Sanyo 25Ah nmc Voltage Drop

Pota

100 W
Joined
May 15, 2017
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147
I have Sanyo 25ah cells from an VW e-up.

I did 12s1p in a gokart, pushing 600amp.

The volt dropped from 47v to 39v... Fully charged 1cell is 4.1amp. How much volt sagg is allowed?
 
That's quite a bit of sag and i'm sure the pack is getting pretty hot by the time you discharge it.

You'll need more in parallel, or a different cell altogether if you want the pack to last. ( or not explode )
 
That said... it actualy DID deliver 600amp to the motor. BUT the volt dropped was big yes.
I expected a better burnout, but maybe this is because of the volt drop?
Do you think this in 2p will give me more burnout and quicker respons, meaning hitting 600amp faster, maybe stay there longer?

What about volt drop, is that less with more in parallelle?
 
You're losing 18% of your voltage under load. Double that pack and the internal resistance will be cut in half.. thus you'll see a 7% loss, which is acceptable but not ideal.

On a low volt, high amp setup like yours, higher voltage will mean more power indeed. You'll see a bit higher top speed as well.
 
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. I realy dont understand why... Therefor i may suspect the batteries.
 
Under a full load, 18% of 82v is 67v. But a burnout probably doesn't draw the whole 600A..

His wheel is spinning a lot faster with a 1:1 and he has much higher voltage, depending on his sag.

You're probably making more torque and less speed. Burnouts need speed.

Makes sense to me.
 
So you think that the gear ratio is so low, that the amp draw will just touch example 500amp before it will go lower because its moving pretty easily?
And With High gear, it will push more amp to turn the tires?
 
12s-2P 400Amp voltsag 0.25V per cell? 15kw powerrrr
12s-3P 600Amp 20Kw powerrr smoking wheels :bigthumb:
 
Ok. I did a test today with 18s1p. 72v.
I also switched the gear ratio to 1:1.
I went full throttle and it rised to 600amp and down to 64v.
But it dident burnout. It did do burnout when i wasent sitting in it.

https://www.youtube.com/watch?v=KObUDN7pMcE

This guy has the same motor as me, only with a 500amp Controller and 110v. He has got 1.16 : 1 gear ratio. Im NOWHERE near!

What can be wrong?
 
His voltage is much higher than yours.. and if the battery pack is set up, even higher under load.

Buy a $10 laser tachometer off ebay and compare his wheel speed to yours.
You'll probably notice that yours is 30-40% lower..

You need wheel speed to make burnouts.
 
Significantly lower voltage will make less torque too because your watts delivered to the motor are lower.

Speed makes burnouts but only requires so much torque.
 
Yes, but he has another movie where he only uses 70v and its alot more burnout than mine
 
Does he also have narrower tires?

Just a thought..
 
Could it be the Series Wound motor? If so, what can be wrong with it?
 
Wait, you have two different motors?
Laser tachometer will sort out the difference.
 
No, we have same motor. Ill try With a clampmeter to see if the amps are for real :)
 
What's his controller though?

Even if you say 500A it could have some peak rating of 1000A or something similar.
 
So you both have the same motor (series wound)

His peak (motor, not battery!) current during burnout is measured as ~500A, yours is measured as ~600A?

You have varied your gear ratio from 2:1 to 1:1 while his is 1.16:1?

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).

More speed at the same torque will give a more impressive burnout but it sounds like you don't have enough torque to even spin the tyres slowly?



Does your controller maybe have a more gentle throttle ramp, so you don't get the same "kick" of torque to break tyre traction, like he does?

Are you sure your tyres are not more grippy than his?

When accelerating your kart against his (drag race), is his faster?


I love your quest to make an electric kart that does monster burnouts. What a great problem to solve :D :thumb:
 
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