[time-nuts] Oncore battery backup (answer to question)

[WB6BNQ]

Robert,

I completely disagree with such a simple answer !  Lets review the issue here.  Joe has not given any information as to the
equipment in question, nor has he stated his desired goals other then by assumptions based upon his questions.

First, which Oncore receiver is he using ?  If it is the older series such as a GT+ or UT+ they are designed to have a
Lithium 3 volt cell soldered onto the board.  The memory draws 5 micro amps at 3 volts and 100 micro amps at 5 volts.  There
is an external connection available to provide the battery back-up off board with a caution of NOT exceeding 5 volts.

The non rechargeable Lithium COIN battery has a discharge function that holds its voltage fairly constant right up until the
end.  They will last a very long time with just 5 micro amps of discharge.

The problem with the Super Cap is the charge circuitry could damage the GPS if not properly protected.  The Super Cap will
not last as long as the Lithium; we are talking years here under the right condition.  Unless you are skilled at changing
small foot print surface mount components, presuming the memory chip is still available, you stand the chance of destroying
the receiver.  Why subject yourself to additional unnecessary expense.  Why add all that complexity to an otherwise simple
application.  If you add up the cost of the CAP and all the parts to charge it and protect the load, I think that would
exceed the cost of the battery.

If your whole existence relies on a single back-up strategy to save your butt, then you should not be there in the first
place.  So, I think it is time for Joe to think all of this through with some proper goals stated and reasoned thought
applied.

Bill....WB6BNQ

Robert Atkinson wrote:

> Hi Joe,
> Yes you can use a supercap. It will directly replace the ni-cad Just make sure the voltage rating is high enough, e.g. 5V
> Ebay item 160495558462 looks good.
>
> Robert G8RPI.
>
> --- On Wed, 6/4/11, Joseph Gray <jgray at zianet.com> wrote:
>
> From: Joseph Gray <jgray at zianet.com>
> Subject: [time-nuts] Oncore battery backup
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Date: Wednesday, 6 April, 2011, 17:00
>
> Recently, the local area had an extended power outage. I have the
> Z3801A on a UPS, but the outage lasted over an hour and the UPS
> didn't. I have the information about adding a battery to the Oncore to
> allow for faster startup. Is it safe to use a supercap instead of a
> battery?
>
> Joe Gray
> W5JG
>
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