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Aug 22, 2017, 07:45 AM
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What did I do wrong?


Hey guys,
I am just getting back into RC as I hit my midlife crisis so although I am not new to Rc, I am new to LiPo batteries. After reading up all about them and the dangers etc., I bought myself an iSDT SC-608 charger and a LiPo bag. Just before I went on holiday this year I bought a cheap chinese RC boat from BangGood (a Feilun FT11). I ran it twice during my vacation being careful not to over discharge the battery, and connecting it to my charger after each use to charge it to storage voltage and balance the cells. I have been storing it outside in a shaded area in a metal bucket.

I came to check it today and it has puffed up. I am now in the process of discharging it with a tail light bulb. I will then drop it in a bucket of salt water for a couple of days before disposing of it. My question is, as per the title, where did I go wrong or was I just unlucky?

Fortunately this time it was just a cheap 4s 2200mah chinese LiPo, but despite my best efforts it has gone bad after two uses. I am somewhat reluctant to get back into LiPo powered RC based on this experience.
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Aug 22, 2017, 07:49 AM
Registered User
How hot was the storage area? I store mine in my cool basement in a metal box. They certainly should not puff if you store them at storage voltage. By the way as far as I know most lipos are made in China.
Aug 22, 2017, 08:57 AM
Registered User
Thread OP
The storage area is outside in the shade. That means as much as 35 celsius (95 farenheit) here in the summer. The basement would be a bit cooler, but even down there it has been 28c (82f) this summer. To be honest all the stories of people burning their houses down has kind of put me off the idea of having them anywhere in the house.

p.s. Just wondering, was I wrong to storage charge straight after running? Should I have left the battery for an hour maybe?
Last edited by stuartthurstan; Aug 22, 2017 at 09:04 AM.
Aug 22, 2017, 10:09 AM
pull up -- PULL UP!!!
Puffing is generally associated with heat. Which could come from high discharge or re-charge rates, excessive voltage at end of charge, or storage. If it got hot during use and you got it even hotter with an immediate re-charge -- maybe the problem. But it would be noticeably warm to the touch.

If none of those apply to you, perhaps you just got a bad one. You sure the summer sun never reached the bucket?
Aug 22, 2017, 11:16 AM
Frankenstein recycled packs
rampman's Avatar
Stuart, I have 2 of those boats with the green 4S 2200 packs and they have been flawless BUT I store mine in the fridge in the 3.7 to 3.9 / cell range.

My guess is that metal can got a LOT hotter than you think as it probably got some direct sun for a bit of time in the early am or late pm. I killed a few thousand earth worms when I was a kid by having my coffee can in the sun for around 1 hour in a boat.

Regardless of the cause, take notice that when you look for a replacement pack you must buy one the same size as most 2200 4S packs are slightly larger and will not fit unless you modify the holder.
OR
Buy a replacement metal prop from Hobby King and run it on a 3S pack (fits easily, longer run time) which is slower but more controllable at WOT. I broke 4 props in 1 day from choppy water and that is why I went to the metal prop. The metal prop on 4S is crazy fast to control.

Rick
Aug 22, 2017, 12:26 PM
Registered User
If they were not puffed before you put them outside then the heat caused it. I would get a metal storage box and store them inside. Temperature is their enemy. I store some in my beer fridge. Putting them to storage charge after using them is the right thing to do. I actually discharge most of mine about to storage charge when flying. I get a long enough flight without discharging them further than about 3.8 per cell. I have had good results doing that.
Aug 22, 2017, 02:17 PM
Retired Electronics Specialist
vollrathd's Avatar
Quote:
Originally Posted by stuartthurstan
Hey guys,
I am just getting back into RC as I hit my midlife crisis so although I am not new to Rc, I am new to LiPo batteries. After reading up all about them and the dangers etc., I bought myself an iSDT SC-608 charger and a LiPo bag. Just before I went on holiday this year I bought a cheap chinese RC boat from BangGood (a Feilun FT11). I ran it twice during my vacation being careful not to over discharge the battery, and connecting it to my charger after each use to charge it to storage voltage and balance the cells. I have been storing it outside in a shaded area in a metal bucket.

I came to check it today and it has puffed up. I am now in the process of discharging it with a tail light bulb. I will then drop it in a bucket of salt water for a couple of days before disposing of it. My question is, as per the title, where did I go wrong or was I just unlucky?

Fortunately this time it was just a cheap 4s 2200mah chinese LiPo, but despite my best efforts it has gone bad after two uses. I am somewhat reluctant to get back into LiPo powered RC based on this experience.
Don't know how much speed you are after, or how much room you have for the battery pack. But a 5 cell 2500 Mah A123 battery would have roughly the same amount of power, at about 35% more weight. With a high powered charger, you can recharge these cells in 15 minutes or less. They are quite a bit more rugged than a LiPo battery pack.

No storage issues, no fire issues, and, they'll last 5 years and 500 cycles with little loss of performance. (I've got over 150 A123 cells in my various models, including this one.)

Giant Corvus Model
https://www.rcgroups.com/forums/show...-Models-Corvus

The 12S3P A123 pack in this model turned a 22X10 XOAR prop at 7200 RPM when brand new. After 190 flights on this pack, the battery turns the same exact prop at 7170 RPM. Maximum current is 132 Amps.
Aug 22, 2017, 02:25 PM
Suspended Account
if you had to bring it up to a storage charge chance are you overdischarged it..since voltages are unknown..id blindly guess at that..over heat is also a problem..i guess you don't know what temps at end of use where?..
Aug 24, 2017, 12:43 PM
Registered User
Thread OP
I didn't measure temps after use, but they were warm but comfortable to hand hold. I'd guess about 45c (113f). I'm also sure that direct sun couldn't get to the battery where I stored it. Oh well, I suppose I'll buy a replacement and see how it goes. Thanks for all your replies guys.


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