Battery fault ? the evidence !

[Mossie]

This is what nearly gave me a heart attack this afternoon. I played back the flight log and there it is...battery drops immediately to 8% from 38% and causes the Inspire to start auto landing . Luckily I got it down with the battery showing 0 % charge ! Check out the battery indicator on the video.
Hope this is just a battery fault and nothing more sinister. This is the second time it's done it, first time I thought it was my fault for not paying attention.

Just realised you can hear my kids flushing the toilet halfway through the video !!!!!!

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

 

[blade strike]

How cold was it?

 

[Michael Dicker]

I think mossie is from Leeds, UK. freezing cold weather outside. 0-6Celsius

 

[Mossie]

How cold was it?

About 8 C, but would that make a battery loose its charge like that ? I thought if it was cold you would just get a shorter flight time.

 

[Michael Dicker]

Not sure if i tell the "true truth" but i try.

These are the Inspire lipos.



In cold temperature the inner cells stay longer warm than the outer lipos, when you fly the Inspire the inside cells stay warm because of the electron flow and the outer cells do warm up slower or even stay cold. You get the best
power curve when a battery has around 35-40 Celsius.

(All numbers are just to examples)
Now imagine a flight in cold weather with a cold lipo. It warms from the inside out, so you have high potent cells inside and weak cells outside. Lets say the inner cells are 100% power and the outside have 50%.
All cells get drained the same. Over some flight time you drain the cells more and the inner cells are at 50%
and the outside cells at 20% because the are colder. The outside cells cant deliver the power they should and suddenly the
lipo fails to give the inspire enough power to stay in the air.

I think the most important thing is to pre-heat the lipos to a decent temperature before you fly in cold weather. They don't have to have 40Celsius even it that is the best temp for usage. More important
is it to have the lipo equally warm.

Do you have a icebox/tiny isolated box? You can buy some cherry seed bags and warm them at home in the oven. Put them together with the lipos in the box, or keep the lipos in a sock to keep it warm and use the DJI Pre heater for 10-15 min. before flight to heat up the outer cells so they are equally warm when you fly.

..sorry for the bad english

 

[Mossie]

Very interesting thanks, I'm flying with the covers on now and it seems ok

 

[Kilrah]

1) Calibrate your battery as per manual
2) "but would that make a battery loose its charge like that ? I thought if it was cold you would just get a shorter flight time." The indication falling to <10% is just the Inspire's way of saying "there's a problem, trigger critical battery actions now". Doesn't necessarily mean dozens of % have "vanished". You should look at the detailed battery info page to see what the actual problem is. Could be abnormally low voltage, a dead cell, etc...