Hello.
I love electric PPG and RC planes and helicopters.
I am planing to buy an SP140 with a 3.7KW battery pack, but my experience with Lypoly batteries in RC planes has prooven that Lipo batteries can catch fire. It doesn’r happen often, but it can happen. So I am really concerned about this point. I think I wont fly confident with a possible fire while flying. maybe its only a 0.1%, but I don’t want to be that 0.1%.
Are these battery packs built in a way that even if they shortcut or whatever can make them catch fire, they are protected against fire getting out of the aluminium box?
The X4 uses LiPo batteries similar to those used in RC model aircraft. Just … huge!
The sp140 battery is comprised of the more robust, LiFe, cells similar to those in cordless tools and electric cars. Also, like an electric car or cordless power tool, the sp140 battery has a built in battery management system.
They still can catch fire but it takes almost intentional abuse. Its probably easier to light up a two stroke fuel tank than a LiFe battery pack. Certainly way, way more likely to have the two stroke quit than an sp140.
It just that they are li-ion, not LiFe
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LI-ion is describes the entire group of lithium based secondary cell (rechargeable battery) chemistry. They all work by moving lithium ions back and forth through the electrolytes.
li-po are lithium polymer pouch cells which are designed for high output, and light weight. They sacrifice robustness and cycle count. Its likely you’ve got one in your hands right now.
Li-fe and others, lithium iron based, are round cells. They can typically be cycled over a thousand times before losing much capacity. I forget which specific anode chemistry the sp140 cells are using but they are not li-po pouch cells, and the pack does have built in BMS. This makes the pack very different, much more robust, than those used in model airplanes.
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Nobody wants to be a statistic. We learn to understand, and take steps to mitigate, the risks. That’s aviation.
There are thousands of texts here in this forum that explain the difference between Lipo, LiFe, Li-Ion etc. 0.1% risk is your opinion. the reality is different.
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Chance are low assuming everything is perfect. if you have any damage to the batter, like if the paramotor tips over while sitting on the ground you can have damage to the electronics and have no idea that has happened. mine shut off in flight then later when I plugged it back in on the ground it caught fire. There was no visible damage to the battery or electronics but it was clearly there. Main problem is that there is no way to tell if there is a problem until it actually happens.
My 2 cents: an eppg that is professionally constructed has: an esc that monitors a lot of parameters. This starts as soon as the system is switched on, for example. The throttle path must be moved from zero to full throttle to a standstill in order to rule out that the throttle grip has a fault.
The temperatures of the motor, ESC and battery are also monitored. If the motor has a false iduction on a circuit, the ESC will already recognize this.
If there is mechanical damage and the motor needs too much torque, for example, the power limitation will also react and will not allow it to start. If a cable somewhere in the system does not have proper contact, the system also reacts.
If you have a stop in the air, it is saved and can be read out later in the flight instrument. This way the setup can also be coordinated very well for the pilot. It is dangerous when building an EPPG if: the builder simply uses any motor ESC and battery that is not explicitly mentioned by the manufacturer as an aircraft motor or ESC.
Then just use a random propeller based on feeling without knowing the phase currents or the power diagram and limit of the batteries under real conditions.
Mechanically, when building a battery, the cells are simply connected with poor quality spot welders and no safety is integrated into the housing and holding system.
An easier way is if you are not 100% sure whether you have done everything correctly. You show your project to an experienced person who is not just a theoretician but can prove through their own experience that they understand their craft. This is how it has always been done for safety reasons in aviation. There are initial tests for approvals of flying equipment.
It’s only at EPPG and PPG that no one takes exams. Therefore, the pilot is responsible for arranging this or doing it himself.
Who has a checkbook for their DIY EPPG here in the forum? I have a manual for each of my DIY EPPG systems in which I document service and changes. For the trike, there are written instructions stuck directly on the trike for the start check. Some people laugh about it at EPPG meetings and say you don’t have a plane…
I don’t care, for me safety is part of flying.
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While both types of batteries operate on the principle of lithium ions moving through the electrolyte, the specific materials used for the positive and negative electrodes, as well as the electrolyte composition, differ between Li-Ion and LiFePO4 batteries(it is often referred to separately due to its distinct properties and applications).
Both Li-ion and LiFePo4 can have cyllindrical, pouch or prismatic shape.
Most electric cars and tools use Li-ion as they have 2x energy density of LiFePo4. Latter is mostly used where weight is not an issue, like ESS, buses or ships(cheap moped or cars have them too).
SP140 have Molicel INR21700-P42A and they should be NMC(which is often denoted as INR)
You can have all the protections in the world, but if it starts to get hot, it is hard to jump out of your harness in the air compared to a burning car. I still believe that the best safety option would be a quick release of the pack mid air.
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Not entirely true. Aircraft use LifePo4 batteries for their electrical systems because they are the safest battery on the market even though they are not as energy dense, they chose safety over weight. My 2 seat aircraft uses EarthX LifePo4 batteries.
In Canada, and some other countries im sure, an ultralight pilot permit is required. An exam, medical, cfi signoff, and currency checks.
Its still focused on ICE engines of course so electric power system knowledge is not tested for.
Dropping a burning LiPo pack is frowned upon by most aviation authorities. They tend to worry about things like that. Fuel burning cars are way more likely to catch on fire than electric ones. Do ICE PPGs have a fuel tank release? Do airplanes? Learn the risks.
Yeah, its controversal but If you have a burning pack, you either drop it and maybe save yourself but damage the property below. Or you go down with the burning pack and also damage everything below.
In both cases you have a risk to do a mess but in one you may walk from it alive. What if we had a system where we could rop it but it would hang by a wire a few meters down, abit complex but better than having a burning brick fall down to the soil. Still think there are quite a few options out there to mitigate risk for pilot, like having a pack that is designed in a way where flames would exit only towards the motor and not towards neck and back of the pilot.
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I like the idea of a quick release, but abother iption maybe could be putring the batteryvin a safety kind of fireproof bag
I think we will end up flying with electric motors feeded with hydrogen fuel cells
I have the impression that many people don’t know how Li-Ion from the brand manufacturers are structured. Even if you short-circuit a cell, nothing happens except that it smells unpleasant and the cell is then broken. Technically it’s not possible to short a whole pack because after a short bang there is no further connection. The only possibility is to set a battery on fire, cause mechanical damage or bad cell connectors that start to glow and therefore partially heat the pack. Therefore, for all those who do not want to build safe packs themselves and do not want to trust a no-name manufacturer, buy batteries with un-38.3 certification or at least TÜV testing for prototype
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Ok update on lipo batteries
I’ve a lot of experience qualified in my engineering trades electronic electrical and RC builder for 46 years
Ok Lipos are not dangerous what so ever if you know what to look for
Ok make sure all cables connectors and loads good fuse if not sure to just above maximum current draw
Only charge at no more than 1/5th of the maximum draw of the battery
For example 5000mA battery charge at no more than 1000mA this is classed as fast charging
Slow charging on a 5000mA would be 100mA or there abouts. Where possible always balance charge and only use a lipo charger and where digitally adjustable is set to the correct voltage
If you only have a standard plug in charger then do as instructed by the manufacturer
Personally I don’t like them as they don’t show you voltage current and state of charge.
Never leave your battery when charging.
Ok lipo batteries can puff up if not used correctly
If this happens do not use or charge
Get a bucket of water add plenty of salt and put the battery in and leave for a week
The salt will safely discharge the battery
Lipo batteries only go bang when cheap chargers are used and left on
Never short any lipo battery out
Always check your battery before use and before charging
Hope this helps clear up some of the worries on these batteries