MTX3-B

iTrader: (5)

Guys,

My buddy n I have 5 packs of IB4200WC and 1 pack of GP3700. We are are casual racers (we race M-Chassis) and more of bashers. I have the following equipments:-

i) Charger (2x) - Novak Millennium Version 1.20
ii) Discharger - Integy Indi Reactor 20 - discharge 20Amp
iii) Conditioner - Spintec Battery Manager Version 1

We will be attending the M-Chassis race in less than 2 weeks. I gave up NiMh cells as they do not have that longevity plus they need to be babysit...i dont have the luxury of time. Bought Team Orion Lipo 3200 but it is only used ocassionaly during bashing. Local track doesnt allow LIPO in race!

Here's the data i gathered for the 6 packs.

Setting on the chargers: Linear 6.0A & 4mV per cell

1) WC-1 IR=75.0
9.39V; 348mAh; 209s==> False Peak
9.57V; 3849mAh; 2771s
2) WC-2 IR=17.5
8.25V; 4627mAh; 2776s
3) WC-3 IR=72.5
9.15V; 1397mAh; 838s==> False Peak
9.63V; 2560mAh; 1536s
4) WC-4 IR=20.0
9.47V; 4187mAh; 2512s
5) WC-5 IR=47.0
9.59V; 4493mAh; 2696s
6) GP-1 IR=77.5
9.57V; 3109mAh; 2035s (charged at 5.5A)

Questions:-

a) Which is the best pack? The one with the lowest IR? I would have thought that having the lowest IR would have the mAh reading pretty close or above the rated capacity of the cells. See WC-2 with 4627mAh vs. WC-4 with 4187mAh.

b) We will be using Tamiya Sport Tuned motor for the race with 10-minute heat and final of 45 minutes. Would the batteries be able to finish the race at their rated true capacity? I reckon the amp draw for the motor would not exceed 2.0 Amp.

c) What would be the recommended practice to keep the batteries in good shape? Using the above said equipments, what would be the correct procedure to cycle the batts?

Sorry for the long winded questions, i just feel that i need to protect our investment to a good cause, with little money to spend in RC. Pitty in this part of the world, LIPO batts in racing has yet to take off.

Views/comments highly appreciated.

Thank you.

wog....supraman

iTrader: (3)

well i cant really answer all your questions but i can answer B.

If you charge the batteries at a high amp (e.g. 5amps) it wont last 45mins...no way will it do it. the amperage these motors draw with NO LOAD is anywhere between 1-1.6....dont forget once you put load on it, she'll be pulling alot more. I believe that sport tuned can easily pull 8 amps....thats a guesstamation (guess/estimate).....coz if i could make mine catch fire....i think it is pullin slightly more than 2amps...

BTW just 4 the record...i did an elaborate test on about 4 motor (2 sport tuneds, a mabuchi 540 and a 45t Integy lathe motor)

results from memory where

Sport tuned 1 1.34
Sport tuned 2 1.21
Mabuchi 0.95
Integy 0.77

@4 volts...average over 3 tests

then i did water break-in, which consisted of the 2 mins in water....dry/cleaning

then they were

sport tuned 1 1.15
sport tuned 2 1.04
mabuchi 0.85
integy did not under go this test but gave out a consistent .75-.78 result.

@4 volts

the mabuchi did not xceed an amp at any voltage i threw at it (7.2v)...

so these motors are capable of pulling well above 2amps

sorry bout the long arse post! :P

hottapole

iTrader: (2)

wat is the recommended discharging rate for stick packs?

Deznuts05

iTrader: (14)

check your Pm

rccardr

iTrader: (8)

With a brand new Sport Tuned (black can) 540, you'll get maybe (maybe) 18-20 minutes of run time, most likely with Battery #5 or #2 since they are the ones taking the most charge. The last 2-3 minutes will be noticeably slower (the car will feel flat) and the first 2-4 minutes will be much faster than the rest of your run. New motor always draws fewer amps.

Figure on two battery changes during the 45 minute Main. Should be fun!

MTX3-B

iTrader: (5)

Thanks for the input. Appreciate it.

MTX3-B

iTrader: (5)

rccardr,

data recorded (average amp) on my much more motor master on the sport tuned motors:-

A) Quick Test - 30seconds at 7.2V

Motor #1 -1.82A; RPM=29,010 (old motor)
Motor #2 -1.56A; RPM=25,680 (bashing motor)
Motor #3 -1.94A; RPM=32,970 (slightly new)

Motor#1 gives sligtly better amp draw compared to Motor#2. But at the track, Motor#2 is faster and punchier. I suppose like what people have said, the track is best dyno

B) I tried using the CTX-Test with 6 cell setting; Numbers recorded were much lower. Don't know why.

I can only recall (if i am not mistaken) someone said that i should look at the average amp reading on CTX-Test since the Quick Test results may be slightly skewed since the motor wont be chewing the juice from the battery at that constant rate for 30s...I don't know, just my guess.

rccardr

iTrader: (8)

I use a straight motor run at 5 volts to check amp draw and RPM, as I have found that data taken at that level is a better comparator than the CTX or 7.2 volts. At 5 volts, my black cans are running around 2.35 amps and 18,750 rpm. New motors run around 15,000 rpm and 1.6 amps. A new motor typically draws fewer amps because the brushes are not fully seated, so there is a limited path through which the current can flow.

wog....supraman

iTrader: (3)

I dont like the Much More Motor Master....thats y i sold mine, like the day after i got it....RPM readings can be way off....according 2 the MM MM my mabuchi did 44,000 rpms.....mmmm i think not....whilst my 15 double could only pull 38...which isnt right again...coz @6 volts it is supposd 2 do 25900 rpm...

just my 5 cents, as we dont have 2 cents here in Australia!

rccardr

iTrader: (8)

Yep, both the MM Motor Master and Orion MPM need to have therubber bushing on the side of the case modified to accept the larger output shaft snout on the Mabuchi/Johnson case. Otherwise the sending unit and receiver won't communicate properly and the readout will be double, half, or 1.5 times actual rpm.

MTX3-B

iTrader: (5)

Many thanks.

MTX3-B

iTrader: (5)

Agreed. Gave up on the rubber bushing. i had replaced mine and it kept getting rubbed by the rotating shaft of the motor. In the end, I gave up. I am only interested to know about the amp draw of the motors. But MM Motor Master is a spledid toy to fiddle with during my spare time