LiPo's and winter weather

[Terry Plumridge 1]

Is there a limit to how cold a LiPo can be and still be used? I'm thinking of 2-3 deg. C. Colder than that I would not be flying anyhow.

[Colin Carpenter]

Several of us fly on bright windless mornings when below freezing. Luv it ! Lipos are kept in bags with hot water bottle. Then into pocket before flying. Seem to get average run times and benefit is mud is frozen!  😂😂😂😂🥶🥶Colin

[Andy Gates]

I too continue flying in winter when ice and snow are on the ground.

 

I do expect lower duration and output from my lipos though due to the cold but it is still enjoyable.

 

I think there will be 2 limits.

 

High current draw aircraft that are taxing the lipos in summer may not want to fly - EDF springs to mind here.

 

Coldness of fingers on transmitter sticks will be the other - gloves or transmitter mitts come to the rescue here.

[John Lee]

I use a small heating pad that operates off a Powerbank, does the job & only costs about £5-£8 from the likes of Amazon, eBay etc. It's stuck to a bit of reflective bubble wrap & sits in the bottom of a LiPo sack.

[John Lee]

But to answer your original question there is a notable drop off in performance of LiPos if they are below about 8C.

[Simon Chaddock]

For true winter flying I make sure the LiPo is well sealed in the plane to keep it from any freezing air, not to difficult to do in a foam job. Yes, keep it warm in car/pocket and fly straight away. The heat of discharge will keep it warm even on long 'cruising' flights. 

[Dickw]

I have a heated "Lipo box" set to 35 degrees C and keep my Lipos in that before flying in cold weather - particularly if planning to fly high current draw setups.

I started doing that many years ago for competition flying so that the battery performance was the same all years round irrespective of ambient temperature, and then found how useful it was for just general flying as well.

Anything you do to keep the Lipos warm is a good idea in cold weather and several good suggestions have already been made in this thread.

 

Dick

[perttime]

I've flown at -10 C. I made sure to keep the pack warm before flying, and restricted airflow to keep it from cooling the pack too much during flight.

 

Fingerless gloves kept my hands happy for a while....

[john davidson 1]

I have found that small lipos , 2 or 3 cell, 1,000  or less are much  more affected by sub zero temperature, obviously they have much less mass. Larger ones have time  to heat up internally too if used hard

[Bruce Collinson]

Same heat pad in Tx box is very useful too, especially with a metal cased Tx.   Back in box, back in car between flights.

BTC

[Terry Plumridge 1]

Thanks for the replies. Now I know what to do.

Cheers, Terry.

[Allan Bennett]

I simply keep my packs in the heated house for a couple of hours after charging them, then take them to the field in a small cooler bag of the type designed for a six-pack of beers.  They warm up further in use, so I've never noticed any reduction in performance or flight duration.

[Ambassador Spock]

On 21/11/2022 at 10:50, John Lee said:

I use a small heating pad that operates off a Powerbank, does the job & only costs about £5-£8 from the likes of Amazon, eBay etc. It's stuck to a bit of reflective bubble wrap & sits in the bottom of a LiPo sack.

Do you find a usb-powered heating pad puts out enough actual heat to keep the bag warm? I was looking at one of those (looks like the same pad actually) but the reviews all say it doesn't provide much warmth at all...

[Trevor Crook]

This may be adaptable to make a heated box, no thermostatic control but there's a posher version with a temperature readout. Not sure if 7W would heat the batteries much, but may keep them warm if they have been pre-warmed indoors for a while.

Love Big Clive's videos!

[john davidson 1]

just been flying at -5 using small 380mah  in a volantex f16, 15 minutes as usual, suspect all the above posts are a load of doodoo.

[Dickw]

2 minutes ago, john davidson 1 said:

just been flying at -5 using small 380mah  in a volantex f16, 15 minutes as usual, suspect all the above posts are a load of doodoo.

What was the battery temperature before the flight?

 

Dick

[john davidson 1]

ambient, tiny one cell 380, should have been affected ,slotted battery cover, plenty cooling,  but no difference to usual

3 minutes ago, Dickw said:

What was the battery temperature before the flight?

 

Dick

 

Edited December 14, 2022 by john davidson 1
more thoughts

[Dickw]

30 minutes ago, john davidson 1 said:

ambient, tiny one cell 380, should have been affected ,slotted battery cover, plenty cooling,  but no difference to usual

 

Ambient - as in -5C?

If you are happy with the performance you are getting then that is fine, and in flight cooling is not the issue, BUT

Battery temperature affecting performance is definitely not "doodoo", and I have many years of logged data from on board sensors to confirm that. One example comparison from my F5B models is attached.

 

Dick

 

[GrumpyGnome]

Deffo not doodoo.

 

Indoors yesterday was cold and my newly charged (well in the few hours before I went) LiPos needed more throttle to prop-hang than usual ....... only by a few clicks but definitely more. And they are not old, worn out cells.........

[John Lee]

1 hour ago, john davidson 1 said:

just been flying at -5 using small 380mah  in a volantex f16, 15 minutes as usual, suspect all the above posts are a load of doodoo.

 

It's not doodoo, you are just not comparing like with like.

 

Assuming you used 80% of the battery in those 15 mins then you consumed 380x.8=304mah.

and you drew an average of 304x15/60=.76amps and .76x3.7v=3watts.

 

That tiny current draw cannot be extrapolated to the performance of, say a typical 3S 2200Mah battery providing 20amps and 230watts. Real world experience, in addition to the laws of physics regarding the increase in internal resistance at low temperatures, bear out that low temperature affects Lipo performance.

[John Lee]

3 hours ago, Ambassador Spock said:

Do you find a usb-powered heating pad puts out enough actual heat to keep the bag warm? I was looking at one of those (looks like the same pad actually) but the reviews all say it doesn't provide much warmth at all...

 

In a word, yes. I've been flying this afternoon in zero temperature & the lipos were fine, albeit they were also in my backpack to keep off the ground & out of the wind.

[Chris Walby]

A few years back I used a couple of near brand new lipos that were probably around +5C in a electric model. All checks complete and took off to be greeted with LVC on the ESC and limp back to the runway. The low temp and high current draw on take off didn't allow the lipo to warm up so basically knackered a £45 lipo. 

 

Warmed the other lipo up and used it for about 4 years of good service IIRC

 

I store lipos at +15C and warm them if they are going to be used circa +20C (winter closer to 35C if the heater is on) and haven' had any issues since. 

 

[Simon Chaddock]

Also remember if you charge a LiPo to full in the warm and then let is get really cold it looses effective capacity so in effect becomes over charged which LiPo do not like!

Try to keep them more or less at a constant temperature.

On the other hand a cold LiPo will not over charge. It will simply neither accept nor deliver a full charge or the intended amps!

 

 

[Trevor Crook]

Performance loss in cold weather is very real, batteries produce electricity via a chemical reaction, and chemical reactions are less vigorous the lower the temperature. Just look at any of the EV videos comparing summer and winter range.

[Trevor Crook]

That's interesting, Simon. I thought if you charged a lipo cold (to, say, 4.1V), when it warmed up the voltage could go higher, which is bad. Could be wrong, would be nice to have a battery chemist to explain best practise.