Oh I managed to solve the problem by accident and now I got it back. I was forced to update the firmware even if I was at 3.57 and lost all my settings. I did motor config again with a medium size outrunner (raptor 2 hubs) and it got all crazy settings like @Pimousse described above. I figured why not try and see how it behaves and it behaved like it should with decent throttle response.
Then I adjusted my settings and it almost killed me again by not being responsive and stopping to accelerate even if I was braking. What did I set wrong? I swapped from -> to (approx)
Motor current max : 38A to 70A
Motor current max brake -38A -70A
Absolute maximum current 150A to 100A
Battery current max: 99A to 40A
Battery current min: -60A to-12A
Did some more experiments and it seems like if I reduce to motor amps to -40/40 again to match the battery max amps it get responsive again. So am I fighting some kind of PID controller here thatâs trying to limit my bat max when I got higher motor amp than bat amp setting? Iâm pretty sure I had it set like this on Ackmaniac and it worked fine.
A sidenote here. Why is there no logic what-so-ever on the battery settings? I set 12S Liion battery in the configurator and select 12Ah capacity. With a Samsung 30Q 12S4P you got 4x3Ah so that should be right? Even if I had a pretty wicked battery outputting more than 20A like the 30Q letâs say 30A/cell it would give me 120A/2 = 60A batmax. The norm however at a 12Ah battery is more like 20A realistic/cell and thatâs 80A/2 = 40A batmax so why the 99A default and -60 charge?
I donât think so. This is what vedder said a month ago on the vesc forum. Itâs really confusing as stated by another user above. The wizard is great making the settings equal on both but itâs a PITA changing the amp settings back/forth on two vescs like I just had to do when testing now.
âThe capacity value for the battery should actually not be divided. Current and regen should.â
Not sure where to ask this but I need to update settings on my dual VESC and I cannot find a micro usb port on it anywhere⌠Can anyone tell me what Iâm missing? How do I connect it to my pc?
If you think that settings need an adjustment, simply re-run the wizard and use the advanced/override settings to manipulate the detection. Thatâs usually faster than manually manipulating values on both VESCs.
Sometimes you want to have non symmetric settings on different VESCs, so changing settings on individual VESCs should be possible. 4WD with non 50/50 power split is one possible example.
Battery settings donât matter so much. Users worry way to much about that. If you pull a lot of amps for an extended period, voltage sag will happen and that will work against overstraining the battery. Using the Advanced/Override option, you can set Batt limits if needed, as described in the documentation. Thatâs two clicks only.
Batt Max can be set higher than Motor Max, but you will never pull more than Motor Max. If Motor max is e.g. 50A, 45Amps is realistically the max that will flow from the battery, no matter if you drop in a value of 45A or 1000A for Batt max. If you run two Motors from one Battery, we are talking about max 90A from the battery. A 4p pack from 30Qs can supply 80A continuous and a lot more peak. Also note that a matching fuse for the battery is a requirement for a safe hardware setup. If you pull a lot more than fuse rating, you will blow the fuse on your innitial full power test runs.
Batt Regen should be set equal to Motor Regen, so that the throttle stick reacts most linear. Braking currents drop very fast with dropping speed, so there is no issue for the battery, unless you ride down a long 45deg incline with full brakes applied at 40km/h + speed. Such a road doesnât exist in reality. The brake should be strong enough to slow you down, and dropping speed always results in rapidly dropping currents. I would worry more about my own life than battery life. Also note that no one will pull full brakes at full speed if brakes are set nice and strong. Full brakes at full speed would send you flying. Thumb = amp limiter.
Batt Regen is a value your battery will only see for a very short period of time. 30A is the bare minimum I set for Batt Regen for a powerful DIY board.
