Cold Battery Warning

[RPP]

On a few occasions recently in Iceland, once I had the P4P up I got the warning that the battery is cold, that I should warm it up. The ambient temperature was around 4º C (39º F) give or take a degree during these alerts. I ignored the warnings and continued flying. I have operated in Iceland in colder conditions before when the temps were around -4º C.

Has anyone had this warning followed by the battery quitting (shutting off) while in flight?

 

[tevek]

My experience in winter over here, whilst only down to 4C, was to either stick the battery in my pocket on the way to the flight site or have the drone hover close by until the temp reached 15C at which point the warning would disappear. I haven't heard of a battery shutting down due to cold temperature given the temp range of the batteries, but I guess it would be possible if they are extreme at either end of that range. Not keen to find out.

 

[CANEKiTA]

I would not continue flying after getting that message, the batteries can be touchy in cold weather.

I use a heating pad to pre heat my batteries before flying

Skip to 1:33

 

[Deleted member 62848]

Hi not mid flight but on takeoff,was very frosty and had to restart motors 3 times,was good after that ,never done it again,as @tevek say i now pocket mine,the old body heat works well

 

[Mark The Droner]

Yes, I've heard of batteries shutting themselves off during flight due to cold (not specifically P4).

 

[With The Birds]

If the pack is healthy (cells reasonably matched you should be fine). Cell internal resistance increases with reduced temperature aiding in temperature increasing when loaded. LiION chemistry can actually continue to deliver power at -40deg C (or somewhere around that, relying on my memory here) however usable capacity is significantly reduced as is discharge rate. Avoid charging LiPO when cold, they can be permanently damaged.

 

[John Locke]

There is higher risk of incurring a 3.00v shutdown with DJI batteries in cold environments if you don't warm your battery before launch. The smarts in DJI batteries will turn off the battery at 3.00v. A cold battery does not work as well at cold temperatures, unable to produce as much power as when warm, say above 20C. The danger is during high stress acceleration, such as full speed forward AND full speed up ascend, this might pull one cell down to 3.00V, which can turn off the battery mid flight, a catastrophic event. You won't be covered under warranty in this case because the cold battery warning is recorded. You should always warm the batteries before flight in cold extremes, you'll get longer flights with warm batteries around 25C because the LiPo chemistry works better.

 

[With The Birds]

There is higher risk of incurring a 3.00v shutdown with DJI batteries in cold environments if you don't warm your battery before launch. The smarts in DJI batteries will turn off the battery at 3.00v. A cold battery does not work as well at cold temperatures, unable to produce as much power as when warm, say above 20C. The danger is during high stress acceleration, such as full speed forward AND full speed up ascend, this might pull one cell down to 3.00V, which can turn off the battery mid flight, a catastrophic event. You won't be covered under warranty in this case because the cold battery warning is recorded. You should always warm the batteries before flight in cold extremes, you'll get longer flights with warm batteries around 25C because the LiPo chemistry works better.

All true. In fact LiION will deliver max capacity and current closer to 40deg C, at the expense or reduced lifetime cycle count finding some means to warm the packs prior to launch is likely the best approach.

 

[Raptorman0909]

I made a battery heater last year and also made a video showing how I made it.

Brian

 

[CANEKiTA]

I made a battery heater last year and also made a video showing how I made it.

Brian

...it was your video that got me started on mine! Works great, Thx

 

[Raptorman0909]

...it was your video that got me started on mine! Works great, Thx

Hey, that's good to know!


Brian

 

[BigAl07]

Has anyone had this warning followed by the battery quitting (shutting off) while in flight?

There was a time when we heard of this too often. It was (my assumption) a Firmware issue because a FW update greatly reduced the frequency of hearing about this happening. I think they had their shutdown threshold a little too aggressive.

A cold battery doesn't have the same "Punch" of a warm battery but the battery will self heat nicely once it gets put into use. Part of the problem is as soon as you take off you are likely to want/request full power for the climb out which is exactly when the battery is not up to optimal operating temps yet.

We use a soft sided cooler with a small hand warmer tossed inside. We keep them inside in "living space temps" until going to the job site because once they get cold they take a while to get warmed back up. Much easier to maintain them at room temp than to try and bring them back UP to room temp.

We preheat all batteries when operating in temps below 40F. We don't leave batteries in vehicles or buildings that might be below 50F if possible. I take my system into my office with me in colder weather so that it's always ready to go if I'm needed 24/7.

