GrassrootsMapping
Chdk Issues

** This issue has been resolved by Pat Coyle; see bottom of page**

Working page for troubleshooting the CHDK script described on Balloon Aerial Photography. Pat Coyle and Jeffrey Warren have had problems with their cameras shutting themselves down in mid-flight. This has happened after anywhere between 12 and 80 photos, and results in no images for much of a flight… very frustrating!!

Testing

Jeffrey Warren: I ran my camera repeatedly on March 11th and noted down how long it took to shut off. I’m taking photos at 10 second intervals.

122 photos
220 photos

If we could find any pattern with how it stops, that’d help; it doesn’t seem to have to do with battery life, though.

CHDK forum topics that may be related:

Suggestions

Based on the above forum entries, we should try:

Cleaning battery contacts carefully
Buying new batteries

And possible reasons for the failure could be:

Camera is sensitive to ‘voltage dropping’; and don’t operate at below 2.4 volts, even if there’s 60% charge left (this is a bit confusing but is from one of the forum posts)

Resolution:

Pat Coyle wrote to the mailing list with a solution:

An update on this issue: Over the weekend, I did a few tests with the SD 400 and the 3 batteries I have. They vary in manufacturer and age from one acquired in January, to one marked 2/07, to another of unknown age, but presumably older.

I need to collate the data, but the number of exposures and early stop appears to be sensitive to battery charge – duh. However, I had not been paying attention to this in my test flights.

However, once I put fully charged batteries in, in ground-tests I got exposure counts of: 299,237, 289, 378, 262, 301, 279, 316, 303. The script ran till the battery was near zero %, then stopped. In some cases there was enough battery left to power up the camera and erase the images, in other cases the message “change battery pack” came up and the camera turned off.

At 10 second intervals, these range from ~44 to 63 minutes, for very usable flight durations.

These were in conditions where the flash activated every shot. I tried turning the flash off, but in script mode this was overridden. With it off, presumably one would get even higher numbers of photos.

The three batteries vary in age and the initial max % shown in battery indicator varied from: ~45, to 75, to 91%. There does appear to be an initial problem in a few of the tests where the script stopped at 1 or up to 33 exposures.

However, my quick takeaway is that I can get very useable durations if I ensure the batteries are fully charged and strong enough that they have a reasonable % max battery indication, e. g., not too old, so don’t take full charge. It may be prudent to take a few images, maybe up to 30, ~5 minutes, before launch to mitigate the early stop failure mode. However, for the high percentage fully-charged batteries this did not appear to be an issue.

New Suggestion:

The LCD display for the camera uses a lot of power. Turn it off and/or go into the settings and dim it down to its lowest level to reduce power.

Also - set focus to infinity so it doesn’t use power trying to figure out where to focus.

Avoid super-fast rechargers that work in 15 minutes or 1 hour, they give a lower overall capacity. Try using a slow charger. The cheapest way is a USB powered charger that takes 8-12 hours to charge. Also, make sure the charger “monitor” ( green/red light for charging/finished or maybe 1-4 bars) for each individual battery, not for pairs. If one battery is weaker or more used up than the other, a pair-monitoring charger will leave one of them unfinished.

If you are willing to spend the money, go to a hobby store and get the really good chargers used by radio control (R/C) car racers to get every bit if energy from the batteries.

If the batteries get really hot from direct sunlight hitting the camera, they will have less capacity. This is unavoidable variability in battery capacity. For this reason, don’t take hot batteries directly out of a charger and start using them immediately.

If you want to spend the money, go to a camera store and get the high end Sanyo Cycle Energy? NIMH batteries - $30 for 4.

Brainstorm idea (I haven’t tried it) - hot-glue a 2 “C” battery holder to the side of the camera and wire it to the battery connectors inside.