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Opinion for using Lower kv motor/6s or higher mah 4s?

Opinion for using Lower kv motor/6s or higher mah 4s?

Old 06-18-2010, 05:44 PM
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Originally Posted by unsp0ken
well that's the thing... you need much less mah when you're running 6S setups so you'll be even lighter, not heavier. people are using as low as 6S 2200MAH batts in buggies for 10 min runs. look up the weight. it's definitely lighter than your 5000MAH 4S. your point would make sense if we tried to run 6S 5000 packs, but almost no one does that.
They shouldn't be running 2200mah packs!

Even if they have a 40C 6s 2200, that's only able to deliver 88amps. This is why lipo fires in 1/8e happen -- people don't understand the electrical principals involved and just blindly use what works for others on the internet or at the track.

The current your motor draws is based on the voltage in the system and internal resistance of the stator under normal load. Let's take the castle 2650 motor I have -- it is rated at 120 amps continuous and they blatantly state that the motor is designed for 4s. Let's consult ohms law and calculate what the internal resistance under their load was (at 16.8 volts, a fully charged 4s lipo).



From the above ohms law wheel, you can see that resistance is v/i, which in my case is 16.8/120 = .14 ohms. Take that known resistance under load and plug it back in with a higher voltage to find what current it would be drawing -- that would be I = v/r. At 6s fully charged, that is 25.2/.14 = 180 amps. If they used a 6s battery for a motor rated at 120 amps continuous @ 4s, it would need to be a 40c continuously rated 4500mah pack to provide 180 amps @ 6s.

The folks that run 6s 2200 packs should be very careful. If they have a 40c, to be safe, they need a motor that is rated at 88 amps @ 6s, or a motor that is rated at ~60 amps @ 4s.

Wayne
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Old 06-18-2010, 06:32 PM
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Originally Posted by Razathorn
They shouldn't be running 2200mah packs!

Even if they have a 40C 6s 2200, that's only able to deliver 88amps. This is why lipo fires in 1/8e happen -- people don't understand the electrical principals involved and just blindly use what works for others on the internet or at the track.

The current your motor draws is based on the voltage in the system and internal resistance of the stator under normal load. Let's take the castle 2650 motor I have -- it is rated at 120 amps continuous and they blatantly state that the motor is designed for 4s. Let's consult ohms law and calculate what the internal resistance under their load was (at 16.8 volts, a fully charged 4s lipo).



From the above ohms law wheel, you can see that resistance is v/i, which in my case is 16.8/120 = .14 ohms. Take that known resistance under load and plug it back in with a higher voltage to find what current it would be drawing -- that would be I = v/r. At 6s fully charged, that is 25.2/.14 = 180 amps. If they used a 6s battery for a motor rated at 120 amps continuous @ 4s, it would need to be a 40c continuously rated 4500mah pack to provide 180 amps @ 6s.

The folks that run 6s 2200 packs should be very careful. If they have a 40c, to be safe, they need a motor that is rated at 88 amps @ 6s, or a motor that is rated at ~60 amps @ 4s.

Wayne
LOL .

ok i'm not even gonna take the time to counter that argument.
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Old 06-18-2010, 07:09 PM
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Originally Posted by unsp0ken
LOL .

ok i'm not even gonna take the time to counter that argument.
Hahahahahahaha oh come on!
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