I once was in a sinking power boat and got pretty powerfully electrocuted when the salt water went over the height of the car battery sized terminals, it appeared the water for several feet in all directions from the battery was electrified and felt like a heavy tasering. Just curious if this is an issue if an ePPG ditches into the ocean.
Related question: will an ePPG sink faster than a traditional paramotor? Normally the tank would provide buoyancy, but I’ve been thinking that I might need to be especially careful around water with the openppg.
Sealed 18650/21700 battery packs have buoyancy. You can see this many times with Tesla cars being able to float while their gasoline counterparts sink. The biggest question is if the SP140 battery is sealed. This would also provide the best resistance to water damage and avoiding electrical shock.
I do wish that more information could have been given on the sp140 before pre-orders became available. For example it still has the weight listed on the website with the old 18650 battery and the new 21700 battery will add upwards of 5 pounds in weight which many buyers may not have been expecting. I would have also liked to see things related to water proof rating, more concrete thrust ratings(not just that it is using 23kw power so it should be around 175 lbs thrust), Specs related to the cells used so we can find battery degridation or they could just provide that information(75% sure its molicel p42a cells), and more information surrounding the performance of various propellers.
Sorry I sound critical. I do think that everyone who buys an SP140 will be satisfied with it, but more information would be really nice for some people before they invest $7k into something like this.
Good questions. Obviously we’ve made a few smaller tweaks and improvements since the SP140 was first announced so we’ll be sure to get all the specs updated on the site as units are shipping. Can’t wait to see how you all like it!
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Thanks guys, can’t wait to get my hands on one. I am 99% sure these type of batteries in salt water isn’t going to be an issue however at some point it might be worth filming dropping a fully charged battery in proper ocean water and feeling if the electricity discharges any distance from the connectors.
You will probably get an interesting fireworks show.
The RC modelers used to dispose of LiPo batteries buy dropping them in salt water. They slowly discharge down to near zero hopefully before the tabs erode away. Then they can be safely tossed in the garbage.
The electronics are not sealed so that would be junk if it even gets too much salt air probably. Though, there is a guy flying an X4 from a beach regularly. The structure should be ok barring any impact damage.
The only way I can see this happening is if the ignition coil was somehow activated. A 12v battery will not electrocute you even if you grab the terminals with sweaty hands.
The 100v or so for the sp140 is a very different matter. Do not grab those terminals! The toaster in the bath tub as a murder weapon works because it’s 120v alternating current.
Let me set the scene, it was a small powerboat with a 40hp outboard on the back and a little 12v marine or possibly regular car battery attached to the deck. A storm hit and i am standing barefoot in the water bailing and waves crashing in but it starting overcoming me, at some point when it was about a foot deep i got a taser like electric shock which nearly crumbles and confused i leap out of the water onto the edge while i try to figure out what just happened, the only electrical item under the water at this point is the battery which is fully submerged approx 1-2 feet away at the back of the boat, dipping my foot back in the water so i can keep bailing instantly induces the same heavy feeling electrical shock, not like static shock, this felt like it had amps to it. The water was very rough and after a few attempts to get back in I gave up, the boat sank and I swam to shore and off to shelter out the storm.
I have often wondered how many drownings in boats are a result of similar electrocutions because if I had have fell initially into the water it seemed possible that I might not have been able to get back up, I certainly lost all dexterity as you do with a taser. I cant find anything about this online. Possibly a faulty battery? I have seen the lipo discharge vids but perhaps we can approach a youtube experimentalist person to try to recreate it with a car battery/marine battery and also try a similar lipo. From what I understand the science of electrical flow can be very tricky to predict the path of, ive read about people dying from really low voltage just because it happened to travel through the body past the heart where it usually just skims across the skin.
I don’t want to freak the ePPG community out, I am a big supporter and think the risk of this situation is so low as to be acceptable however its worth bringing up and perhaps doing some tests on. Perhaps there is even some ways to mitigate it.
