Replacing the battery in a Garmin Edge 305

While cleaning out my study, I found my Garmin Edge 305 GPS sitting in the back of a desk drawer.  The poor, poor neglected device hasn’t had any fitness loving in the last year because its battery was unable to hold a charge more than an hour – down from >10 hours new.   This is a limitation with Li-Ion batteries.

It’s well-beyond warranty.   For a flat-rate repair fee of $79, Garmin will swap it out with a refurbished unit.  That’s 35% of what the unit goes for new, so I was wondering what would be involved in doing it myself.   A quick cruise down the Intertubes showed MTB Guru has already made a great tutorial on the mechanics.  Assuming one has the tools, it costs less than $10.


  • A 3.7V Lithium-Ion batterythis one will fit, but it has slightly less capacity (800mAh) than the original one (850mAh).  I used a LG 8350 cell phone battery (1000mAh): $6 on eBay.
  • Solder – A small tube of 60/40 solder is $1.50 at Fry’s.
  • Rubber cement – you can use the little tube that comes with the ye-old-style bicycle tube patch kits. (I have yet to master the glueless patches. It’s quite possible these just suck.)
  • Dab of super glue.
  • (Optional) Flame decals, leftover from another project.


  • A soldering iron – This was a great excuse to break open the fancy pants one I received as a gift. A cheap $6 hobby model will also do.
  • A third hand tool or an assistant who trusts your handling of a pointy, metal-liquifying tool near their personage. The third-hand tool is $3 at Harbor Freight Tools. The assistant: priceless.
  • A stack of phone books or 160 ICML papers to review. (Ted’s CS Ethics text books may also be substituted.)
  • Mini Philips screwdriver. This is sometimes known as a “jeweler’s screwdriver.”  I don’t wear jewelry, so I’ll just have to take Their Word on that.
  • (Optional) Wire strippers. You can also use scissors or a knife.
  • (Optional) Dremel tool. This will make a neater spot for the larger battery.
  • (Optional) Single-edge razor blade. Oh, so useful!

Step 1: Preheat oven to 350F. Ooops, wrong recipe.

Step 1a: Consider your options. Garmin will swap out the unit for a flat-rate repair fee of $79. If you have other problems with the unit or are uncomfortable with letting the magic smoke out of the GPS, this might be a better option. Otherwise…

Step 2: Congratulations, your warranty is no more voided than it was before. Wedge a fingernail in the seam between the buttons and the base. (In the photo below, the Edge is upside-down.) You’ll need to work around the case twice to break the rubber cement seal.Breaking the seal!


The photo on the right shows the expanding gap. You’re ready to crack (open) the case!

You use a fingernail — not a knife or a machete — to avoid damaging the case.

Step 3: Let the magic smoke out! Set the unit down on its face and g-e-n-t-l-y pry off its back.  If there isn’t a bright, explosive flash, you’ve done it right.


Step 4: That wasn’t so hard, was it? Okay, we’re going to be doing most of our work on the part I’m holding.
However, before we start, some things I want to point out.step04
See this switches? They’re fragile.  Bend them you will not! Unfortunately, once you break open the unit, you’ll have a hard time with these making the necessary contact to the back of the case.  Not to worry, we’ll address that later.
Step 5: If you gently tap this on a soft surface, the main motherboard will pop out.  This would be a good opportunity
to wash the dust off everything.
Step 36: Okay, back to the base.  You’ll notice that the new battery is slightly larger than the old one.  This is a small price to pay for 25% more use per charge.
Step 57: The old battery is held in place by double-sided tape.  Pry it out.
Step 78: Remove the little piece of black electrical tape on top of the battery.Hold the red wire near the battery.  Wiggle it until the wire breaks from the solder point.  Repeat this with the black wire.


Step 100: With the battery out of the way, we need to do a tabectomy so the new battery will fit. There are three tabs on the back – remove them.If you have a Dremel tool, just grind them off.  Otherwise, grip them with a pair of pliers and bend until they break off.


Step 111: Using the wire strippers (or scissors), peel off 1/4″ of insulation from the end of each wire.  Twist the end of each wire so the little strands are tightly wound.  This will make it easier to solder.Warm up the soldering iron.Place the base and battery on your hands-free tool like so:


Step 128: Solder the red wire to the metal strip with the “+” sign.  The black wire will be soldered to the metal strip with the “-” sign.Mr. Huber’s head would spin at my soldering skills, but as long as the wire’s secure and it’s not shorting anything out, we can call this “good enough.”


