[time-nuts] Oncore batteries

Matthew Smith matt at smiffytech.com
Sat Apr 5 02:54:59 EDT 2008

Quoth randy warner at 2008-04-04 02:41...

> Don't pull off the batteries! The boards are populated differently for
> battery/non-battery uses. Your external battery will not be connected to the
> onboard RAM.

Too late - at least for the 'stuck' unit, although I haven't powered it 
with anything connected to the battery pin.  Testing it after removing 
the battery I still got nothing, although I discovered that the fuse on 
the 12V side of the power supply had blown.  I've checked the board to 
see if I had accidentally made any solder bridges when removing the 
battery (I hadn't) and am now wondering if a) the thing drew too much 
current because the battery wasn't present or b) the fuse blew because 
it was old (the power supply and interface came with the VP which was 
out of an old vehicle installation) and I had been doing a lot of 
switching on and off.

What I'd be interested to know is whether the Oncores CAN be run without 
the backup battery.  As Randy says, TTFF is not a concern for me so I'd 
rather have a less complex system that can be restored to a known state 
simply by removing power.

> One last item - Even without a battery a VP will save its setup information
> through power cycles because the older Moto receivers such as the VP save
> this information in EEPROM. To default these receivers you need to
> explicitly send the binary default command.

That explains it!  The battery on the VP is giving the same pathetic 
voltage as the ones on the GTs, yet it always fires up in NMEA mode.

One question - are the mnemonic commands listed in the Oncore manual 
along side the binary commands what I should be entering when in NMEA 
mode?  Can't quite work that out.  I am also assuming that commands for 
the VP are the same as for the the GT/UT for which I have a manual.



Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
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