This is where ackmaniac differs I think regarding the motor max. The voltage to the motor changes atleast in VF control where itâs basically linear but also changes in FOC. Itâs not like you apply 48V to the motor and up the amps slowly. So if you got 30V at the motor and pull 60Amps but your battery is a fully charged 12S do you still pull 60Amps at the battery? On ackmaniac fw I run 70A motor and 40battmax and itâs way more powerful then this firmware at 40A motor max 40A batmax like you suggest should be the same since motor amps is limited by my battmax. I can barely get up hills with these settings where I bombed them with ackmaniac fw at same batmax setting.
Are you suggesting not to set battery current limits? Because thatâs what it sounds like. There is no way for the VESC to know the limits of your battery unless you set them, because a VESC can be used with many different batteries.
Just getting up to speed, then losing brakes due to a blown fuse is NOT how to make a safe setup. You are putting âlosing hardwareâ into a higher importance than âpersonal injuryâ and it should be the other way around. Not getting injured is actually more important than not damaging a battery.
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This is getting pretty misguided. Do you actually skate?
The FWs work the same way. Same settings result in same power output. You can push 80A towards the motor while only 40A flow from the Battery. At 50% duty the motor runs at half battery voltage and can therefore run at twice the battery current. For regen it works the same way, but reversed.
Power output = voltage * amps, no matter what FW you use. Using higher motor max than Batt max gives you higher power at low duty cycle. However, max output power at full duty cycle is limited by Batt max in that case.
We skate a lot and do test things put at the edge of the components involved.
Benjamin and I have built a battery test rig to put battery cells to their very limit.
When looking at the data, you will very fast come to the conclusion that batt settings are not as important as you may think. If your battery pack is matched with desired motor power, worst case is a bit of voltage sag. VESC-Tool has the option to limit Battery Amps, as it always was the case. So if your pack is not matched with your motor power, you can reduce amp flow.
However, we never managed to blow a 100A fuse, even with no batt limits set and using twin 70A on the motor side. 7KW continous is not happening in real world.
Exactly. This was not what you said In the other reply. Did you then read what I said above? If I set 70 motor amps and 40 batt amps my board with vesc stock firmware becomes a killing machine with sluggish throttle response and throttle not going off until almost a second after I release it. At 40/40 it behaves fine and with ackmaniac 70/40 itâs also fine.
Letâs assume you empty a 12S8P pack (30Qs) in one hour, high average speed, average draw 25wh/km. Thatâs a 1KWh pack, drained empty in one hour. Thatâs only 12A average amp flow per motor for a twin. Nothing to worry about. Sure, there will be some high spikes and some free rolling. Your battery will stay quite cool at all times.
Thatâs equal to draining a 12S4P pack in 30 mins.
We took 10A rated cells and emptied them at a 20A continuous. Thatâs way beyond you would ever see in esk8 application.
Ever hooked up a temp sensor to the battery pack?
Simply ad a 10K NTC and hook it up to the VESC temp sensor port. Do a crazy flat out ride and monitor cell temp at the end of a hilly section. That experiment will give you an idea how stressed your cells are.
The Wh/km value is a very good indicator for average amp flow in your system. I guess that your ride style and setup will not stress the battery at all.
If you are worried about your pack or want to limit voltage sag, or run a battery that is not very capable, VESC Tool offers the option to limit the Amp flow and prevent any spikes exceeding the continous discharge rates of your cells. Simply hit the Advanced/Override tab to set a limit. Super easy! We describe the procedure in the setup documentation.
https://vesc-project.com/node/938
At 70A the stator is probably totally saturated. It makes no sense to go beyond the point where the stator is saturated. You can try to find the spot where saturation happens. Pushing a lot of amps through such a motor results in heat, and that will change the resistance of the motor, which affects reliable FOC operation. People had locking up motors because of heat. Itâs wise to monitor temperatures and keep them within an acceptable range.
70A Motor max in another FW doesnât mean the motor will see 70A. Ramping might cause the Amp flow to swell up slowly and in reality your motor only sees 40 to 50A.
Well if it sees 40A with vesc fw it for sure get way more with ackmaniac set at 70. At 40 I cant do the hill up to my house but with 70 it goes like a rocket.
