Questions about BL stuff.

[thecrusader]

Hey everyone-
I was thinking a Lehner 1940, 10 turn Hi-Amp for my Maxx project. Is this a good idea? Also, I was thinking about a BK controller, do they have LVC for lipos or should I buy an MGM. How hard is the MGM to program. The BK seems very easy to program and user friendly, as far as that type of thing goes.
Thanks in advance
Paco

[Patrick]

Lehner 1940's are good motors for an e-maxx. But as for the 10 turn, it depends on what sort of comprimise you want between performance and runtime and what sort of voltage you're going to run it on.
If you're running 12 cells nimh or 4s lipo and want some decent speed I would get a 7 turn, but for 5s or 6s, a 10 turn should work pretty well.
30,000-35,000 rpm is usually how fast you want your motor to be able to spin in an e-maxx for good speed without too much heat.

I don't own or know much about the MGM and BK, but I've heard the MGM is hard to program and that the BK does'nt have a LVC built in, but you can buy LVC's by themselves to use with it.

The Lehners are indeed nice motors and I've wanted one for a long time, but they are hard to get right now. For a truck and 4S lipo (or the nimh equivalent), I'd go for the 1940/8. For 5S lipo, I'd go for the 1940/9. You could just always go for the 1940/8 and run it on 5S when you want to get stupid.

As for the controllers, yes you have choices and each has its pros and cons.

The Quark is probably the reigning king of controllers. I too have been in the market for a better controller and have done a bit of research. The Quarks are know for being very smooth and will handle up to 5S lipo as well as any two or four pole motors. The downside is that they run hot and do need a heatsink and perhaps a fan to stay cool.

The MGM Compro is reputedly a good controller also. It will do up to 5S lipo, runs cool without a fan or extra heat sink, and will run two and four pole motors. It just isn't as smooth as the Quark, although I never saw mine cog with any setup that I had. The programming isn't difficult either. It just takes a bit of getting used to. I had it within 10 minutes. Unfortunately, I believe that I got a defective unit and had to send it in. I'm still waiting to get it back before I make any final judgments.

The BK controllers are very simple. There is almost nothing to program. I found that running it was very abrupt. I mean, there was no easing into the throttle. One second it wasn't moving and the next it was hauling butt. Ours fried within 30 minutes of installing it, but I do have to admit that it was a part of a kit that we got from FineDesign and the esc/motor combo that he sent us was likely not a good combo.

Knowing what I know now, I'd get the Quark and deal with the heat.

[BrianG]

I've only used the MM, BK 12020, and the Quark and like the Quark much better out of the three. Yes, it will heat up a bit, but strategic use of an added heatsink helps tremendously. Any heatsink will work - it just depends on your layout. I don't use fans and the temps are always good at ~130 at the very highest. As AAngel pointed out, they are silky smooth running. Cog free even at very low rpms even with a decent load like uphill or going over small obstacles. They can also run outrunners as well as inrunners (with a programming change)

[thecrusader]

Hey guys, thanks for the info so far. From what I understand, a motor with more winds offers better runtime and more torque. Why are you recommending motors with lower winds? I plan on running 16 nimh cells for now and eventually some li-poly batteries at some point. From what you guys have told me I think I have settled on an 8t high amp. I'm still kind of confused here though, can yall shed some light?

[BrianG]

Well, you pick a motor that will run at a maximum of ~35000rpm with the battery voltage you are using. For 16 cells, you need a motor with a kv of around 1800. The 9XL or equivalent is a good choice. You can always use a motor with a higher wind, like a 12XL, but then the top speed won't be as high. Sure, you can gear up, but you'll start stressing the ESC and batts.

Please understand that I've only been doing the 1/8 scale thing for a few months now, but have built five conversions and have done a lot of experimenting. Thank goodness for inexpensive motors like the Feigaos which allow for all of that experimenting.

I've found that with larger vehicles, like trucks and even 1/8 scale buggies, rpms are something that you want to avoid. Keeping rpms relatively low, keeps the motor in its best efficiency range thereby avoiding unwanted heat. You can usually make up for the lower rpms by running more gear to get to the speed that you want. Once you find the proper setup for your vehicle and power source, you'll have lots of trouble free running ahead of you.

Right now, I'm running an 8XL on 5S lipo in my Muggy (which is a big heavy truck) and it's fast enough to be considered stupid for a monster truck and the torque is unbelieveable. I took mine to a party thrown by the owner of my LHS this past weekend. He's been in and around RC for over 20 years and when he saw my Muggy run, he said that he'd never seen anything like it before in his life. He gave me a Losi 8ight T to convert for him.

If you go with the 10T motor, I think that you might be a bit disappointed with the top speed, although the torque is going to be rediculous. I think that in a heavy maxx, a 9T would be a good solid conservative motor with pretty good top speed and more than enough torque to sling shot you out of holes. If you go with the 8T, it'll get pretty stupid. I've ordered a 9XL for my truck. The 8XL is plenty of fun, but just going fast isn't as much fun as it was when I first put it together.

[Patrick]

I didn't know what voltage you were going to use, so assumed 4s or 12 cells. That's why I suggested a 7t, but for 16 cells I would say the 9t. An 8t would work, but you might have a problem with heat (I'd be more worried about heat in the Quark [if you get the Quark] than the Lenher) and run time depending how you drive it.
The 10t would work too, but top end won't be that great unless you gear it up a fair bit.
The 9t would probably be a good balance, but it just depends how your going to use your car and what you want it to do to decide which motor to get.

[thecrusader]

Originally Posted by AAngel

I think that in a heavy maxx, a 9T would be a good solid conservative motor with pretty good top speed and more than enough torque to sling shot you out of holes. If you go with the 8T, it'll get pretty stupid.

You guys are giving me lots of great info. I'm going to go with the quark controller and a 1940 9t. Wanna get good runtime, and some pretty decent top speed. TORQUE! I'm not worried about heat out of the quark, I plan to make a custom heatsink for it(I'm a machinist)with 2 35mm fans. HEHE.

How do you know you have the proper gearing for a given setup, can you monitor this through motor/controller temps?