QS-motor phase wire upgrade + Sabvoton 350A

[leffex]

Hey

I want to know what benefit I get from thicker phase wires vs original thin wire in performance measures. Also positive and negative battery wires are replaced. I know the resistance in the wire is less and the voltage drop is less because of that. What performance gain in power and effeciency do I get in the motor? (max power figures: 95 volt system, 350 phase amps, 150A max from battery side.)

Calculations beforehand did give an estimate of about 3v less voltage drop or( 1v instead of 4v which means resistance is 3 times less.) Does this simply mean that I have 150A x 3v = 450w extra power input "TO" the controller and even more "TO" the motor via the phase wires? (https://www.calculator.net/voltage-drop-calculator.html)

Before:
Battery positive and negative 1m each of 10AWG
Phase wires: possibly 1m 12-14AWG tinned copper

After:
All wires 4AWG oversized 25mm^2, almost 3AWG 1m each

Pics for fun and sharing

 

[larsb]

Battery wires (do you need 1m between battery and controller? These should be kept as short as possible)
1m 10 awg 3.3mohm
2m 6.6mohm
2m 25mm2 1.3mohm

So you improve 5.3 mohm or a voltage drop of 0.8V at 150A and save 119W (an efficiency gain of 0.8% at 96V150A)

Phase wires:
2m 12Awg 10.4mohm
2m 25mm2 1.3mohm
You improve 9.1mohm

Here it’s more difficult to asses the losses. If you’re a hotrodder using your 350A phase current (accelerating at low speeds all the time) then removed losses are to be estimated from 350A current:
RI2=0.0091*350*350=1115W
But if you’re commuting at high speed then phase current=Battery current, current is 150A and removed losses are 205W.

A sidenote, just to get a reference to the improvements above:
A common 18650 battery of 20s10p of panasonic 18650pf has 30mohm*20/10 so 60mohm resistance.
At 94V150A (i assume 26s for roughly 94V, 78mohm) thats 1755W losses and 12.5% system efficiency drop.

—>If resistances and voltage drops are to be optimized then there are more places to search for large improvements besides the wires

 

[john61ct]

Increasing performance is not the only goal.

Reducing heat can also improve reliability and longevity.

 

[MJSfoto1956]

Increasing performance is not the only goal.

...and looks can be important too!

 

[leffex]

A sidenote ...

Yeah that is pretty interesting. thanks!

What I mean it is pretty good to get 5% more range after fixing new cables? estimate and guesses

I have RC cells but replacing with 5s24p 18650pf block. So it will get 2,4x less resistance than you calculated
https://endless-sphere.com/forums/viewtopic.php?f=14&t=101122&p=1491564#p1491564

 

[larsb]

you should calculate it based on your average current consumption.
96V150A is 14kW and >100km/h constant speed so if you don't commute only at highway speeds then you won't get close to this output. i'd guess realistic improvement is more like 1%.

 

[leffex]

High average consumptions is 63w energy used per km in distance

But I like that I use alot less (I have a higher efficiency) while accelerating and when using higher power but not so much in slow riding conditions rather than other positive aspects.