Safe riding amps?

[Funky]

As tittle says.

I'm little bit confused  about ks18xl safe riding amps. More or less i know it has 30A fuses. And somewhere i read it has 60A "combined" fuse. (Battery if i'm not wrong..) Don't really know the whole details.. What/Where/How.  

I have been hitting 36-38A for about 1-3 second.. So called spikes while riding. (At least that's what i saw in EUC World.)

Here's my questions: How bad is it? Is it safe? At what amps should i start to worry? Thought i may ask, before i hurt myself. 

 

Also same time may ask about motor wattage. I have never gone over ~1800W. At what "Watts" should i start to worry? It has 2200W motor and 4000W peak, so i should be safe till 4000W? 2200W while "normal" riding.?

 

Edited November 21, 2022 by RagingGrandpa
(clarified title)

[Chriull]

6 hours ago, Funky said:

As tittle says.

I'm little bit confused  about ks18xl safe riding amps. More or less i know it has 30A fuses. And somewhere i read it has 60A "combined" fuse. (Battery if i'm not wrong..)

Each of both batteries is connected to the motherboard via a 30A fuse.

6 hours ago, Funky said:

Don't really know the whole details.. What/Where/How.  

I have been hitting 36-38A for about 1-3 second.. So called spikes while riding. (At least that's what i saw in EUC World.)

Here's my questions: How bad is it?

Not anyhow bad at all.

6 hours ago, Funky said:

Is it safe?

Yes.

Something roughly about 18 to 19 A over a slow blow/tume delay 30A fuse is nothing to worry about.

6 hours ago, Funky said:

At what amps should i start to worry? Thought i may ask, before i hurt myself. 

Normally mosfets blow before the fuses melt. The motor current can be much higher then the battery current.

The fuses are (should be) just to protect the batteries in case of short curcuits, like often caused by fried mosfets.

6 hours ago, Funky said:

Also same time may ask about motor wattage. I have never gone over ~1800W. At what "Watts" should i start to worry? It has 2200W motor and 4000W peak, so i should be safe till 4000W? 2200W while "normal" riding.?

The reported wattage shows the battery provided power. Depending on speed and burden there is a huge range how this divides in dissipated power (mosfets, wires, motor coils) and motor output power.

Very roughly is in low speed high burden situations dissipated power huge and motor output power low. The higher the speed the better the efficiency and the higher the ratio output vs dissipated power.

In regard to overleans reported power is relatively irrelevant. Here only the pwm % is the value of interest.

[Funky]

2 hours ago, Chriull said:

Something roughly about 18 to 19 A over a slow blow/tume delay 30A fuse is nothing to worry about.

Normally mosfets blow before the fuses melt. The motor current can be much higher then the battery current.

So 6-8A over said 30A fuse is okey. For short time period. (1-5 seconds?) Even 18-19A is alright? (In my mind it has 30A rating anything over said 30A would get it burned.. That's why i'm confused..)   

And how would i know when mosfets are being overburdened? At what should i be watching? Which setting and how much would be safe amount?

 

In any case the wheel should start to "warn" me, if i would ever do something that's would be to "high" - Right?

[Chriull]

1 hour ago, Funky said:

So 6-8A over said 30A fuse is okey

I'd assume that from the two fuses one is for each battery or the are in parallel.

So each fuse has just to handle (very roughly) half the current.

1 hour ago, Funky said:

(In my mind it has 30A rating anything over said 30A would get it burned.. That's why i'm confused..) 

Time delayed fuses/slow blow fuses can withstand 2-3 times the nominal values for some seconds.

Depends on the specific fuse - don't know which fuse exactly is used here, but some "forgiving" fuse makes sense - fast fuses would have sent many riders flying already...

1 hour ago, Funky said:

And how would i know when mosfets are being overburdened? At what should i be watching? Which setting and how much would be safe amount?

With KS it's mostly experience. A measure for mosfet overburdening would be either  the heatsink temperature (like inmotion) or motor current (like begode/leaperkim). 

KS does not report either. ?The/some? third party apps calculate/estimate motor current - don't know how useful these values are..

1 hour ago, Funky said:

In any case the wheel should start to "warn" me, if i would ever do something that's would be to "high" - Right?

Imho not really. Reported motherboard temperature is too time delayed.

For ks one could just take some battery current at low speeds as limit for inclines, as these is one of the more tempting cases for the mosfet.

