Need help with buggy conversion
 

Hey guys,

I'm new to this forum, and I've posted a similar thread on another forum, but haven't gotten much input. It seems that you guys here are hog nuts about electric/brushless.

What got me hooked is my current parking lot truck. I'm running an RC10T4 with a Mamba Max 7700 system on 3S Lipo. I haven't seen anything yet (aside from a couple of on road cars) that can even come close to keeping up.

Anyway, I'm going to convert my Sportwerks Turmoil to brushless. I know that I want to use a Mamba Max controller, so that pretty much limits me to 4S or maybe even 5S Lipo. I think I've settled on running two 2S packs in series. I'm thinking either maxamps 4Ah packs or Apogee limn 3800 packs. Haven't settled on this yet. I might go with more capacity, but I don't think I'll go with anything more than 6Ah. I want to keep the weight down, because I intend to race this buggy against the nitros.

My big question is, which motor? L or XL can? I've been told, by a reliable source, that an XL motor will overheat if I run it without enough of a load on it. So...I've been thinking about a 9 or 10L motor (feigao that is). I'll get the same rpms/v as the 7 or 8XL motors, but with much less current draw. I'm going to be running on a track with the longest straight being 160'. I figure that 40 mph might be a good target speed to shoot for. This should keep me competitive with the nitros with the hottest engines.

Oh, am I correct in understanding that I want to keep my motor in the neighborhood of 35,000 rpms at full throttle on my power source? This is what lead me to the choice of either the 9 or 10L.

I'd appreciate any advise.

Thanks.

2 2s2p 4000mah maxamps packs will be awesome with the MM, just remember to use a UBEC.

7xl would acutally be ok, and yes, the sweet spot is anything over 28K and under 40K rpms.

More input, huh :005:. (My screen name is the same across a few forums) Read the latest post in your thread on URC. You will see some extra information there :027:.

Hey MetalMan, you know what I mean. :) You were the only one that responded to that other thread.

I was hoping that others running an 1/8 scale buggy could enlighten me.

I would recomend a Neu 1512 or 1515 and skip the L/XL altogether. :)

Shoot for a 2000kv motor and IMO it will work pretty well... L,XL,1512,1515, Lehner 1930 or 1940.... any of them.

I'm running a MM, 1512 1900kv on 4s 8000mah and it's a very nice race setup.

glassdoctor,

As much as I would like to move straight to a Neu, finances really won't allow it right now. As it is, I'm going to have to cannibalize my T4 of its MM ESC, just to get the project off of the ground. In fact, I'll likely have to run the setup on 3S Lipo for now, until I can get some 4S packs. I'm still trying to get my house rebuilt after Katrina and can't justify much of an investment in this "toy."

Anyway, I was just online at onlinemetals.com and ordered some 2.5X2.5X3/16 angle aluminum. That should be thick enough for a motor mount. I also ordered some 3/16" plate to make a replacement bracket for the top of my center diff. I'm hoping that his will be the new home for my ESC. I also ordered some 1/8" thick aluminum channel, which I hope will allow me to fashion a couple of battery trays for my lipos. I really want to protect those from damage.

As for the motor, it's looking like it's going to have to be a 10L or 7XL. I'm just not sure of which one. I understand that the XL will have more torque, but it will also draw more current, which I'm thinking will translate into more heat and less runtime. I'm figuring that the buggy is going to weigh less than 10 lbs, so maybe the 10L won't have a problem with this.

I just went out and stripped my buggy (a Sportwerks Turmoil). It isn't the greatest buggy in the world, but I can drive it and my LHS stocks the parts for it. I was considering keeping the mechanical brakes. This should relieve the motor of having to cover the braking duties. I was going to turn the diff backwards and mount the motor forward of the center diff. I was then considering using standoffs to mount a single battery tray perpendicular to the centerline of the chassis. Then I could run a single 4S Lipo pack and I think that it will still fit under the body. I hope. If I was able to do this, then I could utilize the space under the battery tray for the ESC and radio.

