High Power Prattle (7500W+)

#1

Something that has constantly been on my mind since this hobby took me is a high power drag/race build. I feel like we are barely scratching the surface of harnessing ultra high power builds for things like drag/circuit racing, top speed runs, hill climbs, etc. The possibilities excite me and I’m hoping this can be a place where we can amalgamate information.

Caution: rambling wall of text ahead, feel free to skip ahead.

I am currently charging up hills on a 160motor/120battery build, splitting those figures between two 6384s powered by a 12S3P 60C 6Ah (18 total) lipo pack. This board is stupid heavy, but the build suits my need for it. It can hit 40 and has plenty of torque (but not enough that I’d want to consider gearing for a much higher top speed). This should be enough for me, but it’s not. And even if it were, I’d still want to make something just totally bonkers. I need something faster and lighter.

My plans include motors running at 125A motor/100A battery each, 100C lipos @ ~10Ah & 12S, two single 60V 200A (V)ESCs, as/xt150s, some thick boi gauge wiring, and chain drive. About 3/4 of that is realized (purchased) but there are still a few things that could change (esc’s, I’m looking at you) or that I still need to work out before I start assembly. This thing probably won’t see the street. Prepared surfaces only.

There are people all over the forums/social media who claim they “ride with their Unities maxed out” or whatever, which usually means they’ve set their slider to 120A (max in the UI) instead of 80 battery amps/motor the thing is supposedly rated to, are running batteries not even close to capable of putting out that kind of power, and are using xt90s (or 60s!).
I’m not talking to you guys.

Anyways…

Who’s actually pushing 10hp (~7500w+)? What gear are you using to do it? What special considerations have you had to make for high power? How long can you pull max power before you’re going too fast or your shit is too hot? Have some telemetry data to post? This is the place to post it!

5 Likes
Jet Killshot 40.5 Community Sourced Build
#2

In a race build where you don’t have to worry about weather, it would be interesting to see the heat dissipation you could accomplish with air intakes fans? and big heatsinks.

7 Likes
#3

A wild jason stirs in the distance

10 Likes
#4

I’m with ya there.
I’ve got dual sk8 6374’s at 192kv 16/40 gearing running off lipos running 100 motor amps each. however there is a point of saturation once you hit 100% duty cycle
(i have a 80a bms so I’m limited by that). The peak power is 8800w but like you said it could be more.

#5

I Think the biggest thing is having batteries capable of pushing the current, having esc’s that can sufficiently take and push it. If i could have my settings at 100a motor and 100a battery for each side i would be fucking booming. However it seems hard to find a battery that doesn’t sag at 200a load ya feel ?

3 Likes
#6

Unity heatsinks are nothing compared to what I was thinking.

Actually just slap water-cooling on a fucking not in a box UNITY then run that to a radiator sticking up like a spoiler. That’s what I’m thinking about.

3 Likes
#7

I have a question y’all.

Should I bite the bullet and spend another $69 on 12 more super cells for 60 total?

It could then make a 12S5P or 20S3P of epicness.
I don’t want to miss this 3.99 sale or stock runs out…
But my $69 :persevere:

#8

Actually just slap water-cooling on a fucking not in a box UNITY then run that to a radiator sticking up like a spoiler.

What you are talking about is a ‘Submarine’ …a sleeved type plastic cover like a condom with sealed interconnected pockets and channels running water o some sort of coolant which surrounds battery, vescs and electronics and is connected to an outside multiple fin radiator system.

2 Likes
#9

Yeah after I posted that I got thinking about how to diy an effective water-cooling system for a esk8.

I wondered if you could make a custom silicone mold with tubes running through it for water. The whole vesc would be in contact with the big mushy cold thing. Like a water-cooled Fleshlight for your vesc. Probably a bad idea.

Water cooling still just uses a radiator so you might as well just slap it directly on. Water cooling would be fun for the meme though. I’m more interested in water cooling motors. Possibly hub motors.

1 Like
#10

Probably not water but a non rusty semi-liquid element, more like a gel type coolant running inside of the pocketed Submarine and capable of disipating the internal heat.