Step 13732: After everything cools down, apply a piece of electrical tape on top of the soldered wires.  I routed the wires to behind the battery and applied another piece of tape there, too.The purpose of the tape is to keep the wires from wiggling and breaking off.


Step 14123444: Plug in the USB cord to the base for 10 minutes.  This will give the battery a small charge.  Now, take the circuit board, and press it against the base so the flimsy metal contacts contact.Press the top-left button (power on).  If you see a display, your wiring is fine. If not, look for a bad solder joint or short.


Step 15 gazillion: The little connectors are flimsy and, now that we’ve taken it apart, are likely to wiggle on bumpy roads.  So we don’t have the GPS shut off during a ride, we’ll do some minor augmentation of the contact board.From a thick sheet of paper (I used the cardboard sheath for the single edged razor blads), cut four 1/8″ by 1/4″ strips.

Loosen the two screws about two or three turns.  Pry the board up with your finger.  On each side, insert a two strips.  You want them to be flush with the edge of the board.

Tighten the screws – it should only take 1 turn.


Step 16 billion: Okay, now put the display board back into the front half.  Put both halves of the GPS together and power on again.   We’re just verifying we didn’t misalign the board.
Step 17 skiddoo: Now it’s time to glue this bad boy back together.  Apply four dabs of super glue at the top of the base – see below.Quickly, add a seam of rubber cement around the perimeter.  The super glue is to keep the case from jiggling apart, the rubber cement will provide a better seal while also making it possible to do this again in two years.

Press the unit together!


If you don’t have access to 160 ICML papers, or Ted’s CS Ethics text book, use a stack of phone books. Dang, I get a lot of phone books…
Or, better yet, if you have two ratchet clamps, use those.  The glue should dry in about 20 minutes.
Pop the USB plug in and fully charge the unit!
step99Apply flame decals.  It’s immediately faster!

108 thoughts on “Replacing the battery in a Garmin Edge 305”

  1. So I read through this whole damn thing looking for how the flames will glorify the newly juiced unit and I get to the end and I’m flameless.

    My disappointment will need a backpack – I’m going carry it around for days…

    Where in the hell did you get all those phone books. Don’t they have recycling in the rural environs?

  2. What, and give up my supply of outhouse paper?!

    Verizon and Dex each send us two books (one “Eastside” one Seattle), Yellowbook one. There’s a smaller, sixth book.

  3. Absolutely fantastic post! I love the step by step instructions and photos (that must have taken a lot of time and care!). Like everyone else, I love the flame decals. I’m glad you’re continuing to find good uses for them. 🙂

  4. If you don’t want to use your fingernail, there are some good plastic iPod opening tools that would work great for this.

  5. Thanks. i was looking at paying garmin to send me a new one, but seeing as i can now do it myself, i think i will!!!! thanks again.

  6. Great instructions. While I have mine apart, I need to try and fix the mode button. It broke when I dropped it. Can this be done and do you know of anybody with instructions on how to do this? I need to find some flames for my bike so my bike is instantly faster.

  7. I got the Mode button fixed. But after I put it back together, the display was darker. I can still read it but just barely. Anybody have any ideas?

  8. Somebody told me in another forum to try adjusting the contrast. Thats all it was. Looks great now.

  9. Great post, thanks for the tips. I had problems with my unit turning off during a ride so just put the paper under the contact strip and all is good again! Thanks for all the work and the pics are very helpful.

  10. Awesome! Thanks for the how-to.

    I was wondering if you have the dimensions of the battery? google has failed to find them and I haven’t cracked open the edge 305 yet. I’m wondering if the 1100mAh LGIP-530B or (less likely) the 1500mAh LGIP-920B will fit?

  11. For anyone else landing on this page the original battery dimensions are:
    H: 48.0mm
    W: 30.8mm & 32.6mm (wide spot on one end at electrical tabs)
    D: 5.7mm

    Now if only LG published the dimensions of their batteries…

  12. The comparison photo might be useful. Maybe 55x35x6mm? The extra width and thickness were taken care of by breaking off the tabs on the back of the Edge 305 case. Length wasn’t a problem.

  13. I decided to order both batteries (LGIP-520B and LGIP-530B) and see if I could fit the larger one in the 305.
    Dimensions (in mm):
    Stock: h: 48.0 w:30.8/32.6 w: 5.7
    520B : h: 50.0 w:34.0 d: 5.7
    530B : h: 54.0 w:34.0 d: 5.7

    By removing a few more tabs than Jim (notably the 2 longer ones) I was able to fit the 1100mAh 530B!

