Getting into LiFe, more KAP kit evolution…

As I have got more comfortable using the LeicaX1 I have reached the point where I no longer lug a backup camera with me and the time came to leave the EP1 at base as it was putting in a fair mileage but never being used: it was a case of Leica wins, 1st on weight and 2nd on image quality ( provided I was very careful with the settings, more on this later).

So the field kit for KAP now looks like this:The space in the box taken up by the 2nd camera is now filled with the video receiver and its screen; both items have been found to be vulnerable to damage in transit so I think they deserve a place in the box. The next step is to move up to LiPo batteries: the rig is powered by a 5 AA cell NiMh pack which delivers 6.68v max at 2800mAh so a 7.4v cell should work.

First of all I acquired a charger that will deal with the odd requirements of LiPo. There is no escape from this as the Lithium cells need a very different cooking method to work, the charger has been something of a stumbling block in using the new batteries as they seem to be very expensive and pretty cumbersome but I am fortunate to have a friend who is a keen RC flyer and he has sorted through the blizzard of choice in these and put me onto this unit by ‘GT Power’:It seems to be very flexible indeed and charges up the rig and Tx NiMh units over a ‘Y’ cable in less than an hour using 1.5A output. It will run off a 12vDC input as well as 240AC.

With assistance from my ever helpful local hobby store I was supplied with a LiFe battery rated at 1200mAh at 6.6v for 20 quid. This is good because the LiPo cell voltages (3.7V) just won’t add up to anything that wouldn’t need yet another voltage regulator on the rig but LiFe (3.3V per cell) works out at 6.6V for something close to the ampage I need.

So I tore off home to fit it. Fitting the LiFe pack is a bit of a fiddle as I use the battery as an anchor for the Rx antenna and the rubber bands needed re-threading. The RC receiver (Rx) and altimeter (Gentles AtliOSD) will operate from 4.8V to 9V so no problem there but the video transmitter and preview video camera are limited to 6V. A 6.6V  LiFe 2 cell pack should power the 6V rated components without grief. But for how long?

It powered the rig for about half an hour and then its voltage was down to less than 6V and it cut out. Hardly the performance I was hoping for. The battery wouldn’t even charge now, the charger just reported ‘Low Voltage‘ and did nothing. I decided to get on with something more useful and write the thing off as an experimental failure. An hour later I couldn’t resist the urge to try charging it again and the charger now read the battery so I began a 0.1A charge. 170 minutes later (the charger doesn’t do hours) I had the battery back on the rig- it was indicating 8.6V.

Often my rig spends a long time powered up on the ground waiting for the kite to be happy in the sky, is  the power drain on a 1200mAh supply going to be enough to be sure its going work when it needs to?

1200mAh ‘iP’ LiFe  2s 20C Battery. KAP capacity test 17th/18th June 2011
Charge rate Charge time (Automatic by GT Power 606D) Discharge duration Starting Voltage
0.1A 170mins 2.5 hours Indicated 8.6v dropping to 6.3 under load*
1.0A 120mins 4.0 hours Indicated10.77 dropping to 7.2 under load*
1.0A 77mins 3hrs 15mins Indicated  8.6v dropping to 6.54 under load*
*The load is 3 servos (including a gyro GS1 servo by Scott Armitage), 35MHz RC Rx, ‘Peanut’ Video camera, 2.4GHz 10Mw video transmitter and James Gentle’s AltiOSD Altimeter.

I think, to be on the safe side, I’ll swap the 1200mAh pack for a higher ampage if I can find one at the right weight: there are a few 2000mAh LiFe packs at the 90g mark listed out there but they seem to have been snapped up…the hunt is on!

The weight saving is significant. The LiFe 1200mAh 6.6v pack is 80g. The NimH 6v 5cell 2600mAh pack weighed in at 190g so taking 110g off the rig is not to be sniffed at! I cannot make the wind blow 110g harder so even with my lightest line and biggest kite I have gained some precious lift.

More on Lithium battery technology here

Living with the X1: The LeicaX1 has proved to be a camera that needs careful setting up. The camera performance has improved immensely with the first firmware upgrade. For KAP I have been used to letting ‘Auto’ do the numbers on the camera as I have enough to do at my end without  worrying about the camera getting the exposure wrong. To date this has worked for the Panasonic LX3, Olympus EP1 and Canon Ixus cameras : the X1 is different. With everything left on ‘auto’ the X1 will opt for a wide stop, a slow shutter speed and a nice low ISO (usually 100)  even it what I would consider as ‘f8’ light: fine if you are using the thing on a tripod but useless if its bouncing about on a kite line.  By a process of elimination I have discovered the AutoISO setting is the culprit (it sticks at 100) so by setting the ISO to a fixed number the Auto function seems to get the higher shutter speeds and smaller stops I want. I now run the camera at ISO 800 at minimum and the hit rate has improved significantly. I have probably made life hard for the camera by fitting a PL filter but I think pushing the ISO has balanced this out now.

The Leica X1 firmware upgrade is here

So back to the skies…with 110g less to lift…..

About billboyheritagesurvey

Heritage worker
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