429racer

iTrader: (19)

Has anyone noticed that their cells keep the voltage but runtime drops significantly? I have 2 6 cell Gp 3300's packs (with the green and orange label) that have lost over 120 seconds in runtime but have maintained their discharge average and the internal resistance stayed close to the same. Has anyone had this problem also? I have done the the regular maintenance that is basically store at 5.4 when not in use and not to use them twice within a four hour period. These almost seem like disposable packs (use them a couple of months then you have to get new ones like regular non-chargable transmitter batteries). My friend has had the same result. Anybody know how to get runtime back from these? Thanks!

Ooj

Hi there

I have the same problem as well. I have found that most of the time the run time comes back after you equalise the cells before you charge...I have no idea why....Also helps with the overall voltage and IR

popsracer

Guys;

The runtime loss appears to be normal and most prevalent in the newest Green/Orange label cells. Keeping a partial charge while storing will help minimize any runtime losses.

The good news is that Voltage and Punch seems to be uneffected.

sosidge

Yeah, I've had very bad lifespan (capacity) from some of my GP's. Two packs definitely got overheated by me not letting them cool before charge (trying to run a meeting on two packs when I usually use three or four - shouldn't have done it). Equalising does seem to bring some of the cells performance back.

Ooj

One thing I also forgot to mention was that with my cells, it seems to be a lottery as to their capacity...on any given day. For my old packs just to make sure, I just peak them 20 minutes before while being cooled and then repeak if needed to see if they feel like taking more. Cooling them on the first charge allows me to more quicky do a repeak without cooking the cells. This way I can get some punch as well as have a backup solution for runtime in case the cell is "feeling" like it does not want to cooperate

Maj. Teeth

We've also found that some GP cells do come down on runtime but only experienced some awesomely high voltage gains.

We had a guy who purchased 3 packs of 420/1.172 and after a few months said the runtime dumped on modified 8t. So I took it back and cycled to check, the pack indeed showed only at 385 runtime but the average voltage went up to 1.195. Now this is a 1.172 matched pack but had way enough runtime for stock. Needless to say, he wanted it back. Bare in mind that at this voltage, it can't even be bought off the shelves so Fukuyama is trying to simulate and see how that was possible. Only happens to some packs but I suspect it's because the cells were trained hard with a 30~35 constant discharge @ 10~15 cycles.

We've also found that if you equalize each cell individually down to .90 and store after race day, it will normally come back on runtime. One more thing to try is to cycle them a few times at 20 amps. This will retrain the cells to gain some runtime back but make sure you equalize the cells individually after each cycle.

Dan
Fukuyama Racing

Ooj

.....

Ooj

hey major,

At the moment I am discharging at 20A down to 5.4v/pack and then storing the packs for a week before use again. Before I charge again I tray them to 5.4.

So heres the question.....what is going to be the difference between traying before you store them for a week and then charging, versus traying before charging?

Also what makes traying to 5.4 for each cell different to discharging as a pack to 5.4? Why do the cells get better voltage, AIR and capacity after equalising?

JusBox

iTrader: (1)

How do you suggest equalizing saddle packs? I'm not sure the rayspeed discharger/equalizer i'm looking at can handle these types.

Super Steve

iTrader: (9)

if you just discharge to 5.4 V,
Some cells can have 1.0V and some can have 0.8V etc

Equalizer tray dishcarges .9volts each cell (or what ever it's cut-off volt is)

It would be a good idea to equalize them before storage and equalize them again before charging

JusBox

iTrader: (1)

Yah I realize this now... but i use saddle packs so I may have to lengthen the jumper wire so I can use one of the equalizer trays.

429racer

iTrader: (19)

I tray my packs on my trinity realtime 2. Then wait for the lights to go out then I take them out and let them sit for a couple of minutes before I start to charge or cycle. I have one pack that averages 7.23 volts but has only 460 seconds of runtime with a 91 for internal resistance. So basically there is no way that the runtime will come back? Keep in mind that I never dead shorted these packs.

PitCrew

I have 8 GP packs.

My method is discharge at 20 amps after a race, then leave the pack till next time. Before charging, put the pack on a tray (Indi octane2 - about 5 amps per cell) untill the pack is fairly dead. Then I charge up. This method usually gives me around 3700-3900 charge capacity, and about 3000 discharge capacity at 20 amps. Also, I am seeing over 1.2 volts average per cell at the completion of the discharge cycle ( on the quasar) which is usually between 8:15 - 9:00 Since I first purchased the packs, I have not noticed much of a decrease in runtime, but I have noticed a significant increase in voltage output. Most of my pack, being discharged at 20 amps on the quasar, show over 7.2 volts AFTER 5 minutes of discharge. This is NOT AVERAGE, this is ACTUAL VOLTAGE.

GP ROCK!!!

JoshR 85

HeY!!!


429racer that was a problem w/ all them old ones, but the new ones w/ green and yellow at one end are the new ones and are better and i so far have no prblem still w/ one from sept.

JPHRacer

I bought 6 packs of some green and orange and some rainbow right after the birds last year. I have been running them in 4-cell mod oval for every weekend since I bought them, allmost 8 months ago. Every pack has maintaied its voltage from 4.68-4.72 but have lost a maximum of 40 sec of runtime. For 8 months worth of racing, that is not bad at all. I have yet to see any of the packs loose more then 40 sec, you might be doing somthing wrong if your loosing more then that, and not gaining some major voltage.