    With the 530B length begins to be an issue as there are some components on the mainboard that are getting very close to the battery.

    Also of note: I didn’t add the paper under the contact board. I just carefully bent the tabs out a bit for a tighter fit.

    Time will tell if this setup is robust but so far it looks good.

    Thanks Jim for info and inspiration!

  14. Thanks, Matt. Please let me know what kind of battery life you see with your unit. With the one I installed, I get 12+ hours.

  15. Cedric Cornell

    Thanks for this guide. Most helpfull
    My mode button didn’t work after a crash.
    Fiddly job, but got it done.

  16. wyman mccuil

    Before I undertake the project I’d like to know if you applied heat from the soldering gun to the battery tabs, or to just the garmin wires and let it glob onto the tabs. I’m a little concerned about any heat exploding the battery and projecting me to the undertaker. Not to worry or what? Thanks.

    1. I applied heat on the wire side – so you can think it of being a battery tab – solder – wire mix. When the solder melts, the wire sucks up part of it, remove the soldering iron, and it should stick to the tab.

  17. wyman mccuil

    Oke Doke, I have a $4.85 new LG 8350 battery ordered from [email protected] so it should only be a day or so to get it up the west coast to me. Thanks for all the info. WM

  18. Jim – great write-up especially with the pics. Just completed the surgery on my 305 – it’s in post op waiting for the silicone adhesive to cure. I modified the process in three respects:
    – only needed to remove the single tab and the battery fit just fine (I’m using the LGIP-520B
    – I installed a block of neoprene on the front side of the circuit board – directly “under” the part of the board with the USB/power contacts. Did this since I had noticed that there was the possibility of slight movement of the entire board.
    – lastly wedged a flat piece of heat shrink tubing (cut open and flattened) under the raised portion of the spring contacts. These contacts appear to be much more flexible than I liked and since I had been experiencing the mysterious “shut down on vibration” “non-problem” I wanted to increase the stiffness of the contacts a bit. I had bent them up slightly and noticed that they returned to the original position when the case was closed up again. We’ll see how this all goes.

    Again thanks,


  19. Thanks for the step by step guide with the photos.Having already done the contacts I was pretty confident going in that I could do it but having the photos for reference was a big help. I used the same battery you recommmended and as was previously posted, only had to remove one of the tabs in the case for a perfect fit. I will say to be careful with the soldering iron as the plastic around the battery terminals melts very easy. I have now gone from a dead battery in fifty miles to using only two bars on a century.
    Thanks again,

  20. Pete Watford

    My power button will not hold in, will the paper trick remedy that for me ?, battery seems fine

  21. @Pete – The power switch is on the circuit board itself – it might just need to be realigned.

    The paper trick is for intermittent flaking out of the GPS. Typically, what happens is you’ll be doing something that shakes the GPS enough to cause a momentary gap in the connectors, powering it off.

  22. Completed with the same battery. My hands are not as steady as they use to be so I was sloppy with the solder. The spillover on other terminals on the battery was a problem. I gently filed off the solder so it was only on the + and – terminals and it works fine. Thanks for the instructions very helpful.

  23. Had problems with salt build up under switches to where they would not function. Was able to flush with water/alcohol to restore operation. Bad idea if rubber membrane is torn.

    Use a tiny amount of LPS-1 lube on contacts before assemblying. It forms a thin film conductive layer at contact points. Amazing stuff.

  24. Thanks for going where I was reluctant to go. My 305, out of warranty, started dropping the satellites under completely clear skies, just as we started down the coast in 2009. I suspected a cold solder joint as it seemed somewhat weather dependent. When I got home I contacted Garmin and they promptly agreed to exchange the unit for no cost without any push on my part. Good folks.

    As for the battery change out, if my unit was in good shape, I would rather use an external battery supplement or charger than risk cracking a perfectly good case. I built a small charger on our trip which worked perfectly – see photo here The only drawback is that the power regulator can get wickedly hot.

  25. Thanks for this detailed “how to”. I was about to order a new bike computer because me edge would only last about 45 minutes before it died. I love the features on it but hate the fact I have to recharge it everytime I used it. The only thing I changed during re-assembly was to use clear silicon instead of the rubber the cement. I used a toothpick to a fill the small groove in the bottom half of the case to hopefully make it air/water tight. clamped over night, seems solid. Hopefully it will come apart easy in 2 years! Thanks again, this was the best $10 I ever spent to keep my edge still working.

