Just like the mad Doctor was trying to get life into his monstor, I was on a quest to get more out of mine. I'm always looking for a reason to go into my garage and tinker. When the face of my Garmin 305 popped completely off, an opportunity presented itself the very same way a lighting bolt brought Frankensteins monster to life.
Out for a ride a few months ago I was wearing the 305 on the inside of my wrist. Time seemed to slow down when the top half came completely off after I pushed the lap button. Once the horror and denial of what just happened subsided, "Ah crap!", quickly turned into "Hmmm? I can work with this"
With the guts of my precious 305 hanging in the wind, thoughts started to pour into my head about how I was going to make this 305 last for hours on end. Time to tinker. (insert evil laugh).
However, before we get into all the gory details of 305 surgery, let me offer a few tips of how you can get more time from the 305 without having to expose it's guts to the world.
TURN OFF:
The GPS antenna (Indoor Mode)
The audio (Beeps)
The backlighting
Show Map
By turning off these power suckers, you can gain a lot of life out of a 305 without losing the features you need. All you lose is the mapping feature of Google Earth. NOTE: You do need the GSC-10 cadence accessory to keep the other features, like speed and distance.
So with the above features off and using a GSC-10, you will still have;
Speed
Cadence
Heart Rate
Distance
Time
Do this and you will gain not just minutes of battery life, but hours. In my first test I managed to get 21 hours of life from the 305. The last 3-4 hours of the 21 I even turned the gps antenna back on. The purpose of this was to show that if you aboslutley must have pace for your run, the gps antenna could be turned on in T2 and you'll have some juice left over to show pace on the run.
So there I sat in my garage with a sleek 2-piece Garmin 305 in my hand. "What's my goal?", I asked myself. "Why bother?" Then it hits me - Texafornia, Mike Keller and other endurance runners! I must forge ahead to the operating table for them. What long distance ultra runner would not love to have a GPS enabled watch that can survice their runs on one charge. (Mwa hahaha, insert another evil laugh). My goal is now defined!
Extend the battery life of a Forerunner 305 long enough for a 100 mile run.
How was I going to do this? In theory it was easy! “Add another battery dope”. Obviously the space inside the 305 is cramped already. So another roommate was out of the question. What was needed was an external battery with a connection to the 305.
“Would this work?” Maybe not, but I was gonna have fun finding out. If the patient died, there was always Ebay. So off to Target for the battery.
Specs:
$20. Sanyo. Nickel Metal Hydride. 3 cell. 3.6 volt. 800mah
Electricity 101:
For those interested in knowing what mah are, here it is in a nutshell. It’s the capacity of the battery. So a battery that is labeled 800mah is .800 of 1 amp. Mah is pronounced “milli-amp hour”. So if you had this battery hooked up to a device that pulled 400 mah, technically the battery should last 2 hours. A 100mah drain "draw" on the battery, in theory it should last 8 hours.
The battery in a Garmin 305 is: a 3.7 volt, Lithium-Ion, 750 mah battery. I’ve had past success getting the 305 to last 20 hours on a charge. That means by turning off all those bells
and whistles, that “draw” on the battery. This equates to roughly 38 milliamps/hour. So by adding in another 800 mah I should get a 1550 mah battery. Or a 1.55 amp hour battery. With the Garmin 305 pulling about 38 milliamps that should last 38 hours! Yup, you heard me right….38 hours! Possibly 20 hours with the GPS antenna on.
BUILDING THE - FRANKENSTEIN 305
STEP 1 :
Gather all the materials required.
The Patient (The 305)
The new battery (Sanyo battery from Target)
New leads.* (Connectors used to connect and disconnect the external battery) Radio shack.
*The leads I used were from RC airplane batteries. Any small connectors will do.
Heat shrink tubing. Various sizes.
Scissors
Small soldering iron.
Solder
Tip cleaner
Exacto knife
Drill and drill bits. 1/16 to 7/64th.
Electrical tape
Red Bull, Vodka & Ice in tumbler (Just kidding) sort of.
TURN OFF:
The GPS antenna (Indoor Mode)
The audio (Beeps)
The backlighting
Show Map
By turning off these power suckers, you can gain a lot of life out of a 305 without losing the features you need. All you lose is the mapping feature of Google Earth. NOTE: You do need the GSC-10 cadence accessory to keep the other features, like speed and distance.
