A123 M1, 7XL, Quarky E-Maxx project
 

Hi there, im just posting the starting point for my BL emaxx project

Specs so far:

Fiegao 540C-7XL
Quark Monster Pro (integrated massive heatsink behind motor for cooling)
5s2p A123 battery pack
uBEC
HiTec 120oz/in servo
RD Logic Spikes tires on RD Logic rims
FastLane Machine diff cups
MIP CVD's, center RC-Monster CVD's
RPM suspension arms, and axle carries

Your project will be interesting to me, considering I will also be using 5s2p A123 cells and a Feigao 540C 7XL in my Revo. But, I'll be using it with the Mamba Max.

Very nice start! Cant wait to see some pics when the final product comes to life! :)

Oh ya, for sure we can compare results. I just love it when i hear people using the A123 cells, it's the direction we need to go in. They are just simply better batteries.

The chassis will be a Gorrilla Maxx style design somewhat. The upper chassis will be 6mm aluminum machined (you can see a rough sketch in the pic) that will screw to the bottom chassis plate (also machine lightened), in combination, i honestly think it will be THE most rigid/durable chassis to appear in the western world ;)

I plan to use 7075-T6 aluminum Alcad, the tensile strength of this grade is 85,000 psi, common 6061-T6 Alum is about 45,000 psi. Very high strength indeed, also very high fatigue resistance, which is needed too.

I used my A123 6S1P setup at the track yesterday. I would have used them racing but they dump right around 15 minutes so I didn't want to chance using them in the 15 minute Main. I am running 6S1P and they don't give me the punch my 5S1P Kokam 20C 3200mAh cells do. My next project is 8S1P A123's with a 12XL. I'm just waiting for word on the esc. 8S1P should give me the Punch and run time I am looking for.

Oh yah, the A123's you NEED to double them up, you are working them too hard running single cell (it's only 2.3Ah), doing 2p you get 140 amp cont. plus more punch from higher voltage, and more than double runtime.

8s1p running a 12XL would be a monster for sure, but i think you are better off going 6s2p running a 8 or 9XL motor. Which I should have done... i should have got the 8XL running (i got 7XL) 6s2p pack. For more power and runtime.

I guess you can call me an efficiency freak because I'd rather get my runtime from higher voltage than running packs in parrallel. I guess I feel that if I'm going to add extra weight by adding cells, I'd rather run them in series and get the benefits from the higher voltage than waste the opportunity by running them in parrallel. 8S will significantly reduce the current needed from the batteries and boost my run time as well. 8S1P should get me well beyond the 15 minute mark for the Mains. 8S1P is lighter than 5S2P and I'd be willing to bet the run time won't be much different. I can't say for certain until I get the opportunity to actually test it. I'm waiting for the esc and I'll post my results. :017:

it will be more efficient slightly on the motor end of things, but the batteries will be drawing alot of amps from only single cell. Maybe 8s1p will do for the 12XL, if you are racing, then i guess its sensitive....

I must say that I am happy with the run time I am getting from the 6S1P. They seem to deliver more mAh's than what my Lipo's are rated for.

From what I've read, the M1's drop voltage when the current exceeds 50amps or so, thus the need for 2P. My 6S1P setup has just about enough power but the power just isn't quite there. I'm pretty sure that 7S1P (with appropriate gearing) will do the trick. I'll have to wait until the phantom cell becomes available so I can add an extra cell to my soderless power tube for 7S1P.
I am certain that 8S1P will reduce the current needs to a level where the M1's can provide adaquate power because if 4S2P can provide enough current, an 8S1P should cut the current draw in half thus eliminating the need for 2P.
If 8S works well with the 12XL I will most likely go 9S1P and a neu 1515 2Y.

Great project! Keep us posted on developements.

I'm considering 5s2p or 6s2p A123's as well.

You see zero, another person here who takes higher voltage over higher current, this is not for nothing.

Projects are always nice. But if it will be the strongest designin the west? you got the 32p gears that will fail on you sooner or later.

About the diffcups; did you bought them already? i would not put my money on a 6061 cups, i would get a 7075 instead. the contact area of the shaft that holds the bevel gears presses real hard into/onto the aluminum, since 7075 is a harder grade, they will wear less fast.

