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  #16  
Old 07-16-2006, 11:33 PM
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Unhappy

I have MSN messenger on this pc (work) but all outbound connections are blocked from here except http and https
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  #17  
Old 07-16-2006, 11:39 PM
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Then if your like me you need to stay away from the coffee, lol.
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  #18  
Old 07-17-2006, 07:42 AM
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I did some more measurements tonight with the other packs (again all tests are wheels-in-the-air). This time I extended the run times to 20 seconds - mostly so I could see what the cells did over a period of high load.

Overall the GP1100's fared ok (better than last time although I can't explain why). The SC1700's were fine and dandy (although not enough cells to be fun) and the LiPo caused a very small thermonuclear meltdown inside the ESC.

I need a higher current ESC I think... Anyone heard anything good about the bigger Mamba escs?

GP1100 x 9
- voltage fully charged (unloaded) : 12.12V
- voltage @ full throttle (20 sec) : 9.6V
- unloaded voltage after 20 sec run : 11.63V
- ESC temp after 20 sec run : 60C
- current draw @ full throttle: 20A
- est. speed (from venom meter) 85 km/h
- glitch? : not as bad as when i did the first set of measurements for some reason but still present. Only difference this time is that the pack was seperated from the car so the electronics were a good 3 inches away.

SC1700 x 6
- voltage fully charged (unloaded) : 7.74V
- voltage @ full throttle (20 sec) : 7.02V
- unloaded voltage after 20 sec run : 7.46V
- ESC temp after 20 sec run : 33C
- current draw @ full throttle: 15A
- est. speed (from venom meter) 62 km/h
- glitch? : no

3S Lipo 1800MAh
- voltage fully charged (unloaded) : 12.46V
- voltage @ full throttle (20 sec) : 11V
- unloaded voltage after 20 sec run : 12.23V
- ESC temp after 20 sec run : 98C
- current draw @ full throttle: ??A
- est. speed (from venom meter) ??km/h
- glitch? : not unless you count a meltdown


I ran into some trouble with the LiPo pack this time - because i was testing over 20 sec rather than 10 sec (like the last set). I wasn't monitoring the ESC temp during the run - just measuring it after so this last test was cut short after I smelled smoke (and the ESC insulation started visibly smouldering). It would seem that 10 seconds was about the maximum amount of time the ESC would tolerate the load from the lipo/400 combo.... Talk about finding out the hard way.

The temp reading was taken a little late too - allow for about 20 seconds cool-down (and a lot of swearing) before I had the presence of mind to point the temp gun at it.

I pulled the power immediately at that point so I didn't get a chance to do a current reading or check the RPM from the venom meter. Since the VSM is basically an RPM guage with a multiplier on it, though I calculate the measurement at around 97km/h (8km/h per volt as consistent with the other two measurements).

At that point I unplugged everything and set it aside to cool down -- fingers crossed it still works (I'm working up the courage to try it again).

soooo..... i have no idea why the 1100 pack ran nicer today since nothing else about the car has changed. I've got it on a discharge cycle as I type this to see what the cell voltages are when discharged... maybe that will tell me something?

The run with the LiPo pack was a frightening thing to behold. Smoke aside, all 4 wheels were ballooning to about 150% of their usual diameter with the high rpm and the noise was pretty amazing. I think next time I'd prefer not to be holding it in my hand - I had visions of trying to explain to a surgeon why there was a 20T pinion embedded 3 inches into my face.
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  #19  
Old 07-17-2006, 06:14 PM
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Glad to see that no damage was done.....How new are the Gp's by the way......did you at least cycle them 5 times before you used it.
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  #20  
Old 07-17-2006, 07:09 PM
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we never cycled the batteries - I only read about this practice a week ago actually... The cells themselves are probably the best part of a year old but they've only been used on a track (say) 5 times? (this is a testament to how little time we get to play with toys these days!)
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  #21  
Old 07-17-2006, 07:49 PM
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Just remember that when the batts come from cold storage like yours....you should always charge them back up and discharge them again....repeat the cycle a few more times and you will notice the battery pack will be brand new again. And when the you know the battery pack will not be used you should always charge them up fully.
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  #22  
Old 07-17-2006, 07:50 PM
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toasty esc. if its ok. cheapest option would be to put a mamba motor in there now.

Sounds like if we want to run the rcer motor, we'd need to put a new esc and lipo in there

Quark 33a ESC

Might be worth an enquiry about this little esc if the mamba is toast
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  #23  
Old 07-17-2006, 07:54 PM
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that esc should handle the 400 bl motor since its rated for 33amps........its suppose to be guaranteed not to cog as well.....i know some users on Half eight that have that combo....and i hear nothing but praise....must be that good.
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  #24  
Old 07-17-2006, 09:54 PM
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i was briefly contemplating the Mamba Max.. rated to 100A and will take a 540.

I'm a bit reluctant to give up on the Mamba purely cos I have the programming cable (and it's that cool).

pricey though - what are the quark ones worth?
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  #25  
Old 07-17-2006, 09:59 PM
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you can still use it....just put it in a different model.....dont know where you can find one.......but im sure other members will also help out as well.
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  #26  
Old 07-19-2006, 11:52 AM
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22 amp with the car in the air is a lot !

Take a look at the Graupner Genius models, nice small ESC's.
But you are sure the motor is OK, not one of the coils is damaged ?

I am running a BK-Warrior 7020 on my Lehner 1020 motor and the pushed/matched GP1100 cells can handle it easy running it with 30+ amps up to 100+ km/h
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  #27  
Old 07-31-2006, 02:57 AM
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How would I check for a damaged motor coil? You're the second person to suggest that as a possibility... It does *feel* a little stiff to turn but without something to compare against it's a bit hard to tell what's normal.

I sent the (now destroyed) Mamba esc back to Castle for repair...

How did your GP1100's fare as far as voltage drop goes? At around a 20A draw mine got pounded down to less than 1V per cell on a fresh set.
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  #28  
Old 07-31-2006, 06:49 AM
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My only suggestion would be to send the motor in for repair.....the motor shaft should spin freely by hand....and if you say it will not do that then something in the inside of the motor has gone bad.
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  #29  
Old 07-31-2006, 10:34 AM
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If you have a digital resistance meter (most digital V/A meter has it) you can meassure the resistance between 2 wires. There are 3 different meassurements possible and compare them. All 3 should be the same.

I did not meassure the voltage drop of my cells but did choose for the pushed/matched ones because they have a higher voltage and a lower resistance so a lower voltage drop an a high rating current
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  #30  
Old 08-01-2006, 07:03 AM
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Just tried measuring resistance... i don't know if it's my meter but i found it difficult to get a reading. Looked like all 3 combinations of 2 wires had around 0.1 ohms resistance (i say "looked like" as the measurement would drop off to zero after a couple of seconds)

I took a quick look online and that figure seems to be about right

(link)

Sounds like i just need a beefier ESC to make this thing work. I might get the Mamba repaired and sell it I think.
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