1 Like
#11

Mineral oil esk8.

2 Likes
#12

your reminding me I need to go dig out my old PC watercooling stuff and see if any of the GPU blocks might fit VESCs :slight_smile:

2 Likes
#13

I have what i would consider a farley high power board, its not in the “ulra high” category but it does shift. It was not really built for racing but built to perform well and keep up when being ridden by a fatty.

Its an AT board with dual 6880 motors, Unity and external heatsink and 12s4p 30q. Im currently running up to 100A per motor and 100A battery which i feel is higher than most. Being a big guy so i am able to pull high amps for sustained periods of time whilst accelerating.

Some logs . . .

My best 0-25mph time is 4 seconds with an all in weight of around 150KG. I know its not the fastest but its not bad considering my weight.

in the log you can see that for the first 2 seconds i sit on the 200A motor limit as the battery current ramps up to 100A. Then I hit the battery limit and sit for the next 2 seconds being restricted by the battery current. Then the battery sag gets me and power starts to get reduced by the Unity as the pack sags below the low voltage protection thresholds.

This means that for around 2 seconds im pulling around 4kW continuous from the battery before it finally gives out.

But does this hold true in the real world?

This is a recent log from a 2 floor carting track. You can see that i still manage to reach 200A motor current and almost 90A battery current during track racing (despite never reaching more than 22mph). After 10 mins of heavy riding both esc and motor temps were stable at around 60*C.

What this has told me so far is that the main limiting factor on this board is the battery pack. a 4P 30Q pack is simply not powerful enough to deliver the kinds of current required for a “ultra-high” performance board.

Compared to similar boards . . .

Whats interesting is that when people try my board they are often surprised by the power (torque) it has which i find interesting because the spec is nothing that unusual for an AT board. I often get these types of comments from people who own a nazare or kaly.nyc board which in theory both have far larger battery and similar hardware setup.

This leads me to the conclusion that most are playing it very safe with their ESC settings. Also i often see builds here with 63100 or 80xx motors and big ESC’s but the truth is that few have the battery systems to use the power these can deliver, your just carrying unnecessary weight if your system cant utilise the full power of the motor.

Unlocking more power

Im currently planning a 4WD board and im loosely targeting 10KW. Going 4wd this becomes easy as all components only need to be rated to 2.5KW per wheel which should be easily achievable. It has the added benefit of having twice the grip when you put that power down on loose terrain.

The main problem im likely to face again is going to be finding a suitable power system. The current plan is to have a long range 12s9p 30q pack which should be able to deliver around 8kW in short bursts for daily riding. Then when i reach the limits of this i will have a hot swap style light weight lipo pack for racing.

10 Likes
#14

These times 6 for a 12S3P 2250A capable pack? That’s continuous too, you can have up to 4500A (3s) bursts. Who needs more battery than that, ever?

#15

Reading about such big batteries makes me want a huge one for power but my biggest concern is price/longetivity.
What is the average life of a pack with correct high and low cutoffs with everyday riding?
I know there are too many variables in this question but when do you change your pack?
Every 4 years?

#16

I think this is a question to ask if you’re going to commute on it

#17

Well i would prefer just to have an idea on this question as some of us don’t know/ have never built a board yet.

#18

Well over time the cells lose total mAh capacity over cycles, so Li-Ion could last 2 years or more if treated right and is big enough for your needs so that it isn’t draining fully all the time. Have no idea for lipo, but pretty sure they lose capacity over use as well. Depends how much you use the battery will detemine that. If you’re safe about it, it will last awhile. Probably not 4 years though.

1 Like
#19

this is true. However it becomes fucking enormous under your deck and costs a million trillion $$$'s. According to a dude from HobbyKing, the graphene’s are actually marketed as better, yet the new Nano tech plus’s are actually far better under load. of course this is to be proven but yeah…

#20

When ya-all get your HP boards built, come up-hill racin with us on the West Coast. 2020 should be a fun year.

16 Likes