So with the above features off and using a GSC-10, you will still have;
Speed
Cadence
Heart Rate
Distance
Time
Do this and you will gain not just minutes of battery life, but hours. In my first test I managed to get 21 hours of life from the 305. The last 3-4 hours of the 21 I even turned the gps antenna back on. The purpose of this was to show that if you aboslutley must have pace for your run, the gps antenna could be turned on in T2 and you'll have some juice left over to show pace on the run.
So there I sat in my garage with a sleek 2-piece Garmin 305 in my hand. "What's my goal?", I asked myself. "Why bother?" Then it hits me - Texafornia, Mike Keller and other endurance runners! I must forge ahead to the operating table for them. What long distance ultra runner would not love to have a GPS enabled watch that can survice their runs on one charge. (Mwa hahaha, insert another evil laugh). My goal is now defined!
Extend the battery life of a Forerunner 305 long enough for a 100 mile run.
How was I going to do this? In theory it was easy! “Add another battery dope”. Obviously the space inside the 305 is cramped already. So another roommate was out of the question. What was needed was an external battery with a connection to the 305.
“Would this work?” Maybe not, but I was gonna have fun finding out. If the patient died, there was always Ebay. So off to Target for the battery.
Specs:
$20. Sanyo. Nickel Metal Hydride. 3 cell. 3.6 volt. 800mah
Electricity 101:
For those interested in knowing what mah are, here it is in a nutshell. It’s the capacity of the battery. So a battery that is labeled 800mah is .800 of 1 amp. Mah is pronounced “milli-amp hour”. So if you had this battery hooked up to a device that pulled 400 mah, technically the battery should last 2 hours. A 100mah drain "draw" on the battery, in theory it should last 8 hours.
The battery in a Garmin 305 is: a 3.7 volt, Lithium-Ion, 750 mah battery. I’ve had past success getting the 305 to last 20 hours on a charge. That means by turning off all those bells
and whistles, that “draw” on the battery. This equates to roughly 38 milliamps/hour. So by adding in another 800 mah I should get a 1550 mah battery. Or a 1.55 amp hour battery. With the Garmin 305 pulling about 38 milliamps that should last 38 hours! Yup, you heard me right….38 hours! Possibly 20 hours with the GPS antenna on.
BUILDING THE - FRANKENSTEIN 305
STEP 1 :
Gather all the materials required.
The Patient (The 305)
The new battery (Sanyo battery from Target)
New leads.* (Connectors used to connect and disconnect the external battery) Radio shack.
*The leads I used were from RC airplane batteries. Any small connectors will do.
Heat shrink tubing. Various sizes.
Scissors
Small soldering iron.
Solder
Tip cleaner
Exacto knife
Drill and drill bits. 1/16 to 7/64th.
Electrical tape
Red Bull, Vodka & Ice in tumbler (Just kidding) sort of.
STEP 2:
Remove the face. Mine popped off from fatigue. However with a proper wide flat thin screwdriver, you can easily work the Garmin top half off. NOTE: The front face holds all the electronic guts. It’s NOT connected to the battery. So it will just come off. The bottom "shell" of the 305 holds the battery and brass contacts.
STEP 3:
Take minute to ponder why you just opened up your $300 watch into two halfs. Accept that you can’t go back now. Take a sip of the Red Bull & Vodka.
STEP 4: Preparing the Spare Battery.
Cut off the connector on the new battery you bought at Target(Sanyo). Splice the new connector to the leads of the this battery with solder and heat shrink tubing.
End Result Spare Battery
Step 5:
Using a very flat wide screwdriver, slowly pry off the battery from the 305. It’s held down with a square piece of very strong double sided tape. Cut the leads to the 305 battery.
IMPORTANT: The leads are very short! Cut them a hair shorter on the side of the battery, favoring the side of the shell. This will leave you with a tiny bit more to work with inside the 305 shell.
STEP 6: Strip off about 1/8th of an inch from all 4 leads. Battery side and 305 side. Don’t mess this up. Take your time! Use the exacto blade and slowly “score” around the insulation and remove with just your fingers.
STEP 7. Take another sip of your favorite drink cause we’re about to drill holes. Using the smallest drill bit you have, drill a hole into the casing of the 305 where you see in the picture.
Then proceed up in drill bit sizes until you can barely feed in the other lead for the spare battery. Cut it to length (3-4 inches) after you feed the end through the hole. Strip each end about 3/16” of an inch.
The spare battery lead in place. Ends need to be stripped.
