[time-nuts] Re: St Veran gravity red-shift misson

[Tom Van Baak]

Magnus,

I'm glad you got to experience the challenge of powering cesium clocks 
on a road trip! Fun, yes? Here's what I used:

AC system -- I tapped off the car's battery with dual 100 A fuses and 
thick wire to feed in parallel two 80 Ah batteries below the passenger 
seat. That gave redundant, low impedance, 12 VDC for two sinewave 
inverters, one per battery, to supply 120 VAC to two power strips, the 
A-bus(AC) and B-bus(AC). All AC feeds used standard IEC cords, no custom 
wiring was necessary.

DC system -- I removed both rear seats and bolted into place a frame for 
eight 120 Ah VRLA batteries arranged in series and diode-or parallel to 
create two redundant independent sources of 24 VDC, the A-bus(DC) and 
B-bus(DC). All DC feeds were done with Anderson PowerPole [1] connectors 
and accessories.

5071A system -- Each clock had internal 24V battery packs re-made from 
fresh EnerSys Cyclon 2.5 Ah cells. Each clock was powered by 120 VAC 
from an AC bus, and also powered by 24 VDC from a DC bus. Note that the 
internal backup battery inside a 5071A is slowly charged only when AC is 
present.

Attached are two screen shots, from page 56 and 57 from [2], that show 
some of the setup.

I carried long AC extension cords so that when "shore power" was 
available at any point during the experiment I could power any AC bus 
from that source and/or recharge the main 8x VRLA batteries using marine 
battery chargers that I brought along.

As you found out, the logistics of failure-proof clock power is quite a 
bit more complicated than any of the 10 MHz and 1PPS timing stuff!

I'm impressed with your use of solar panels. I wish I could do that, but 
solar doesn't often work well in the Pacific Northwest, and my power 
requirements are higher due to multiple clocks and related electronics. 
But my car is a Toyota Highlander Hybrid which acts as an efficient 
generator if non-battery power is required. It's not quite as "green" as 
solar, but it works in all weather.

/tvb

[1] http://leapsecond.com/pages/powerpole/diode-or.htm

[2] 
http://leapsecond.com/ptti2020/2020-PTTI-tvb-Atomic-Timekeeping-Hobby.pdf


-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2020-PTTI-tvb-Atomic-Timekeeping-Hobby-page56.jpg
Type: image/jpeg
Size: 293863 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20230724/c8475a2b/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2020-PTTI-tvb-Atomic-Timekeeping-Hobby-page57.jpg
Type: image/jpeg
Size: 243089 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20230724/c8475a2b/attachment-0001.jpg>