General Battery Life

[RMB677]

A topic I haven't noted is how does one determin that a LiPo battery is nearing the end of it's service life. This was brought to mind when I noticed the 3S battery I used this morning was slightly swollen after use, voltage was still above my minimum of 11.3V. Its the first time I noticed a battery with a noticable swelling.

 

[murankar]

That one is bad. It could cause damage at a moments notice.

 

[RMB677]

Muranker,
Thanks for the reply. That raises another question, how does one safely dispose of a LiPo? Throwing it in the trash could possibly start a fire.
Roger

 

[Tony]

If this is a Dynam battery, they are known to do this and still work for a long time. A puffed battery could be a number of things. If you are able to charge it up with teh cells at the same voltage and after running they are at the same voltage, and you are still getting the same mah out of it, then you should be fine. But with the cheap cost of batteries right now, it's worth it to just dispose of it and order new ones. As for disposal, there are recycling centers out there for this kind of thing.

 

[RandyDSok]

The following is copied directly from a PDF file found on ThunderPower's website... also remember that questions that are as simple and easy as this... are often easy to find the info with a simple web search which is what I did to get the following and it only took a few seconds.

Unlike NiCd batteries, lithium-polymer batteries are environmentally friendly.
For safety reasons, it’s best that LiPo cells be fully discharged before disposal (however,
if physically damaged it is NOT recommended to discharge LiPo cells before disposal -
see below for details). The batteries must also be cool before proceeding with disposal
instructions. To dispose of LiPo cells and packs:
1. If any LiPo cell in the pack has been physically damaged, resulting
in a swollen cell or a split or tear in a cell’s foil covering, do NOT discharge the battery.
Jump to step 5.
2. Place the LiPo battery in a fireproof container or bucket of sand.
3. Connect the battery to a LiPo discharger. Set the discharge cutoff
voltage to the
lowest possible value. Set the discharge current to a C/10 value, with “C” being the
capacity rating of the pack. For example, the “1C” rating for a 1200mAh battery is 1.2A,
and that battery’s C/10 current value is (1.2A / 10) can be used,
such as a power resistor or set of light bulbs as long as the discharge current doesn’t
exceed the C/10 value and cause an overheating condition.
For LiPo packs rated at 7.4V and 11.1V , connect a 150 ohm resistor with a power rating
of 2 watts (commonly found at Radio Shack)to the pack’s positive and negative terminals
to safely discharge connecting it to an ESC/ motor system and allowing the motor to run
indefinitely until no power remains to further cause the system to function.
4. Discharge the battery until its voltage reaches 1.0V per cell or
lower. For resistive load type discharges, discharge the battery for up to 24 hours.
5. Submerse the battery into bucket or tub of salt water. This container should have a lid,
but it should not need to be air-tight. Prepare a plastic container (do not use metal) of cold
water. And mix in 1/2 cup of salt per gallon of water. Drop the battery into the salt water.
Allow the battery to remain in the tub of salt water for at least 2 weeks.
6. Remove the LiPo battery from the salt water, wrap it in newspaper or paper towels and
place it in the normal trash. They are landfill safe.

 

[RCD]

Muranker,
Thanks for the reply. That raises another question, how does one safely dispose of a LiPo? Throwing it in the trash could possibly start a fire.
Roger

You could stab it to start a bonfire. lol

 

[murankar]

Thats along the lines I was thinking when I posted what I did. Just that the picture in my head was of heli going up in smoke.

 

[RMB677]

After flying another helicopter, my coax, last evening I found that that battery was warmer than normal and after a post flight check the voltage was lower than expected vs the time I flew. Putting 2+2 together I'm of the opinion that the 100 deg temps we've been having do affect the use of the battery. I'm going to have to knock a couple of minutes off my flight times with this hot weather.

 

[Tony]

Yeah this weather sucks. I have opted to stay inside during this time, but it's allowed me to get other things done.

 

[Chris O'Hara]

Slightly swollen batteries don't always occur because of to much run time, sometime we end up with batteries that just don't discharge the way the ratings claim. It's probably not the issue that you have here, but with all these inexpensive batteries you never know who is telling the truth about what their product can handle. For example I had a HK Turnigy 3S 2200 rated at a min. of 35C continous. 2.2 x 35 = over 70 amps! I was using it in my Trex doing basic flight, and when it landed the battery was very hot and swollen. My ESC was pulling less than 40 amps during that time! Lesson learned....go with decent batteries. I now prefer the Sky Lipos from Hobbypartz, they are inexpensive, ship from the U.S., and discharge at their given ratings. -just my 2 cents