Upgrading 3.7 lithium battery with bigger mA lithium battery

[Mustwin351]

I have been having trouble locating information on upgrading an MP3 players 3.7v lithium battery with a higher 3.7v mA lithium battery. Currently I don't know the miliamp hour battery it uses now as it is unmarked but would like to use say a cell phone's battery.

Obviously my first concern is safety and wanted to know if anybody knew anything about this or could possibly point me in the direction to find out.

Thanks.

 

[Fish4Fun]

Mustwin351,

First the good news: from the player's point-of-view 3.7V is 3.7V, no problems there.

The bad news involves any "built-in" charging, this could prove to be problematic. There are several different lithium battery formulations with numerous different charging technologies associate with them, and they are NOT necessarily compatible. Some battery packs have a charge controller built-in, many use an external charge controller either built into the device's circuit or built into the charger itself. Without certain knowledge about the existing battery/charger you cannot proceed safely.

A Spot of good news. I assume the point is longer run-time AND that the MP3 player has a "charger" that connects to the player? If the connection is a standard mini-USB connector, or a standard wall-wort type connector, you can safely assume the MP3 Player's charge controller is either in the battery pack or in the MP3 Player's circuitry allowing you to use an "external" battery pack to extend the player's run-time. As long as the external battery pack's output voltage is within the MP3 Player's input voltage range, you will be fine.

Before going into more detail, you will need to provide information about the MP3 Player's charger, connectors etc. (AND, of course, if an "external battery pack" is an acceptable solution.)

Fish

 

[Mustwin351]

Thanks for the great information Fish!

Yes you are correct the idea is for longer runtime. Also the MP3 player is charged via a mini usb connector and an external battery pack is fine.

Also on the current lithium battery their is a PCB board. Would this have to be the charge controller?

If so then is it safe to substitute any higher amp hour3.7v lithium battery so long as it has a charge controller on its battery as well?

 

[Fish4Fun]

I would suggest the external battery pack voltage be within the charging range of the OEM charger....that is, if the device is designed to be charged by a USB connection, then the circuit is designed to be charged by ~5Vdc. I would NOT attempt to charge it with more than ~6Vdc. It is quite possible it could handle considerably more, but if it cannot, you risk permanently disabling the charging circuit.

As far as AH (Amp-Hour) rating, go as high as you like. Think of voltage as how "deep" a pool is, and think of Amp Hours as the "Area" of the pool. If the pool is 1m^2 and 3.7m deep you have 3.7m^3 of water, if another pool is 1000m^2 but still 3.7m deep, you now have 3700m^3 of water! The "pressure" at the bottom of both pools is the same, but you get a lot more water out of the larger pool before there is a corresponding change in pressure.

Sorry for the slow response time, I was caught in a time sucking vortex ;-)

Fish