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SpEEdyBL
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05.04.2008, 02:32 AM

That doesn't explain why 6s wont be enough. All your saying is that 12s is better than 6s, while you don't prove how much of an advantage there actually is (where is your actual data?) Not everyone is trying to break the land speed record with a monster truck. I would be more concerned about lipo failures than having a setup that runs 20 degrees cooler than what is already acceptable. The more cells there are in a pack, the more vunerable the cells are to undervoltage, since a weak cell has to go way below the safe limit before the mean voltage of the cells in the pack triggers the cutoff.


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azjc
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05.04.2008, 02:52 AM

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Originally Posted by SpEEdyBL View Post
That doesn't explain why 6s wont be enough. All your saying is that 12s is better than 6s, while you don't prove how much of an advantage there actually is (where is your actual data?) Not everyone is trying to break the land speed record with a monster truck. I would be more concerned about lipo failures than having a setup that runs 20 degrees cooler than what is already acceptable. The more cells there are in a pack, the more vunerable the cells are to undervoltage, since a weak cell has to go way below the safe limit before the mean voltage of the cells in the pack triggers the cutoff.

With higher voltage you can run a lower KV motor and this setup will pull less amps meaning less heat than a lower voltage and higher KV motor, and since your motor is pulling less amps with the higher voltage setup you can run a lower capacity pack to get the same runtimes. Your motor will pull a certain amount of watts all the time, Volts X Amps = Watts, the average 1515 or XL size BL motor will pull 1500 watts, if you want to compare different setups you can divide the 1500 by the voltage amounts and this will get you in the ball park there are other variables Gearing, weight of vehicle, wheel size.

Last edited by azjc; 05.04.2008 at 03:13 AM.
   
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lutach
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05.04.2008, 03:15 AM

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Originally Posted by azjc View Post
With higher voltage you can run a lower KV motor and this setup will pull less amps meaning less heat than a lower voltage and higher KV motor, and since your motor is pulling less amps with the higher voltage setup you can run a lower capacity pack to get the same runtimes. Your motor will pull a certain amount of watts all the time, Volts X Amps = Watts, the average 1515 or XL size BL motor will pull 1500 watts, if you want to compare different setups you can divide the 1500 by the voltage amounts and this will get you in the ball, park there are other variables Gearing, weight of vehicle, wheel size.
Right on. Plus the lower Kv motor will have more torque. This concept is true with brushed and brushless. The more turns you have the higher the torque. The less turn the higher the Kv. Most people usually runs HV for speed runs mainly because of the added bonus the HV provides for high speed runs. If one has a 100A 12S controller and he runs at the AMP limit, he'll be getting over 4000 watts of power. Now if he wants to race and changes the gearing for around 40mph, I'll bet he'll only see spikes of maybe 80A and only on hard acceleration, but he will average around 20A or so instead of 50A+ with less voltage.
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lutach
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05.04.2008, 03:09 AM

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Originally Posted by SpEEdyBL View Post
That doesn't explain why 6s wont be enough. All your saying is that 12s is better than 6s, while you don't prove how much of an advantage there actually is (where is your actual data?) Not everyone is trying to break the land speed record with a monster truck. I would be more concerned about lipo failures than having a setup that runs 20 degrees cooler than what is already acceptable. The more cells there are in a pack, the more vunerable the cells are to undervoltage, since a weak cell has to go way below the safe limit before the mean voltage of the cells in the pack triggers the cutoff.
I can't prove to anyone who hasn't done a efficient HV set up yet. I ran my 1521/1.5Y with 10S lipos geared the same as my 1521/1Y and everything ran just warm. Now with the 1521/1Y on 6S everything runs much warmer. You have things mixed up and it shows that you have never ran anything above 6S. You still think only because one wants 12S he'll be trying to set a record. How can I set a record on 10S with a 1521/1.5Y since the unloaded RPM is 38850. I ran my 1521/1Y with 10S and it was awesome, but that motor is at it's best with my 6S and it's unloaded RPM is 35009. Now with 10S on the 1521/1Y I saw spikes of 169A, but after 9 minutes of running the truck the average was only 10A and I only used 1685mAh out of 4600mAh. I haven't posted data yet of the 1521/1.5Y plain simply because of me running the 1521/1Y with my 6S packs that I'm trying to get as many cycles as I can to test how good they are. If you want I can give you some data of my 1521/1.5Y on 10S in a couple of days. Lipo failure are most common by users not following simple rules. Good lipos hardly fail under the right conditions. The only lipos that I had that failed under the right conditions was my MA packs. All the others were abused by me. Most people need to learn that HV is not for speed only. Ask the folks who does have a HV set up not for speed. They will tell how good things run. Some folks are even running a 55A controller on 10S and having great results. It's just simple common sense and experience with HV that proves to people how good it is.
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05.04.2008, 11:58 AM

Quote:
Originally Posted by SpEEdyBL View Post
That doesn't explain why 6s wont be enough. All your saying is that 12s is better than 6s, while you don't prove how much of an advantage there actually is (where is your actual data?) Not everyone is trying to break the land speed record with a monster truck. I would be more concerned about lipo failures than having a setup that runs 20 degrees cooler than what is already acceptable. The more cells there are in a pack, the more vunerable the cells are to undervoltage, since a weak cell has to go way below the safe limit before the mean voltage of the cells in the pack triggers the cutoff.
Ok, I will say that for most situations that 6s would be fine in a mt geared for around 40mph. Given a sytem properly setup for 6s and another that has a motor with half the kv on 12s, the 12s setup will pull half the amps that the 6s does, and produce more torque. Plus the batteries can be half the capacity and provide the same runtime (most likely more). I am sure that a expernisve motor in a hv setup will run cooler, but not so cool as to fail. Most find a feigao xl to be ineffiecent, and heat up to much, such as a 7xl on 4s. I run a 14xl on 8s lipo and it performs fine, in a heavy savage, and I use a 60amp air esc that barely gets warm. Plus I can get away with 12c lipos, my 3600 polyrc lipos only cost 120 bucks (30 each for 2s 3600 12c packs x 4). I would love to see another 120 dollar lipo compare to this setup in either 4 or 6s. The lower loads placed on the cells by a hv setup will help the cells stay in balance. High current draw is what causes cells to come out of balance. Hv just makes sense for larger,heavier vehicles. More torque, less load on the battereis, and cooler running with cheaper equipment. For me hv is the only way to get a feigao to work properly, but then they are great value!
   
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