E-LST2 Project
 

Hi all – I haven’t posted much but have been lurking here since my first purchase from Mike back in July of this year. Since then I’ve put together a couple of trucks – G2R and an MGT. but nothing I thought really worth posting since most of what I did wasn’t too radical and has been done and posted here already. I guess that can be said of my latest project too but here it is anyway. It’s still a work in progress but it’s finally up and running. There are a few things left to work out (battery trays, location of mounting esc, clean up wiring) but I thought I would post what I have done to get to this point. Here is a short list of what has gone into it so far starting with a completely stock LST2 roller. I pulled out the OS30 which is now sitting in a parts bin (anyone need a nearly new OS 30?) and fabricated a motor mount using 2” 1/8” thick aluminum angle. The mount will eventually be beefed up to 1/4 “ thick angle to deal with any flexing issues but for now it’s doing the job for the initial test runs. Thanks to all who have braved the risks of testing the Mamba Max and posting their results or otherwise I may not have attempted this project.

Motor = Neu 1515 1Y 2200kv
ESC = Mamba Max with external UBEC
Batteries = Maxamps 4S 8000 mah (2 2s2p packs in series) and I have also run 5S 4000 mah (3s and 2 s in series)
Single speed conversion running stock 63t spur and 25t brass pinion

So far so good. Even with the wheelie bar attached this thing will flip on it’s lid even while rolling at about 10mph (5S lipos). There is so much torque even with the 2nd gear only single speed. I have not stressed it out yet due to the fact that I haven’t figured out a way to secure the battery packs yet – so no major jumps just yet. Right now I fabricated a temporary tray out of polycarbonate and taped the batteries down. I’ll have to go to something a little less brittle. The electronics seem to be happy. After several speed runs nothing is over 110 degrees. Looks like there is room to go up on gearing. According to Brian G.'s speed calculator (thanks Brian) it's currently geared at around 32mph. The MM is set up for forward only. Motor braking is turned off. Braking is handled mechanically via third channel mixing.

http://members.cox.net/tg_19/elst1.JPG

The roller
http://members.cox.net/tg_19/elst2.JPG

Single speed conversion using Robinson Racing slipper parts
http://members.cox.net/tg_19/elst3.JPG

Bolt pattern of the stock spur and RRP slipped is a match
http://members.cox.net/tg_19/elst4.JPG

Mamba Max with UBEC wired
http://members.cox.net/tg_19/elst5.JPG

3" servo extension with red wire clipped to bypass MM internal BEC
http://members.cox.net/tg_19/elst6.JPG

http://members.cox.net/tg_19/elst7.JPG

Roll bar is getting a workout during initial testing!
http://members.cox.net/tg_19/elst8.JPG

Here is a short video of the truck bashing about. Please cut my cameraman some slack. It was either give my 7 year old son the video camera or the controls to the e-lst. Apologies for the music drowning out the sweet whine of the Neu, but I felt I need to spare everyone my son’s and his 5 year old sister’s commentary.
http://www.youtube.com/watch?v=rpkbuyXOg6Q

As I mentioned earlier, this is very much a work in progress. I welcome everyone’s comments and suggestions. Thanks everyone for a great forum.

Cool, that's one BIG pinion.

Do you have a weight on that beast?
I like it. It is pretty bad Arse. :)

Looking good..!

Looks SWEET!!

What gearing are you running in that thing? Hows the mamba handleing the weight of that beast? No heat issues on the Mamba?

?

'Single speed conversion running stock 63t spur and 25t brass pinion'
'even with the 2nd gear only single speed'

you can do the rest with the calculator of Brian.

How's the motor mount holding up? It looks rather thin. In my experience using 1/8" thick aluminum as a motor mount, it bent very easily from minor things.

I just put it on a scale with 5S 4000mah batteries. 12 pounds 14 oz. Mind you this includes roll bar and wheelie bar. Wheels and tires are Losi 420's with Bowties. I can shed a pound or more by getting rid of the roll and wheelie bar but not unitl I learn to control it.:026:


Serum - thanks for addressing the question about gearing. The nice thing about the RR Slipper mod is that I can bolt up different size Robinson Racing spurs. I would have to go with 32 pitch pinions but they are much easier to get in the very tall tooth count than mod 1 pinions.

As for heat/temp issues that was addressed in the original post as well. Adn if you could bear to watch the whole video I can be shown taking the temp readings.

MetalMan - As I said in the original post, the 1/8 inch mount is holding up for initial testing and will eventually be beefed up once I'm happy with a gearing choice.