 

[Mark The Droner]

I heat my flight battery any time the outside temp is below 20 C. I have a system worked out. Been doing it for years.

 

[RPP]

There was a time when we heard of this too often. It was (my assumption) a Firmware issue because a FW update greatly reduced the frequency of hearing about this happening. I think they had their shutdown threshold a little too aggressive.

Why is there a shutdown threshold at all? Shouldn’t the smart battery logic be to try to be on at all times during flight unless there’s a positive command from the controller to shut down?

 

[Mark The Droner]

I think Lipos in general are designed to shut off at a certain point because otherwise they will sustain permanent damage. But yeah, when we stick them in a quadcopter, that kind of logic doesn't make much sense.

 

[John Locke]

I think Lipos in general are designed to shut off at a certain point because otherwise they will sustain permanent damage. But yeah, when we stick them in a quadcopter, that kind of logic doesn't make much sense.

Yes, apparently it's common that pilots forget to turn off the craft battery, store it, and forget about it. Although I've never done that, I have forgotten to turn off my RC, which fortunately starts beeping at me as a reminder.

To protect DJIs liability on this kind of battery mistreatment they program the craft battery "smarts" to turn off at 3.00v. This control logic is local to the battery, so it will turn itself off if left on, even if the battery is not installed in the craft. Theoretically a good battery that has been charged properly will never have a cell reach 3.00v during flight, but it might be possible if the battery is very cold, in which case the LiPo chemistry to produce power is hindered. That's why you get the cold battery warning, because of the high risk.

You would think DJI would be able to program the battery to never turn off during flight, but DJI told me at a trade show that's not possible, otherwise they would have. This means there is no communication path from the flight controller to the battery, which seems odd, but possible I guess. It appears there is only a one way communication path from the battery to the flight controller, disclosing power usage, voltage level, etc, to provide monitoring capability of remaining power.

 

[BigAl07]

Why is there a shutdown threshold at all? Shouldn’t the smart battery logic be to try to be on at all times during flight unless there’s a positive command from the controller to shut down?

Because at a certain level of discharge there is irreparable damage done to the battery. That's part of the problem with buying "Smart" technology... sometimes it's too smart for it's own good. If you buy a product that uses a "standard" battery then you don't have to worry about this feature but you do have to understand LiPo chemistry, LiPo charging/discharging, LiPo maintenance and so much more.

Most people buy DJI because they want to plug a single cord in, charge it and not have to know anything more than "Hit the launch button". That's what we call "Smart Battery Technology".

 

[With The Birds]

Yes, apparently it's common that pilots forget to turn off the craft battery, store it, and forget about it. Although I've never done that, I have forgotten to turn off my RC, which fortunately starts beeping at me as a reminder.

To protect DJIs liability on this kind of battery mistreatment they program the craft battery "smarts" to turn off at 3.00v. This control logic is local to the battery, so it will turn itself off if left on, even if the battery is not installed in the craft. Theoretically a good battery that has been charged properly will never have a cell reach 3.00v during flight, but it might be possible if the battery is very cold, in which case the LiPo chemistry to produce power is hindered. That's why you get the cold battery warning, because of the high risk.

You would think DJI would be able to program the battery to never turn off during flight, but DJI told me at a trade show that's not possible, otherwise they would have. This means there is no communication path from the flight controller to the battery, which seems odd, but possible I guess. It appears there is only a one way communication path from the battery to the flight controller, disclosing power usage, voltage level, etc, to provide monitoring capability of remaining power.

The 3V cutoff is the default LVC factory set value in the Texas Instruments MCU DJI employs in their batteries. It provides a good safety margin. It’s nit the low voltage that permanently kills a LiION cell it’s hitting zero capacity. By leaving the setting at 3V the cells are only likely to be permanently damaged by self discharge.

 

[RPP]

Because at a certain level of discharge there is irreparable damage done to the battery. That's part of the problem with buying "Smart" technology... sometimes it's too smart for it's own good. If you buy a product that uses a "standard" battery then you don't have to worry about this feature but you do have to understand LiPo chemistry, LiPo charging/discharging, LiPo maintenance and so much more.

My point is that the smart logic is flawed. I would rather lose a battery than lose the entire bird.

 

[With The Birds]

My point is that the smart logic is flawed. I would rather lose a battery than lose the entire bird.

I wouldn’t say it is flawed, simply because by the time you have hit the LVC you are likely to suffer a cell collapse shortly after in any case. It’s not a huge inconvenience to monitor remaining capacity and individual cell voltages in flight.