Brushless help please

[Feight]

Hi, I posted my thread in the electrics section when I had intended to post it in this section.
Probably the result of a lack of sleep and way too much coffee.

http://www.oople.com/forums/showthread.php?t=37870

I'm quite tempted by the tekin, it's one of the two systems I've really been looking at, the MMM is the other that floats my boat.
I was just thinking that I'd probably need to cram 4s under the shell to make 1700kv be worthwhile.

[Marvin]

1700KV is primarily a 5S motor.

You are under the misconception that 4S is bigger than 3S - only so if you just add an extra cell. Taking a 3S pack and a 4S pack that have the same power, one should be no bigger than the other. A 3S 6600mAh pack has the same power as a 4S 4950mAh pack. They should offer the same run time when combined with an appropriate motor and gearing.

In fact, a higher voltage set-up will give a higher efficiency, assuming that the two set-ups are geared for the same speed, therefore the higher voltage will give a slightly longer run time. This is why you run lower KV motors on higher voltages, and higher KV motors on lower voltages, to achieve approximately the same overall motor RPM, then use the same gearing to get, say, 40mph. They use the same power as each other - the same job is being done. However, the equation Power = Current x Voltage, shows us that the higher voltage results in lower current, which means less heat, and therefore higher efficiency - less power is wasted. Therefore, the lower voltage set-up will use a tiny bit more power - and so the run time will be longer with the higher voltage.

Have a read of the guide, then I'll help with anything you don't understand, or have problems with.

The Tekin is fine, as is the MMM. For higher voltages (5S, 6S) definately go with the Tekin, for lower voltages (3S) go with the MMM. The lines fade with 4S, and either will do nicely - though the Tekin may just have the edge - but it is more expensive and the motors are more fragile. Conversely - the MMM's case is poor as it may split unless braced, and the fans are weak.

[ek9russ]

Where is the best place to get the Tekin systems from? Are Much More Racing distributing them in the UK?

Thanks

[JonyNitro]

Aswell as fusion hobbies, But if i was you I would buy from RC monster, if you are getting the tekin combo, maybe the 1900 combo, then get the hot wire, and still have money left over after import duties, and anyway it is only warranted for 120 days after purchase, but still can send it away? if anything does happen

[jamiekerr14]

Have a tekin RX8 1700Kv combo in the for sale section for cheap and hotwire!

[Feight]

I first read your guide a few days ago and I keep coming back to it. It's what's been making me think 4s is a much better option. But I wasn't sure I had the space under the body for it, but I've had a play with some cardboard and a ruler. I've got options

I had originally thought that the 2500kv would be the best option for a 3s setup.
I've been told by some that it's too much and by others that it's too little.
The problem I was having was most of the higher kv motors I could find had small shafts.

Anyway as 4s is on I'm thinking the 2050kv is a good option.

The only reason I asked about the 1700kv is because I'm eyeing up Jamie's system. Might have to go for it and replace the motor