  26. I also would like to say thanks for your fun to read and useful guide! I was about to replace my aging 305 since I could barely get a single day of commuting (around 1.5 hrs) logged. I followed these steps exactly (except for I only removed one of the tabs). I charged it and put it by the window and recorded 14 hours 14 minutes before it died — very nice! One note: I do not believe the first charging in step 14123444 does anything since the circuit board needs to be attached for charging to work.

  27. Thanks for the post, you saved my Garmin as it wouldn’t charge via USB. I took it apart, cleaned and adjusted the contacts and reassembled and now it connects and charges. Also you can just pry it apart if you use a small screw driver and run it along those edges but this does do more damage the the rubber seal, but with as many falls as mine has taken you won’t notice. Thanks again!

  28. Thanks for the post. It was actually a fun little project and saved money in the process even with buying a soldering iron and some of the other little tools. I think the biggest pain for me was getting it apart. That sucker was on pretty tight.

  29. Carl Gilbert

    Instead of phone books, you can put some zip-ties around the unit to hold it together while it dries. The shape of the unit makes this work well.

  30. Jim,
    Followed all the steps and my Garmin works perfectly… except… I cannot get the reset button to reset the Garmin. Did I misalign something when I glued it back together? The start/stop button works but nada on the lap/reset. Any thoughts would be greatly appreciated.

  31. Hi. Followed your instructions to a “T” and everything went as described. However, the unit no longer works. Specifically, when I plug in the mini USB cord, the battery charging indicator goes on and eventually reads Battery Charging Complete. Pressing the power switch while the unit is connected to the cable results in the unit turning on and beginning the satellite search. But, the moment I pull out the cable the unit goes blank. Pressing the power button when not connected to a cable will not power up the unit.

    Any ideas?

    1. Sometimes the Edge get very, very confused. (Mine did this before the battery replacement, but I could never determine why.) Try doing a reset (pressing the “Mode” (reset/lap) and “Power” buttons at the same time) and then recharging it again. (If that fails, you may need to check the battery – perhaps it’s not holding a charge.)

    2. Carefully check your battery against the picture in Jims “Step 128”. On my battery the poliarity idents are wrong. It’s easy to tell due to the shape of the battery so it can’t be put in the phone back to front.
      If it’s back to front the unit will function normally when connected to the mains, but do nothing when not connected to the mains.
      In addition the Garmin will switch to “Battery Charging Complete” within a few seconds of being connected to the mains. You may also see an orange light on the charger.

  32. Thanks for the post it was great. Very easy to follow and works like a champ. Thanks again

  33. Second Post. Its been one week, and four rides with my new replacement battery in my Garmin 305. It Is working better than new. Having four rides without recharging and still 2 bars left on the charging icon. thanks again Dan

  34. (Sorry, I had comments in hyper-moderation mode because I’ve been seeing a lot of spam.) Glad it worked for you.

  35. Jim, I followed your step by step procedures and my 205 works like a charm. It cost me around $15 ( battery and glue ). Just a note here, if your unit does not charge or come on, it may just be locked up. Plug it into your computer then press the MODE/LAP RESET buttons for 10 seconds and ta dahhhh your in business!

    Thanks, John

  36. Great guide thanks! I found a couple of the springy tag contacts had broken off, so I soldered a section of HDD ribbon cable between the two sets – now it’s hardwired!
    Just a note of caution – despite not being advertised as such I ended up with a Chinese battery & the polarity on the label was wrong! Pay attention & you’ll be fine, but don’t trust the label if it’s not a genuine battery.
    Thanks again.

  37. Thanks for posting this, Jim. I followed your instructions and added a second spacer (like MTBGuru posted) made from a glueless tube patch. My problems with short battery life and wonky USB connectivity are now gone. $6 invested in a battery and Third Hand tool. I didn’t have any locktite glue so I just used rubber cement liberally and clamped with C-clamp and quick grips.

  38. thanks so much for the detailed instructions!!! having the pics was a major help. mine stopped charging all together so just went ahead and changed the battery out with the one you used. works great! thanks again!

  39. Thanks so much! Found the LG battery on eBay for $2.96 shipped. I used the soldering iron to remove the wires off the old connection to get a tinned stripped section of wire loaded with solder and ready to go. I also used the old double sided tape to better hold the new battery in place. Finally, I skipped the step with the paper under the connectors and have had no problems (so far). After 5 hours of riding, the new battery still registered 3/4 full. This is a great hack!