*edit I should add it was a fiberglass boat and a friend has said that it might have been acting as an insulator while the ground was connected to the water… come to think of it i might have had one foot outside the boat in the water while I was trying to dip my foot back into the salt water in the boat… creating a circuit.
Hello, your question is of course justified!
Your story about the starter battery in the boat is understandable and true. Each person can take it differently, so different stories about similar incidents.
to your question:
Basically, the higher the volts, the easier it is to penetrate the skin layer and allow high currents to flow. An eppg battery has an extremely high short-circuit current of more than 5000 A.
This means that the volt does not drop in salt water even after several minutes. if the volts are below around 60 V, you have a small chance of surviving if you fall into salt water. from around 90 volts the chance of survival is almost zero. in the dry up to 120 volts are sometimes not a problem because the current cannot flow because of the resistance.
if a pilot is in salt water, the current can reach the surface of the body very easily. e.g. small cuts take up the current very strongly and are a high risk. But the dangerous thing is that the water gets to the mucous membrane like for example. nose, mouth, ears. the eyes are particularly dangerous. as soon as water in zb. If swallowed in the stomach or lungs, the whole body will be paralyzed.
The position of the battery at eppg lies on the upper body, heart and brain perfectly to kill the pilot in salt water very quickly. if the pilot survives he has to go to a clinic in any case, since it is to be assumed that blood smudges form when electricity flows through the body for longer.
there is a chemical breakdown of the tissue in the body and blood. In principle, you never fly so low over water to reach land in the event of an engine / motor failure, so the problem of salt water and eppg does not exist.
Competition pilots are an exception to pylon competition.
they have life jackets and people in the lifeboat as well as divers to help. everything is just a gasoline engine and a special tank for environmental protection.
Electric ppg are prohibited for pylon over water (even over fresh water).
if you are careful with eppg and adhere to the principles of safety, it is a very nice, safe hobby.
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I was reading one article that said that you would be better to be in salt water if a battery was dropped in because salt water has a lower resistance than your body which helps limit the current that flows through you. You have been building E-ppgs far longer than I have known they existed and I wonder if you had any input on this?
I did have one thought that I would love input on. I am no expert on water conductivity, but I was wondering if it would be possible to use some type of electrically conductive material for the netting. The goal would be to act almost in a way like a Faraday cage and the lines could help neutralize the charge of the water near close to it in an attempt creating a ¨shield¨ between the electronics and the pilot. I haven´t done any research so I have no idea if it would work at all, so any input would be great.
I use my X4 at the beach exclusively and always keep in mind what you described (glide versus sink) and the wind direction, to make sure I can make it back to a dry surface upon landing. I never make a turn over water until I know I have the glide to make a full 360º to clear any obstacle.
Murphy’s law is always there at the back of my helmet. This is why a jettisoning reliable system would be a great thing to have on the SP-140 or any other e-PPG.
Here I got lucky because if that happened a few hundred feet further in front of me, I would have been facing a wall. The beach ends and there is a bulkhead - the tide was high with the water splashing against the barrier. Worse case scenario I could have landed halfway up the cliff and dry grounds 4 PROPS - YouTube
Phil
How did the battery fall from its mount? We’re you using gliderpilots rail system, did it break? The props hit the batteries and no damage to the batteries? Glad it all worked out okay!
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Yes please. Details! We all want to know what went wrong so that we can assess our own exposure to the issue.
My own fault it was. I had designed a release system that worked on the round but, that day I forgot to fasten on small velcro on my left shoulder. A quick release cord was supposed to be held in place by the velcro as I always did. The cord was too long by 1" and due to the vacuum created behind any prop, aided by the glide airspeed, it was enough to make it happen. For sure I though it would never go through the net or under it. Chain reaction, 1,2,3,4 props. Somehow one must have hit one Bonka cable or two and so on. Actually the connections disconnected fine but the block of 4 Bonka was flipped and fell inside the right side of the net which didn’t brake.