For this ks18xl riders should have battery current alarms they experienced as safe?

For some real warnings manufactures would need a temp sensor on the heatsink (for some calibration) and a "mosfet temperature simulation" in firmware based on the measured motor current and ambient temperature.

Edited November 19, 2022 by Chriull

[Tawpie]

Remember that fuses, and especially the automotive style ones we have in our wheels, are the last ditch effort to prevent catastrophic overheating of the wires and battery. In order for a fuse to blow, something else has also gone seriously wrong—like a MOSFET shorting and not destroying itself.

The fuses are not expected to save the MOSFETs, they're there to save the wires and battery.

Is 40A battery current too high for an 18XL's MOSFETs (KS reports battery current)? I don't know! We'd have to know the part number they use and understand some of how they drive the MOSFETs.

We tend to think that max weight rating for a wheel is due to mechanical limitations like the axel, but it most certainly also includes considerations for the max payload that the electronics can manage. Heavier riders use more power to remain balanced, to accelerate, and to lift up hills. Provided you're within KS's published ratings for speed, payload etc., I would expect that you are alright BUT the closer you get to 100% of anything, the higher the risk of failure.

Does the 18XL report safety margin to EUC World? That's the number I'd use.

IMO, motor 'rating' is a term we misuse. Historically it's used to estimate how much -continuous- heat the motor can withstand before thing start to melt or demagnetize. Regardless the 'rating' of the motor, what matters is the motor temperature. As long as that's ok, you motor is going to be ok. Besides, the motor wiring is able to withstand far more current that the rest of the system (batteries, wires, mosfets, connectors) so it'll remain happy until it gets too hot.

[Seba]

On 11/19/2022 at 6:53 PM, Tawpie said:

Is 40A battery current too high for an 18XL's MOSFETs (KS reports battery current)? I don't know! We'd have to know the part number they use and understand some of how they drive the MOSFETs.

No, it's perfectly safe value.

On 11/19/2022 at 6:53 PM, Tawpie said:

Does the 18XL report safety margin to EUC World? That's the number I'd use.

Of course. More, this is not calculated/estimated value, but value provided directly by the mainboard firmware.

[Funky]

40 minutes ago, Seba said:

No, it's perfectly safe value.

40A so called spikes? Or continuous, multiple minutes on 40A?
And at what "A" one should start to worry?  

Edited November 21, 2022 by Funky

[Seba]

1 hour ago, Funky said:

40A so called spikes? Or continuous, multiple minutes on 40A?
And at what "A" one should start to worry?  

Brief values of 40 A are completely safe. Even higher current spikes are OK, as long as you keep continuous current below 30 A. Fortunately, both mainboard and battery of 18XL are rated for it's nominal power of 2200 W. This translates into theoretical ~40 A near the 0 % battery (theoretical, because in this condition wheel will constantly tilt back due to low battery voltage) and ~30 A when battery is full (both values accounts for voltage drop). Also keep in mind that 18XL can be overpowered up to 4000 W for a brief moment of time, and brief doesn't mean milliseconds, but rather few seconds. This is why it's best to use safety margin value for a measure of available power.

[Funky]

1 hour ago, Seba said:

Brief values of 40 A are completely safe. Even higher current spikes are OK, as long as you keep continuous current below 30 A. Fortunately, both mainboard and battery of 18XL are rated for it's nominal power of 2200 W. This translates into theoretical ~40 A near the 0 % battery (theoretical, because in this condition wheel will constantly tilt back due to low battery voltage) and ~30 A when battery is full (both values accounts for voltage drop). Also keep in mind that 18XL can be overpowered up to 4000 W for a brief moment of time, and brief doesn't mean milliseconds, but rather few seconds. This is why it's best to use safety margin value for a measure of available power.

Yeah i have set my "safety margin" at 20%. Lowest it ever has been was 17%. So i'm pretty safe. (Who ever made EUC World - He's the man!! Props, respect and so on..) 

And as i never ride lower than 45% of battery i'm also good.  

[Paul A]

3 minutes ago, Funky said:

Who ever made EUC World

 

It's member Seba, the person quoted.

[Funky]

5 minutes ago, Paul A said:

 

It's member Seba, the person quoted.

Pshh don't tell him that directly.. Or his ego may get too big. Wink, wink.

Edited November 21, 2022 by Funky