So guys, I need some input. Should I go with the L or XL motor? Am I wasting my time trying to keep the mechanical brakes? What about the battery on the tray on standoffs across the back?

Thanks.

IMO. The L will be enough motor, but the XL will run cooler and have a little more kick to it, so XL gets my vote. I would also say that the XL would be a better chioce to run with the Mamba Max also. I have found that the MM runs better with a 2 pole motor than it does with a 4 pole motor like the Neu. Castle is working on an update for the MM to fix that, but for now I still think the XL will be a better match.

As far as the mechanical brakes go, I think you are wasting your time. Real estate is preciuos on a buggy chassis and your buggy will not be that heavy relative to a MT and I dont hear of people having issues with the motor braking on the 11 lb revos and maxxs. So your 8.5 lb buggy should be no problem.

Hey, the Turmoil is a pretty good buggy... it can hang with the big boys on the track. I know a sponsored guy who kicked some but with one last summer.

On 3s, my gut says go with the 10L.... I don't know if I can explain? While it may not be the perfect setup I think it will run well. The motor is the cheapest part of the project... if it's not right or you kill it, then it's a relatively small loss. And it's not like a 10L won't work... it just might run a little hotter. On 3s though, it should not be as hot... and not as fast. And on 4s, you might just need to find a "happy" gear for it.

My first conversion was an 8L on 10-11 cells. I never ran it much though because that's when my Hacker controller smoked, and by the time I had another controller I had changed the whole car and modified the motor. I took the rotor from the 8L and stuck it in a C50 Hacker can.

Heh, I just went through all of this with my Hyper 7 conversion. The thread is right here:

http://www.rc-monster.com/forum/showthread.php?t=5302

A gallery of pics of the conversion is here:

http://gallery.rctrack.info/sleebus_jones/Hyper7/

I went with the 10L motor for mine, and the MM controller. I'm running 11/46 right now. With the 3S 2500mAh Apogee pack in there, my speed is right around in the 26 mph range. I have put 12 cells on it, and that puts the speed in the 34 mph range. With both of these combinations, the motor and ESC stay cool. Running 12 cells, the motor gets hotter than the ESC, so I'm going to go up a few teeth to 13/46, which will put me right at 40 mph.

As it is right now, with the 3S in there it'll spin all 4 panthers on concrete with no problem. The 12 cell is pretty silly, but it's heavy (1.6# of batteries) so I'm planning on going LiPo to shave weight and add power. I'm looking at the maxamps 4S 4000mAh pack for that.

Sleeb

I re-read your original post... so I see you will be going 4s it sounds like. I think a 10L is fine for a (relatively) light buggy, esp considering Sleebus's comments.

If you have to you can always put a sink and fan on the motor. But try it and see...

I don't want to sound wishy washy, but I was just trying to buy a motor, but all they have in the 540C is the 9L. What about that motor?

Thanks for the comments guys.

Oh, what sort of runtimes are you guys getting with your setups? I haven't settled on a particular pack configuration yet. I'm looking for that perfect compromise between weight and runtime. I was going to go with 4Ah 2S packs, but now I'm thinking that I might want to go with at least 6Ah 2S2P pakcs. I'd like to be able to run for 20 minutes. My track is going to 15 minute mains and the electrics will be required to make an obligatory pit stop, but I'd rather just make the obligatory stop and just sit there rather than actually HAVE to change batteries.

I have a 540C 9L... I have only run test run it.... never even got a full pack on it. It is very fast on 4s... ran well I thought. It seemed to get hot quicker than my Neu 1512 but it's also a hotter wind.

I'm actually planning to put the 9L into my old buggy... it's currently sitting there but not hooked up yet.

Gear it 10/46 or 11/46 and it will be good. I don't know if 6AH will get you an honest 20 minutes but it should be close... 15 minute main no problem.

