I guess you always have to make stark choices, then.Amazon usually has 12v versions available for as little as $39.95. I have a cheap one in each if my cars, used mostly to help out others who left lights on or other such troubles, and they work extremely well while taking very little space.
I keep a cart style big bruiser in my hangar for my 28v helicopter; curiously, one good brand is Stark, same as my last name.
My master is a keyed switch for exactly this reason. I love that folks want to look at my airplane; not so big on their poking their fingers into things. I remove the key when not with the airplane.If I had arrived earlier at the Santa Ynez Airport Day I would have been part of the event with letting kids sit in The Predator to get their picture taken and pretend to fly her. I usually have a line of them waiting for their chance to sit in an open aircraft and I often talk them through the takeoff. Most are not able to keep their fingers off the switches and I carefully check them after each sitting.
I suspect that is what happened despite being in transient parking and not being around to give permission.
Two rows of toggle switches are all in the down position when not flying.
When I returned to the aircraft two of the toggle switches were up. The master and the alternator. The master activates a relay and the alternator switch activates the field coils in the alternator. Both drain the battery when The Predator is not running. I have a battery about the size of the one in most motorcycles and when I went to fire he up after four hours she showed eleven volts. That is just enough to make noise but not enough to turn the engine over. Like many aircraft the battery is buried and hard to get to. It is possible to jump her but the hook ups are very near the propeller. I have jumper cables with a plug just for that but they are large, heavy and not something I haul around.
Probably a good idea Brent. This is the first time this has happened in fifteen years and over 2,250 hours of flying. I usually am there to monitor little fingers. I suspect it was not a pilot who thought it was ok for him to put his child in the aircraft without permission. The challenge only escalated because The Predator is hard to jump start or hand prop. It was a great excuse for an adventure and a test of my attitude. It all turned out great and makes a good story.My master is a keyed switch for exactly this reason. I love that folks want to look at my airplane; not so big on their poking their fingers into things. I remove the key when not with the airplane.
Interested to know your Lithium Battery story. Very happy with my EarthX lithium so far.Ya, when things don't go according to plan, one usually at least has a good story to tell !
If you have a lithium battery, things get a lot more complicated when it dies. Ask me how I know...
I too have an Odyssey battery, now. Nearly five years and in the winter months it mostly just sits in the cold, not on a charger. It is still going strong.
Apologies to Vance in adVance for the diversion from his main topic.Interested to know your Lithium Battery story. Very happy with my EarthX lithium so far.
Thanks for the detailed reply and I echo apologies to Vance, but I guess the topic is dead batteries at the moment. The EarthX does appear to be more sophisticated with a built in electronic brain that monitors charging and battery health with a warning light to monitor any battery problems, excessive discharge etc. As I have electronic fuel injection, battery issues are a major concern. I feel pretty comfortable that should my warning light notify me of a battery discharge or charging problem in flight, I should have 45-60 minutes to land before my fuel pumps will not function. I was having an issue where I was concerned voltage during flight was not climbing enough but that has now been corrected. (Long story)Apologies to Vance in adVance for the diversion from his main topic.
My lithium battery was not an EarthX, it was an "Avio", made in Italy. I am not sure why it died, but its simple construction did not allow the possiblity of charging its individual cells. As you probably know, unlike with a lead-acid battery, one cannot merely hook up a trickle charger to each end of a pack (4 cells). So it was toast.
In attempting to order a replacement from Italy, I found that it held too many amp-hours to go by air. This meant it would have had to come by sea, which looked to be a wait of quite a few weeks (at best). It's a good thing it didn't die on me away from home!
So... I found that I could fit an Odyssey Extreme (TPPL/AGM) PC310 in my battery tray with very minor modifications. I ordered one online, and it came within a few days. It weighs six pounds. My Avio weighed three. This was a no-brainer solution for me. As mentioned, it's now 5 years old and still in good shape, despite being left uncharged, in extreme cold, multiple times, for months at a stretch. It is inexpensive, relatively speaking, and a piece of cake to recharge (or to replace) if necessary. All for the price of three pounds added weight, or about half a gallon – six minutes worth – of fuel.
Why did my LiFePO4 battery die in the first place? It's possible, that, as in Vance's case, my master switch got left on when I was on the ground, although I never actually saw this. OR, it's possible my regulator wasn't providing the just-right in-flight voltage. I am no electrical engineer, but my son is (he works for SpaceX, yay (no relation to EarthX 😊)) and he tells me that each cell of the lithium battery needs 3.5V to charge (or 14V for four cells). According to my engine monitor, I top out at about 13.9V, at flight revs. Which is perhaps just a tiny bit low, so over the long haul... Also, if one cell starts to go bad, there it likely to be a problem charging the other cells using the engine (bear in mind also that any overcharge voltage (>3.65V/cell) will damage the cells fairly quickly).
I understand that EarthX (unlike Avio) provides a pretty sophisticated recharger, which is able to monitor the charge of each individual cell and top them up separately, as required. But is this actually possible in flight? Do you hook your battery up to a plug-in charger between flights? Do you take one with you on long trips? What do you find to be the great benefit of a lithium battery?
It seems to me that they are just not worth the extra trouble – at least in this application – for the amount of weight saved.