Battery-bypass hacking an MP3 player

Thread Starter

Byff

Joined Jun 26, 2019
7
The background: a few years ago, I purchased an inexpensive media player, an Eclipse. Nice feature set for the price, and reasonable memory capacity. I loaded it up with "driving music" and kept it in my car for the most part. And for a year or so, all was mostly well. But usability issues were present from the start. The player will not operate if the battery is too low, as one would expect. But when you plug the device into a charger, it has to charge FULLY before it will let you operate it in any way. This can take a couple hours. I want to emphasize that it cannot be charged and operated at the same time. This wasn't too big an issue, though, when the battery was relatively young.

The problem: the battery has cratered. It's non-replaceable (although I could solder in a new one if I had to and could find one). It has responded briefly to reconditioning, but that in itself is an irritatingly long process, and the results last only a few days. I've basically given up on the battery at this point.

The project: to bypass the battery altogether, so that when plugged into a USB port, the player thinks it's fully charged and ready to go. The battery has three leads, two of which are obviously the power (+V / GND) connections and one of which, I presume, is the voltage-level sensor. If I can get the battery charged one last time, some quick probing with a voltmeter ought to straighten out which is which.

The theory: that by supplying a steady +5V to the power and sense lines, I can trick the Eclipse into assuming it's got a fully-charged battery. This should be a very easy fix, just rerouting the wires to pins on the MP3 socket.

The question: is this theory sound? I'm assuming the battery is a five-volt, and that it's charged by simply running power through it in reverse. Are my assumptions reasonable?
 

djsfantasi

Joined Apr 11, 2010
5,688
The assumption that the battery is 5 volts is a big one. Do you have any reason to choose 5V? It could be 4.7V or an 9.4 battery supplying an onboard voltage regulator. Are there any markings on the battery (and if you could attach a picture, that would help)?
 

Thread Starter

Byff

Joined Jun 26, 2019
7
The 5V assumption is based on the USB charger...from what I understand, USB cables provide 5V at 500mA.

I'm working on getting you a photo...I'm danged if I can remember how I disassembled this thing last time, as the two screws I've just removed don't do the trick.
 

nsaspook

Joined Aug 27, 2009
6,483
The battery could be a 3.6V. That's something I can test if I can ever get it fully charged again.
What is the exact model? A quick search show several battery replacement procedures for Eclipse media player. After a battery replacement my old Linux (gnomad2) compatible ZEN V plus 4GB ran like new again and it's still worth $100 used for some odd reason.
 
Last edited:

Audioguru

Joined Dec 20, 2007
11,251
The battery is a common available Lithium Polymer (Li-PO) type. The 5V powers its charging circuit. It is 4.2V when fully charged, about 3.7V when half-charged and about 3.2V when it should have its load disconnected so that it does not discharge to a lower voltage.
The charging circuit and circuit to detect 3.2V are very important because a Lithium battery can explode and catch on fire if they work poorly.
 

Thread Starter

Byff

Joined Jun 26, 2019
7
Thank you. I'll plan for a long-term solution that includes replacing the battery, but for the time being, bypassing the battery is more within my means. First I'll do one more cycle of reconditioning in order to try to fully charge the battery, so that I can check the leads for the voltages you provide here.
 

Thread Starter

Byff

Joined Jun 26, 2019
7
I think that wraps it up, except for minor details. Obviously if I'm bypassing the battery, I can't just run a wire from the USB port to the circuit board (since the Eclipse is expecting 4.2V instead of 5V). I could use the voltage drop from a large resistor to downregulate the voltage, which is wasteful, but the player would only be used in my car, where there's current to spare. Alternately, I could run power directly from one of the 12V sockets and cobble together something around an LM317 to give me the required voltage. This is where experimentation begins.

Thanks, all.
 
I know this is an old thread, and i'm sure you've long accomplished your goal, but i figured i'd comment, as i am working on something with the eclipse 180 pro as well, also regarding the battery. mine works alright, although it could hold its charge a little better, but i am essentially building a new mp3 player from all the internals, and while i'm at it, upgrading the battery to a huge capacity. i am adding in bluetooth capability, and will create a new case to fit that and the large battery. in so doing, i came to discover that if the battery is completely removed, it runs perfectly straight from the charger, no mods required. in fact it displays a full charge, much to my amusement. just thought i'd throw that out there, and my apologies if its annoying that i dug up this old thread again.
 
Top