Lemon Battery Videos

Construction of a lemon battery – for kids

Info about voltage of a lemon battery for interested kids.

Juice batteries in glasses – magnesium cell has more power – for older kids.

Hydrogen Gas Production – just a fun clip for us to see bubbles.

Cycle sensor batteries

Today, the black-bike started auto-pausing and ate lots of my track. I played with sensor alignment, but realized it was a failing battery.

At home, the multimeter showed 3.065v for that one’s original battery, and 3.05V for the white bike’s once-replaced battery.

I can’t remember when I changed the batteries last. My internet searching indicates that I failed to post about it. In theory, I should get 1.4 years or 500 hours. The best I can tell, I’m getting 400 miles or so.

I replaced them both with fresh, 3.30v CR2032 cells. Unfortunately, these were bulk batteries, and I actually threw several away as being faulty in storage.

I may also need to adjust the wheel magnet, so I can be spaced a little closer, but I’m using monster magnets which trip the sensor from 2″ away.

I thought I might be leaving the magnets such that they intermittently trip the sensor when not in use, but maybe not. The HRM (heart rate monitor) sensor has been replaced, and is down to 3.01v. For good measure, I replaced it with a new 3.31v cell. I think I got 65 hours out of the last one, but it was in the 2.7 volt range when I was losing signal from it. Obviously, it’s much closer to the cycle computer than the speed/cadence sensor.

Anyway, there’s not an easy reminder system for battery replacements, so I’m going to set up a reminder to swap all of the batteries every 5 months.

That’s a little too often, but it’s much better than getting into a ride and having half of the track missing because it keeps auto-pausing.

New UPS batteries

The storm last night performed a UPS test that was long over-due.

Unfortunately, the server UPS failed. One battery was 0V, and the other was 8.6V.

Both 7AH-12V batteries were replaced with new 9AH-12V batteries.

The old ones were the factory batteries, plut into service 2008-07-03 as per:

The UPS seems happy with the new batteries. They should provide a little longer run-time.

I’ll add a reminder to replace them in 5 years.

Upgraded UPS

Belkin F6C1500-tw-rk installed.
USB to the Windows based backup server which will shutdown if power is off for 30 seconds or more.
RS232 to the Linux primary server which will shutdown at low-battery point.
Full load (modem, router, switch, both servers) is 25%.
Deep cycle test with this load dropped to 68% within 1 minute and 30% within 13 minutes.

I expect that the load without the Windows box would be about 18% of max, so I think 25 mins is a reasonable full-cycle expectation. Maybe more with the LCD in power-save mode.

At battery low warning, the linux box will shutdown, and the UPS should shut down at full depletion, which might be another 20 mins or so. Too bad the router won’t serve up dummy pages. :)

Both servers auto-power on if they’ve been unplugged, even if they were shutdown gracefully before.

The monitor should email or notify if any part of the UPS fails, or when the battery is due for replacement. (July 2, 2011).

I think this is an acceptable solution compared to instant death before, especially considering we get 3 brown-outs per week and one power loss per month here.