[time-nuts] Oncore battery

Pete Stephenson pete at heypete.com
Mon Apr 25 11:34:08 UTC 2016


I have several 5V Oncore UT+ receivers of the type that did not
include a rechargeable on-board battery, but didn't want to bother
with lithium primary batteries or rechargeable batteries and their
associated holders so I opted to use supercapacitors. Specifically, I
use the Panasonic EEC-F5R5U105 supercap with a capacitance of 1F and a
max voltage rating of 5.5V.

Charging is easy: I simply run 5V power through a diode and a resistor
sized to prevent exceeding the diode's current limit and the capacitor
charges in about 20-30 minutes. The diode prevents the supercap from
discharging through the resistor when the power fails.

I use a 1N4148 small signal diode rather than a 1N400x-series diode
because the 1N4148 has a smaller reverse leakage current. A 240 ohm
resistor keeps the peak current to 20mA (the diode can handle up to
200mA forward current) and the capacitor is charged up in about 20
minutes after power-on. Adjust the values for your specific needs.
Once charged, it maintains the Oncore's RAM for several weeks with no
power.

On Mon, Apr 25, 2016 at 12:25 PM, Azelio Boriani
<azelio.boriani at gmail.com> wrote:
> Panasonic ML621 or equivalent. Alternatively you can use the battery
> pin (pin 6): remove the onboard battery and use en external primary
> cell (CR2032 or equivalent). See pages 15 to 21 of the M12M user
> manual.
> <http://www.ilotus.com.sg/~ilotus/sites/all/themes/zeropoint/pdf/m12m/M12M%20-%20User%20Guide%20%28Ver%201.0.0%29.pdf>
>
> On Mon, Apr 25, 2016 at 2:11 AM, Joseph Gray <jgray at zianet.com> wrote:
>> Can anyone recommend a rechargeable lithium coin cell that is a direct
>> replacement for the ones that come on some Oncore receivers? Something
>> I can order from Mouser or Digikey, if possible.
>>
>> Joe Gray
>> W5JG
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-- 
Pete Stephenson



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