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Old 07-28-2014, 03:29 PM   #46
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Does anyone compare the wattage rating of Lipos?
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Old 07-28-2014, 03:52 PM   #47
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"I've seen mod oval cars able to dump a 7000 1s pack in 3 minutes. Do that math and you'll see some serious amp draw numbers."

So thats 350 amps avg in 3 minutes.

If you figure a good 3.5 turn is what 750-800 watts?

Divide that by the low voltage of 1s and taking into account the immense heat and loss of efficiency, its possible to see an avg. amp draw approaching 350.

Oval is constant throttle more or less isn't it?
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Old 07-28-2014, 04:09 PM   #48
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I doubt that 3.5t motors were designed to run at 3.7 volts... No wonder the amps get so high, but until these lipo manufacturers figure out a way to standardize their product and test each of the packs that come out of their mills, with numbers printed on them like the Nimh packs, then we will always have those packs of the week discussions... I'd rather invest in supercapacitors to boost lipo performance instead !!!!
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Old 07-28-2014, 04:09 PM   #49
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Wouldn't that be 140 amps average for a 7Ah dump in 3 minutes? Just like EA said?

3 minutes = 20C.

Even some off road dirt cars average around 50 amps, struggle to run 10 minutes if that with the best 2S packs. Peaks over 150 amps.

We have some amazing amounts of power available these days.
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Old 07-28-2014, 04:46 PM   #50
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Quote:
Originally Posted by d16dcoe45 View Post
"I've seen mod oval cars able to dump a 7000 1s pack in 3 minutes. Do that math and you'll see some serious amp draw numbers."

So thats 350 amps avg in 3 minutes.

If you figure a good 3.5 turn is what 750-800 watts?

Divide that by the low voltage of 1s and taking into account the immense heat and loss of efficiency, its possible to see an avg. amp draw approaching 350.

Oval is constant throttle more or less isn't it?
ummm i think your math is off...
7000mah =7a for 1hr
7ah=7a for 60 min
still with me?
7a x60min = 420a for 1min to dump a 7000mah pack
so 420a 3min is ?
140a avg load over a 3min run
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Old 07-28-2014, 04:56 PM   #51
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Quote:
Originally Posted by jlfx car audio View Post
ummm i think your math is off...
7000mah =7a for 1hr
7ah=7a for 60 min
still with me?
7a x60min = 420a for 1min to dump a 7000mah pack
so 420a 3min is ?
140a avg load over a 3min run
You are right, 140 avg. My mistake. Common sense should have told me that a 350 a avg would cook any RC connector and melt solder. I could imagine even 140 avg hurting some components too!
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Old 07-28-2014, 05:01 PM   #52
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Its ok i have done it many times . Lol
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Old 07-28-2014, 05:04 PM   #53
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Guys, stop living in the past... Graphene Supercapacitors in parallel with lipo packs are the future... No need to waist time figuring out which battery is better anymore...

Last edited by bertrandsv87; 07-28-2014 at 08:29 PM.
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Old 07-28-2014, 05:05 PM   #54
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Quote:
Originally Posted by d16dcoe45 View Post
"I've seen mod oval cars able to dump a 7000 1s pack in 3 minutes. Do that math and you'll see some serious amp draw numbers."

So thats 350 amps avg in 3 minutes.

If you figure a good 3.5 turn is what 750-800 watts?

Divide that by the low voltage of 1s and taking into account the immense heat and loss of efficiency, its possible to see an avg. amp draw approaching 350.

Oval is constant throttle more or less isn't it?
We did some test with a 3.5T measuring current draw. We found the peak current draw was about 220A.

140A constant over 3 minutes is impressive for the Lipo they certainly get warm with 50A constant load.

What size wire and connections are they using? I am amazed wires and connections don't melt.
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Old 07-28-2014, 09:20 PM   #55
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Guys who were using cheap bullets and wire were having issues melting the negative bullet off the battery wire. Most switched to 10 gauge wire. The batteries would come off around 150-170 degrees after a run (After they figured out the motor setup and ran 4 minute races). Some brands were swelling badly some were not.

To answer someone elses question the mod guys were getting around a 100x42 track in 3.0 seconds. The lift in the corner is for a spit second really! So it may as well be wide open!

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Old 07-28-2014, 10:02 PM   #56
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That is impressive.
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