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What Would Happen if A Bulging Battery was Prevented From Separating From Drone in Flight?

JAW

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What would happen if in flight the battery began to bulge badly but was held in place by one of those devices that prevents it from popping off, like a Velcro strap or plastic bracket? Could an in-flight fire possibly result? What warnings would you get while flying, if any?
 
What would happen if in flight the battery began to bulge badly but was held in place by one of those devices that prevents it from popping off, like a Velcro strap or plastic bracket? Could an in-flight fire possibly result? What warnings would you get while flying, if any?
No idea here. The batteries are marketed as smart and I know they will prevent charging when hot but I have seen nothing per turn off with overheating. Then there's the question of how well the safety measures work and how fail-safe are they. Forced into thermal runaway from continued high current draw fire can be a result, usually quite violent a lot like an explosion.
 
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Either way strapped or not your drone is a goner, it either plummets to the ground or turns into a fireball.
The fireball scenario could cause major damage depending on where it lands.
After my accident that prevents me bending to pick up my drone properly I was contemplating a strap, after struggling to get hold of it I antecedently piked it up by the battery clips, it was at this point thinking it could have caused the battery to disconnect in flight that a strap seemed like a good idea.
After reading the post I am not so sure.
 
the battery would become extremely unstable if it was still even working which would mean the drone would be getting a unreliable source of power as there would be lots of cell deviations. I’m not sure if a fire would occur but the battery would definitely heat up
 
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Here is an article on DJI battery operations: DJI Mavic 2 in Depth Series – Part 1 – Intelligent Flight Battery

It states that it has short circuit protection which may initiate prior to thermal runaway if the overcurrent condition is detected to be a short circuit. Some rudimentary information is displayed by the software e.g. battery temperature and cell voltage levels which can be indicators of a damaged or worn out battery. I don't see anything that would provide further information such as cell internal resistance. Obviously, if flight time diminishes it is a good indicator that the battery may need to be replaced.
 
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unfortunately no strap battery ejects,drone falls to earth
with strap battery shuts off or catches fire before impact with earth
sad fact both result in a damaged drone but there might be a chance to get it down safely if the battery remained in the drone as during descent very little current is being used to remain aloft so for me the strap wins by a short head
 
What would happen if in flight the battery began to bulge badly but was held in place by one of those devices that prevents it from popping off, like a Velcro strap or plastic bracket? Could an in-flight fire possibly result? What warnings would you get while flying, if any?

So we know from flying the drone in the RAIN without a wet suit that the battery when the connectors get wet; You get a Warning that says
( The battery can no longer connect to the drone .) Followed by the Drone flipping over instantly.

Each connector on that battery plays a specific role to the drone thus when the battery starts to swell inside as long as the connectors do not pop off or even move slightly your drone
can continue to fly back home and land.

This is the reason why people use straps and such to protect the battery from moving.

If the battery swells when constricted in the drone , it is likely you will not be able to remove the battery without damage ..

Both the Straps and Plastic Brackets and the Wet Suit try to Limit that movement ,

The Wet Suit does it best as it seals the Drone battery all the way around the perimeter of the Battery
which allows for zero movement on either side of the battery.


Phantomrain.org
Gear to fly your Mavic in the Rain and Float on water.
 
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I've had three batteries swell on me. The swelling wasn't enough to cause unlatching. The worst of the three had a weak latch to begin with, so it could unlatch in flight. I pulled that one apart to where I broke the latch sensors so that one won't fly.

Anyway, I tested under controlled flight (close by hover low to the ground) and flight time diminished only by a minute or two compared to a new battery.

My conclusion is that the main issue is with the physical issues from the swelling where the batteries are otherwise just fine. They won't likely burst into flames. Anyway, if it were to become unstable, it would more likely burn up during charging than during use.

The main issue is with becoming unlatched and falling out, or the battery losing electrical contact with the AC.
It is only the center two pins that are for communication. The pins on either side of the two center ones are for power and are redundant, the redundancy for more current and less contact resistance.

Straps may prevent the battery from falling out, but there's still a chance that the AC lose electrical contact with the battery.
 
I've had three batteries swell on me. The swelling wasn't enough to cause unlatching. The worst of the three had a weak latch to begin with, so it could unlatch in flight. I pulled that one apart to where I broke the latch sensors so that one won't fly.

Anyway, I tested under controlled flight (close by hover low to the ground) and flight time diminished only by a minute or two compared to a new battery.

My conclusion is that the main issue is with the physical issues from the swelling where the batteries are otherwise just fine. They won't likely burst into flames. Anyway, if it were to become unstable, it would more likely burn up during charging than during use.

The main issue is with becoming unlatched and falling out, or the battery losing electrical contact with the AC.
It is only the center two pins that are for communication. The pins on either side of the two center ones are for power and are redundant, the redundancy for more current and less contact resistance.

Straps may prevent the battery from falling out, but there's still a chance that the AC lose electrical contact with the battery.

Thanks for that break down of the Pins , so what interesting to me is that we know that the battery will continue to put out juice under water and yet Water will take out the battery by causing it to flip over so what pin is really causing the Drone to flip over ;

As mentioned you do get the split second warning that the battery has disconnected and can no longer communicate with the drone before it flips . ?
 
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I've had three batteries swell on me. The swelling wasn't enough to cause unlatching. The worst of the three had a weak latch to begin with, so it could unlatch in flight. I pulled that one apart to where I broke the latch sensors so that one won't fly.

Anyway, I tested under controlled flight (close by hover low to the ground) and flight time diminished only by a minute or two compared to a new battery.

My conclusion is that the main issue is with the physical issues from the swelling where the batteries are otherwise just fine. They won't likely burst into flames. Anyway, if it were to become unstable, it would more likely burn up during charging than during use.

The main issue is with becoming unlatched and falling out, or the battery losing electrical contact with the AC.
It is only the center two pins that are for communication. The pins on either side of the two center ones are for power and are redundant, the redundancy for more current and less contact resistance.

Straps may prevent the battery from falling out, but there's still a chance that the AC lose electrical contact with the battery.
until the voltage suddenly and unpredictably drops to near zero and the drone comes down
 
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until the voltage suddenly and unpredictably drops to near zero and the drone comes down
Bingo! This is an aspect of the drone that I am uncomfortable with. Once a battery has swelled it has been, imho, badly compromised. With age and or stress batteries have an increase in internal resistance. This should be visible with the battery under load as the voltage will sag more than a "good" battery. Unfortunately, I have seen no easy way to test the internal resistance of these batteries. So, to continue the saga, a battery with increased internal resistance will still try to provide the requested power of the load. The voltage will sag below normal limits and the current will attempt to increase to make up the loss. This is a flywheel or snowball effect that can occur very rapidly. The current flowing though the high resistance will cause increase in temperature and pressure causing the swelling and another cycle of increased heat. At least with batteries such as the 18650, this can end up with boom. Obviously the chemistry is different but nothing to play with. I'm going to see if I can watch battery voltage under heavy load next time I fly. I haven't looked yet. This may be a way to predict battery life.
 
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