  40. Mike Toscano

    thanks for the tip Jim – great idea. I am mid-replacement and found my battery was connected to the main board and not the USB-port side (as in your pictures. I assume its all the same I just have to keep my polarity straight. Also, any suggestions on checking polarity of incorrectly labeled batteries?


    1. Mike: I’d use a voltmeter. I found a very cheap one at Harbor Freight Tools (~$4). (Failing that, you might try just plugging it in and see if it powers up. My battery came with a small residual charge, enough to show the hunting satellites screen.)

  41. Joseph Keays


    Great Site and very helpful. I have fixed 1 Garmin thanks to you. However, I was so close to fixing my other garmin. After soldering/connecting the new battery, I accidentally pulled one of the wires out/off from the circuit board. From what I can see, it looks like the broken connection was not soldered; it looks as though it was “glued” with a clear goop to the board. Not sure how to proceed to reconnect the wire to the circuit board. BTW, from you pictures, the battery connection wires are connected to your contact board and not the circuit board, but mine are directly connected to the curcuit board.
    Any thoughts? Help?

    Thanks in advance


  42. Michael Faulstich

    Thank you so much for posting this guide!

    I just did the heart transplant and the unit powered up normally. Whoohoo! Hopefully it will now be able to stay with me during my century rides again and not crap out halfway through.

    I used a Dremel tool to reshape some of the tabs rather than removing them completely. For closing the unit I used RTV rather than rubber cement. This seals it up nicely and waterproof but will likely be a little easier to reopen should the need arise in the future. I also placed a piece of neoprene in the location “Steve” indicated above.

  43. Uh oh – got it open, but the mode button (switch) fell out in 3 pieces…

  44. anthony chalupa

    great article, thank you so much as it saved me $70 plus bucks plus other guys in our racing group are excited to be able to fix theirs as well.

  45. Very helpful article — thank you! What does the small circuit do that’s taped to the battery — is it a charge controller? Would it be better to retain this by clipping the foil tabs and soldering these to the replacement battery?

    1. To be honest, I don’t know. I assumed it was to simplify assembly of the GPS by separating the solder points from the main board — the unit’s speaker is also connected.

    2. FWIW, I clipped of the little circuit board off the old battery, and it mounted nicely on the new battery (I used the Fuji NP-45A camera battery, which fits perfectly). The circuitry is a charge controller for LiIon batteries, and you’re probably better off using that.

  46. Bob Heitzman

    I just wanted to tell you how much I absolutely appreciate what you did by taking the time to document so incredibly (and humorously too) the steps to replace / upgrade the battery on the Garmin 305 not to mention the fix for the powering off issue. I had been moaning internally for the past three months as my unit would shut off during my rides. I replaced the battery and made the stabilizing change on the contacts and yesterday had a glorious ride with lots of hills and distance and the Garmin worked superbly capturing all the stats. Thank you thank you thank you! You rock man!

  47. Thanks for a truly helpful article! You just saved me $70! I love doing stuff like this…and screwing the manufacturers in the meantime for designing products this way.

    1. Update: Success! Battery on E-Bay…$3.05. New bottle of rubber cement…$3.50. Joy in saving $70…priceless! Thanks for a funny and well written how-to article. Keep ’em coming!

  48. Great! i just fixed my garmin edge 305 with this tutorial.

    i used a battery from my digital camera (fuji xp30) and this also worked. this is a 1500mah battery. i bought this battery on ebay for 5$ or something. it’s a smaller battery and fits easly in the case.

    Thanks! my garmin works like a charm now.

  49. Just a quick note to say thanks for the guide. Very helpful and quite funny. 🙂

  50. Well done. As an electrical engineer and someone who is willing to take almost anything apart, I gotta tell you I could not ask for anything better than this. Spot on and — if you don’t mind my saying this — your Garmin is highly photogenic. Perhaps our Garmins could get together and maybe try swapping data. Mine’s clean, I promise.

  51. Would it be possible to rig a power source through the usb as well? Just curious. Granted your no longer free as a bird with no umbilical but it might work with external battery. Just spinning the perverbial wheels.

    1. Sure – the primary disadvantages are the USB port’s pretty close to the clip. Vibration/elements would be bad.

  52. Lol… Let the magic smoke out… you’d think this was designed by the British Joseph Lucas..

  53. Dave Market

    I just wanted to say you have nice finger nails. Not too short, not too long.

