Motor Help

I need help. I have a hyper 7 with a mm speed control. I have two 5000 4s trues rc lipos and an 8000 4s true rc lipo. I had a feiago 7xl that I fried yesterday. My question is this, My buggy will see track duty mostly. My track that I race at has a fairly technical setup and the straight is 110 feet. The problem is the main is 30-35 minutes long!!!!! I need help in finding the right motor to run this long and be reliable, any suggestions?

Here is a link to the track.

http://hobbiesextreme.com/7.html

[BrianG]

Normally, I'd say to go up on the voltage to something like 6s and get a 10XL to reduce current, but the MM limits your voltage options. 4s is about the highest you can go (although some people can get 5s to work). The only other way is to get higher capacity batteries. Or, if you can give up a little top speed, you can gear down.

Sometimes, it helps to reduce the start power in the ESC. The initial take-off and instant acceleration pulls a lot of current, and if you can limit this somewhat, your runtime will increase.

A 35 minute main may be tough to hit. You could simply pit once to swap out batteries. To make things faster, come up with a battery release system and a way to swap them without taking the body off so battery swap is quick. Nitros have to pit approx every ten minutes, so that should make up for the battery swap time.

I am not opposed to doing a pit stop and a battery change, but I am looking for a motor that can handle that kind of long time abuse. Brian aren't you using a neu 1512 2d. Is that too much motor for my needs? Would a feiago 8,9, or 10 xl work? Would a neu motor 1512 2.5d or 1515 1y be a good choice?

[BrianG]

Yeah, I'm using that motor and it works very well.

The trouble with Feigaos is that they tend to heat up over time more than a higher quality motor. The 1512 is very fast and I can run VERY long and keep the temps at or under 130*, even geared high. Given my experience with the 1512 and the power/speed it has, I think a 1515 would be overkill.

So You are recommeding a neu 1512 2d for my setup amd the rigors of the track I race at.

[BrianG]

Yeah, I would go for a higher-end motor if you can swing the price tag.

I get about 40 minutes of runtime on 4s 8Ah Maxamps packs last time I checked - and just ask glassdoctor, I'm not gentle on the throttle! However, this was when geared 46/16, which is quite high (~50mph top speed). 46/12 or 46/13 would be a much better choice for track use and would increase runtime, yet still get decent speed (~35mph). I would say changing my gearing would get me another 5 minutes of runtime. If so, that equates to ~10.5A average amp draw. With 4s 5Ah, that would give close to 30 minutes. Of course, your 4s1p 5Ah pack is lighter than my 4s2p 8Ah pack, so your runtime should be even better.

So, I would say to upgrade to a Neu 1512 2d or 2.5d, run your 4s 5Ah pack, gear 46/12 for the 2d or 46/14 for the 2.5d, lighten up the vehicle where possible, and reduce your start power/increase punch control. This should extend your runtime and keep everything cool. Of course, there will be some trial and error to get the speed/runtime/punch combination the way you want, but you might be able to squeeze the full 35 minutes on one pack.

[bdebde]

I would say there is likely no way to get 35 min on a 5000 mah pack. I think you will need more mah or a battery swap pit stop. I run a light buggy with a lehner 1930, and I can barely squeeze 30 min out of a 5000 mah pack.

[Cain]

great info already here. Seems the concensus is that the 2.5D is a fuel sipper!

I have a question related to this, why does the 2D draw close to near the same amps as the 1.5D? looking on impakRC or whatever its called, the 2.5D is like 75Amps or so, then the 2D and 1.5D are in the 120s.

Exactly how does this affect runtime.

Brian,

Thanks for all of the help, I appreciate your shared knowledge. I am now looking for one of those two motors, any idea where I can find one?

[BrianG]

Cain: It's all but impossible to compare the amp draw of different motors because there are so many variables to consider. But if you have two identical vehicles (gearing, weight, voltage, etc), a lower kv motor will pull less current, but at the expense of speed.

cobrawes: I don't know where to find a motor at the moment. Your best bet would be to contact Mike and ask him directly...

Thanks,

Will do. By the way I do hav an 8000mah 4s lipo that should get me the 30 minutes, but it is a little heavy. By the way I found a 1512 2d. can't find a 1512 2.5 d

[BrianG]

Yes, it should. I get over 30 minutes and I'm geared high. Gear to 46/12 and you should be at or over 40 minutes. Still use the punch control and start power to help reduce the initial high currents for even better runtime. I can't guarantee anything, because runtime also depends on drive style and terrain, but you should be at your 35 minute goal. You'd have to run it and see...

[Cain]

The 2D is not a bad choice I am hearing. You may just want to pick it up since the motors are so rare.

Heck, if you don't like it, I'll could swap my 2.5D with ya if you want or you could just buy it from me.


Brian: Thanks for the info, I really appreciate it!

Found a couple of neu's one has a smooth can, will that be a problem in regards to heat?

no, fins are more of a gimmick honestly. Some help, some dont....