@solice77 i just realized you don’t really need the dv6 s. The dv4s would be totally good enough for your setup because you have 6355 motors you can’t really push them as hard as the dv6s is capable.
The DV4s is able to push up to 100 motor amps per side and it’s on sale right now for Black Friday. Comes out to $145 each. Do it - you’ll enjoy the extra power. 
I don’t see how that is much better than my current setup if I’d still be limited by the battery amps. Right now I can put motor amps at 100a if I wanted. I’d still hit a wall at 50a battery with it. But I’d just have more torque off the bat.
If I understand correctly, if motor is 100a, and duty is 50%, assuming 50v, that’s 25v*100, 2500w. Since my vesc can push max battery of 50a, 2500w is the limit. So essentially 50% duty is already 100%. It just shortens the throttle ramp, but I am not gettting any more real power out of it. Or am I understanding things wrong?
I guess what I am thinking is my battery is 270a so that’s 67.5a per, if I get a vesc that can push 70+a battery, that would be utilizing the full potential of my battery pack. The dv6 seems appropriate in that respect.
Not really tho…
I’m not going to try to understand your math or assumptions here, because it’s not as complicated as you’re making it.
You have dated, underpowered ESCs at the moment.
If you switch to an esc that can push 100a motor per side, with 4wd, 140kv, and 4.8 gear ratio, you’re going to have a very powerful board. For hill climbing, you need motor amps. Unless you are thinking about flying up this hill at 30mph, stop worrying about battery amps and duty cycle considerations.
To me, the increase in motor amps would be worth $300. You could try running your 4.12’s at 75a, but you might blow them up
I’d need a parachute
I was going off what rosco had shared, have you read this?
So here is what I see:
Total battery current was only 64A max total over all runs. That’s just 16A (64A/4) per ESC. Since you have this set to 60A per ESC (240A total), you definitely aren’t hitting the battery current limit.
Battery current is roughly motor current * duty cycle. And duty cycle is roughly motor voltage / battery voltage, which means duty cycle ends up being roughly a % of top speed. At these relatively low speeds climbing the hill, the duty cycle is low so the battery current is also low. Basically this setting isn’t your limit and and 60A per ESC is totally fine from a reliability standpoint.
Temps also look great. Max of 42C for the ESCs and 60C for the motors is great and leaves some room to work with.
Battery voltage also looked good, as you only dropped to 3.5v per cell meaning this also wasn’t throttling anything.
You did, however, bump up against the max motor current of 60A on 3 different runs, with the longest time spent at max motor current at the triangle on the map.
Basically, try turning up all 4 ESCs to 80A motor with no other changes. I think it will make a significant difference without blowing anything up. You could even start with 70Ax4 just to see if it is enough.
I did some acceleration tests with a Dragy GPS a while back, and even on this 2wd build, motor current made a very noticeable difference in performance.
If I understand correctly, if you run motor amps at 100, and 50% duty cycle, you are in fact hitting 100a at 1/2 voltage, which the ESC could handle as a short burst. It seems the battery current limit would be hard to hit on a board where you are not hitting top speeds often or for prolonged periods. I mostly do hills and my top speeds usually <10mph as far as my remote is correct.
Also, the flipsky 4.12 is rated for 50a continuous and 130a burst. How do you reconcile that with my numbers? If I put motor amps at 130a, I should be able to use it as long as the vesc doesn’t overheat it seems. Not that I would, but theoretically.
Anyway, thanks for looking into it. I will try your suggestions and report back.
This is more or less correct. Battery current limit comes into play at higher speeds with a heavy load (like climbing a mountain pass).
Current ratings are mostly heat related rather than a hard limit. If both mosfets fail shorted, likely thousands of amps will flow between the battery and the motor, at least for a very short time until something blows up. The VESC limits this insane current by using the motors inductance, which slows the rise of current over time, and turning on the mosfets for just a short period of time until the desired current level is reached. The more current, the hotter things get, but if the duration of high current is really short then it may not get hot enough to be a problem.
Flipsky rates that controller at 50A/240A motor current
In practice, it’s not going to be able to do 240A since the current shunts can only measure about 165A on that hardware design.
(3.3v / 2 / (1 mOhm shunt * 10 V/V gain)) = 165A
… but Flipsky is just copying (with little understanding) what Vedder wrote in the post where he released the design.
https://vedder.se/2015/01/vesc-open-source-esc/
And that number ultimately comes from International Rectifier’s datasheet for that mosfet
But as you can see, that number also has a ton of caveats, whether we are talking about the package type, the actual silicon limit, or a pulsed limit (turning the mosfet on for just 400 microseconds or less with huge amounts of current behind it) which can do nearly 1,500A. But even this number is often calculated rather than tested, but that’s a whole 'nother topic.
So both from that data and personal experience, I think 80A is a reasonable motor current setting as long as the default temperature settings of 85C/100C are used.
That’s/your amazing man. Hardly ever does one get such a precise answer.
It’s been raining here so I still haven’t tried it out but I’m certain it should do it now.
So went for a ride with the new settings 80a motor 50a battery and I’m confident I can make it up the hills. The mud made it challenging, but definitely saw and felt the power there necessary to make it. Wheels just spun at the top and had no traction to continue. Just a matter of skill now and good terrain.
Here’s the logs if anybody is interested.
2023-11-19_11-36-02 50a battery 80a motor.csv (3.1 MB)
Here’s a quick summary:
Max motor current 254a
Max battery current 94a
Input voltage dropped to 40.8 from 46.5
Few fault codes: DRV
ESC max temp 44c
Motor max temp 42c
Not sure why the esc threw some fault codes but it seems to be a one off at the beginning of the ride, and on the same slope. I kept hitting the throttle until the motors squealed and couldn’t go more.
The battery voltage drop seems to be what could limit further potential. At 40v I am probably hitting some sort of throttling with the BMS or some other setting I have not checked yet in vesc. Maybe I could add a copper sheet to my solely nickel strip welded battery to reduce the resistance?