  54. What is the longest lasting battery out there now to replace my OEM Garmin 305. I guess I might as well do this too before next season.

  55. lol, awesome post. I hope the forerunner 305 is similar in changing batteries. Mine is on it’s last death throws so as soon as I get a new one I am going to attempt this, hoping to get a back-up watch out of it. If not… atleast I had a good chuckle out of your post!

  56. Bob Thibodeau

    Tried this again. I did it on my 305 about 6 mo ago and had some old rubber cement and no super glue. The procedure went perfect until about 5 mi in to my first ride when the top popped off coming off a curb and a car ran over it. If it had not cracked the screen I could have fixed it.

    Got a replacement on ebay and now it’s battery went bad. Since I still have the battery I got up the nerve to try again. This time I went out and got a new bottle of rubber cement and super glue. I also followed the directions to a “T”. The unit is charging now. Tomorrow will be the test, I have a 50 mi ride in the AM, a 15 mi ride at noon, and a 20 mi ride at night. I might just add a few small pieces of tape to be safe…. :^)

  57. Jim,

    Great photos and all but!!!! May I suggest that you connect the battery to the small circuit that is on the side of the OEM battery. I beleive that is probably a low voltage shut off that protects the rest of the circutry when the battery voltage reaches a very low state. I didn’t do a lot of research but assume Garmin did not throw that on the battery for the heck of it. I did connect my bettery to those tabs with two wires which were soldered to the new battery. It may only be a filter for the charging circuit, but I thought it may have some benefit.
    By the way thanks for being adventuresome with this issue I was having less and less life plus started the shutdown on rides as well.

  58. Quick question. I have a camera battery Canon NB-4L that is 35.56mm wide, is this too much to fit in? It says the ones you guys used are 34mm wide.

    1. I think it should work – there’s a tiny bit of a gap on the side of the battery (see photo). You may need to break off the other tab.

  59. Well. I tackled this project over the weekend. I used a 1200 mAh replacement battery for a NP-45 camera battery. Works great so far. Thanks for the information!

  60. Hi Jim,

    Thanks for the detailed instructions … battery replaced and patient recovering well … all charged up and ready for the next bike ride !

  61. I used a 1500lmAh battery and I’m pretty disappointed in the life of the new battery. I had it going for 3 hours total and had one bar left which is pretty much what had with the old battery. I was definitely smaller than the original battery. I’m going to continue to test and willl report back to this forum later.

    1. The battery brand that I used was from Econmax which I bought on ebay for $3.19 from gooddealseveryday. I was surprised that it was smaller than the original Edge305 battery yet it was rated at 1500 mAh 3.7v. Stay away from it! Someone else on the list had used a NP-45A camera battery. Now I have to go through this all over. I have a LGIP 530B 1100mAh on order so we’ll see how that goes.

  62. Jim, I’m assuming in your procedure you did not move the tiny circuit board from the original battery over to the replacement battery? I’ve seen a couple of people post about moving it over to their new batteries so I wanted to check back with you to see if you were ever able to determine what that circuit does and if its needed.

  63. Mark, I did not move the tiny circuit board from the original battery as pl suggested. On Jim Rogers’ blog, he also just soldered the result to the battery as I did.

  64. I tackled this yesterday and the unit worked fine during a ride today. I am curious as to how long you let yours charge before using it. Mine indicated charging was complete after just a few hours. I also discovered that the buttons on my unit are pretty well shot, so I will have to look for a replacement top cover. All that said, I never would have undertaken this without your post, so thank you.

  65. This is a really useful blog, some of the comments have also proved to be of help. I replaced the battery with an NP-45A 1250mHa one from an Ebay seller. This fits exactly in the space left by the old unit and only required a piece of double sided tape to keep it in place, it is also the same thickness as the old battery so does not require any modification to the contact pcb. The old battery does have an overcharge protection circuit attached to it, but this does not need to be soldered to a replacement battery which should already have overcharge protection built in, it is just that the Garmin battery has this as a visible part on the exterior. I also found an adhesive which is flexible and waterproof, but should be strong enough to keep the the case together, this I found in our local Lidl store called “Power Glue” by Pattex a division of Henkel AG.

    The most difficult part is getting the case open which takes a lot of patience. A pity Garmin could not have come up with a better way of containing the battery without compromising sealing of the unit!