In a way, even if it worked as designed and released the batteries during ground tests with the motors OFF, it is a totally different scenario with 8 blades rotating at thousands of RPM added to a bit of a mixture of yaw/roll/pitch and whatnot, it was a failure.
My system was different than which of gliderpilot but likely based on the same gravity concept. The Bonka(s) plus their holding plate were on a pivot at the base of the batteries. By falling/dropping back, I believe that the battery box or supporting plate with the batteries attached to it, would ultimately hit the batteries or box no matter what the design is if the propellers are spinning. Even if they were not spinning, the clearance between the tips would not be enough to let the box go in between them without contact. And for sure, the props will not stop rotating to end up in a perfectly vertical parallel alignment to give enough space for he battery pack to go though.
I am not that familiar with gliderpilot’ s design, but unless I am wrong, the only way for it work successfully would be for the batteries to drop as one block straight down vertically behind the propellers blade - no tilt of any sort. Unless I am missing something, I would love to see a ground test with the 4 props at full blast the way it was during my climb, because what’s done on the ground too often does not relate to the real thing in flight.
I guess none will be willing to take a chance and demolish their machine for a ground test😁
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Thanks for explanation. Glider pilots rail isn’t meant for quick release. It’s just a nice way to mount the batteries. I use his rail system along with Velcro strap going around the batteries/frame for backup in case rail fails. I have hard time seeing a quick release of the batteries actually working inflight as it seems to be the case. Too many obstacles for the batteries to avoid in order to fall clear of the frame/props.
I designed a few versions and updated them as I went along. I have to say that the Bonka have been pretty reliable so far and that, in addition to what I know about PG/PPG gives me more peace of mind. But I always have this thought at the back of my head about what could and how I would deal with with an unwanted situation. It is a worry but I came to accept it to a certain degree. Somebody needs to invent batteries that do not catch fire or will not send electricity all over the place if immersed in water🤪
Phil,
My batteries are mounted on a CF plate and also need to fall away when the props are not spinning. Thanks for posting…but sorry you had damage.
Bill
Perhaps it’s just me but I feel safer in my X4 with those batteries than I did with a 2 stroke banging its way through a few liters of highly volatile fuel in a plastic tank.
I think the ESCs or wiring on the X4 would be melting before those motors could draw hard enough on the Bonkas to get a thermal runaway event. I suppose a short is always possible if the wire insulation starts to melt but it would take a short to make the wires that hot.
Shrapnel from a prop strike event could impact a battery. It would likely be away a pretty shallow angle. I’d be way more worried about a chunk of a 140cm prop from a 2 stroke going through my wing.
Hey Bil,
The thing is that the gap between the blades has to be wide enough at the right moment for the block to go through and during my ground tests, it hit every time to a greater or lesser degree. At times it only snagged the tip of a blade, sometimes a few of them. I was giving a quick light acceleration just to move the blades; when they stopped randomly I carefully pulled the quick release cord while holding the battery pack as it fell backwards, all in slow motion. Did it a dozens of times and the props never really aligned for a clear passage of the battery pack. It is random so it is an issue. The blades are short and thin but could hold quite a bit of weight before snapping, and surely the weight distribution would be unequal at best and who only knows what would be in an emergency which may not be due necessarily to the blades getting destroyed first, but rather experiencing a fire in midair.
Also, there would need enough pull on the connectors to separate them. They are really tight when connected together, and 8 pairs of them can hold quite a bit of weight.
Ideally there should be some kind of system that disconnects the electric connections easily under a sudden gravity pull to let go the battery drop vertically behind the propellers. The other solution would be to have 100% fireproof cells (heat and impact)
Maybe someday soon…
What made me a bit nervous in my case was that the net didn’t brake which is good in a away, but bad because it held 25lbs of battery weight and stopped the battery cables from reaching their full length to give enough pull to separate the connectors. I forgot the exact number, but a few were still connected to the battery terminals after I landed. In other words, the whole sequence was unpredictable in the way it unfolded and would not be duplicable.
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