Sanyo 25Ah nmc Voltage Drop

[Pota]

Okay, ill try explain it, thanks alot btw

First off, we have the same motor. Prestolite MTY4001 36v stock.

Just look at these two videos
https://www.youtube.com/watch?v=BGwtqgN_7no
https://www.youtube.com/watch?v=KObUDN7pMcE

the first is with EXTREMLY grippy wide tires.
the second is with normal gokart tires.
he is running 1.16:1

Same setup in both videos, only different tires. He is running 110v 500amp open revolt controller. In other words, yes more volt than mine, ive tested 84v, but again. today i tested 48v, and the burnout WITHOUT me in the cart is the same, just less high rpm wheel spin. (spun the tires at 480amp+ with the test yesterday @ 84v and today @48v, so seems the volt doesent make any different in when it starts to spin, both at 480amp+)

I did a test today with 48v. Pushing it against the wall, i wasent in the cart, so it only had around 60-70kg load at the back tires (motor and frame). Still same gear ratio 1:1. I added a clamp meter to be sure that the data from the controller wasent wrong, and yes, they was correct, i peaked 662amp @ 48v.
It started to spin the wheels at around 480amp+.

With me in the cart it would NEVER do any kind of burnout, and the wheels wouldent spin.

The motor is wired in this way
Plus to S-1
S-2 to A-1
Ground to A-2

Brush picture. I got 8 of these.

 

[neptronix]

If motor is the same and motor current is the same (or better) then your motor torque will be the same (or better) regardless of battery voltage. If gearing is the same (or lower) then axle torque will be the same (or better).

Unfortunately not the case with BLDC motors. You will see a jump in torque with voltage because the total wattage converted back down to phase amperage can be much higher.

You can even check this on the ebikes.ca motor simulator. Take this link and change the battery to the 66v dewalt battery. You'll see a ~20% boost in torque.

https://www.ebikes.ca/tools/simulat...6_SA&cont=C40&axis=mph&blue=Lbs&batt=B3623_GA

But we need motor speed to make burnouts, which comes mostly from voltage, not amperage in this case. OP does not have the same motor speed because of a combination of huge battery sag and lower battery voltage to begin with.

 

[Pota]

Btw. This is brushed to brushless.

 

[999zip999]

3p...

 

[Punx0r]

Wow, that's some torque he has!

Neptronix, I think this the motor both karts have:

http://vi.vipr.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=350858345897&t=1408739782000&tid=223353071&seller=bullseyeindustrialsales&excSoj=1&excTrk=1&lsite=0&ittenable=false&domain=ebay.com&descgauge=1&cspheader=1&oneClk=1&secureDesc=0

AFAIK on anything brushed, motor current = battery current. The controller simply chops the supply with PWM to deliver reduced voltage & current to the motor.


I'm running out of guesses and my knowledge of non-PM DC motors is pretty thin, but since this motor has separate connections for field and armature and I'm not sure what systems both your controllers use, are you sure both motors are connected in the same configuration RE: series/sepex/compound? I'm wondering if maybe he's accidentally or deliberately miss-wired his motor and is putting way more current through the field winding than intended?

This guy is running about 100v. 1:1 gear ratio and 500amp controller. He does INSANE burnout.
Im having 600amp, and have been running 82v. with 1:2 gear ratio. 1 on motor and 2 on axle. But im NOWHERE near that kind of burnout.

Probably a silly question, but just to check when you say "1 on motor, 2 on axle" I assume that's twice the number of teeth on the axle sprocket and not 1 revolution on motor = 2 revolutions on axle? I.e. your motor is geared DOWN not UP. I appreciate you said you also tested it at 1:1 and there's not much room for confusion there...

 

[Punx0r]

3p...

The OP is delivering 600A to his motor on a 1P VW e-up pack

The other guy is delivering 500A to his identical motor from (according to Youtube comments) a Leaf & VW pack


600A @ 1P on the e-up cells is 24C which is leaning pretty hard on them but what is the other guy's pack like? I can't tell from image of the battery at the end of the video if it's 1P or 2P. Either way, Leaf cells are good for, what, 10C?

 

[Pota]

Wow, that's some torque he has!

Neptronix, I think this the motor both karts have:

http://vi.vipr.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=350858345897&t=1408739782000&tid=223353071&seller=bullseyeindustrialsales&excSoj=1&excTrk=1&lsite=0&ittenable=false&domain=ebay.com&descgauge=1&cspheader=1&oneClk=1&secureDesc=0

AFAIK on anything brushed, motor current = battery current. The controller simply chops the supply with PWM to deliver reduced voltage & current to the motor.


