Mr RCTech

iTrader: (2)

All the new chargers that charge 20 or more are safe to use.

Never had any issues with lipo batteries or charger.

I wouldn't charge the lower price cells above 1C.
Talking about Nano tech, Gen Ace, etc.

I personally don't run them for the low grade of materials use to produce.

avs

iTrader: (2)

i think you are painting with too broad a brush.

gens ace are generally underrated on capacity and C-ratings. heli pilots charge the gensace batteries at 5C with great results.

they also refer to the nano-tech's as nano-puff's.

RogerDaShrubber

iTrader: (6)

My Gensace packs are safe to 5C and my Hobbyking packs are safe to 2-5C depending on the packs. At home i charge my packs at 10A the max my dual charger will allow, at the track i charge them at 1C which is what our rules allow. Never had a failure, never had a pack puff, and my packs balance up nicely and I only ever use these low end packs.

Oh and the nano tech packs are rated to up to 15C charge, it depends on the packs, i know a mate of mine who is into planks charges 20 lipos at a time off his massive charge outfit at insanely high amps, all of them Turnigy branded, 20 packs come off his charger in 15 mins, ready to fly. It is the plane, helli and boat guys who are really pushing the envelope when it comes to high amp charging us car guys really do not have anything on them.

Mr RCTech

iTrader: (2)

In competition the Gen Ace, Nano tech A-grade just fell off to fast.
The voltage did stay up.

Didn't trust charging at 5C

Had better results with Trinity,Reedy,SMC,Venom lipos.
These packs the voltage where higher longer on the discharge cycle.

bkspeedo

iTrader: (5)

For those interesting in seeing how battery Ir effects voltage drop in your battery I threw together a spreadsheet at 3 different current draws.

In summary most packs at room temp are around .006 ohms. If charging a pack at 40 amps can drop the Ir to .003 ohms this would provide an additional 0.030 volts @ 10amp draw to your motor over an entire run which in 17.5 TC would equate to about 70rpm on the straight.

The bigger story is punch out of the corner. An Ir of .003 @ 30 amp draw would provide an additional 0.090 volts to your motor over a battery with an Ir of .006 ohms.

When you’re a top level driver at a big race this could be what gets you a TQ. There are other factors as well, Motor winding resistance, Motor Rotor strength, car setup, tires, etc that would negate this advantage but that's what competitive racing is all about. Putting all the puzzle pieces together so you’re the fastest person on the track. This is why the same person does not win all the time, one of these pieces is missing when someone else has it all together.


I have to say reading this thread has been a bit of an eye opener for me just like it was learning about rotor strength at Nats this year.

Xpress

iTrader: (3)

I still think the performance improvement is due to heat in the battery. I don't have a 40amp charger, but I have an old battery discharger that puts about a 35amp load a battery. I have been "warming" my packs between heats where there is time for them to cool (hours between rounds) by charging at 10a and then 15min before the run discharging them for 3 min @ 35amps and then repeaking at 20a.

Do you have the equipment to compare the two types of "warming?"

bkspeedo

iTrader: (5)

I do not. I'm going off of what other people are saying about the Ir of the battery dropping due to heating of the cells. Whether physically heating with an external source or the battery heating itself from current is up for debate.

The only reason i can think heating a battery by discharge\charge would be different than an external source is the it slightly changes the chemical structure of the battery materials effecting the Ir differently. I think the only way to truly know is for a manufacture to do experiments on cells and give feedback, which I doubt will ever happen.

For now everything will be independent opinion. In my opinion heating a battery with an external source is far more dangerous than doing it by charging.

xevias

iTrader: (1)

Hey EA,

Do you know what other major brands your battery factory is also making?

In Shanghai, my problem is I having to trust the locals when they say "this is the best battery." Currently it is the Thunderpower 65C 6000mAh. I'm not sure it is the best. What do you think?

I suppose I could ask Scotty to transport a few of yours over here when he comes for the Asian On-Road Championships.

Thanks

BeLiPoWa

Hi, I have just got a pair of new Team Powers 2S 7200mAh 75C batteries. What's your opinion about them?

I usually charge my LiPo batteries at 2C rate and never got one of them puffed or had any other problem, but I plan to use this batteries only for racing and reading here I think can be good to charge them at higher current.

I have an iCharger 206B, so do you think it's safe/recommended to balance-charge them at 20A from its first charge?

Thanks.

Best regards!

Mr RCTech

iTrader: (2)

You are correct.
Its not just one thing.
Voltage and IR is HUGE racing in competition.

Also, driving and handing is too.

Robertcooper88

iTrader: (15)

I know you want the lowest IR as possible but what is considered really low?

Mr RCTech

iTrader: (2)

.007-,009 ohm IR range throughout the pack cycle.

Its simple!
The Lower the IR the better the battery pack.

Team Grid RC

iTrader: (3)

Regardless what you charge at, either 1C or 5C, any Lipo can go stupid and fail with a fire.

I am using both Lipo Sack and the Turnigy Bunker box and believe the steel box is much better. The nice thing about a sack is light weight and easy transport of many bags at once. The Turnigy can be transported unassembled and assembled at the track.

The best and safest way is a steel cash box for $5. And forget the myth that a seal box can explode with a exploding Lipo.

http://www.youtube.com/watch?v=6M5ftkN9PtY

Mr RCTech

iTrader: (2)

Side note if you have packs that are older 20 amp + brings them back to life with the high charge rate... Proven multiple times..

SS LS1

iTrader: (23)

Does one high amp charge cycle refresh older packs for just that one discharge cycle only ? Or does one high amp charge lower the IR somewhat permanently so future 6-10 amp charging will also show improved output for awhile?