Yeah.. using the bow ties saves over 776 grams..... stock tires/wheels are 1776.... bow ties are 1000.... :) looks good dude.... I used a flat aluminum tray (2 1/4") highter than the main chassis.... and I place the batteries up there and old it down with battery straps.. I do not have pictures of this yet.. but I made it for both of the lsts....

Project Update
 

I was finally able to get it out to the track but unfortunately the day was cut short after two pretty ugly laps. I had 5S 4000mah in at the time. There is definitely enough power to easily clear the quad but it helps if everything is lined up. I have to work on some suspension tuning as it definitely handles differently from my nitro version. Here's a short vid of the truck at the track ending in a not so pretty collision with the rail.:035: Battery tray, electronics and such all survived the impact. The only thing broken was the right front spindle where the turnbuckle attaches. The truck looks slow at the track only because I was driving very poorly...err...cautiously.:dft001: It never got past half throttle. Maybe 3/4 for the approach on the quad. Again, please pardon the poor driving - once it's dialed in a little better I'll post another (hopefully better) video.

It looks like the power will get away from you. That is always a good thing some times.

Updated with new video
 

Some holiday practice time at the track. I went with 4S 4400mah batteries this time and it appears to be just right for this track. My lap times are comparable to what I do with my nitro LST2 and the only limitation at this point is my lack of driving skills:005: Here is short video of the best string of laps that day. The first couple laps are pretty brutal but fortunately it got better before I broke anything. A few more adjustments to dial it in and I think I'm good to go.

Either it is undergeared or something slipping like crazy.. but your slipper looks fixed to me, correct?

Can it be it was in high gearing?

Hmm - does it really sound like it's winding too high? Everything is running cool but now I'll have to check things out. The RR slipper is just a means to mount the stock spur. I'm still using the stock LST2 slipper setup but it is pretty tight - or at least I thought it was. It may very well be undergeared. I'm waiting on another pinion at the moment which will add another 2t to the setup. I'll see what happens.

I agree with rene.
It don't seem like it is doing all it could.

And here I thought it was just the driver that was holding things back. After further inspection it appears my mesh was too tight. I backed off the pinion and things are much better. Thanks a lot for your input. That's why I love this place:043:

If it was running cool with bending.
You could or should be able to go up on the tooth count of pinion.

Sound reasonable to me.

Yeah, 4S2P maxxamps packs will give you more power than the movie showed!

Good to hear you found an error.

Another update
 

Just got a new 5S 6000mah Maxamps pack this week. Here it is at the track with the new pack. Just got an Eagletree micro logger too so here is what the packs were doing during that run. Only one intersesting point at about the 3 1/2 minute mark. Voltage dipped below 15V at the same time I registered the highest amp draw at just over 120A.
http://members.cox.net/tg_19/e-lstamps.bmp
http://members.cox.net/tg_19/e-lstvolts.bmp

Sorry for the large files.

Interesting... Wonder what Austin thinks of that voltage drop at 20C?


Something looks weird though. That drop looks rather severe.

BTW: Nice driving.

That's odd.

Your 'minimum voltage claims a 15.74V, and looking at that graph makes me think that is the dip at 19 minutes.

Did you get the 6000 pack with 12 or 14 awg wire?

at 11.5 minutes, the 108A peak makes the pack drop to 16.3V.

Just remember, RCs look slower form the drivers stand... it's not the same as when you stand next to them and bomb over your parking lot ;)

Zoom in in the voltage drop at the ~3:30 min. mark by starting at the top left corner of it and dragging the mouse (while the left mouse button is held down) to the lower right corner. See if you can post a picture of that, so we can get a better idea of what that drop is really like.

http://members.cox.net/tg_19/eagletree1.JPG

Your right Serum. That is odd that the software did not register this point as the minimum voltage. There really was not anything out of the ordinary that I can think of that happened at that time that would result in that kind of amp draw. From the time that everything was plugged in and switch on to the time that the video started rolling was maybe one minute so whatever it was would have beed captured. I'm guessing that it was the initial launch (slight wheelie) after I staged the truck.

The 6000 mah pack has 12 guage wire with Deans ultra plugs. One nice thing is that I'm very pelased the Mamba Max held up for the almost 20 minute run. Unfortunately, I wasn't able to run any longer as I was having some issues with my battery straps. I'll need to make some adjustments to accomodate the larger pack. It will also be interesting to see how the system handles an addition 2T on the pinion as I just received one but have yet to put it in.

Thanks for the feedback everyone.

It registered it on this graph.

12.05 min

Nice info and footage.