Got a question for y'all...

[SunnyHouTX]

If my dragster discharges about 185mAH in 1.4 seconds on a given run down the drag strip, what do you think is the burst amp draw of the system?

[_paralyzed_]

not enough info.

I will say a maxcramps lipo could put out 17 kilajoules of power in a single dragstrip pass, underwater and unbalanced

[pinkpanda3310]

I take it this is no help?

[brian015]

.185Ah (3600sec/hour) /1.4sec = 475Amps average

(at this rate, you would discharge a 5000mAh battery in 38sec)

[What's_nitro?]

475A?

[suicideneil]

Whats the mah capacity of the pack- you could work out how many Cs that is then. Assuming 5000mah though, thats... 95C burst. Wowzers...

[snellemin]

Is hard to tell though. You would need a high speed high amp logger to really tell. Highest Ampdraw is at 0 rpm and then you start to move and ampdraw goes down.

[SunnyHouTX]

Originally Posted by _paralyzed_

not enough info.

I will say a maxcramps lipo could put out 17 kilajoules of power in a single dragstrip pass, underwater and unbalanced

All I can say is:

Originally Posted by pinkpanda3310

I take it this is no help?

It also gives 475.78 A, but I think that's the average draw.

Originally Posted by brian015

.185Ah (3600sec/hour) /1.4sec = 475Amps average

(at this rate, you would discharge a 5000mAh battery in 38sec)

Originally Posted by What's_nitro?

475A?

I think that's right, but the burst would be cool to know.

Originally Posted by suicideneil

Whats the mah capacity of the pack- you could work out how many Cs that is then. Assuming 5000mah though, thats... 95C burst. Wowzers...

40C/80C 4200mAH 3S Thunder Power lipo. So the burst rate might be higher still. About 113C.

Originally Posted by snellemin

Is hard to tell though. You would need a high speed high amp logger to really tell. Highest Ampdraw is at 0 rpm and then you start to move and ampdraw goes down.

Agreed. But in the absence of high frequency and high amp data loggers we can guestimate till the cows come home

So if the average is 475 A, could the burst be about 950 A? I think it might be possible, or more even.

[SunnyHouTX]

Just looked at the link that pinkpanda3310 posted, and it does list burst current.... at 2,854.69 A
I used the pack voltage as 9V because that's about where it's at, at the end of the run (going on EagleTree data from the past, pack voltage as low as 5.5V at the initial throttle hit). Based off that, the link also lists:

Average Power: 4,282.04 W (5.74 hp)
Estimated "Burst" Power: 25,692.24 W (34.44 hp)

Is that (burst current and burst power) even in the realm of possibilities?

[crazyjr]

If that amp reading is right, I know the cells will not stay at 3.7volts per, but using that, it says you hit 5272.5watts. divide that by 750W(roughly 1HP electric) you get 7.03HP. I'm impressed, wow

Edit: Just read sunny's post before mine, wow!! I believe some of you are really starting to maximize the power of brushless and starting to get the true power out of it

[SunnyHouTX]

I think so too. But hard to say what'll happen if you sustain that level of performance for more than 2 or 3 seconds.

[What's_nitro?]

If indeed you are getting 25KW peaks, we're talking microseconds here. Any longer and everything would go POOF! 475A seems like the real peak A draw, average I would guess is around 60A, sustained maybe 40-50A.

BrianG if you could confirm this I'd appreciate it.

[BrianG]

Personally, I think that 185mAh in 1.4 sec IS burst for the most part.

That power calc page is meant to calculate average draw over a much longer run (statistics work better with a larger sample). Using it in that 1.4 sec duration will result in pretty skewed results.

[nuz69]

Note that 5275 Watts is the input power, you must mulplicate it by the efficiency of the system to get the real output, and during bursts, efficiency drops, doesn't it ?
Lets say 70% efficiency, that gives how many output HP ?

[SunnyHouTX]

Originally Posted by BrianG

Personally, I think that 185mAh in 1.4 sec IS burst for the most part.

That power calc page is meant to calculate average draw over a much longer run (statistics work better with a larger sample). Using it in that 1.4 sec duration will result in pretty skewed results.

I think so too (skewed). I just wanted a ballpark number for the peak current in that 1.4 seconds. My conservative guesstimate is 950A like I posted above, even for a milisecond or two.