Serum, i am prob the biggest high voltage freak around, i was just mentioning to him my experience when using 1p or 2p. I've built a Tesla Coil, i'm sure you have no idea what it is or how it works, mine discharges at 750,000 volts @ 350KHz.
You can let the arcs stream off your hands with no ill effect.

What does 32 pitch have to do with anything!? Gears wear out, thats a simple fact 'Serum'. And when i say the best in the west, do you really think someone means it? Are you just looking for stuff to bicker about?

No, you are absolutely right, i have got no idea what that is, now if you'll excuse me, i need to put someone on my ignore list..

You arrogant a-hole

Oh !? I'm an A-hole now? You know what, all i can do is laugh at ppl like you.

Go ahead, twist and turn your way around till you get your truth....

who the f do you think you are stating a thing like 'i'm sure you have no idea what it is or how it works'

Based on that i think you are an arrogant ass who thinks he knows it all..

Now get out of my way you little annoying prick.

Guys! Come On!

Zeropointbug....relax a little. This is a friendly forum! We enjoy the company of and are friends with other members here. It's no competition. Leave the attitude elsewhere.

Serum has a point with 32P gears. Mod1's are stronger. Thats why I designed my new MAXX slipper with them.

Oh i'm relaxed. I am just at a loss of a reason why ONE forum member has a grudge against me? It's quite odd really. What does get out of my way mean? You are posting on my threads? :032:

One of the things that has made RC-M forums so great has been the sharing of information and the lack of "attitude" of the members. This has kept everything friendly, supportive, and fun.

Your comments were aggressive in my opinion and "pushed Serum's buttons" so to speak. We all welcome your opinions and experiences so please share but "chest thumping" isn't tolerated too much here because it isn't necessary.

Just keep your post & comments "friendly" if you know what I mean, and it will all work out great.

So, everybody take a deep breath and start over! It's all good.

:027:

Believe me, i don't want to create 'enemies', but i really don't see how i was pushing Serum's buttons. He has attacked everything i say, calling me ignorant, and arrogant.... isn't that an oxymoron?!

Ditto! RCM is a very friendly forum, check your attitude at the door! I don't post much but that's mainly because I am still doing a lot of searching, reading and learning. I suggest you do the same zero.

Obviously you feel offended if i ask you how your 'facts' are measured.. and you can't get a straight answer to it either. You only 'presumed' facts.

And the other posts we had going back and forward... You ask something on a forum and you can't stand if i tell you my opinion on it. (like with the capacitors, in which you eventually told me my input was 'completely irrelevant' or the 32p vs mod 1 gears) you just wait untill a person tells you what you want to hear and (Brian who agreed on using 32p gears)

Terrible sorry, but this kind of made me come to a certain comclusion about your personallity.

and then your worse post became a fact;

I am not interested in tesla coils, so i probably know less from them than you, but my other hobby is (was) building speakers, in which i am relative far grown, but who am i to say to you that i know more about speakers than you do? I won't because that's not in my nature. And that was the part that was bugging me the most.

K, the capacitor thing, you said adding more cells would do it, im just saying that was irrelevant to the discussion that caps will help or not. The 32p gears was not my post, the post was about the 5mm bore pinions against the R.R. spur, Mod1 is stronger yes, i never said they weren't, i'm saying 32P will be strong enough, I think i 'want' them so there is a weaker link in the drive train, and there is simply easier to get a hold of.

About the 7XL getting to 60mph in 1/8 buggy, can it not? And the 1950 to 70mph, is that not the case?

The Tesla Coil thing was errogant of me, yes, i'm sorry for that. But check them out here, very neat. It is some sight, i'll tell you.

All is good Serum, nothing every came between us.

No, the detail was that you stated an 1800 kv 1940 would do 70 mph and a 7xl (2200 kv) would be less fast. they have got about identical torque, or a slight advantage for the 7XL

This is the post i am referring to;

http://www.rc-monster.com/forum/show...54&postcount=8

Here is the post of my measurements of the power it takes to get a truck to speed and to stay on speed;

http://www.rc-monster.com/forum/show...6&postcount=22

this is the movie of that truck, and it is not doing 50 mph, it's fast, but no 50 mph.. my guess is that it goes about 40-43 mph)

http://rc.stuurmijmail.nl/flicks/emaxx%205S.wmv

I know a Tesla coil, Nieles his dad build one too, (allmost neighbour) and i watched it for a while. It looks nice..

