in charged 14500s. But I'll probably just use the mouse until it dies then swap the cells.

Comments

[ParatrooperChad]

If you are not comfortable with the disassembly, a "dummy" or blank AA mock battery insert will work placing it in the RIGHT side and the live battery in the left.

[mathnitrof]

Hello,

After 5 years of use, how is your mouse?

One thing that worries me, the batteries I bought are currently charged at 3.9V (2800mHA). It is 1V more than two 1.5V Alkaline. Does the mouse take it well?

Thank you very much for sharing this very good idea.

[cfcubed]

Hi,
The mouse with this mod is still working, there's been no ill affects from the somewhat higher voltage. But because it gives up the low battery warning, its my least used mouse. Use it with a laptop that I use less than our desktop Macs.
Not that big a deal tho since I keep a couple wired mice around for when the batteries go anyway.
Thanks for the thanks:)
Chris

[mathnitrof]

You know what guys. I think I have ben fooled. There is no such 14500 of 2800mAh in Ultrafire's website. The maximum capacity for 14500 is 1200mAh. The battery voltage reading was 3.9V yesterday evening. Today, I thought my mouse was dead. I took a look at the voltage it was 2.99V. Be carful guys, there is a lot of contrefit batteries and electronic stuff these days. I knew it and I got caught. I got 4 of those batteries for $10 US really not expensive for such capacity.

The same seller, king-future, on Ebay.ca sell 6 X 3.7V 18650 9800mAh Li-ion Rechargeable Battery for $12. Usually, the capacity of size 18650 is near 4000mAh and cost $4 for one cell.

[cfcubed]

I chose not to try to economize on rechargeable cells or chargers. As in most all cases, you get what you pay for. Safety and endurance are good reasons to stick to respected/reviewed cell brands from reputable/reviewed sources. Spend time on BudgetLightForum reading battery & charger reviews (e.g. HKJ's evals) prior to purchases.

Also, per my write-up suggest sticking to *protected* cells for this application. It's regarded as unsafe to attempt to charge fully discharged unprotected cells.
Note: If a protection-disconnected protected cell is ignored a while chargers may refuse to charge it (reads 0v). The trick I use to "wake up" such protected cells is to parallel them with a charged cell for 30 secs or so. It's always brought them to a chargeable state for me.

Good luck.

[mathnitrof]

I was too excited and in a hurry to try this very clever solution. This is not what will stop me. I have already been reimbursed by the merchant who told me that he was very sorry for this situation and that he will tell his supplier (Yeah right ...).

I totally agree with your security philosophy, there is no compromise to be made. The only economy that interests me here and this is the case for all those who appreciate this Insctructable, is to eliminate the consumption of alkaline batteries and have a reasonable time of use with rechargeable batteries.

I will do more research to find the batteries I need.

I also really appreciate the follow-up and advices.

Thanks again,

[cfcubed]

Not to beat a dead horse, but to be sure its clear IMO & to my knowledge of it:)
> "There is no such 14500 of 2800mAh / The maximum capacity for 14500 is 1200mAh."
Yes, in fact digging into HKJ link leads you to tables of test results (e.g. lygte-info.dk/info/batteryIndex.html) where you find no 14500 is good for > 1000mAh. Using only 1 cell may yield about what a pair of good quality AA rechargeables do, ~ 2 weeks.

N.B.: IIRC I did this mouse work just before Apple's Lithium rechargeable Magic Mouse 2 ($80?) came out. Also DIY'd because I owned 3 non-rechargeable ones so had one I could sacrifice:)

[mathnitrof]

Thanks cfcubed!

Great info this website!

4 weeks is better than what I get from my rechargeable batteries.

The iMac I am working on has already been repaired once. The graphics card was dead. I baked it 8 minutes at 400 degrees Fahrenheit two years ago it is still functional.

Best regards,

[mathnitrof]

You know what guys. I think I have ben fooled. There is no such 14500 of 2800mAh in Ultrafire's website. The maximum capacity for 14500 is 1200mAh. The battery voltage reading was 3.9V yesterday evening. Today, I thought my mouse was dead. I took a look at the voltage it was 2.99V. Be carful guys, there is a lot of contrefit batteries and electronic stuff these days. I knew it and I got caught. I got 4 of those batteries for $10 US really not expensive for such capacity.

The same seller, king-future, on Ebay sell 6 X 3.7V 18650 9800mAh Li-ion Rechargeable Battery for $12. Usually, the capacity of size 18650 is near 4000mAh and cost $4 for one cell.

[ZaheerK]

I don't know hwo this worked out for you , but from my math this seems to be futile. 3.7 @750 MAH = 2775 MAH *2 for two batteries: 5,550.

If you use rechargeable Eneloops 1.2V @ 1900 MAH = 2280 x2 for two batteries = 4560.

Basically that is 82% the capacity of the Li-Ions. So all this work is for a gain of 18% extended life, plus you need those batteries and charger. Now of course with higher MAH batteries it may be worth it, but according to this and despite my electronics background i would never do it.

[cfcubed]

N.B. (no editing comments, heh)

> So all this work is for a gain of 18% extended life

My initial li-ion results (29 8h days of use) vs. Eneloop reports I've found on net (14 8h days of use) suggest a gain of 100% extended life.

[cfcubed]

Thank you for your comment, I'd wanted to post a status update. My Li-ion mouse worked perfectly for 29 full-time work days before (as expected) suddenly stopping. I'm now testing/using new Duracell alkalines in an unaltered mouse to compare run-time. Added edit reflecting users reporting about 14 days of run-time for Eneloops (please add comment if that's off the mark).

There's one critical variable missing in your maths: the batteries' voltage vs mouse's low-voltage shutdown (calibrated for 1.5v AA cell usage). Speaking WRT batteries' nominal voltages, two NiMHs start out @ 2.4v and only function down to the mouse's low voltage cut-off (2.1v ??, need to measure). The parallel li-ions start out @ 3.7v and, as protected cells, have internal 2.7v cut-off, so mouse uses their full capacity.

> plus you need those batteries and charger

As I stated I already did for other purposes (flashlights) and wouldn't a prospective Eneloop user have to do same? But clearly from the warnings (DISCLAIMER, DISCLAIMER Redux) the rational & non-DIYers are discouraged from attempting this instructable. Their wise choice is to purchase Eneloops + charger & use them, even if the run-time is half what this li-ion converted mouse's is.

> despite my electronics background i would never do it.

No one is asking you to:) This, like many instructables, are for DIYers with parts around, time to kill & the desire to blaze a new trail, even if sometimes a seemingly "silly" one. In many cases, as in this instructable, the easiest path is to avoid any modding or building & instead purchase an acceptable off-the-shelf solution.