Author Topic: How are TV remote docking station battery contacts wired to prevent a short?  (Read 1463 times)

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Offline dparson

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Hi all, can anyone explain how the battery contacts work on a device with a battery charging docking station?  I have a TV remote control similar to the one pictured with one of these docking stations and I can't understand why there is no voltage on the gold contacts on the remote, but when you place it into a docking station the battery within it can be charged. 

I was working on my own project with a small 2 pin modular contact but realized there is something special going on with the remote since you can short the contacts on the remote and no current flows.  How does one add this feature to a 2 pin contact that's used to charge a battery?  Thanks for any help!

- Dave

Offline Zepnat

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It'll probably have a battery charger IC between the connector and battery.
Something like the TP4056, which is designed to prevent power coming out of the battery back to the charge socket.

Online Richard Crowley

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You kids with your new-fangled integrated circuits!
It could be something as simple and prosaic as a diode!

Offline SeanB

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Very likely a bridge rectifier, and the base has a 6VAC current limited ( either from using a transformer with very poor regulation and a very thin secondary winding with high resistance or with an external resaistor or PTC thermistor) output, that is then used to charge the battery either with a resistor or a charge controller.

Looks like your remote probably has a charge controller, and probably has a lithium pouch cell inside to power it.

Offline dparson

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Ah I see, the remote does have a charge controller, the base station has 8.6VDC on it's pins and they are recessed to prevent shorting out.  The remote's pins sit into the base station and that's how it all works.  Thank you all!

Online ConKbot

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1/10-1/20 C or less constant(ish) current source, and a diode in series with 2 Ni-Mh cells.  And could be it

With lithium polymer cell, an integrated charge controller (i.e. max1551 ) would be easy. 

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