STEP 8: THE TOUGH PART
Sorry about this. You now have to join and solder the leads together. THIS AINT EASY! Put down whatever drink you are drinking by now. Reference the picture in Step 6. These leads need to be soldered together along with the original 305 battery. Red to Red. Black to black.
IMPORTANT: There are two ways to hook up multiple batteries.
SERIES vs. PARALLEL
In series the volts double but the amps (capacity) remains the same.
In parallel, the volts stay the same but the amps double.
Picture 10 people holding hands in a circle. That’s a series.
Now picture a 10 person conga line holding the person in front at the hips, that’s parallel.
This has to be hooked in parallel to work right!
With much dexterity and new curse words learned, I got them soldered together and covered with black electrical tape. There was no room for the heat shrink tubing in there.
STEP 9:
REPLACE THE COVER – Use either a two part 30 minute drying expoxy or a CA glue. CA is Cyanoacrylate glue. (ie Crazy Glue) I used a type found at local hobby shop. Ever so slowly with a fine tip, slowly let the CA glue whick into the creases of the two halves. Work your way all around and let it dry over night. Another option would to use a two part epoxy. Seal off the hole where the lead comes out with some CA glue or epoxy.
IMPORTANT: There are two ways to hook up multiple batteries.
SERIES vs. PARALLEL
In series the volts double but the amps (capacity) remains the same.
In parallel, the volts stay the same but the amps double.
Picture 10 people holding hands in a circle. That’s a series.
Now picture a 10 person conga line holding the person in front at the hips, that’s parallel.
This has to be hooked in parallel to work right!
With much dexterity and new curse words learned, I got them soldered together and covered with black electrical tape. There was no room for the heat shrink tubing in there.
STEP 9:
REPLACE THE COVER – Use either a two part 30 minute drying expoxy or a CA glue. CA is Cyanoacrylate glue. (ie Crazy Glue) I used a type found at local hobby shop. Ever so slowly with a fine tip, slowly let the CA glue whick into the creases of the two halves. Work your way all around and let it dry over night. Another option would to use a two part epoxy. Seal off the hole where the lead comes out with some CA glue or epoxy.
STEP 10: Connect the external battery. Connect the 305 to the charging cradle and charge
So here I sit. It’s now noon. I did the above in about 2 hours this morning. However, my empty cocktail glass tells me it's 5pm somewhere. The Frankestein 305 is sitting on the charger with the external battery attached. It should be charging both batteries.
So here I sit. It’s now noon. I did the above in about 2 hours this morning. However, my empty cocktail glass tells me it's 5pm somewhere. The Frankestein 305 is sitting on the charger with the external battery attached. It should be charging both batteries.
For comparison I also connected my wifes 305 to charge. If hers stop charging first I'll know it's charging both batteries. My wife's should stop charging in about 3 hours. Mine, about 4.5 hours. I'll throw the battery in a ipod arm band to wear on my wrist next to the Garmin.
Full charged it was time for some test runs. I’ll turn on my wifes “normal” 305 and the Frankenstein at the same time & sees which one dies first. Then again, can Frankenstein ever really die!?
RESULTS:
TEST #1. GPS ANTENNA ON FOR ENTIRE TEST;
Frankenstein 305 - 14hrs:14mins:32secs
Normal 305 - 11hrs:02mins:54secs
TEST #2. GPS ANTENNA OFF (1st 10 hours)
GPS ANTENNA ON after 10 hours elapsed
Frankenstein 305 - 22hrs:52mins:44secs
Normal 305 - 17hrs:39mins:29secs
Normal 305 - 17hrs:39mins:29secs
TEST #3. GPS ANTENNA OFF
Frankenstein 305 - 45hrs:22mins:39secs
Normal 305 - 30hrs:25mins:17secs
Normal 305 - 30hrs:25mins:17secs
Summary: Well I got some interesting results. Not exactly the one I wanted but interesting none the less. Test #1 only proved to yeild me another 3 hours above a normal 305 with the gps on. Test #2 showed the most promise but still doesn't show me that it can last long enough for a full 100 mile run. Test #3 was the most shocking. In the last test the Frankenstein was nothing more than a bike computer (no gps). It lasted an entire 15 hours longer than a normal 305. It surpassed my intitial guess of 38 hours by 7 hours!
Thinking about it days later I realized that you could make two or three external battery packs and take them with you stored in a running belt. This would allow you to use the GPS feature for 30 hours, changing out the batteries on the go. The internal battery would likely keep it's charge and therefore the unit would not shutoff. So until I learn to run for 30 hours I'll leave this monster alone.
-Jet