  66. Have now used my Garmin 205 with replacement battery as described above on several rides including a 60 mile ride today. There were no problems whatsoever, the case did not fall apart, all switches worked and the battery kept going throughout. Battery life should increase over the next few recharges but so far very impressed!

  67. I have followed your procedure to a ‘T’ and all is well except I have lost the little tactile mode button.

    It looks as though it pops on.

    Does anyone know where I can get one?


  68. I just twisted wires together and used some adhesive lined heat shrink tubing to insure wires stay together and had battery in and back together in 30 minutes even with clipping those 3 tabs, which took the longest of all tasks. Great write up, thanks, been on a roll, Garmin 300, Ipod 4th generation, next is to see what I can do with wifes Nano if anything. Fixin stuff sure beats spending more on the same. The new 800 as neat as that is…I spent a weekend figuring out how to put DI2 on my almost 20 year old litespeed, I needed something easy for a change.

  69. Thanks, Rich. I’m always glad to hear of others who love to take apart and try to fix things. I did the battery in my iphone 4 a few months ago and was surprised how easy it was.

  70. Thanks for the how-to! I’ve just fixed up my Edge 205 (battery had completely gone after almost 5 years service). The fix has survived two rides – it appears to have worked like a treat! Cheers

  71. Just did it. My 305 was only doing about 6 hours at best. No good for the century rides. I bought the 1200mah NP-45 battery from ebay seller eforcity.

    Case can be separated with a dull butter knife without incurring any damage.
    Just keep gong around…

    NP-45 battery fits with no mods. I salvaged double sided tape from original battery.

    I used shoe repair rubber cement for the perimeter and 4 dabs of super glue gel on the four corners of the case. Thought about smearing a small amount of black silicone around perimeter to ensure water tight seal. Maybe later.

    After installing the battery I gave it a charge on the truck cigarette lighter and it took much longer to charge than previous.

    I’m doing a run down test on it now and I estimate that it has extended operation to 11-12 hours (It’s been on for about 6 hours and there are still two bars left.)

    Thanks all.

    1. William Hodges

      Hello Dean

      Per your battery replacement post how is the “1200mah NP-45 battery from ebay seller eforcity” working out? I need to change my battery out.



  72. Did it. Almost lost one of the tiny screws…miracously found it. Thanks!!

  73. Declan Fleming

    Thanks! Just swapped out my battery and it’s compressing and drying now!

  74. Hi Jim,

    Just wanted to say thanks on your excellent post which boasts with sound logic, good and descriptive writing and illustrative pics.

    My EDGE 305’s battery had only recently deteriorated to the point that made me (only) contemplating about performing the surgery on the unit, but what sped me into this was the unit going dead after being left for overnight charging.

    Quick googling revealed this excellent post, together with a couple more of documented and well written dwellings into similar issues with this type of Garmin GPS device. I will mention,, and, although this list is by no means exhaustive. Since you are the first one whose post initiated me into fixing my own unit, I am replying here, although much, much later than the original post had been made.

    I addressed both battery replacement as well as the known issue of bad contacts between the two halves of the unit – one containing the battery, small PCB with mini USB connector (which also carries one PCB contacts for connection to the other half), and the other sporting the main PCB with all the electronics, display and micro switches, and also carries the springy contacts that connect to the previously mentioned small PCB in the bottom half of the shell.

    For battery, I opted for non-original Nokia’s BL-5CB (some generic Chinese replacement), as it’s cell has sufficient capacity (1000 mAh, although stated on the battery is only 750 mAh), and the CELL dimensions are such that it does require breaking of only one tab, while the portion of the unit near the pcb-mounted sensors is not compromised by battery size. I peeled the skin and removed the charge-control electronics from the battery, and soldered onto it the CCE from the original battery. The main reason for this was the fact that Garmin’s CCE was smaller and I could soldered it in the place which suited the space available. I wrapped it with electrical tape and even put the original sticker and the double-sided adhesive tape for sticking the battery to the lower half of the shell.

    The problem of insecure contacts I solved by soldering two additional wires between the points on the small USB-carrying PCB where the wires from the battery terminate, and the corresponding points on the main PCB. I opted for this, instead of going straight from the battery to the main PCB as I wanted to ensure that the small PCB and thus the USB connector does not depend on the contact quality but to sport soldered connections, as with this solution ensured is that charging of the battery also does not depend on contacts. For other contacts, the ones not carrying power, solution was found in making a thin cardboard wedge placed underneath the spring contacts, which adds to the spring force, which should suffice for the contacts that do not carry any significant current.

