Want worn out transponder no longer holds charge.

[dlabout]

Hi everyone,
I wanted to see if anyone has an old transponder that no longer holds a charge. I'm interested in seeing if the batteries can be replaced.
I'm more interested from a tech. perspective than anything.
If I can make it work I'll post up the instructions.

So if you have a transponder that you're no longer needing, let me know.

Thanks,
-Doug

[Scored51]

Hey Doug,

I hear where you're going with this and let me share what I've found. If your considering doing this as a side business, you have three issues with this process...

One: the battery is potted so you will need to take the time to be extremely careful in digging out the battery that is soldered quite well to it's contacts and enclosed in a plastic case.

Two: The nickel metal battery that powers the transponder is a special battery specifically designed for high heat applications. Since the application is potted, there is no ability for the battery to vent. Therefore, a Radio Shack equivalent may cause a "thermal event" if charged too quickly or even possibly during normal operation. However, once you track down the manufacturer and a distributor and the correct battery for the application (as I did), the minimum order will set you back more than $1,100.00 and then you will also need to maintain an account with the distributor for minimum annual sales. The good news is the batteries are a little over $3 each so you would only need to repair roughly 350 units to cover you're initial stock order.

Three: All of the transponders you are asking about are still under a pro rated warranty from AMB-it. Depending on the serial number of the transponder this could mean coverage of 50% ($210) towards a new transponder if there is a problem.

Sorry to post this, but I've been there and done that in an attempt to solve this theoretical issue for racers who will still be with us for the 2011 season. (This is the calculated end of the design life of the transponders the MRA purchased originally. ) I haven't finished looking into it, but it seems silly to attack a problem with a product that hasn't occurred yet, is still covered under the manufacturer's warranty, and cannot be accomplished any cheaper at this point by performing the surgery ourselves.

You can also search this forum for other posts, as this has been discussed previously.

- Chris Dale. MRA #51
Transponder Manager 2006-

[benfoxmra95]

screw the batterys, Im diggin out the battery in mine and going to hard wire it to 12v, straight to the ignition.

the charger is a 12v input, I know that the battery may output less voltage, but that's a simple trip to the electronics store for a $3 transistor that'll output the right voltage and bleed off the rest of the unused voltage.

Gallant can jump in here anytime and tell me if Im heading down the right path on my theory, Im sure he's already reverse engineered something here for this scenario.. the guy never sleeps, he's on a the corellian 72 hour day like men in black

[OConnell]

You would use a voltage regulator, and some capacitors to create a LPF to clean up the juice from the bike. Could be done with a set of 3 transistors, but the pre-packaged voltage regulators at $2 will work much better. The only issue is that Voltage regulators produce heat (by shunting the excess power), so you would probably have to keep the regulator outside of the sealed housing.

If you wanted to go super cheap, you could create a voltage divider with 2x $0.05 resistors, but it isn't the ideal solution, for several reasons. You *COULD* do the same with a single transistor, but it would suffer from the same issues as the resistive divider but even more sensitive, and all noise would be amplified, creating a need for more complex LPFs.

[dave.gallant]

blah blah blah.

Put a 7805 in there and plug it in. Done!

[OConnell]

Ha...

Basically what I was saying, but in far fewer words. :lol:

I still think that a simple LPF would be a good idea on top of the voltage regulator.

Plus, do we know that the Voltage output of the battery is consistant with the 7805, IIRC its for TTL, not CMOS. Either way, a similar unit could be found for 3.3v if thats what it uses.

[dave.gallant]

Ha...

Basically what I was saying, but in far fewer words. :lol:

I still think that a simple LPF would be a good idea on top of the voltage regulator.

It will all be moot once it cartwheels outside turn 2 at Pueblo.

[OConnell]

Good point. Although the $0.20 in capacitors and resistors and 3 drips of soldier will be the least of your worries at that point.

[dave.gallant]

Good point. Although the $0.20 in capacitors and resistors and 3 drips of soldier will be the least of your worries at that point.

Usually I am mentally going through my spares bins to see if I can fix it by the next race.

(or, if I am on my scooter, I am looking for the Percoset and calling my orthopedic surgeon!)

[TRK]

You guys have issues................and too much time on your hands. Just use a flux capacitor and be done with it.

[Scored51]

...a similar unit could be found for 3.3v if thats what it uses.

By the battery I've extracted from a "deaded" unit, it is 1.5 volts. But if we were to use any external electronics to correct the bikes 12 volt source, why not simply use a nickel metal battery (external to the unit) from Radio Shack. You could buy a pack of four of them and be able to charge the batteries (for you and three of your buddies) by the time you've eaten breakfast and gone to the rider's meeting? Just a thought...

Hmmm, and we'll be cutting down on the overuse of nearly extinct flux capacitors in the world.