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Dec 31, 2016, 12:30 PM
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Thread OP

3s Batteries Puffing - HELP!


Ok folks, here's the skinny:
I'm a noob when it comes to electric power systems, and I also like to build and modify....
I was given an old Mini Skyfun, and I am upgrading the electronics to make her zoom!
I have a brushless inrunner from a swap meet - (no name/label) - but it works well.
I tested it w/ a 5.5x4.5 prop w/ a 30-amp max esc and a 3s 1000mah 30c DBY baby-brick battery.
Ran the pack dry in a power test, generating tons of thrust for this featherweight airframe.
The inrunner ran hot - but not 'burning' hot - (looking for a heat sink, btw!) - and the esc only got 'warm', so, all good!
The test took about 3-4 mins, varying the speed from low to running it max for about 2 mins straight.

Problem is, the battery got 'kinda hot' and it swelled up - 'puffed', I believe they call it! The power did not drop, but I am worried that I am destroying the batt! (Puffing can't be good!) The battery case DID return to it's original shape - mostly - but I need to know how to make it work AND save my batts!
My Question - does the esc size/quality make a difference in the discharge? (It's a regular 30-amp Heads Up esc.)
Would a higher C-rated battery make a difference? Like a 40c or 50c? I know I will need to add cheater-holes to the airframe to get more air around it, but for my tests it was next to the frame, not in it! (I don't have a problem varying thrust from low to wot in flight, but how can I protect and get the most out of my batteries without the heat and the puffing?

P.S. - The motor is the exact same size as the e-flight 400 inrunner - can I 'make' a heat sink to help keep it cool or does anyone have any 'spares' to sell?
I love the prospect of getting this bird into the air, but I want to make sure I can have more than 1 flight without destroying the battery, or is 'puffing' the cost of speed? Upgrade the esc, upgrade the battery or swap out the inrunner for a different motor? HELP the noob, guys!
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Dec 31, 2016, 12:35 PM
Registered User
Thread OP
BTW - the C rating on batts seems to be a joke - I need some real power without adding too much weight, and I worry that the battery may die or explode in mid-flight w/o disastrous results!
Thanks!
Dec 31, 2016, 03:44 PM
Registered User
A larger ESC won't change the amps the motor is drawing, though it should make the ESC itself run cooler.

There are two ways to reduce the amps: One is to use less throttle; the other is to use a slightly smaller prop.

More cooling holes -- for air to get out as well as to get in -- will help with the temperatures. If you can't hold a finger on the motor for more than a couple of seconds, that's too hot, and may damage the motor in the long run.

In theory a 1000mAh 30C battery should be good for 30A but, as you say, C rating is at best a bit of a guestimate -- at worst, outright fraud.

Since the capability is Ah x C, to get higher capability you can either increase the C or the Ah, or both. Doing it by increasing Ah has the added benefit of longer flight duration. Anyway, you should certainly aim to eliminate the puffing, for that indicates that the battery is over-stressed.
Dec 31, 2016, 04:10 PM
Suspended Account
over taxing battery (its puffed its done).. by prop size .. that's why things are hot warm....solution smaller prop annd less throttle..and a new battery heck u had a 30 c battery no power king but not all that,,most C rates are highly exaggerated YES.. and high C and more mah will be more weight.
Dec 31, 2016, 04:17 PM
Registered User
I'm surprised no one has suggested yet - you really need a watt meter. You pushed your battery beyond what it could handle. That battery is probably toast. If you knew the amp draw you placed on it during that test run you would have a better idea what change(s) you should make to either battery and/or prop. You would also know if your esc is up to the task.
Dec 31, 2016, 06:01 PM
Space Coast USA
hoppy's Avatar
Right on Yoda!

Got to know the amp draw!
Those full throttle runs may have been out of sight on the ampmeter.
Dec 31, 2016, 11:45 PM
I hate waiting for parts
Mike_Then's Avatar
That's what I was going to say. Need to put your power system on a wattmeter. Sounds like it's drawing way more power than that tiny battery can provide.
Jan 01, 2017, 12:22 AM
Registered User
Definitely good advice on the wattmeter, it's an essential tool for any sort of electric power system experimentation. Without one you're simply guessing.

Also yes it's a well known fact that C ratings on batteries are mostly fantasy, the true C rating is usually about half what is printed on the pack.
Jan 01, 2017, 06:55 AM
Registered User
flypaper 2's Avatar
Biggest killer was running the batt DRY. That's a big no,no. Should always have 20%capacity left in the batt after a run.
Jan 01, 2017, 10:42 AM
Unregistered User
vimy g eaou's Avatar
3s Batteries Puffing....

I hope they have good taste:

Havanas
Carrillos
Olivas

I can imagine they would be expensive to maintain though. I can see why your're upset.

..... what was that I just drunk?