I am a straight forward type of guy, it wasn't my intention to show you this way.

[QUOTE=zeropointbug]

The Tesla Coil thing was errogant of me, yes, i'm sorry for that. But check them out here, very neat. It is some sight, i'll tell you.
QUOTE]

The Tesla coil is very cool. We built one in an EE class many years ago. Thanks for the link!

Aren't we talking about a 1/8 though, these weren't facts, merely guessings. But shouldn't a 7XL take a 1/8 buggy to 60mph? Oops, about the 1940, i was thinking of a different motor, not the 1940 8t. I was thinking the 1950 series, don't know what turn, maybe the 6 turn?

Tesla Coils are very neat, i can light up 8 foot flourescient tubes 20 feet away from it, all i do is stick one end in the ground. It discharges 4 foot streamers, btw. I'll maybe put pictures of it up when i get my latest one finished, 100% made from 1/2 inch acrylic, very pretty.

Basically, disagreements are going to happen. That's just the way it is when a bunch of people with different opinions get together. But there is a difference between blatantly saying "You're wrong" and "I read something that doesn't agree with that statement. Here's my reasoning...". Debating is good. Fighting or degrading others' opinions and statements is not.

OK, off my soapbox now. :)

I think a lot of motors could reach insane speeds if geared high enough, light enough, use enough cells, etc. But the setup won't be reliable. Excessive heat, current draw, etc will surely result.

Brian, ya, i don't think you would want to use the DeWalt 820 duals for racing anyway, they would get too hot (if not hot, outright burn up), but hey do have very large replaceable brushes, huge comms, and large wire #, weight in at 480 grams. Only good for bashing. It's quite impressive though really, considering...

I must say, i lost interest in brushed setups about 5 years ago.. brushless is the key to an efficient setup.

well, ya. I kept delaying it, and delaying it. But honestly the dewalts are by far the best bang for the buck. You just need batteries that can handle it.

BTW, Serum, i have to admit your truck is one sweet ride. Very neat and all.

custom chassis...wheelbase? 348mm, same as Revo 3.3?
 

I am designing my chassis right now, and am wondering what you huys think of the emaxx at 348mm wheelbase. The stock is 305mm, this is too short (obviously) for the amount of power om putting through the truck. It will take more power when longer, correct?

Do you think 348mm is slightly too long? I could make it the same as the extended GMaxx chassis which is little over 30mm longer.

What do you guys think? 348mm, or 335mm wheelbase?

I want to know as many opinions as possible.

I think the gmaxx chassis extended will be almost 348mm.

Is it, well 348mm it is then... then i can run Revo 3.3 bodies like the crowd pleazer.

It's not that it takes more power when it's longer. consider the input i gave you on using a centerdiff;

Some truggy-racers actually make their truggies shorter, to turn on a dime.

I put these two topics together, to keep it more clear.

Indirectly it 'could' take more power because you are keeping to front tires down more easily thus being able to accelerate faster... wouldn't this be the case.

I guess i have to use 6061-T6, 7075-T6 is 3 times the cost of 6061. Oh well, still will be super strong.

I will be posting up a blue print some time to get some comments on critical areas.

chassis design
 

It's a really bad pic i know, try the word doc, it's 1 MP.

This is the third revision upper chassis sketch, just thought I'd post it up before i put it on CAD. The left side is the front, and right is rear. the brace is made from 6mm thick 6061-T6 alum, it will be milled to varying widths as you can see.

My truck in the end, will weight roughly 180 grams lighter than stock e-maxx truck.... with almost 5 times the power. :027:

How do you post pics larger than 640x480? Any help appreciated.

Simple: Use a image hosting site, or host it at your website if you have one...

Yes, and use a redirect on the site. (simple HTML)

if you want to post a picture;

[ img ] www . domain . com / pics / pic001 . jpg [ /img ]

I would loose the square angles, it's a PITA for cleaning and round would add a lot of strength as well.