The 6000 packs are still pretty light all things considered, and pretty easy to fit in the car.

I believe that mtucker ran a 540C 9L. I think it got hotter than he wanted, he mounted a fan on it or something if I remember correctly. I've got the 10L with the RCM heatsink/clamp on it and even running 12 cells it just barely gets warm. Granted my gearing isn't that tall (11/46) but I'm quite pleased with the performance.

If the weather holds out, we'll be shooting video this Sunday. It'll probably go up Sunday night or Monday morning. If you want to hold off until then, you'll be able to see some picture proof.

Sleebus

With longer runtimes I couldn't get my 540c 9L not to overheat. Any over about 10 minutes it would overheat that was without fans. I tried gearing, but ultimately it still overheated. I finally gave up on it and got a Neu 1512. That was a huge difference. Ran so much cooler. I think you would have better luck with a 10L. Mike does have the 10L in stock http://www.rc-monster.com/brushlessmotors.php?pg=2 it is the 11th one down.

OK, I'm ready to order a motor. Gotta do it. The conversion is keeping me up at night. Just take a look at the time stamp on this post. :)

I just want to make sure that I have things right. I was considering either the 10L or the 7XL. If I go with the 7XL, I'll be rewarded with cooler temps and longer runtimes, is that right? I'll be running on 4S lipo. BTW, what sort of runtimes do you think I'll get on 4Ah 4S packs?

As I said, I'll be running this in an 1/8 scale buggy. It has a stock 46t spur. What pinion should I get? The longest straight on my track is 160' long and I want to keep up with (preferably pass) a nitro buggy with a Novarossi 21-5 on it. I'm figuring that I should gear for about 40 mph, maybe a tad bit more.

And...does anyone know how to harden a mod 1 pinion. RC Monster is out of the hardened pinions and I can't wait.

Well, I'm not sure if you thought of the current draw of the 7XL.

The 7XL is pretty close in KV to the 10L. However, the problem then is that it is a 95A draw motor. You are running at the ragged edge of the limits of the ESC at that point. Also, a 4Ah pack (assuming it's 20C) ain't gonna feed that motor, because you're looking at 80A continuous out of that pack. To me, the 7XL seems to be asking a lot of the pack and ESC...I may be wrong, I'm sure someone will tell me if I am. :)

I think I'd get the 8XL, which is 83A, pretty darn close to the current capability of the 4Ah pack and definitely easier on the ESC. Personally, I'd prefer a R/C that's slightly slower, but doesn't catch on fire! :005:

Or maybe I'm just screwed in the head with my above thought process? :032:

As for the pinion, search tower for "century motor gear 1.0"



Sleebus

Are you running a single 4S pack or two 4S packs? I ask because on a single 4S pack and a 7XL you can overheat the Lipo pack at towards the end of the run. I know this from experience. I've puffed a couple of doing exactly that. so if your running a single 4S, do like Sleebus says I would go with 10L, 8XL or even 9XL. If you are running two 4S packs I think you might be able to get away with a 7XL, but even so, I would still recommend a 8XL. It is worth it to get the right motor so you don't have to spend a lot of time and money messing around with gearing, fans and ultimately other motors.

For what it's worth, the 8XL and 9XL are closer in kv to the Neu motors many of us are running. 1700-2000kv.

You are correct in saying that the 7XL can draw quite a bit of current, but it will not pull that current all the time. Just think; if a motor pulled even 80A all the time on a 4Ah pack, runtime would only be 3 minutes! Since most of us get runtimes of at least 10 minutes, the current has to be an average of 24A. Of course, there will be peaks when you take off from a standstill or accelerate heavily where motor current will exceed 100A, but all our car ESC (MM included) is made to take those peaks and more provided the duty cycle is relatively short.

