I have started to get in the habit of keeping the Alta powered while changing the flight batteries and wanted to check if there are any negatives in doing so. The positives are the Alta doesn't have to reboot after each battery change and we don't have to wait for it to lock onto satellites. The only negative I see is that the fly timer keeps ticking so you have to do some maths to get your current flight time. It would be great if there is a way in the app that you can reset the flight timer to avoid this.
Actually, in my experience, the downtime between battery swaps gives me an opportunity to check and double check all the instrumentation. If you're in that big of a rush, you're kinda asking for trouble, or at least I would be. There's my $0.02. And worth every penny IMHO.
Is there any issues with batteries trying to equalize for the brief time you have one new one plugged in and before you pull the plug on the second used one that you are about to remove? I'm sure you could do that quickly, but for a brief moment you would have very different voltages between your 2 batteries which are sharing the same power system. I am completely unfamiliar with how the Alta would handle a rush of energy between the 2 batteries (if the Alta allows that to happen) but thought I would at least put the thought out there for you or others to consider. And does anything worse happen if the person pulling the plug on the second used battery has any trouble with the connectors sticking or if they slip momentarily and the 2 batteries stay connected together for an extra few seconds.....?!?!? Maybe someone from Freefly should chime in or you should do a quick support ticket with your question for them to address anything from a technical side related to how the Alta handles this.
I could see a case where it might be advantageous to do this if you were on a boat or a moving vehicle (although I'm not sure what actually happens with the SYNAPSE boot cycle). As Michael says above, you should write to support and see what they say.
I suspect, based on the power distribution board I saw when doing the ESC firmware upgrade that the discharged battery will, for a few hundreds of milliseconds it takes to change the battery, "drink from the electron fire-hose" of the fully charged battery. Personally, I would hesitate to do this as it falls under the "possibly the best known way to fry a power distribution board with beaucoup Amperes" as the internal resistance of LiPo's is so low that a large current might flow. For the geeks, imagine if a cell is at 4.2 volts and is connected to a cell at say, 3.3 volts, with only, meh, 0.005 ohms of internal resistance per cell. So, given that there are six cells, that's 6 x 0.005 or 0.030 ohm of internal resistance (I studied applied mathematics as you can tell). The voltage difference will be 5.4 volts for a 6S battery. So, according to that nice Mr. Ohm, on good days, i = V/R, so that's 180 Amps. On the other hand if the discharged battery is down to 3.0 volts per cell, the voltage difference will be 7.2 volts and the in-rush current will be 240 Amps. Then there is the question of whether a voltage spike might do a nasty to the ALTA's electronics -- I'm not sure such a spike will occur, but perhaps some Freeflying folks could comment? Perhaps it will not fry the power distribution after all? But do we feel lucky today, ladies and gentlemen? Prior experience suggests that neither Mr. Maller nor I feel *that* lucky. Andy
I have a parallel "Y" harness that I can use on my lipo power cable for Epics and now the Mini that I made just for this purpose, to keep the Epic powered up while I change out the 4S 3800 mah pack, which has to happen way too often. BUT, I have never done it due to the concerns listed above and I would never do that with one of my Octocopters. For starters, just like brushless gimbals the gyros will drift over time and each reboot resets the gyros and accelerometers. I do not own an Alta and I have no idea if they have "motion booting" like the Movis, but that solves the problem while on a boat about needing to keep the machine booting up in fear of it not rebooting. Wayne Mann www.HeliCamHDmedia.com
Wayne; The Epic and Mini have all kinds of built in voltage and current related protection. You can do a hot power swap on both these cameras without issue (per both manufacturers). On the Mini its a must as there is a glitch in the latest FW that defaults SDI-1 to off with each reboot and your AC has to move in for a fix with the plug in monitor! (if your like us, you prefer an AC spends as little time around the aircraft as possible). As for the MoVI, Down Link, and FF, just shut them off and then power em back up. None take as long as a camera reboot. As for a volt spike triggered by an amp surge, Higher amps equals lower volts. Please correct me if I'm wrong. But personally, i wouldnt even think about a hot swap on the aircraft!
Thanks for the info Chris. We have not run into the FW issue on the Mini that you speak of. That must be a very recent update. I will plug my "Y" harness into the power cable so that I can keep the camera powered up. That will make things flow much smoother. Wayne Mann www.HeliCamHDmedia.com
Hi Chris, i didn´t hear about that glitch, either. Can you confirm this? My Mini is rented out til 10th of april, then i will check this... Thanks, Wolf