I'm running out of guesses and my knowledge of non-PM DC motors is pretty thin, but since this motor has separate connections for field and armature and I'm not sure what systems both your controllers use, are you sure both motors are connected in the same configuration RE: series/sepex/compound? I'm wondering if maybe he's accidentally or deliberately miss-wired his motor and is putting way more current through the field winding than intended?

This guy is running about 100v. 1:1 gear ratio and 500amp controller. He does INSANE burnout.
Im having 600amp, and have been running 82v. with 1:2 gear ratio. 1 on motor and 2 on axle. But im NOWHERE near that kind of burnout.

Probably a silly question, but just to check when you say "1 on motor, 2 on axle" I assume that's twice the number of teeth on the axle sprocket and not 1 revolution on motor = 2 revolutions on axle? I.e. your motor is geared DOWN not UP. I appreciate you said you also tested it at 1:1 and there's not much room for confusion there...

Correct. THATS the motor i have, i bought from that guy, but a newer one

Yes, thats what ive been thinking aswell, maybe the wiring is different. I think ive done it right, but there may be another way to increase the torque alot.

Correct, example. 18teeth on motor, 36 on the axle

I mean, it wont help me with the amp going from 1p to 2p. Because 1p already gives me 662amp at peak And you know, it actualy is around 600amp for maybe 5sec!

 

[eee291]

Do you have the same sized tires as that guy?

 

[Pota]

Do you have the same sized tires as that guy?

Yes, but thats not the problem, even with car tires. I have WAAAAAAYYYY lower torque. There are other things that make mine alot weaker.

 

[neptronix]

AFAIK on anything brushed, motor current = battery current. The controller simply chops the supply with PWM to deliver reduced voltage & current to the motor.

He said it was brushed to brushless..

Anyway, wheel RPM data from both karts is missing and i suggested speed is the main factor here.

[youtube]T1beC8eALYA[/youtube]

As i demonstrate here, wheel speed makes smoke, and all you need is enough torque to start the reaction..
Crystalyte 3548 ( fastest winding available ) spinning at ~950rpm on a very soft tire.

See how much smoke i made in just a few seconds from all that friction? it's the wheel speed that causes the tire to get hot enough to vaporize.

 

[Pota]

Mine make INSANE smoke at 84v With noone in the gokart. But With me sitting in it, its a different story, it wont spin.

 

[Punx0r]

There's definitely something weird going on as it looks like an apples-to-apples comparison between your karts but he is clearly making way more torque at the axle than you despite you have a bit more motor current and shorter gearing :?

It would be great if one of the guys knowledgeable on non-PM brushed motors could comment.

 

[Pota]

Some say it may be my brushes advancement. @ DIYElectricCar they say im loosing 80% torque if its 30% Advanced.

 

[redline2097]

Whats the total weight of Kart + You?

 

[Pota]

150-200kg

 

[Joachim]

try 18S 2p

 

[Punx0r]

Some say it may be my brushes advancement. @ DIYElectricCar they say im loosing 80% torque if its 30% Advanced.

I was going to suggest the DIYElectricCar forum as those guys are much more experienced with large brushed motors.

Looking at the news photos above I'd guess your motor is wired in a series configuration. I was thinking if it was intended to be shunt or sepex this might restrict power by placing a relatively high-resistance field winding in series with the armature, but your measurements show this isn't the case. As with the suggestions of increasing the battery to 2P or 3P, your motor is drawing plenty of current, it's just not using it to make torque like the other guy's is. Presumably it's wasting it as heat instead, so maybe you're onto something with the brush timing. Maybe someone monkeyed around with the motor before it got into your hands?

 

[Pota]

Some say it may be my brushes advancement. @ DIYElectricCar they say im loosing 80% torque if its 30% Advanced.

I was going to suggest the DIYElectricCar forum as those guys are much more experienced with large brushed motors.

Looking at the news photos above I'd guess your motor is wired in a series configuration. I was thinking if it was intended to be shunt or sepex this might restrict power by placing a relatively high-resistance field winding in series with the armature, but your measurements show this isn't the case. As with the suggestions of increasing the battery to 2P or 3P, your motor is drawing plenty of current, it's just not using it to make torque like the other guy's is. Presumably it's wasting it as heat instead, so maybe you're onto something with the brush timing. Maybe someone monkeyed around with the motor before it got into your hands?

True, but no, the brush timing was good.

But i havent tried reversing the motor.