Thanks for all of the comments. Of course, I'm confused again. I've done research on this forum and found multiple references to the advantages of running the 7XL, which included better torque, more efficient running, cooler running AND longer runtimes. The longer runtimes is what threw me, because the 7XL is a 7 turn motor and in my experience, 7 turn motors DRAW CURRENT. I was confused, but figured that there must have been something that I just didn't understand, yet. Still, the max current rating issue was still hanging in the back of my mind. I hope that someone can shed some light on this issue.

As for the batteries, a single 4S pack would be the easiest for me. I've also been considering a 4S2P 6Ah pack. A 20C 4S pack should be able to handle 80A constant. The 4S2P pack should be able to handle the current draw easily. I was going to run MaxAmps packs, but they kind of dropped the ball on my last order. It seems that they are running behind on orders and the delivery time is kind of up in the air. I ordered two packs on the 18th and they were just shipped today. Maybe I'm spoiled, but that's too long for me. In fact, I don't even need those packs any longer. OK, I'm going off on a tangent now. Anyway, I might have to get the mount down before I settle on the battery configuration.

As for the gearing on the kv of the motor, I'm still thinking in terms of nitro engines turning at 40,000 rpms. I'm just learning that I don't have to spin an electric motor that fast. Are you guys just running the ultra low kv motors and gearing up?

What kind of speed could I expect from an 8 or 9XL on 4S lipo? Runtime on 4S 4Ah lipo? What about an 11L? Am I going to have heat issues with an 11L? Would an 11L have enough power? I need better acceleration than a nitro buggy with a hot engine (Novarossi 21-5) AND I NEED to be faster. 40 or 45 mph.

Thanks.

Or maybe an 8XL? Aahhhh, I'm about to start tearing my hair out!!!

Sounds to me like the 8XL would be a good choice. Sometimes we tend to over-analyze things. To a great extent, gearing can equalize the differences between a 7XL and 8XL. Everything is a trade-off... and like you said, a motor can't both have longer runtimes and draw more current at the same time, compared to another one.

Based on your need for speed I would say skip the 9XL.

The 7 or 8 is a toss up... I know hte 8 will have to be geared pretty high to get up to 45mph. My 1900kv motor clocks 45mph on when geared 18/46 on 4s packs. It's stupid fast even though the gearing sounds way tall. But there is a limit to how big a pinion you can put on there.

That's why I would leave the 7XL as an option if you really want to do 45mph on 4s.

So... 7 or 8? Both can be stupid fast with the proper pinion.

I would suggest putting a good 40mm fan on the esc and either a fan or heatsink on the motor.

I don't know, but I think that I have a rather unique situation. On the other hand it may not be so unique. I, personally, could be satisfied with a buggy that will run at 30 or 35 mph. In fact that's what I generally had my buggy running when I was running nitro. The standard short track setup for me was 13/46 with a Novarossi P5X. It had plenty of torque (for nitro) and it got to top speed pretty quick. That was fine and dandy when I was running in the B mains. Before I took a break from the hobby (pre-Katrina) I found myself in the A mains more and more. The guys regularly running in the A mains are hog nuts. As short as our track was, I was actually loosing time to other drivers because they had a faster engine. Besides, I'm not going through all of this trouble to wind up with a buggy that is slower than the fastest nitro buggy out there. When I was running nitro, it was not unusual for me to burn through a gallon of fuel, non stop. A testament to the reliability of the Novarossi engines. I want to be able to run as long with my electric AND be quicker and faster. What that translates to is that I don't want to have to deal with heat issues. If that is something that I won't be able to get around, then I'm going to abandon the whole thing.

I'm going to go ahead and get the 7XL. It's probably going to be the best choice, but from what I understand, I'll have to run something other than a 4S1P pack. I'll have to go to 4S2P to be able to keep up with the current demands.

OK, assuming that I go with the 7XL, do you guys have any recommendations for pinions to get to start at a speed of about 35.

