I’ve always set my motor max larger than battery max. I mean, at least in earlier releases we had to as running with low duty cycles (less than max speed) we have to increase the amps on the motor to get enough power to accelerate properly. (Or at least I do with my single 6355 and about 15-36 pulleys).
I don’t have my board where I am, so I can’t test the 70/40 vs 40/40, but I don’t recognize what Trampa is trying to explain. Maybe @Minim should post on the VESC-project website and try to get an answer from Benjamin. Or maybe someone with knowledge of the FOC implementation could shed some light on this?
Bloody hell lads, haven’t updated in a while, but was seriously caught out with the new software… 4 hours of dicking around with software and hardware scratching my head as to why I had F-all power till I copped my remote end points need to be manually written before continuing with the wizard… Didn’t even say it was checking for endpoints on the page, only I noticed the values were changing when blipped.
Maybe I’m an imbecile, but shouldn’t this really be spelled out in the wizard, like ‘set end points, write, next page fool’?
This is the exact reason why I run 70/40 since I need the torque when starting off the line and doing steep hills while not at full speed. A wild guess here but I don’t think I’m alone wanting this. Since I believe that the Engineers at Samsung set their limits for a reason I’m not interested in increasing batt max and shorten the lifespan on my batteries. A better way to solve it is to set the motor amps as high as I can while not saturating the motor and setting batt max as high as the battery can accept. The ackmaniac software takes care of this and makes it smooth atleast I never noticed this bug with that firmware. With vesc original firmware I have the problems mentioned above with sluggish throttle response when going off throttle after full throttle.
“Also note: Symmetric settings (Battery Max = Motor Max, Battery Regen = Motor Regen). will give you perfect linear negative and positive acceleration. No need for funky Watt control modes. The more asymmetric you go, the more you will experience a non linear response. Your battery has to be able to cope with the currents anyway if you want good brakes. You can’t store the generated energy in the UNIVERSE.”
This is from the post you linked to. I disagree that this is the best solution. Since this post was simplified let’s simplify it even more. You got a motor that can deliver peak performance at 60A but your battery can’t deliver to the full potential as the speed goes up (lets’s say 30A max). The reasons for this can be many (weight, danger ++) but we want the best from what we got right? So If we go by your suggestion above we should lower battmax/motor max down to 30A so we can set 30A motor max and 30A battmax. Do you agreed that we then sacrifice a lot of acceleration/hillclimb potential of this setup? The half motor max is a TON of performance lost that both the motor and the battery could handle within specs.
Another thing is that when we need power is when we increase speed. If we are cruising at 25-30km/h it’s barely using any energy compared to what it does when accelerating from a dead stop or climbing that hill. So the demand for power is often when you have lower duty cycle so there is almost always potential to use more motor amps than batt amps.
It’s also easier to speak in watts here because it is the energy produced we feel at the weels. We don’t feel amps or volts. If I want 2000w at the motor I have to allow for higher amps down low then up top since we can’t beat physics.
Exactly what I mean You are however confusing me with the «40/40»-approach (i.e. equal max settings on motor and battery). I need more motor amps running from standstill than my battery max should be.
Other than that I think @Minim said it well in the last post.
You would simply use 70/70 if you need more motor power. The 70A from the battery will only happen for short periods and in reality your battery will not be under more strain than at a 70/40 setting.
That’s because of the average amp flow, which is quite low anyway.
If you empty a 12S4P in 30 mins, you will have 24A average amp flow only.
The peaks will be higher for sure, but a 30Q can easily cope with that. They are rated 20A continuous. Peaks can be higher. In reality battery Amp settings don’t matter so much.
What matters is average amp flow in reference to battery size and cell rating.
If that is a high value, you will see more voltage sag, no matter of your settings.
This is getting ridiculous. We need to set battery max to not push our luck with the batteries in our builds if we want max performance from our motors.
I get that you did some garage test with a thermometer and concluded that the packs could handle it but the engineers at panasonic/samsung/lg ++ set their limits for a reason. I trust them. I might push my luck a little but but I won’t set it to almost double of spec like you suggest with upping it from 40 to 70.
Do you think Frank is taking decisions regarding the battery amps? It’s Ben for sure, right? Ideal would be to search for answers on his forum. Someone might have answered it already.
All I’m saying is that battery amp settings are not as critical as a lot of user thinks. Most of the time amp flow is low and most of the time you don’t ride at full duty cycle in combination with a high workload.
Vesc FW allows you to dial in any setting you like. The cooler you run the cells, the better and that has a lot more to do with your ride style than your settings. In reality your cells will only see some more spikes if you dial in higher Amp settings.
I agree with you but the default setting of 99A makes me cringe as we see so many users getting concerned when setting up their new vesc for the first time.
Where V_batt is the battery voltage including sag.
It is easy to understand why it is difficult for i_motor to be high at high speeds. When the speed is less V_bemf is pretty low and so to have large motor current we just have to bump up the duty_cycle. But when speed, hence duty cycle, is already high enough, the difference between V_batt * duy_cycle and V_bemf is small. So the motor current can’t be as high when compared to lower speed. Hope that made sense.
@trampa Hi Frank, I’m trying to download the vesc tool from the vesc project website, but I think the website is down or has been removed. Do you know where I can download the vesc tool? Thanks.
Hi everyone, I’m trying to download the vesc tool from the vesc project website, but I think the website is down or has been removed. Do you know where I can download the vesc tool? Thanks.
You are however confusing me with the «40/40»-approach (i.e. equal max settings on motor and battery). I need more motor amps running from standstill than my battery max should be.