need to go slower to go faster??

For 20 minutes you would need to jump up to a 5s 5000 pack to do it consistently. I have run 20 minutes with a 5s 4000 pack in a race, but it is on the very edge. The 1515 2.5d is more suited for a truggy. If you gear down, you are probably going to start running hot as there won't be enough load on the motor.

I would highly recommend a 1512 3d (1700kv) or the 1y (1850) kv for 5s. I pretty much just race with 5s 4000 packs since our mains here are just 15 minutes most of the time.

You only need to gear for 37-40mph.

The only way you are going to get 20 minutes consistently under race conditions (plus warm up laps) is to get the 1512 3d or the 1y and use a 5s 5000 pack. You MIGHT get it with a 5s 4350 pack, but it will be real close.

[stum]

Originally Posted by bensf

You should measure how much energy is in a battery using this formula. Ah x V = how much energy there is. (Watt/hours)

4S 5Ah
and 5S 4Ah have exactly the same amount of stored energy.


Are you saying that a 20s 8k pack has the same amount of energy as a 2s 8k pack?

It's not that simple boss.. a 20s 8k pack would not only be impractical in RC the weight would be ~1480grams vs ~365ish.. I could outrace you with any 1:8 setup me on 2s 8k and you with 8s 8k :P I can imagine how efficient your truggy/buggy would be with that much added weight :P don't forget about the wind resistance calculation for a brick that size and the balance issue you now have and the fact you can't hit any jumps, or at least land them.. lol :) how much did that ESC cost to run it?

And as noted above it has a lot to do with where the motors peak effeciency is as well if you are under the 30k rpms or way over it you will have negative effect to calculate as well.

mAH = gas tank, AMP rating (c rating) = fuel line, Voltage = Octane

You have some cars capable of 40mpg, while some only do 12mpg on the same size tank, you have slightly better operation and mileage with higher octane fuel vs low grade in the same car but if you burn too hot you can destroy the motor at the same time, you can't take the car that does 40mpg and expect 100mph but the car that can do 100mph won't get you 40mpg.

Same with rc's and setups.. way more to calculate than a simple 'same amount of energy' statement and that isn't even true, as you have to factor in the batteries capable amp draw not just voltage x mAH, you have to use your mAH and c rating to figure out amp draw and multiply the amp draw by your voltage to get a usable watt/hour (as I did above). And that doesn't even start to tell you which is going to be more effecient with out looking at all the other items. The fact that you can do over 45 w/o heat issues tells me your motor has a slightly higher kv rating, thus more than enough RPM's to not have to worry much about the little votlage from 4s to 5s, again this was a change to speed up your lap times.. and get you beyond 20minutes. I have raced 20minute mains w/ my 4s 5k 30c packs w/o any issues with a few warm up laps to boot, no 50% chance of not making it.. lol.

EDIT: YA know.. I just noticed you have a 2.5d reading back, and only geared for 43.. I was reading two different configs and lost track, for some reason I thought you had the 1.5d (2700kv) and were pumping it w/ 5s.. hehe my bad on that end and it will change how effecient it is, with a the 2.5d you will be at a fairly low RPM on 4s, usable as I race the 2.5d on my erevo truck now geared for about 40 on a 4s config and it's perfect (I have run a 20min main w/ it as well). Took 3rd in the last a-main of the year behind the two local pro's (pro series pro's).

So ya with that low of RPM you'll want to stick w/ 5s and gear down, heh :) I'll just shut up now :P

[rootar]

gearing down does not help the runtimes at all it actually shortens them cause im using more juice and full throttle punches rather than 3/4 throttle punches......

and yes at the batts limits and i dunno if id dare run them in a truggy, they arent the best batteries by a long shot but they are very good for the money and people around here are more inticed to convert some of their buggies if they can get a decent priced setup. mine runs great i have no real complaints, my temps are great, its tough as nails and i love it, but im nit picky and ive got till december and then till next year to do anything and every thing to make it as bullet proof and as good as possible.


hmm i was looking at the Hacker 14L motor specs state it as a 35 amp motor and 50 amp peak that would be ALOT of difference over my 80amp 1515....... ut somethng tells me those spec arent exactly right but can anyone chime in?

[crazyjr]

Originally Posted by brushlessboy16

I would adjust the punch control maybe 40 percent or to a degree where you do not get wheelspin.. then i would drop down a few teeth on the pinion and drop my timing down.. Combonation between puch and gearing will bring down the amp spike a good bit, and the timing will keep motor temps down... less wasted heat means more power and runtime..

I never use the punch control, did once, thought i had a bad motor after a while. I know use the epa on the transmitter now

[crazyjr]

Originally Posted by rootar

gearing down does not help the runtimes at all it actually shortens them cause im using more juice and full throttle punches rather than 3/4 throttle punches......

and yes at the batts limits and i dunno if id dare run them in a truggy, they arent the best batteries by a long shot but they are very good for the money and people around here are more inticed to convert some of their buggies if they can get a decent priced setup. mine runs great i have no real complaints, my temps are great, its tough as nails and i love it, but im nit picky and ive got till december and then till next year to do anything and every thing to make it as bullet proof and as good as possible.


hmm i was looking at the Hacker 14L motor specs state it as a 35 amp motor and 50 amp peak that would be ALOT of difference over my 80amp 1515....... ut somethng tells me those spec arent exactly right but can anyone chime in?

on the first thing, yes and no. Yes, in that gearing down, you will spend more time at max RPM, but there is really not much load at max (should be at top speed) to gear up and limit the time at top speed, that should be more load. I could be wrong, but that's how i see it.

On the amps on the 14L and the neu, I think thats air load. Both are plane and heli motors first and thats how they are tested. Cars load motors a bit different, the spikes are stronger to overcome mass and friction on the ground

[rootar]

yes but a 35 amp air load compared to an 80 amp airload????? thats alot of difference. and i was told by the maker of these lipos that they would handle a big 80 amp motor, so we gave them a go.... so far so good so


im really jsut trying to find the best setup possible so when i can start doing better in the race they will start paying more attention, and ill know what kinda setup to tell them to run, and beable to use the lipos if theyd like.