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Old 03-09-2009, 08:28 AM   #1
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Default For a 1/8th scale conversion is it worth using 3S or 4S Lipo over 2S?

For a 1/8th scale conversion is it worth using 3S or 4S Lipo over 2S? If so what are the advantages and disadvantages? Im planning on using a mamba set up but if temps can be an issue with higher voltage even in the mamba I wouldnt mind sticking with just 7.4V.
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Old 03-09-2009, 08:39 AM   #2
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In general you are better off with higher voltage and a lower KV motor because the whole system should run cooler and more efficient. I have saw a guy run a Mamba Max and a 4S with an 1/8th scale motor in his buggy and do quite well as far as temps go. You could run two 2S in series to make a 4S system if you wanted to. I ran the Novak 6.5 HV system last year in my Truggy using 3S and it ran all right but it got a little warmer than I wanted, so I am switching to a 5S or 6S system this year to get it to run a little cooler and a little more efficient.
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Old 03-09-2009, 08:54 AM   #3
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Oh ok, that does make sense to get a lower kv motor and up the voltage. As far as runtime and speeds wats the difference between a 2S and say a 5S?
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Old 03-09-2009, 09:10 AM   #4
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I have not run a 5S yet, I am waiting to get my new Tekin RX8 and T8 motor which probably won't be until the end of the month since that's the projected release of them. Are you asking what would be the difference in running the 2S on the same K/V motor as the 5S?
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Old 03-09-2009, 09:13 AM   #5
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yes
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Old 03-09-2009, 09:22 AM   #6
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Well I am not 100% sure on the amount of time but I think there would be a significant difference in run times, if you use say a 5000mah 2S and a 5000mah 5S, the 5S should run much longer. The only thing is it would not be a good comparison on the same motor. If you use a high K/V motor it will probably get rather warm and probably thermal on 2S because of the weight of an 1/8th scale unless you ran really low gearing and even then I am not sure, or if you ran a low K/V motor it would be really sluggish on 2S. If you ran that 5S on the high K/V motor that thing would be ballistic, if you are just looking for speed runs this would be ok, but for racing you would want the lower K/V motor. I run the Tekno setup and use the clutch on my truggy they say that you want to keep the electric motor relatively the same RPM as a nitro engine, so 30,000-34,000 rpms roughly.
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Old 03-09-2009, 09:55 AM   #7
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If you want at least some power without overheating, 3s is the absolute minimum you should do. As far as 2s and 4s on the same kv motor, theoretically 4s will have twice the power/speed as 2s but the point of using higher voltages is to lower the amp draw. Using a 2s pack with a 4000kv motor and 4s with a 2000kv motor will produce similar power, but to get that power the 2s pack will have to dump twice the current. This can be detrimental to the pack as most 4s setups already draw spikes over 150 amps.
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Old 03-09-2009, 10:09 AM   #8
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the stuff is designed to operate in a certain range. If you are running it at 250 amps and 7.4 volts instead of 125 amps and 14.8 volts it could damage it if it is designed for 150 amps & 14.8 volts. The total power is not everything in the equation.
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Old 03-09-2009, 10:16 AM   #9
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So then whats the best esc/motor combo for two (2) 6500mah 30c 2S Lipos?
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Old 03-09-2009, 10:28 AM   #10
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Quote:
Originally Posted by RaV3N View Post
So then whats the best esc/motor combo for two (2) 6500mah 30c 2S Lipos?
Are you asking for Brand Name preference or Kv rating? Are you racing or just bashing? Do you have a projected run time you want to hit? What vehicle are you putting this in?

You'll be able to tailor make this setup for your situation.
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Old 03-09-2009, 10:35 AM   #11
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Well I want to put those batteries in a 1/8th scale buggy or truggy and im aiming for a 30min runtime, which one of those batteies on a novak set up already gets 35min runtime.
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Old 03-09-2009, 10:39 AM   #12
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Quote:
Originally Posted by RaV3N View Post
Well I want to put those batteries in a 1/8th scale buggy or truggy and im aiming for a 30min runtime, which one of those batteies on a novak set up already gets 35min runtime.


have you read the conversion thread yet? you should do that if you think 2s will work in a 8th buggy conversion before you spend any money.
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Old 03-09-2009, 10:55 AM   #13
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Well I want to put those batteries in a 1/8th scale buggy or truggy and im aiming for a 30min runtime, which one of those batteies on a novak set up already gets 35min runtime.
Neither. You would need a pair of 8000 mah packs(making it VERY HEAVY), or to run it really slow to make 30 minutes. For example. When I run my 8ight E with a 2100 kv motor on a 4S 5000 mah pack, I get a little over 20 minutes of run time(that's running smooth consistent laps and not using the brake as much). With the 2200 kv system in my Jammin truggy, using the same battery, I can barely make 15 minutes if I really sand bag. Most of the time I get about 12 minutes.

The track you run on and the way you drive can make a huge difference too.
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Old 03-09-2009, 11:26 AM   #14
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Oh so then im better off sticking to the smaller scale single battery configuration for longer runtimes then??
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Old 03-09-2009, 11:41 AM   #15
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looking for 30 minute runtimes consistently regardless of track conditions is going to be pushing it. What I am seeing is that tighter track conditions lend to less pack being used, and more runtime being acheived. really open tracks can burn through a pack at a quicker rate for sure.

You best bet may be to plan for a battery swap and work out the details with the nitro guys as far as if you need to pit or not if doing a swap.

Now based on this, with a 4S setup, you should look into a motor KV range in the low 2000Kv range. I currently run a Neu 1512 2.5D motor in my RC8 combined with a 4S 6000mah lipo, and it feels right. great power, but very controllable.

I ran 2200Kv Mamba Monster setup in my truggy and it has loads of power there.
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