はじめに
手順 1 に進むMost "new" old stock backbeat fits suffer from low cell voltage, such that the onboard charger cannot recover the device and operate normally. The coin cell chemistry and construction are quite robust and may be able to be recovered without replacing the Varta CP1654. Follow this guide to "wake-up" the coin cell and recover the device!
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First we must check if this device would benefit from battery revival / recharging. Plug in a charger and make sure that the ear piece red lights illuminate. This will indicate that the onboard charger, regulator, and electronics are functioning.
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However, if the unit is incapable of holding a charge, you should see that it will pull no current from the wal-wart charger. Not required, but you can see charging current from a USB power monitor such as the Klein Tool ET920.
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If the red lights do not turn on, then this repair guide will not able to assist you; a deeper level repair is required.
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Identify the left earpiece.
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Stick a dull knife or pointed object under the gasket opposite side of the ear loop.
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Pull back the gasket covering the edge of the pushbutton cover; taking care to not rip or tear the rubber. If glue is holding onto the rubber, use an exacto knife to carefully cut it back.
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Carefully separate the glue from the tangs holding the button cover to the battery assembly and outter housing.
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There are four tangs in total, three are easy to access with the gasket out of the way.
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I used an exacto knife, but becareful to not cut any wires coming down from the ear loop, or destroying any of the detents which hold the button cover in place.
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Take your time, the attachment to the battery housing is much stronger than the strength of the plastic cover.
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With the button cover removed, you can run a dull knife down through the sides to free up the glue holding the earpiece to the main housing.
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Apply gentle pressure to pull the earpiece away. Be careful to not rip the very short speaker wires.
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With the earpiece removed, we can get access to the battery charging terminals. Identify the location of the cell positive and negative terminals.
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The negative terminal (cell ground) is a large soldered tab. The positive terminal is the second lead from the square IC chip.
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Remove the silastic wire bonding to expose the ground and positive lead. De-solder and tape back the cell positive ground to protect the unit's electronics from the charging current in the next step.
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Solder appropriately colored wires on to the two terminals.
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Check battery voltage, it should be at or near 0V.
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Apply a charging profile consistent with the battery datasheet. Varta CP1654.
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If you lack a battery charger, a low voltage supply through a current limiting resistor can work. Limit charging to 1C rate (<60mA) and increase voltage periodically as battery voltage recovers.
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If the charge voltage does not raise above a 1V in a few minutes, the cell is most likely damaged beyond repair.
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DO NOT APPLY VOLTAGE OR CURRENTS GREATER THAN THAT SPECIFIED IN THE DATASHEET. THIS MAY RESULT IN DAMAGE TO THE CELL, ELECTRONICS, OR PERSONAL INJURY!
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If you do not know how to properly recover the battery, it is recommended that you stop charging at ~3.5V, and allow the onboard charger to complete the rest after re-assembly.
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Solder the positive battery wire back to the second position solder pad.
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Apply glue to cover the exposed wire and ground terminals.
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Continue reassembly in reverse order.
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Once assembly is complete, complete the charging process with the USB cable.
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If you have it, it is recommended to monitor the charge with a USB power meter.
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Note: the battery will require a few deep cycles (empty -> full) to re-stabilize after being drained for an extended period of time.
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To reassemble your device, follow these instructions in reverse order.
To reassemble your device, follow these instructions in reverse order.
2 件のコメント
Hello,
Thanks a lot for this. I have a unit that corresponds perfectly to what you describe. Brand new but does not hold the charge more that a 1 minute. Your fix seems beyond my abilities. not so much the soldering but the charging, I have no charger and barely understand the jargon about the resistance :) , and I don't have any such equipment. Would it not be easier to replace the battery?
Hey Valdo,
Replacing the battery is a better solution, but it is a more complicated disassembly process (as you can see from the guide). There is a small chance that you can recover the battery with usable amount of life this way to reduce the risk of breaking something on the battery pcb.
David D -