BTW, will going with something like a Lehner 1930 or 1940 really make that much of a difference. I want to stick with a two pole motor for now. The only thing I've settled on is that I WILL be running a MM controller.

glassdoctor,

Is your 1900 kv motor a feigao, or is it a better motor? Do you have problems with heat?

It's the Neu 1512. It will run pretty much all day long without too much heat issue. I did get it too hot once but normally it would run all day under 180, and if there is some air getting to it I don't think it would get much over 160. That's not bad for long races.

I also have a Neu 1515 1700kv in a Jammin truggy, geared for about 30-35 mph with a single fan blowing on the motor and esc. It will run on my small track nonstop and never go over 160's. I have run it for well over 30 minutes.... it has a 12ah 4s pack.

I would really recomend a high end motor like a Neu based on what you say you want, to keep things running as cool as possible. But there does seem to be a little cogging issue with the MM/Neu combos right now. I hope this can be resolved so I can recomend it without a doubt.

I don't know what other motors are like... Pletty or Lehner I assume will run cooler like the Neu. Rotary Rocket is running a Pletty/MM combo and reports no heat, no cogging.

I would guess about a 14 would be a good gear for the 7XL, but you might want to check BrianG's speed calculator and see what the #'s say.

Sorry... all this discussion still doesn't clear things up really does it?

The 7XL is relatively cheap... so if it burns up then you will know for sure. ;)

I'm tired of thinking about all of this. I need this thing to go fast. It was pretty fast as a nitro, and I need it to be faster. What would be the point if it wasn't faster? I'm thinking that I'm going to go with a 9L. I could be wrong, but common sense is telling me that the 7XL is too much motor. The lower wind motor is going to give me less runtime and less speed. The 9L on 4S will spin at about the same rpms as my nitro and if it will run cool with a 13t pinion, then that would put me at a good starting point. What I mean by cool is within spec.

If it overheats on the above setup and I can't run it the way I want to, I'll just go back to nitro.

There's one thing that I don't understand about these brushless motors. That is their ability to generate torque. Does the torque go up as you reduce the number of winds, or is the ability to generate torque a constant among a line of motors? I mean, do all L can motors generate the same amount of torque with the number of winds affecting only the number of rpms/v?

The 7XL isn't too much motor, it's controllable power in a buggy. I used it on 14 cells in my Mugen, and pretty much loved that setup. On one hand, you say that you want to go 30-35 mph just like your nitro buggy, while in the last post you say' i need it to be faster' i don't think that speed is the thing you need. it's acceleration that's the most important. (so traction and torque are important) a 50 mph truck can loose a race from a 10mph truck, if you catch my drift..

The 8XL will give you more runtimes, and can be geared a tad higher than the 7XL while the 7XL will drain the batteries quicker.

The 7XL is an impressive motor, it runs like crazy, and can't be beaten by it's cheap price. If it's geared properly it won't run too hot. and if you want to play it safe, get a rc-monster motor-clamp/heatsink. (which is a wise thing to buy anyway)

Thanks for all of the advise guys. I think that something about the torque that these motors generate has dawned on me and I think I have a better understanding of what I need.

The only thing that's keeping me from going with the 7XL is the low turn of the motor. I really want the runtime. Again, my choices boil down to either the 7XL or the 10L.

I would just jump on the 7XL, but the 10L is still lurking in my mind. I keep coming back to the fact that I'm going to be running this in an eight pound buggy. Not a 10+ pound monster truck. I'm wondering if I really need the torque of the XL motor. I really hate to keep going back and forth with this, but I'm really limited on battery. I made a motor mount tonight. I used an Emaxx mount. Not the stock one, but the optional one. It's about 4mm thick and is OK. It looks nice. I just ordered some 7075 aluminum plate cut to 2.25x3" to make a better mount. I got 1/4" and 3/16" thickness to see which works best. Anyway, after I set everything up, it appears that I won't be able to go with a dual battery setup, because if I do, I won't be able to really protect the batts from the bumps and bruises that come with racing. It looks like I'll have to go with a single 4S pack. Due to weight, I'm figuring it's either going to have to be a 4S 8Ah pack or a 4S2P 6Ah pack. The limited capacity has me worried about runtime.

