# Edge 305 Battery Replacement



## mhatten (Jan 1, 2006)

Has anyone actually tried replacing the battery on the 305. My 305 is well out of warranty (coming up on 2 years) and doesn't run for longer than 3 hours when fully charged. I understand that you can send them into Garmin for a battery replacement... but I think $85 plus shipping is a bit steep.

Here are instructions and pics on how to take it a part. And I've found several places to buy 3.7v li-ion batteries for less than $10.

Also... several of the batteries are double the 800 Mah of the edge battery... so run times should be significantly longer than the original battery.

Has anyone done this?


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## rockymtnway (Nov 14, 2004)

Interesting thread, but it doesn't sound like you'll get a battery with twice the capacity to fit inside the case. That said, I'll give serious consideration to building an external battery that will last through a 24 hour solo once I have a 705 or suitable replacement in hand just incase I screw up my 305 forever. As for replacing the existing battery, it sounds easy enough, but it doesn't sound like too many have gone before you.

I wonder if a company like this could either do it for you, or supply a superior battery that would still fit inside?


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## mhatten (Jan 1, 2006)

Thanks for the reply.....

For a "1 to 1" replacement... I think this  is a good option. It has the same mAH and looks like it fits. I wouldn't be surprised if its the same battery used by the company you mentioned. Its dimensions are 2" x 1.44" x 0.17". The Edge dimensions are 2.6" x 3.7" x .9"

The larger capacity battery I was looking at is here. My concern with it is its diameter. The length and width don't look like a problem at all. However, I won't know exactly what I need until I crack open the edge and measure the existing battery.

6 to 12 hours is all I would ever need. If I ever planned on doing a 24, I'd get an external battery. I simply need the simplicity that the current battery should offer now.... i.e. Ride/Download/recharge while connected to the PC.


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## rockymtnway (Nov 14, 2004)

I think that's all most people need. Unfortunately, there's a few thousand of us who want twice as much and the external battery solution isn't all it's cracked up to be. The unit isn't truly sealed if you have something in the mini-USB port and I destroyed my first Edge during the 2006 24 hours of Moab (in the miserable pi$$ing rain). Also, everytime you plug and unplug, you risk the unit turning off or locking up (happened several times in longer training rides). Changing batteries in the external unit was also a pain, since I had it PVC taped to the stem. 

I, like most Edge owners, have a love-hate relationship with it. When it works perfect, it's one of the coolest products on the market. When it doesn't, it's pretty easy to feel like hucking the thing along side the road into the bushes and going home to put your Polar back on (which has a battery that lasts 15-24 months).


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## ric426 (Jul 13, 2007)

*Alternative replacement battery*

I was checking out this thread last night because the battery life seemed to be getting shorter on my 3 year old 305. I looked around online for a replacement, but I need to have mine working again before I leave in a couple of days and didn't want to run the chance of it not arriving in time. Then it dawned on me that a lot of cell phone batteries have similar specs, so I started checking the batteries from the various current and old cell phones around the house. It turns out that the stock battery for an LG VX8350 is almost a perfect fit and is rated at 1000mah, so it should have a longer run time as well. You can get them on ebay for around $10, but some of the aftermarket batteries are rated at 850 mah, but that still matched the Garmin stock battery specs. All I had to do to install it was clip the battery wires close to the battery, cut off one tab inside the case that goes on one side of the battery and solder the existing wires to the contacts on the battery. Before I glued the case back together I treated the contacts that connect the two halves with Deoxit contact treatment to prevent possible contact problems later. It all fit back together perfectly and so far is working fine. Just thought I'd put it up here as a possible and easy to find alternative.


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## GEOMAN (May 30, 2006)

ric426 said:


> I was checking out this thread last night because the battery life seemed to be getting shorter on my 3 year old 305. I looked around online for a replacement, but I need to have mine working again before I leave in a couple of days and didn't want to run the chance of it not arriving in time. Then it dawned on me that a lot of cell phone batteries have similar specs, so I started checking the batteries from the various current and old cell phones around the house. It turns out that the stock battery for an LG VX8350 is almost a perfect fit and is rated at 1000mah, so it should have a longer run time as well. You can get them on ebay for around $10, but some of the aftermarket batteries are rated at 850 mah, but that still matched the Garmin stock battery specs. All I had to do to install it was clip the battery wires close to the battery, cut off one tab inside the case that goes on one side of the battery and solder the existing wires to the contacts on the battery. Before I glued the case back together I treated the contacts that connect the two halves with Deoxit contact treatment to prevent possible contact problems later. It all fit back together perfectly and so far is working fine. Just thought I'd put it up here as a possible and easy to find alternative.