    Care must be taken to plan for routing of the two additional wires to not interfere with other components of the unit.

    For gluing and sealing the unit, since I could not find the Loctite 380 locally, I used Loctite 480 which is practically the same less the fact that it has lower viscosity than the 380 – not desirable but usable.

    Finally, I applied the closing pressure to the unit by applying two carpenter clamps.

    That solved all the problems with my EDGE, which I still prefer to the newer model 500, which seems to have much greater incidence of button malfunctions, although (as far as I know, at least) no issues with internal contacts.

    Thanx once again for making me do this.

  75. I didn’t want to post until I used it for a few day. THANK YOU! THANK YOU, it works great. I haven’t had this much battery life ever. I’ve sent it in to Garmin three previous times ($80) each, it has always worked coming back but has never had the battery life as advertised. Also, I don’t have to figure out how to reprogram it and save all my settings. Thank you again.

  76. Thanks for the excellent instruction and the humor. I just completed this. I decided on getting the original flavor of battery which came with wires so my procedure differed slightly. Instead of soldering the original wires to the new battery I soldered the new battery wires to the small circuit board. I did use your suggestion to lift the little circuit board with the razor cover paper. Instead of the phone books which I didn’t happen to have I use several 25 pound bags of lead shot. It was not quite as humorous as the books but it worked well. I am now doing the first discharge cycle. I hope to be riding with it again soon. Thanks again!!

  77. Sudhindra Aithal

    Thanks for the post Do you know what the 2 overlapping metal discs next to the battery are for. In my Forerunner 305, half of the top disc corroded and broke off when I removed the battery.

  78. Thanks for the great instruction.

    In my 305 on the circuit board there is a gray toroidial shaped gizmo, about 3/8″ dia. In the eye of the toroid at the bottom there’s like a clear window. Well, dangling around inside the eye, on was a speck of something, looked like a 1/32″ length of wire insulation. Whatever it was, I lost it. Was this something vital, or just a piece of loose junk?

  79. Hi Jim,

    Thanks for all this information. I first used it to fix a broken (loose) power button 2 years ago (used a glue gun to get it back in place–still holding well), but earlier this week I decided to put in a new battery. The battery swap went fine, but my piezo speaker no longer works. During the battery replacement, the center wire to that speaker pulled up. I re soldered it but it will not work. Are those things overly sensitive to soldering gun heat? Key question is–does anyone know where I can get a replacement speaker (I haven’t had any look searching online) or has anyone here had this happen and fixed it some other way?


  80. another Jim


    Thanks for the great article. I never undertook a soldering project like this before, but following your instructions was a breeze. I used a toothpick dab of flux on the wires and battery though and it stuck beautifully.
    One problem though was that I clamped it with some clothes pins and the next day, when all was dry, it powered on, but the mode button turned it off and none of the other buttons worked. I did all the reset methods and nothing still. I began using my fingernail around the edges to open it, but decided to try it once more and now it all works great.
    This all might be because the Rayovac battery I used was very large and I removed the 2 posts that aligned it and snapped back in.

  81. Dennis Trabant

    ….. now a few years later and some of us, way over here, are still using and loving our 305 edges even though the flames went out a couple of years ago. NOTE: You can still get the LG battery online. The replacement went well and works great for me. Instead of the paper shim under the usb contact board, I gave the spring-fingers a little more tension by bending them slightly upward. Did that by sticking a small straight-bit jewelers screwdriver below the contact fingers into the bend. I also cleaned the contacts with isopropyl alcohol on a q-tip. Just be careful and don’t leave any cotton threads in there and don’t bend the contact fingers very far = raising them 1 mm is plenty.

  82. Bruce Braley

    A replacement battery just arrived. I should have found your post first, because the replacement is only 850mAh.

    I am also going to do my Edge 705, which I use much more often, but I like just tossing this one in my trunk bag on my 3-speed errand bike. It still works for short rides, but I hate losing data when the battery doesn’t last as long as my ride does. I nearly always forget to turn it off when I am doing my errand, so a ten-mile ride might take me several hours.

    I haven’t done the job yet, but given the almost 100% success rate of those who have commented, I’m confident that it will go well. Potential bonus–my down arrow button stopped working years ago. I hope a repositioning or such will restore that function. You can’t turn the contrast back down once you turn it up without resetting the device!

    Great tutorial, Jim! Thanks for your time and effort that has benefitted so many!

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