Has anyone actually run a 10L in a buggy? I'd like to know how it went.

There is no way to know definitively if a given setup will work ok, be fast enough, or be perfect, etc... it may come down to how you drive and what the track is like. The same setup might work great in one situation but overheat in another with the exact same car.

Let me add to the total confusion :) I have not run a 10L and I only testran the 9L. What I have run the most is a frankenstein motor... that is part Hacker and part Feigao. It's a 12L but it may not run like a normal 12L, but I have no idea. It seems to be faster than it should be... in fact the 9L felt pretty similar when I ran it.

Anyway, I raced the "12L" hybrid and it was fast at 11/46... and easily thte fastest car on the track at 13/46. It was retarded fast as I was told a couple of times. I think the MM could handle this motor esp if I put a fan on the MM. But this motor would thermal a MGM 120 and Mtroniks Truck, which I ran with the built-in bec. That could have been the problem with the Mtroniks.

Hope this helps.... I guess if you keep the buggy as light as possible I can understand going with the L over the XL. You should be able to get it under 7.5lbs with a 4000 pack. Both my cars are right at 8 lbs.. the Kyosho on 6000mah and the 8ight on 8000mah.

Buy both.It'll give you a reason to build another car with the motor you don't settle on this time.:027:

pinolelst

I really hate being so ignorant about something that interests me so much.

I just don't understand. If the 12L would thermal the escs that you mentioned, how is it that a larger motor (ie, 7XL) that draws more current and has fewer winds going to run cooler? Is it just because the 7XL is so much more efficient that it produces less heat?

OK, well let me ask this. With a proper load, can I say as a general rule that an XL motor will always run cooler than an L motor with a similar kv rating?

Do you think that the MM can handle the 7XL without stretching it? Should I just go with the 8XL? I want my whole system to be comfortable.

LOL, yeah, I was just looking at the gorilla stuff and I already have the urge to get on ebay and find me a Revo roller.

Anyway, I just used the calculator and it appears that around 8 pounds of load is the max for an L can motor. I think I'm going to play it safe and go with the XL. Runtime or no, I can't have the thing over heating on me. Besides, the 7XL appears to be able to get me to 40 with relatively mild gearing.

The torque is pretty much consistent across the can size. That's because the max torque is determined by the amount of magnet engaging with the coils. IF you can feed the max current that motor wants, then you'll have the same torque. It's not the same as brushed motors at all.

I think i've said this before, but I'm running a 10L in my 1/8 buggy. I'm about to shoot some video of it today, I'll be running it on 6 cells, 7 cells, 3S LiPo and 12 cells, all so anyone watching can see the difference. With the 11/46 gearing now, I can tell it could use a bit taller gearing. I've got a 13T pinion on the way, which should be about perfect. According to my calcs, a 13/46 + 4S should have plenty of torque and hit 40 mph easy.

Sleeb

Yes... in general an XL should run cooler with the same load. I think in reality the XLs run cooler because they can pull a higher gear at a lower rpm (wihta lower kv) in other words, guys have switched out an L for an XL.... but normally the XL has lower kv.

