jlfx car audio

iTrader: (37)

Ok ive owned many different chargers. Never 2 from same company
From the old gfx lipo to the new 820 Tp. With turnigy 6*4 charger inbetween.
I have owned batterys as cheap as the turnigy 4.0 to my newest TPg6 6600 2c with 30different ones in between(smc/revtech/tp/TP/fantom/promatch)
Almost every pack ive owned has puffed in a matter of a few months balance charging every charge on some hand once a day on others . Now i will say i just got the new TP820 so none yet with it.
These batterys have not been mistreated in anyway. The turnigy charger has been the charger for the most of these batterys (9of10) +-1
Now for my question .(sorry for my ramble)
Does a lipo charger charge a battery with frequency modulated dc current (like a esc feeds a motor voltage at a particular rate )or with a 100% rock steady voltage . (Or amperage untill max V value is seen )
Reason i ask is i wonder if they do charge at a high frequency or no frequency could this be a reason for swelling cells? Or could it even aid cells from not swelling .
Kinda like back in the old days with zapping nicads /rc2400 cells to make the do better last longer? Hope this makes sence to someone . And if u get way im asking but know of a better way to explain so others can follow by all means help.lol tks for ur time

crusey_aus

iTrader: (3)

Lipos are charged in two phases called CC/CV

Phase 1 or Constant Current
Battery is fed full voltage (specified cells) at the full current rate you specify

Phase 2 or Constant Voltage, activated when a cell hits 4.2v (some a little lower)
Voltage held steady and current tapered off until all cells are all at 4.2v
Bleed current is used to stop the weaker cells from being over-charged while the others catch up

Cycle terminates when cells are balanced and charge current drops to a percentage of user inputted charge rate (usually 1/10c but some are adjustable)

Fast / Slow charge cycles just vary the termination rate (1/5c or 1/20c etc....)


Cheers

jlfx car audio

iTrader: (37)

that i know but does voltage come to the battery as a signal or as pure DC current? Even our expensive dc powersupplies when pushed to the max have a frequency they opperate at but is unnoticeable at lower demands because of the capisitors in the rail. So if we r pushing our chargers to max amp current does this produce a signal within the voltage that could help or hurt the cells??

gulio

iTrader: (32)

If I understand what your asking correctly you are asking about differing chargers and puffing cells. I can say without much of a doubt that it isn't any of your chargers' fault.

If every pack has puffed within a month I would bet money on 2 things (and probably both of them together which makes it worse) That is a bit too much current being drawn during the use and/or a bit too low of voltage at end of run.

What do you think? could these 2 be the culprit?

jlfx car audio

iTrader: (37)

Well these batterys r ran in spec TC 17.5 car and vta car that i am very competative with. Never ran them down near 7v much less 6v. Matterfact i havnt ever put in over 4500mah back in any pack ive ever owned. Actualy my tc pack is 99% of the time only getting2000-mah at most and 1000-mah on vta packs per charge
Packs r atleast 25c and most r 40-65c packs current ratings.
So yea dont think so packs have never been hot comin out of car. Packs have never puffed in car . I store my packs for 2-3weeks at a time wirh all my other rc gear still mounted in the cars unpluged at 60-75% charge. I just wonder if the quality of charger could have something to do with cell life ?

skeasor

Wish I had an answer for you. But I can say I dont think it's the chargers you've owned. I've have some pretty crappy chargers in the past and I still have Lipo batteries that are close to 2 years old and still work without a problem. However, these batteries have been used in rc aircraft and not rc cars. But, I dont think that should matter too much. I've always charged them at 1C at the rated Amperage.

I'm new to electric rc cars and I've only had my battery for about a month and still havent had any problems with it. It seems odd that your batteries are puffing after a short amount of time.

I dont think the quality of the charger has anything to do with the cell life though. An amp is an amp no matter what kind of charger. I think quality of the charger depends on bleed current, max amp, wattage, etc...

jlfx car audio

iTrader: (37)

I guess i want to here that my thunderpower 820 was a good investment since its 2x the price of 2 of the turnigy 20a chargers.

AreCee

iTrader: (1)

It's a very decent charger.

As for the batteries puffing, I agree with the statement that it is the current draw in use and /or deep dischaging (while under load not at rest).

I had the same issue using 10C - 30C batteries in my TC in 17.5 open. That was a few years ago and batteries were not as good as now. Even the cheap batteries in the 40C to 60C range are better than the best from four years ago.

Once I started using Turnigy, Gens, Blue, NanoTech I found all my puffing was history. The puffed ones were big names; IP, Trinity, Pro-Match, SMC. Same chargers too. I think I puffed one G-Force 3S 800mah when I forgot to store it with a storage charge but all the others are fine.

skeasor

Thunder Power makes really nice stuff. You'll have a good charger for years to come. Definetly a good investment.

Dave H

When they puff, is it all cells, or just one cell?

jlfx car audio

iTrader: (37)

Its usually both cells and it usualy happened within the 2 weeks between racedays . Put up pack 80deg room thru the summer and 60deg room in winter unpuffed and 2 weeks later its swolen . Packs had atleast 70% charge but not over 90% . Usualy static voltage was about 7.8v- 8.1v in storage.
Paxks were always balanced atleast everyother charge. With about 6-10 charges per raceday.
I will say i have a first gen orion 3200 hard case lipo (ran in a mini) 5yrs old its still flawless and has sat in 100deg heat& below freezing many times

gulio

iTrader: (32)

There's a good chance that the high storage voltage has as much to do with the puffing than the other 2 things I mentioned. It may be a little of all 3 combined. This is my best order guess to remedy and stop this on future packs.

Storage voltage should be reduced to 3.7 volts/cell resting. Temp can also be reduced.
Current can be reduced.
Ending voltage can be reduced (increased , run shortened)

jlfx car audio

iTrader: (37)

So storage voltage is 7.4 volts. ??

crusey_aus

iTrader: (3)

No, 7.4v is too low

Storage should be 3.85v / cell or 7.7v for a 2s pack

Roughly 50% energy depleted

7.4v is around 20% remaining

Cheers

jlfx car audio

iTrader: (37)

Thats what i thought. In that csse ive been storing rhem correctly voltage wise