I recently procured an iFly, and while waiting for weather and personal schedule to align so that I can actually fly with it, I've been playing with it at home. I contacted Adventure Pilot to request some info on power consumption and told them I was thinking about building my own rechargeable battery rig, and they pointed me toward the iSun BattPak device (NOTE: AP does NOT formally endorse or support the BattPak--they just mentioned it to me as a device that might already do what I was proposing).
I decided to pick up a BattPak and see how well it would work as an external power option for my iFly, and ran some tests over the weekend. Thought I’d share the results with anyone who might be curious.
The iSun BattPak is a device that’s designed to be both a battery charger and a power supply. (The “iSun” name is because the manufacturer designed it to be compatible with some small solar arrays, which could be helpful in providing power in the woods or something, but that capability doesn’t interest me.) Unfortunately, the manufacturer does not have any product information regarding the BattPak on their website, so the only info available online is what's posted by vendors.
The BattPak:
- Can hold 10 AA or AAA batteries
- Can recharge 2-10 batteries via the included AC adapter, or 2-6 batteries via the cigarette lighter adapter
- The charger is relatively simple; there are much better battery chargers available.
- The charger will support NiCad or NiMH batteries (but not a mix of both at the same time)
- The charger should not be loaded with batteries of different capacity or different states of charge (i.e., don’t mix 2000mAh batteries with 2700mAh batteries, and don’t mix fully-discharged 2000mAh batteries with half-discharged 2000mAh batteries)
- Has a cigarette lighter jack built-in to its chassis
- The BattPak will supply voltage according to how many batteries are inserted (use 5-6 for 6V loads, all 10 for 12V loads, etc.)
- Anything that uses 12V DC power via a cigarette lighter adapter could potentially use the BattPak as a source
- Can be found online for $20-$40 plus shipping. (The lowest price I found was a vendor on Amazon.com.)
Some vendors include a FAQ for the BattPak with additional information. Here’s one site that does, but note that some of the questions in the list only apply to the solar panel product and not the BattPak product: iSun solar panel and iSun BattPak FAQ
I had a number of unused 2000mAh Sanyo Eneloop low self-discharge NiMH AA batteries available, which made this a relatively inexpensive experiment. I picked up a few more to get the 10 required for a full load in the BattPak, charged them overnight in a high-quality charger (I use chargers that deal with each battery independently, instead of the BattPak that deals with them as a group), then loaded them into the BattPak and plugged the iFly into the BattPak using the cigarette lighter adapter.
After the iFly booted, I made sure the screen was set to full brightness, then started a GPS simulation with the imaginary plane flying due east at 200kts. I did this for two reasons: To ensure the iFly was “stressed” in case the processor draws less power while idle than it does while actually processing, and also to create a record of run-time in case I wasn’t around when the batteries ran down.
I happened to be looking at the device some time later when it began to shut down from low voltage, and the flight timer read 2:28 (2h 28m) just before the screen disappeared. I plugged the iFly into AC power and loaded the “past flight” corresponding to the test run, and it had recorded a flight distance of 485nm, which agrees within a couple of minutes of what I saw on the flight timer as the unit shut down (I don’t know how frequently the flight data is saved, and I know it took me a minute to get the GPS simulation started, so I was comfortable with the minor discrepancy).
I recharged the batteries overnight, and repeated the test. This time I was not watching when the iFly shut down, but the “past flights” log for the second test showed a flight distance of 511nm, or about 2:35 of flight time.
Based on these two data points, I conclude that my batteries can provide approximately 2.5 hrs of runtime for the iFly using the BattPak as a power source. This is more than adequate for any scenario I can envision for using this BattPak in flight (I'm happy with anything reliably over an hour or so). I have numerous small electronic devices that can operate from a 12V DC source, so I have other potential uses for the BattPak besides my iFly. I’m happy I picked it up. (Note that batteries of different chemistry, construction, capacity, or age, or charged with a different charger, or operated in a hotter or colder environment will certainly yield different results, so the standard caveat applies to anyone trying to use my data to predict performance in a different situation: “Your mileage may vary.”)
I have no affiliation with the company that makes the BattPak, and I do not endorse it for any particular use. I’m just sharing my observations from a very simple test, for whatever that's worth.
Jim