As for my 12L Hacker/Feigao... I'm not the only one who had the MM work where several others had failed. RotaryRocket had the same experience with his buggy, using a Pletty Maximum motor. And remember, my motor may be pulling higher amps than a normal 12L. I clocked it with my gps at 55 mph on an old 4s lipo. And this was geared 13/44... it did 40+ at 10/44. So I think this motor runs faster than a 12L is supposed to. If I geared that thing 18/46 with better lipos I wonder what it would do? 65+? :)

The 7XL does have fewer winds, but it's not a "hotter" motor. It does have more ability to pull high amps but it also has inherently more torque so it won't work as hard to do the same job as an L size motor. Check out the charts that show the resistance and idle current of some different motors... the numbers don't change much for a given kv... XL,L or S.
http://www.hackerbrushless.com/motors_b50constants.shtm

Again, thanks alot guys. I do have the 7XL on the way. As I said, I made my motor mount, so I know what needs to be done. I ordered some 7075 aluminum sheets cut to 2.5X3". All I'll need to do is drill and tap some holes. Do you guys think it would be better to have the motor off to one side, but mounted toward the front of the buggy, or center mounted with the gear engagement being above the center diff? My intention is to be able to mount two 2S packs. One on each side.

Or...do you think it would be better to just mount the motor in a conventional way (off to one side toward the back) and have all of the "equipment" on one side of the buggy and the battery (single 4S2P pack) on the other? I'd love to be able to use a single pack, but the buggy has to have a good weight distribution for racing purposes.

I just don't know what battery chemistry to go with. I have lipos, but they worry me. They are fine for bashing, but I don't know about racing 1/8 scale buggy. I can recall some crashes that I've had running nitro, and I seriously doubt that a lipo cell would have survived them in tact. Of course, my concern is with the fire that will result from a pack being punctured. I'd hate to think that I could looose my whole buggy (not to mention other buggies and corner marshalls) because a battery was damaged in a crash.

I believe that I have three other altenatives. The first is the A123s. Considering the ability of these cells to deliver current, I might be completely happy running a pair of 2S2P packs. Assuming a 10A charge rate, I figure that a pack will charge in 30-40 minutes. Of course, it would be expensive considering that I'd need to buy two pack and two chargers; or, more ideally, four packs and two chargers. How do you guys think the 7XL will run on the A123s? Will I be giving up much by going with 4S A123 rather than 4S Lipo?

My second consideration is lithium manganese. These also have the ability to charge at a 2C rate, but I don't think that they deliver as much current as the A123s, although they do have the voltage of the Lipos. At $75 a pack, it would only run me $300 for two sets of 2S2P packs. Of course, I understand that there have been problems with the 3.8Ah packs. I can find them, but don't know if I'll get the bad ones. I could move up to the 5.8Ah packs, but the price doubles and so does the weight (just about).

My last alternative is good ole nimh. I can get IB4200 cells for under $6 each and just load them up into the solderless tubes. For the price of the other chemistries, I could get a butt load of nimh cells and just run two 6 cell packs.

Again...comments please.

Thanks,
Tony

I would go with LiPo's to be honest. If your that worried about them, I would do some preventative measures that will ensure there safety. I have seen some companies put CF on the top and bottom. That should prevent alot of things that could happen. Another option is make some kind of box for them. There is a Revo around here somewhere that has a little box for LiPo's. It was made of 2 pieces of L profile aluminum and a small hinge (piano I believe he said) and lined with foam.

butt load of NiMh (12 cells :) ) = 1.8 pounds
4S 4000mAh LiPo = 0.8 pounds

You make da call! :dft003:

Sleebus

Some Lexan would be a good choice too. That way you could see if there was a cell starting to puff, or if the heatshrink gets melted like I saw from another user here (can't recall who ATM). But, won't encasing the packs reduce cooling efficiency because of no airflow?

Weight is definitely an issue and going with the nimh would be counter productive on that issue. I did order some 6061 aluminum channel. The channel is 47mm wide, while the battery is 34mm wide. I'm considering using the 2100HV cells to make my packs. Although they are a bit thicker than what maxamps usually uses to make car packs, they are also considerably shorter and narrower. This would allow me to protect the packs with some sort of dense foam on three sides. I don't think that I'll want to completely encase the packs. I want to be able to visually inspect them.

Where can I get lexan and/or carbon fiber. I've heard that carbon fiber is really easy to work with and tha CA bonds it like concrete.