Multiple Battery Setup

On Thursday, February 9, 2012 5:37:29 PM UTC-5, JohnDeRosa wrote:
... A FLARM transmitts and anything that
Transmitts (transceiver, transponder) is THE variable and can be
massive power hogs...

Please, FLARM takes very little power !
For PowerFLARM, keep the backlight turned down to minimize draw...

Thanks,
Best Regards, Dave "YO electric"

On Feb 9, 8:37*pm, Dave Nadler wrote:
On Thursday, February 9, 2012 5:37:29 PM UTC-5, JohnDeRosa wrote:
... A FLARM transmitts and anything that
Transmitts (transceiver, transponder) is THE variable and can be
massive power hogs...

Please, FLARM takes very little power !
For PowerFLARM, keep the backlight turned down to minimize draw...

Thanks,
Best Regards, Dave "YO electric"

Please excuse anything demeaning to the FLARM. The only power
requirement specifications I have found are in the PowerFLARM manual
which says, "Supplied power must be 12 V DC nominal at 500mA". 0.5A
is nothing to sneeze at but is probably the instantaneous maximum.
Does someone have some real world power requirement information for
the various (US) FLARMS? I have not found an online FLARM or
PowerFLARM Brick manual (sources?). Thanks.

On Thu, 9 Feb 2012 14:37:29 -0800 (PST), JohnDeRosa
wrote:

. A FLARM transmitts and anything that
Transmitts (transceiver, transponder) is THE variable and can be
massive power hogs so keep those on a separate battery

A Flarm transmits at only 50mW power. The power consumption is
negligible, always less than 100mA, and it includes a GPS engine
capable of NMEA communication.
A radio in receive-only mode, will use more power than a Flarm.

And, if I were low on battery, Flarm is still the latest "switch-off"
option, considering the benefits for safety.

aldo cernezzi
www.voloavela.it

On Thu, 09 Feb 2012 04:33:04 +0000, RAS56 wrote:

I enjoyed your article and just completed 2 test runs using the rig you
detailed..I was mildly surprised to find 2 identical batteries with
identical manufacture dates vary significantly on the results.

Battery #1 took 4:13 to run down to 11.5 volts, at about 5:45 it hit the
"knee" at 10.5V described in the article and started dropping rapidly.

Battery #2 lasted almost an hour longer...5:10 to hit 11.5, then longer
than 6:30 to get below 10.5V.

Both batteries were 12V 7.5 AH SLA.

I just did the same: bought a pair of Yuasa 12v 7Ah SLAs, call them D and
E, because A, B and C dropped off their charge curves when tested during
the week before last. A and B had also been bought together in 2008 and
had both been measured at a bit over 6500 mAh then, but both were under
4000 mAh this time.

I put them both the new batteries on my three phase mains charger to top
them off as soon as they arrived. E took over an hour longer to top off.
Then I measured them with a Pro Peak Prodigy II charger/cycler. E ran the
device while I measured D. Then both went back on the mains charger and
this time D ran the device while it measured E.

Results: D was measured at 7003 mAh and E at 7510 mAh

I was a little surprised at the difference since, with both batteries
being the same model there's every change they're from the same batch.

The Prodigy II isn't what you'd call a heavy duty discharger and self
limited itself to 0.4A despite me being optimistic and asking for a 0.7A
rate. IIRC it has a 5 watt discharge limit. I As this somewhat less
current than we'd expect to use during a flight and all batteries show
lower capacity the faster you discharge them and the colder they are. IOW
this over-estimated the in-flight capacity due to the lower current and
higher temperature during my test, but thats fine: I do the same tests at
about the same time of year and am only interested in the relative drop
in capacity from one year to the next.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |