You can't :) I thought of that when I typed it... but you are running oval right??

2s3p on right side, 3s3p on left.... of course you may not want to do that.

My gut says 2p would be enough. How much impact do you think the extra weight of a 4p would have?? More weight will help it stick to the track but at some point it will hurt accel out of the turns enough to not be worth it.

IMO 5s will be fine on the 9L

Hey what about a 6s?

Cool. Those packs will make a huge difference. (once you go Lipo... You never go back:018: )



5s on a 9L will get really hot... really fast. At least it did in my maxx.

glass, no oval.. that was the reason for starting this project, but the track wouldn't let me run my rc.. so now i'm building for fun. racing, drags, ect..
no 6s because of quark's "6s problems"

j, the packs got hot? or the motor? think it might stand a chance in a 5lb car?

The motor gets hot. Its just the rpm that does it. On 5s you take it way past its peak effiency range and it just starts generating a ton of heat. Your right about the light car you might be better off than a truck. Shouldnt hurt to give it a try, just pay attenetion to the heats.

(Ive never had an issue with the truerc lipo packs getting anything more than slightly warm in any setup)

sounds good.. i've run an old hacker b50 8S on 16cells before for ~6-8min at a time, w/ a hard driving style, so I figure a 9L shouldn't be a problem for short periods.

I was thinking of short runs on the oval...

I really think 8000mah will work very well in the car... and I don't think you will like the brick the car will be going any bigger.

What is the final drive ratio of this car?

I was wondering about target speeds for this... fdr and the tire diameter to get estimated speeds for your setup. I don't know what the tire dia is though.


But knowing that the nitros can hit 70mph... and guessing that the nitros likely max out around 40k rpm?? Just duplicate whatever rpms they are pulling and you will get the same top end... or beat them by a little bit. ;)

Nitros are 2 speed trannys. This is a single speed. Are you just running using 2nd gear only like an emaxx? Or are you using a diferent gear ratio?

glass, the tire dia is 3".

j, I'm using the stock "2nd gear" spur, which is a 45t. I'm not sure what the recomended clutch gear would be for nitro.. I didn't get a manual w/ the car.

also, I got the stuff I ordered today.
the lipo's didn't have deans plugs on them.. which I swear I added, and if I didn't, the email I had send before I made the order said female deans =\
so I need to order some deans plugs now.. also, I plugged the packs into the 505's.. one of the packs blinked a few red leds, then went to solid green. the other pack blinked cell 3 for about 2 minutes, then went to green, but only for a few seconds, then went back to blinking on cell 3. then green again, and ect.. continued this for about 5 minutes, and unplugged it, because it won't stay solid green. only momentarily? i'm not sure if that means the err/check LED is blinking? or if it's going solid, and then deciding cell 3 is still out of balance?
and I forgot, but ordered a lipo sack today while at work.

Seems like cell 3 is out of balance if it keeps flashing the red. It's a small imbalance, though, suggested by the fact that every so often it thinks the pack is balanced.

ok, I just wanted to make sure it wasn't "blinking" the err/check led.

I'm not sure where you are on this car... I what motor/batt/gearing you are going to run. Maybe I need to go back and read the thread for a refresher. :)

You said once that you had a 1512 2.5d in the car but then mention a 9L...

I crunched basic #'s on the 1512 and 5s lipo geared 6:1 and 3" tires.... note that this is just "back of the napkin" math and it's just meant to be a basis to go off of.

I think you can break 60mph depending on how stong the lipos are.

Not accounting for some losses (efficiency etc) the numbers say 61mph with the battery holding at 3.2V per cell. I think this is about right because I'm guessing the volts will actually be a little better than that, which may offset the "real world" losses. On paper, in theory,..... doesn't always translate to real world results.

At the very least I think this setup would do mid 50's (that's assuming 3.2v per cell and 10% loss from the "paper 3"#)

Paper #'s:
3.5v = 67mph
3.2v= 61mph
3.0v= 57mph

1512/2.5d / 5s2p 8000mah lipo / 20/45 for gearing.

I've been using http://www.scriptasylum.com/rc_speed.html quite a bit, because i've seen alot of people post that it's been very accurate for them..

I also put in the figures for Nic Case's cars. his 160mph setup was calculated at 158, and the 130mph setup calculated at 135mph. good enough for me :)

i'm pretty sure I need to get a new pinion made up, and possibly try a higher kv motor.

I've got a 540c-9l that I've never used, and has been sitting on my desk for 6 months lol. I just got 3 female bullet plugs for it, so I'll be able to try it out in the car.

Don't you think the 2P setup weights too much? I am working on a serpent as we speak, i like it's light weight, but the 5S2P maxamps packs i have got are too heavy for it IMO..

Serum, he was originally gonna run 2 of those 5S2P packs in parallel for 5S4P 16,000mah....Now I think he is gonna run 2 of the 5S1P packs in parallel. Not sure though...

yeah, what squee said.
the two 5s1p packs feel lighter than the 16subc's. (i don't have a scale to weigh), and the car was very easy to drive and very quick off the line w/ the weight of 16 subcs, so the lipo's shouldn't be a problem.

Yeah, i know what they weight, but still.. A 5S2P pack of the maxxamps 4000 cells is relative heavy.

bump lol.

i have to keep this short, but an update.
first, my quark quit making the programming tones.. but the three startup tones are still there.. kinda makes programming a hassle.. anyways..

oh and the front belt on the car is cut down the middle around about a 3rd of the belt... but it survived a short test run, and looks like it won't cause any problems

before, with the nicd's, i had all power related settings turned up, and did 48mph. w/ the lipo, i had everything turned down, as well as throttle epa 25%. in a walmart parkinglot, i hit 55.1mph. i also hit a snow bank, and a pack popped out.. no damage at all, which surprized me.. it looked worse on video lol. i'll try and up that tommorow. here's some pics.

charging setup
http://a4dtm.com/xr8/pictures/1.JPG

pack that fell out of the car
http://a4dtm.com/xr8/pictures/2.JPG
http://a4dtm.com/xr8/pictures/3.JPG

front belt cut?
http://a4dtm.com/xr8/pictures/4.JPG

http://a4dtm.com/xr8/pictures/5.JPG
http://a4dtm.com/xr8/pictures/6.JPG
http://a4dtm.com/xr8/pictures/8.JPG

wiring headaches
http://a4dtm.com/xr8/pictures/7.JPG

Damn... 55.1mph at 25% throttle... Can't wait to hear about this thing breaking the sound barrier :).

sick... just like we want it. :D

Damn man! Imagine at 100% throttle! :|

I seem to recall a lot of advice to go lipo.... hmmm..... hee hee

I am currently working on a simular project; my goal was to keep the batteries inside the chassis and make it fair light. 5S was the number of lipo's i was heading for. my goal was a decent 60-65 mph. Hearing these numbers makes me want to jump my tools and drop the other projects for a while..

Though 55 mph on 25 percent; my guess is it will do about 85 mph @ WOT

quite literally too based on the pack ejection that just happened... :005:

Too funny..

sorry guys, throttle wasn't 25%, it was turned down 25%.. aka 75%.
but all the quark's settings were as soft as they could be set.

That sounds more realistic.. :p With better cells i am sure you can get higher speeds!

waiting to get a spur adapter made up.. i emailed mike, awaiting reply.. i'm getting anxious

oh, another quick question.. from what i've read, the packs shouldn't be discharged below 3.3v/cell? the highest cutoff on the quark is 3.0v.. and it goes all the way down to 2.2v?
i've got it at 3v right now, but is that safe?

also, i'm re-charging one of the packs right now, and it's at 998mah.. so i've run the car for about 12 minutes total, and it's drained about 2000mah. so w/ 8000mah, it looks like I'll have about 45min run times @60mph

Higher than 3v/cell would be better, but if 3v is the highest it will go, then you might just have to live with that. You could get an external LVC, and set that to a higher voltage, though.

more bad news.. another run today, and while doing a 4wd doughnut (cyclone), one of the packs ejected it's self..

i knew that this would be a problem from the last time a pack ejected it's self, so i used 2 zip ties on each pack, to keep it from sliding out sideways.. well both zip ties broke, and were no where to be found.. and the pack slid a good 40 feet from the car..
there's a copper colored ribbon that wraps around the connector end of the pack, and that got damaged.. is that cable for balancing? or ? there's pack didn't puff or anything like that, just a little knick. what should i do now? send it back to true-rc to rebuild the pack? or is that even needed?
picture:

http://img260.imageshack.us/img260/5853/p3150064sm6.jpg

If the cell itself has been punctured, its probably best that cell be replaced. However, its just a scratch or dent, you may be ok.

Don't take my word 100% though.

This is the reason why I am building a sort of protective box for my new packs. I'm going to get some flightpower packs, and I'm going to take some sheet metal and bend a little case for it. The case will also allow it to key into the slots in my Gorilla chassis, which, combined with double straps, will prevnet nearly any possibility of ejection. I used the same type of key-in method for my current Lipo's and they haven't budged even after some hair crashes. However, in the event that it does get ejected, the case will protect it, since my design will have it nearly completely surrounding the pack.

I believe the 'ribbon' is only a type of strapping tape, maybe a fiber type of 'kapton' tape?

The balancing wires are just regular wire like what you see at the tap connector.

Looks like no harm done.

Now, you really should put a side skirt on the battery trays... ;)

ok, i was hoping that was the case.. the cell's not damaged at all. it just barely broke that ribbon/tape. not dented or cut anything below that.

when i designed the bottom plate that's on the car now, i was deciding between maxamps or true-rc.. true-rc's are wider, and the cad file i sent was made to fit the maxamps. so the batteries don't sit perfectly flat, and resting on the side of the tray..

that's the only reason they've flown out twice =\ i'll come up with something much more secure on a revision.

That's the biggest PITA in lipo cells; all the different sizes they come in.. With nimh there was some kind of standard..

http://img220.imageshack.us/img220/7...em10resmd7.jpg

hmm..

I am able to hold them in the chassis!

(need to look for the right sized lipo's, true..)