Archived: the OG noob question thread! 😀

[pundahh]

Nope, not for me. I did grab them second hand though. I wouldn’t have connected in the wrong polarity.

Would I measure by tapping the prongs to the positive and negative awg wire going to the vesc pcb?

[xsynatic]

The whine itself is pretty new. The right belt stays in the same position, but the left one wanders when turning backwards (don’t drive backwards)

[Venom121212]

I’d tighten all the bolts and not worry about it unless you feel performance problems.

[xsynatic]

No problems at all so far. It just annoys the hell out of me because i know that the sound wasn’t there before.

Well the only other things were these 2

[Venom121212]

Hmm yeah worth a shot swapping them out. I can hear it much better in the first video.

[professor_shartsis]

I read somewhere that motors run most efficient when there the load is around 75%.

What do they exactly mean by this? Do they mean motor amps? So for a 80 amps max motor if you put it at 60 amps it runs most efficient?

That’s a question for @professor_shartsis

Efficiency Control Mode

To prove the algorithm works suppose we have a motor which is: 190kv At the present moment the motor is turning: 1000rpm We can calculate the voltage the motor is generating (back emf voltage) from: 1000rpm / 190kv = 5.26v bemf Suppose I am accelerating and want instantaneous 85% electrical to mechanical conversion efficiency, what voltage should I apply to the motor? 5.26v bemf / 85% = 6.18v pwm effective voltage What is the motor current (assume motor is 0.05ohm)? (6.18v - 5.26v) / 0.…

You can calculate the motor current in BLDC mode via:

(V_voltage_pulse_width_modulated - V_back_emf_voltage) / R_resistance_winding_ohms = I_motor current

Through a quirk of physics:

V_back_emf_voltage / V_voltage_pulse_width_modulated = E_electrical_to_mechanical_conversion_efficiency_instantaneous_%

[Flasher]

Anyone know how proportionate is the lifespan of a battery pack against different charge currents?
I have a 12s6p 30q. Was charging with a 4a charger.
Now I’m using an 8a one. I’d like to basically know how many cycles I can go before seeing a change

[stratoglide]

It’s on the 30q spec sheet expect slightly worse results for anything greater and slightly better

for anything less

[Flasher]

That’s a discharge cycle spreadsheet…
Doesn’t help me much with calculating differences in cycle count when theres a change in charging currents for the same spec’ed pack

[stratoglide]

4A charge on there as well is what they’re tested at

I’m trying to say it’ll maybe extend the life a bit charging lower but 4A per cell is what they’re tested at so, your fine might squeeze a tiny bit by always charging lower buts it’s negligible imo

[Flasher]

On my phone…was too small for me to see…
Is doubling that charge equal to half the cycles? Or is there more to it?

[stratoglide]

More too it haha it’s a 22A 70 degree cut off vs 15A discharge.

But 4Amps is within spec for a single 18650 so a 6 p pack is good for 24 the difference between 4 and 8 is minimal.

[Flasher]

Doesn’t feel minimal with the speed at which I just saw my pack charge to full

[stratoglide]

Haha fast charge for 30Q’s is under an hour which means any 30Q pack can be charged in under and hour lol but yeah 4amps is like minimum for a 4p pack for faster charging 1-1.5 Amps per cell in p group is what I aim for

[Flasher]

So I guess I’m fussing about nothing then. No way in hell I’d have the budget for an 18+amp charger
I’d rather put that into a new pack

Edit: just found out monster chargers exist

[farnam]

Do we have someone from https://diyelectricskateboard.com/ here? I need to know if they repair shorted TB ESCs and how long it takes

[Flasher]

@farnam
Why not just talk to @torqueboards?

[xsynatic]

You mean swapping the bearings or the belts? ^^

[Venom121212]

Bearings. But while you’re there check your belts out for any rocks stuck in the teeth or signs of damage.

[xsynatic]

ah got it. Belts are fine. No cuts, broken teeth or anything that shouldn’t be there.