Quick tip: How to NOT Puff Batteries

xuzme720

Dedicated foam bender
Mentor
Ya, this is Great!, Thank you! I read through the manual for my charger, and it appears to not auto balance, so i need to get an auto balancer. I know Josh and Josh did a video on that, like 20 bucks, Totally worth it!. So i guess its an 80% rule hua? Thats good. Do you have any suggestions for a battery charging setup? Like.... a cinder block or something? (In the event something were to go wrong.)
A few people have gone to a cinderblock for charging, but truly, it can be any nonflammable surface that can withstand the heat. The fire usually doesn't last long but it burns hot! The cinderblock offers protection from spreading and helps contain any mishap by the simple expedient of covering the block with another nonflammable item such as a couple of bricks, a heavy sheet of metal, etc. The main thing to consider is the chemicals released into the air when a lipo fire occurs. you don't want that stuff in your house, so ventilation is a concern as well when planning on a charging location.
 

darkmatter2222

Junior Member
A few people have gone to a cinderblock for charging, but truly, it can be any nonflammable surface that can withstand the heat. The fire usually doesn't last long but it burns hot! The cinderblock offers protection from spreading and helps contain any mishap by the simple expedient of covering the block with another nonflammable item such as a couple of bricks, a heavy sheet of metal, etc. The main thing to consider is the chemicals released into the air when a lipo fire occurs. you don't want that stuff in your house, so ventilation is a concern as well when planning on a charging location.

so... what your getting at here is, charge them at your friends house? got it. Thank you xuzme720!
 

jetpackninja

More combat please...
Mentor
I haven't seen any discussion about what 1C or 2C is or how to calculate it.

I use 3S 2200mAH batteries. When I charge them I use a Turnigy Accucel 6. I balance charge at 3.3A. At what C rating am I charging and what is the formula to know so I can convert to a 4S?

Charger has two main settings - voltage and amps - volotage is set by how may cells 2s,3s,4s etc - charge rate is set by amps

3.3 is over a 1c charge for your 2200mah batts

No conversion needed 3s set your charger for 3s charge set for 2.2 amps is 1c
For 4s set your charger for 4s- if they are 2200mah 2.2 is a 1 c rate
What charger are you using? most 4 button chargers operate very similarly... check youtube for vids

1000 mah is 1 amp
 

jetpackninja

More combat please...
Mentor
So I think the second most important thing to discuss is how to put out a fire should one occur. I would assume that a standard fire extinguisher would not work. What type of fire extinguisher should you have on hand?

Charge outside. A proper extenguisher may keep other cells in the pack from burning, but these fires happen so quickly that I don't think you are going to be able to put out the initial fire. Are you going to watch each charge with a fire extinguisher pointed at the battery ready to go? Like xuzme says above- consider the amount of smoke that is released when one of these go off. This smoke stinks and is very toxic, you don't want it in your house. I don't even want it in my garage. The impact of the risk is enough that I moved all of my charging outside.

Check this video out where Lee places a bag of sand over the cinderblock bunker.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
"No conversion needed 3s set your charger for 3s charge set for 2.2 amps is 1c"

How did you arrive at 1C for my 3S = 2.2A? What is the mathematical formula?

Are you telling me that the C rating is based on the Amp rating of the battery and not the cell count? This would be profoundly different from what I was taught when I got Lipos to start with.
 

tramsgar

Senior Member
How did you arrive at 1C for my 3S = 2.2A? What is the mathematical formula?

Are you telling me that the C rating is based on the Amp rating of the battery and not the cell count? This would be profoundly different from what I was taught when I got Lipos to start with.

Then you were taught wrong, I'm afraid. That is the definition of the somewhat unscientific C-rating. Think "times storage capacity"-rating. 2200 mAh is 2200 mA for one hour. Remove the "for one hour" and you get the amperage capacity factor of the battery. Instead of giving a C-rating, you could just as well just specify how many amps you can draw from it safely, and how many you can put into it. But as that is linear with the capacity, C-rating is used. Hope that didn't confuse anyone =).
 

cranialrectosis

Faster than a speeding face plant!
Mentor
So C rating is a percentage of mAh and is not related to number of cells. 2200 mah at 1 C = 2.2A. Or put another way (mAh/100 = C) or (C*100=mAh). It also has nothing to do with the 45-90 C rating for discharge.

Thank you. Sometimes you really do use that algebra from school.
 

xuzme720

Dedicated foam bender
Mentor
Not a percentage. C=mA directly but since we charge in Amps and not milliamps, you just convert the mA to A to get your C rating. It's actually 1000 that you use to convert as in 1000mA per 1 Amp, so 2200 mAh battery can charge at 2.2Amps and an 800mAh battery can be safely charged at .8 Amps.
Does that help?
 

tramsgar

Senior Member
So C rating is a percentage of mAh and is not related to number of cells. 2200 mah at 1 C = 2.2A. Or put another way (mAh/100 = C) or (C*100=mAh). It also has nothing to do with the 45-90 C rating for discharge.
Yes the C rating takes a number stating stored energy and uses it as a number for current flow. That's why it's so confusing because of the sloppy use of units. Also see xuzme's mA -> A conversion above. The discharge C-rating can be seen as a battery quality number, because batteries of similar quality have similar C-rating independent of the battery's capacity.

Thank you. Sometimes you really do use that algebra from school.

Yep. Every day. Only now it's fun.
 
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petedotnl

New member
C=capacity stated on the battery so if discharge of 30C is possible then it says 30times the capacity. charging happens at a slower pace and is also mentioned on your battery. mostly 1C but latest battery's come at 1 to 5C. For example 3s 3700mAH rated 20C you get 74A (74000mAH / 1000=74A) discharge rate. and if you get a charge rate 3C then you can charge at MAX 3 times 3700mA = 11.1A (11000mAh / 1000=11.1)
 

xuzme720

Dedicated foam bender
Mentor
C=capacity stated on the battery so if discharge of 30C is possible then it says 30times the capacity. charging happens at a slower pace and is also mentioned on your battery. mostly 1C but latest battery's come at 1 to 5C. For example 3s 3700mAH rated 20C you get 74A (74000mAH / 1000=74A) discharge rate. and if you get a charge rate 3C then you can charge at MAX 3 times 3700mA = 11.1A (11000mAh / 1000=11.1)
The cell chemistry's HAVE gotten better to allow charging at higher C rates, BUT peaking the charge out at a higher C rate can still shorten the life of the pack. Chances are unless you are competing with these packs, you won't notice the difference but I still charge all my batts at the 1C rate, even my 3C packs. For me, it's just a bit of peace of mind to charge them at what I know is better for the chemistry. And since my flying is usually done in the backyard, I can use the extra time I'm not packing planes and driving to the field, to charge a little slower.
It works for me and your mileage may vary. Just be careful out there. Don't become a statistic or a "what not to do" video on YouTube.