I’m sorry I mean max motor current. Currently set at 70 amps per side and I have 7 inch wheels. I’m a big guy tho, putting these batteries to the test. About 265
And 190 kv motors 6374 which I know isn’t optimal for torque
Ah cool, thanks for the info. You could theoretically set the motor current to whatever you want and the battery would be fine, as long as the battery current was set appropriately. So I currently run a board with a weak battery and set for torque where I have 70A motor current and 15A battery per side. The battery isn’t allowed draw more than 15 (normally), so it doesn’t care about the motor current and it can “handle” that just fine. If I set it to 40A battery per side and went fast up a steep hill at the same motor current, then the battery might need to issue a complaint.
I’m not expert in what settings are too high for 6374s, anecdotally I’ve read people saturating their motors (ie reached the max capacity, all extra current just turned into heat) at ~70A, but the real answer is to check your motor thermals and make sure you don’t detonate the ESC
If the motors aren’t overheating (ideally use a logging device and temp sensors, but checking by touch is better than nothing), you can use higher current.
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Ok. So I have discharge bypassed on my bms, 70 amps for max motor current, and 70 amps max battery current (per side). I figured this was appropriate since 35 x4 is 140/2= 70 amps max per side?
The 6374’s can handle 80 amps at least in my experience, I’m more worried about damaging the battery pushing it to 80 amps max motor current and 80 amps max battery current. (Per side)
So 80A motor doesn’t hit the battery harder, only battery amps hit the battery. Also, the P26A isn’t really a 35A cell, it can only do that in low ambient temperatures and ideal conditions. Mooch rates it for 25A.
IMO (someone else feel free to correct me) you’d be better off with ~85A motor, and 50A battery. Do test it though to see if your motors overheat
Edit oops I fixed a mistake sorry
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Ok, thank you for your advice, I’ll definitely give it a shot. I’m still a little confused how the motor can draw 85 amps when the battery is set to 50 amps.
Edit: I tried 80 amps on a flipsky a few months back, and the motors did not get too hot, but my battery max was also up there.
Oh yeah that’s fair. Basically the ESC switches power on and off to the motors in very fast cycles. At 20% speed, it pushes 85A into the motor for ~20% of each cycle. This “on time per cycle” is the duty cycle. [1] [2]
The ESC has large capacitors that average out the current draw across cycles, so instead of seeing very quick spikes of 85 the battery sees an average of (85)X(0.2)=17A.
Biiiig simplification there, but there’s a thread on it with a few explanations
[1] The reason the motor isn't jerky when you're turning the power on and off all the time is:- It’s got a lot of mass and rotational energy, so it’s just really hard to change its speed with a pulse that’s 0.00001s long
- It is an inductor, which stores and releases energy in its magnetic field. If you don’t like electronics, this functions similarly to intertia in a spinning mass.
[2] I’m using 85A assuming full throttle. The same maths applies at any other value: ie half throttle at 60% speed would roughly look like (42.5A)X(0.6)=25.5A
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Just read through that and found the same answer. Thanks so much! Will be testing soon as I can.
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It could be done with the right tools and skill but that design is far from optimal.
A better approach would be to weld pieces of round tube on the square profile that the bolts would then pass through.
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Lads,
I’m kinda confused.
It’s about braking behavior. I came back from buying groceries and as always got annoyed by how quickly i saturate my battery regen amps (7A per side) Why only 14 amps? Cause I’m only using a 2p p42A pack and 8A per cell is the safe limit i believe.
But what i noticed is that i immediately hit the max 14A, the motor amps weren’t that high this having weak brakes. After the strong brakes kicked in the battery amps went down and the motor brake current “increased”.
Weak brakes
Strong
Is it just because the speed increases the battery regen amps while not needing alot motor amps?
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The simplest answer is that higher the battery amp regen number, the better your high speed braking.
Braking power is the reverse of this chart, specifically the part in the yellow box for your situation. If battery amps are constant, phase amps are more powerful at lower speeds.
Another way to think about is to ignore motor amps and remember that volts * battery amps = total power.
So 14A x 37v = 518w. You are limited to 500 watts of braking power with those settings. That might be fine when you are doing 5mph, but will be inadequate when doing 20 mph. Your mass carries a lot more energy moving at 20mph, and you need more energy to slow that mass down (I’m not calling you fat, I swear).
The only way to improve high speed braking is to increase the battery regen number. It’s been said before on the forums that some people are OK with the potential of reduced cell life by going over the datasheets charge rate as a trade off for strong high speed braking. Since that charge level is so brief, and you only hit those numbers under full braking at high speeds, the impact to cycle life may not be that bad.
Another option would be to add a braking resistor that absorbs the excess power so you could safely raise battery regen amps… but I’m not sure if there is a good off the shelf option for that.
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Is there a way to use active/smart braking over UART? I can’t find any options to set it outside of PPM control. Currently using Flipsky VX2 with VESC 4 fw version 3.4, VESC tool 0.95
On two VESCs I have, one is FSESC 4.2 on FW version 3.103 using Ackmaniac tool, another is a Maytech VESC 4 on FW version 3.40 using VESC tool 0.95. I’ve been using a Flipsky VX2 remote. The remote works and I can set the motor parameters just fine, but I have no controller options under UART:
The UART option looks like this on both of my VESCs. What’s going on? What should I do if I want to adjust my throttle/braking curve?
This is all UART has as far as options go.
UART has no customizability in terms of curves or modes on the vesc tool. It’s all done on the remote itself. If it doesn’t have options, then you’re out of luck.
e:
apparently:
If you use UART then you set the throttle curve under VESC remote tab
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isn’t this just NRF?
I have never used NRF, but I know those settings apply when using UART input 
Tha’s good to know, wasn’t aware.
So the explanation is:
Everything works as intended, it needs more energy to get your fat fuck to a stop so increase the amps for stronger and especially safer breaks which as a trade-off will hurt your cells life.
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The throttle curve doesn’t do Hyst Reverse or Smart Reverse
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Correct. its just a matter of remapping the throttle input.
My response was to this statement which was moved here from another thread.
So…with UART, the remote settings are found under “VESC remote”.
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