Just Lucky

Cold weather is here but I want to keep flying. What is the lowest allowable temp before damage will occure to nicd, nimh and lipo batterys?
As temps reach this point what precautions need to be taken to preserve battery quality?

Ryan CSRC

I have never had any permanent damage on batteries because of the cold. Anywhere below about 40 degrees F or so and lipo's will start to perform poorly, but it is just while they are cold, and is not permanent damage. The performance comes back as soon as they get warm again.

Ryan Lefevre
www.CommonSenseRC.com
The Go To Guys For Electric Power

gil_mor

This is from FMA Web site:
Is this true?!

gil_mor

Nobody knows?

Red Scholefield

My Feedback: (9)

All battery technology is temperature sensitive, the lower the temperature the more critical the charge rates. I don't see any reason that Lithium should deviate from this. Any chemical reaction is altered as you reduce temperature (or raise it for that matter).

Red B.

Living at 60 degrees north I have had plenty of opportunities to try cold weather flying :-).

It is not advisable to fast charge NimH and NiCd batteries at temperatures below 32F unless you somehow can keep them warm (above 50F).
Slow charging is possible, but not practical.

One also have to consider that the available capacity decreases at low temperatures. For NiCd/NimH batteries, depending on the discharge current the available capacity at 0F may be approx. 60-80% of the capacity at room temperature. This is especially important to consider for Rx and Tx batteries where the discharge current isn't high enough to cause self heating. I strongly advice you get a battery checker that puts a load on the battery when testing in order to ensure that there is enough juice left in the batteries before every flight.

Another low-temperature problem is that the LCD display on typical transmitters will stop operating at low temperatures. Usually the Tx itself will keep on transmitting at even lower temperatures. The lowest temperature that I have been operating my JR "computer" PCM transmitters and receivers at is approximately 0F. For temperatures below that I switch to my old "analog" Futaba FM gear that will continue to operate at temperatures well below what I consider to be flyable conditions.

Another thing to look out for is stiffness in control linkage, which tends to become worse at low temperatures. Nylon servo arms and control horns tend to become brittle at very low temperatures. For that reason I have substituted these with metal parts in my SSE cold-weather aircraft.

I have rather limited experience with LiPo:s at low temperatures but they seem to perform worse than NiCd/NimH batteries. At 0F I have found the available capacity to be roughly half of that available at room temperature. Voltage is also depressed. Using some Sanyo LiPo:s I had lying around I found that the voltage at 0F was only 3.5 V compared to 4.2V at room temperature, thus reducing the margin to the 2.7 V/cell cut-off voltage of my JETI motor controller.

Edit: I forgot about low temperature charging of LiPo:s. Very little information seem to be available, but after talking to one of my friends in the Swedish Armed Forces I learned that they do not charge LiPo:s at temperatures below 32F.

Update: I found a Kokam Lipo data sheet were the operating temperatures for charging and discharging are 0C to 40C (32F-104F) and -20C to +60C (-4F to 140F) respectively, which seems to agree with my own findings

gil_mor

Wise words guys, Will keep that in mind.
Thanks

weathervane

Can I jump in and ask a quick question? I am new to electrics so pardon my lack of knowledge on the subject. I store my LI-POs in a strong box out in the garage. Do I have to worry about the cold temps. I can put them in an insulated box if it will help. I would also like to know about winter storage. Should they be fully charged first?

-Andrew

flyinsolo11

Andrew I hope I dont take your thunder...

I had a question as well- if I go out and use my LiPO battery in below freezing temperatures, but charge it in warm temperatures, will it damage the battery?

Again, sorry if I stole your thunder, Andrew...

Red Scholefield

My Feedback: (9)

NO.

flyinsolo11

lol, thanks Red.

waynem

My Feedback: (58)

I did not see a answer to weathervanes question. I also have some planes stored outside in my trailer. Will temps. down to 5 degrees hurt life or lipo batterys at the storage voltaged? Thanks for any help.waynem