Wow! You are bright! Thanks for the info, much appreciated.

Frankly, we've sold over 8,000 Edge 305's and I rarely (if ever) hear of battery failures. The product has been out for a couple of years now so time will certainly tell. Your post offers an option for those who are out of warranty and willing to take a risk at fixing it themselves.

Thanks again.


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## ric426 (Jul 13, 2007)

GEOMAN said:


> Wow! You are bright!


There are many who would disagree... 



> Thanks for the info, much appreciated.
> 
> Frankly, we've sold over 8,000 Edge 305's and I rarely (if ever) hear of battery failures. The product has been out for a couple of years now so time will certainly tell. Your post offers an option for those who are out of warranty and willing to take a risk at fixing it themselves.
> 
> Thanks again.


No problem, always glad when I can give back a little. In my case it wasn't a battery failure, just a gradual loss of run time to the point where I was getting a low battery warning after a couple of hours. I'm doing a century (road ride) in a few days and didn't want it to die part way through the ride, so I went ahead and changed it now. From what I understand any rechargeable battery has a limit to the number of discharge/recharge cycles before it starts to lose capacity. I bought my 305 when they first came out, so I'm sure it's been cycled at least a couple hundred times. 
Other than poor reception in the woods resulting in flakey speed display, it's been reliable, so I'm not complaining. It never has switched over to the speed sensor properly when it loses reception, but I hear that's a common problem.


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## GEOMAN (May 30, 2006)

I've got about 400 cycles on mine and it is still going strong... Won't last forever though.


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## slocaus (Jul 21, 2005)

In this subject of 305 battery. I found something interesting by accident. 

I usually download rides from my 305 every two or three rides, turn it off, and leave it on the charger. I was down to about 4-5 hours time until the battery symbol was empty, but no warnings.

I accidentally left it on while charging, and on a long 8 hour day, the battery symbol only lost one bar. I have been doing this now, and just leaving it on while charging, and am getting much longer runtimes. I left in turned on, sitting on my desk at home, not plugged in, and it went somewhere over 13 hours before it turned off. Cool. 

Nice to have your experience there, ric426, with DIY battery swapping. :thumbsup:


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## GEOMAN (May 30, 2006)

slocaus said:


> In this subject of 305 battery. I found something interesting by accident.
> 
> I usually download rides from my 305 every two or three rides, turn it off, and leave it on the charger. I was down to about 4-5 hours time until the battery symbol was empty, but no warnings.
> 
> ...


If we can validate this procedure, it should be circulated everywhere!

This is good stuff!


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## slocaus (Jul 21, 2005)

If others try it and report back.

I usually ride from home, so I take it off the charger, install on bike and ride, powered up the whole time. Off the bike and back to the charger.

If I am riding after work, I turn it off in the morning after removing charger, and it still gives me that longer life.

On days I commute to work, I turn it off while working and then turn it on for the ride home (13 miles in 45 -55 minutes each way). I'm still seeing the battery indicator showing full at the end of the 9-10 hours from leaving home to arriving back, and powered on for one to one and a half hours.

I plan a 10K climbing day later next month, so we will see how it does on a dawn to dusk ride.


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## KINBOY (May 23, 2004)

Well posted this on the MB forum to get more input. There are some good minds there.
KIN


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## GEOMAN (May 30, 2006)

slocaus said:


> If others try it and report back.
> 
> I usually ride from home, so I take it off the charger, install on bike and ride, powered up the whole time. Off the bike and back to the charger.
> 
> ...


I will...


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## Bolo Grubb (Nov 27, 2007)

any updates? anyone elase replace a battery on their own or validated the recharge procedures?


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## ric426 (Jul 13, 2007)

Mine was still working fine with the VX8350 cell phone battery, right up to when my riding season ended abruptly 4 weeks ago with a hard crash. The 305 is fine though. It even recorded my hike out of the woods and back to my car. :madman:


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## mrm1 (Apr 22, 2007)

Not to revive a dead thread, but the link at the top is broken and I need to open my 305. Does anyone know the URL of the thread with the pics?


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## slocaus (Jul 21, 2005)

Google is your friend.

http://www.jimcarson.com/2009/replacing-the-battery-in-a-garmin-edge-305/

http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

Those are two of 100s of hits.


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## mrm1 (Apr 22, 2007)

Thanks, I just found one of those too ... Your 2nd one has better pics than the one i found.


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