:ha: :lol: :lol: :ha: Nah, that never happens does it Zmann? It has, err, never happened twice now as I recall. I'm still slightly deaf in the right ear, and I think H I may have a scar...

Seriously guys, the latest cells are so stressed we should all move to lipo asap.

the little fellas a week old now ,time to update the avartar ;)

i would be lucky to make run time of 8 minutes in a mini using those cells :lol:

Looking at your discharge times your cells are quite low on capacity. Anything below %80 is considered dead.

Cell 1. 680 seconds at 20 Amps = 3778 mAh = %90
Cell 2. 645 seconds at 20 Amps = 3583 mAh = %85
Cell 3. 630 seconds at 20 Amps = 3500 mAh = %83


One Unmatched and unzapped IB4200 stick pack I bought was 4222 mAh at 20 Amp discharge.


Charles

You might be the same as what I used to be. Too much drop in speed around corners and too much current accelerating back to speed.

Go back 10 years. We used to run 1100 mAh NiCD with 1/12th scale and with a Sports tuned 540 we ran 10 minet races. I could never finish a race while others easily finished. All to do with smooth driving and correct gearing.

Also, He said 'Lap Times' only. Nothing about runtime.


Charles

Good point! :nod:

Hey Dad, I've finished adjusting the steering trim for the 12th on the 3PK for you now... come and lift the damn controller off me!!!

No that wouldnt be in your interests either unless you wanted to pay a huge premium on batteries. However, you will also find that batteries have changed a lot. I havent heard of a battery supplier stating that any of the IB4200s or EP4200s the predominant batteries in Australia require any specific pre-conditioning which you have mentioned. Although im not sure what the .1C or .2C refers to do you mean Amps?

Battery characteristics have changed quite dramatically, particularly with the new 4200 mAH cells. My battery supplier states that it is a good idea prior to first use to put in a small charge (i think it was like about 300 mAH) equalize the battery (ie to 1.0v) then allow it to sufficiently cool (maybe an hour or two) but this is primarily to minimise the chance of false peaking which seems to occur when such cells have been left unused for any period of time.

Im my opinion your comment "When Matching cells the matcher is Totaly ABUSING the cell" i believe that the comment is uneducated, and could be misconstrued by novice racers reading this thread. Any racer who knows his stuff understands the advantages of matched cells and will always use them, budget permitting....

Besides i wouldnt be surprised if battery matchers were just taking left over cells (which they couldnt find 5 others for to form a matched pack) to bunch them together as a loose unmatched packs.

One thing I have been trying to find is what Internal Temperature damages a NiMH cell. So far the only answer I have found is around 80 Degrees C.

If the outside temp reaches 60-70 Degrees C during charging or discharging then you can bet your life the internal is 80 degrees C.


I just did my first 1C charge on my Sanyo RC3600HV's and I was quite surprised at the cell temperature. It only reached 47 Degrees when it Delta Peaked. Maybe thats why Sanyo recommend a -10 mV Delta V setting. I was not going to try that value as it seems far too high. But with the low temperature at a 1C charge then maybe Sanyo is correct. -10 mV delta V is needed to reach the "High Voltage Platform". Would anyone realy consider using -10mV per cell Delta V on NimH cells !.


The GP's and IB's go MUCH higer in temperature with a 1C charge. I found a 0.75C charge just holds them at 50 degrees C when they peak.


Charles

1C is the rated capacity: 4200mAh = 4.2amps @ 1C. (Us lipo users know this well. My 4800mAh lipo is to be charged at 1C, which is 4.8 amps.

Totally agree with you mangoman, 100%

seems cell 4 is the best as it was the highest initial untouched reading

Charging a Cell above 1C is "ABUSE". ALL manufactures I have seen state the Max charge Current is 1C. Including GP and Intellect.

Try doing some research from Manufatcures sites about NiMH batteries. Sanyo recommends the 4 cycles at 0.1C charge and 0.2C discharge before pumping them.

0.1C means 0.1 times their rated capacity. IE, a 4200 mAh cells means charge it at 420 ma for 16 hours.


Another thing I forgot to mention. People are mad about Equalizing their cells using special equipment. Doing a 0.1C charge for 16 Hours does equalize the cells during charging. Thats why Manufactures tell you to do a 0.1C charge for 16 Hours after several cycles to Equalize them again.

You will also find that most Manufactures Data sheets showing Discharge curves at differant currents also state they charged them at 0.1C for 16 hours before each test.


Charles

WHOA 10mV per cell?!?!?!?!? that is scary

Wow, 4611 mAh from a 4200 mAh Cell. That is one hell of a Super Cell.


Charles

Yes but Mosc_007 you seem to be talking about batteries which are old generation, that no-one uses anymore.

I challenge you to find any current battery manufacturer/supplier that recommends people charge their batteries at below 5Amps. (That is NiMH 4200+ mah)

and 4600 mah from an equalized current generation 4200 cell is quite normal when new.

almost reached 70deg...... imagine at a 35 amp discharge rate