Quote:
Originally Posted by kizzmo
Problem is, the battery got 'kinda hot' and it swelled up - 'puffed', I believe they call it! The power did not drop, but I am worried that I am destroying the batt!
No kizzmo, your not destroying your battery at all, it's already in past tense. The current draw is beyond the battery's capacity limits as everyone else has suggested.
Last edited by vimy g eaou; Jan 01, 2017 at 10:55 AM.
Jan 02, 2017, 09:48 AM
Registered User
Thread OP
Thank you all for the information and suggestions, I really appreciate it! I have already 'skimmed' the wattmeter forum, so I am learning its uses and functions. My questions:
Since I don't know what the motor is, (long, 'gold in color, same dimensions as an e-Flite 400 inrunner!), I am not sure WHAT this information from the wattmeter will tell me! But, most importantly, what are the solutions and real-world options?
A) Smaller or lower-pitch propeller - (Had similar result w/ APC 4.7x4.2!) Doesn't my thrust decrease even more every time I prop down? And how much smaller should I go?
B) Larger ESC? (The esc did NOT run hot, it just got warm... (And from what abenn said, a larger esc won't help with the problem, anyway. So the wattmeter will probably not show that I exceeded 30 amps during my test.
C) Higher C-rated battery: I am using a 30c now. Will a 45/50 or even 60 C rated battery make a difference? And the higher the C rating, the heavier - and larger the battery, again affecting performance. Do I start with new 40 C batts or new 50 C batts first? Is there a higher quality, better-performing lipo battery out there that 'puffs' less? (Name please!) Will it make a difference?
D) Scrap the unknown brushless motor - and go for testing a 3700k Gens Ace outrunner instead? (I also have a BL Hacker motor (from a swap meet) to try, but would I have a similar result, or worse- or will this expensive motor make a difference?
What to do first, second or third, gentlemen? I need REAL solutions!
Thanks again, and sorry if the answers have already been suggested... I'm still very much a noob, so please be kind!
Jan 02, 2017, 09:59 AM
Registered User
Thread OP
P.S. Is what 'vimy g eaou' said true? Is that battery that puffed in earlier testing now dead? (BTW, it has returned to its original shape! Should I not try to recharge or recycle it, (or is it now just a paperweight)? I don't want a higher mah battery, that will be too much weight for this tiny airframe - that originally flew w/ a tiny 900mah 2s 20c batt. (I'm trying to use a 1000mah 3s 30c DBY batt. Should I go w/ the highest C rating I could find, and will it not puff? (And what is that - 40C? 45C? 50C? Somebody teach me - please! Sorry, I just don't understand... -thanks all
Jan 02, 2017, 10:17 AM
Registered User
flypaper 2's Avatar
Biggest thing right now is too keep from killing the batt!!
Most trans. now have a timer. Put your plane up for , say 2 mins. on the timer. Land and recharge the batt. Don't worry about C rating right now, only the rated batt capacity.
After charging the batt, the charger should show how much you put back in, say 50% of its capacity. If it's a 2000 ma batt, it will show 1000ma put back in your batt. Ideal is to use about 80% of your batt. You don't want to run it till it's empty.
Put up another flight for 3 minutes, then recharge. That may take you down to the 80 %, so now you use the timer for each flight .
If you use a higher capacity batt. say, going from 2000 ma. to 3000 ma, you can see where you can set your timer for, say, 4 minutes. As long as you have that 20% left in the batt.

Gord.
Jan 02, 2017, 10:25 AM
Registered User
flypaper 2's Avatar
If you want to try to recharge your batt. be very careful.
Hook it up to your charger and put it in a metal pot. Set your charger to NICAD, then charge it till it says 3 volts per cell or 9 volts for the 3 cell batt. Don't take your eyes off the charger as it will come up fairly quickly.
Now switch your charger over to LIPO and balance charge at the 1 C rating. Keep an eye on it till it's fully charged. It should charge up to the 4.8 volts for that batt. then shut off after it balances it.
If everything works out right , it should be good to go.

Gord.
Jan 02, 2017, 11:15 AM
Registered User
Quote:
Originally Posted by kizzmo
P.S. Is what 'vimy g eaou' said true? Is that battery that puffed in earlier testing now dead? (BTW, it has returned to its original shape! Should I not try to recharge or recycle it, (or is it now just a paperweight)? I don't want a higher mah battery, that will be too much weight for this tiny airframe - that originally flew w/ a tiny 900mah 2s 20c batt. (I'm trying to use a 1000mah 3s 30c DBY batt. Should I go w/ the highest C rating I could find, and will it not puff? (And what is that - 40C? 45C? 50C? Somebody teach me - please! Sorry, I just don't understand... -thanks all
It's hard to give you specific recommendations without knowing where you are with your current setup. The watt meter will give you real time readout of both watts and amps. That will let you determine which of your components (motor, battery, esc) you are overtaxing and by how much. Am I correct in understanding that you changed from a 2s battery to a 3s with no other changes to the setup? If so, it is no surprise you are having problems. You increased your input voltage by 50%. If you use the same prop, the power draw (watts) will increase significantly. You almost certainly need less prop. How much less? It depends on your watts and amps now and that is where the meter comes in. I know you are hoping for a quick specific answer, but we are all kind of guessing at this point. If you keep flying electrics the watt meter will be invaluable and they are not expensive. A cheap one is fine. It is cheaper than batteries and esc's.


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