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  #1  
Old 05-27-2018, 03:26 PM
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Default Upgrading a 48V 1,000W motor for more power

I have a MY1020 48V 1,000W brushed PMDC (Permanent Magnet Direct Current) motor
...& the YK31 48V 26.7A controller that came with it

It's fun but, I want more power

So, from what I understand (so far anyways)
...to get more power (speed) out of this motor
...we gotta apply more power (Amps) to it

There seem to be a few options available

A couple available from Electric Scooter Parts .com
https://electricscooterparts.com/spe...ers48volt.html

Like the SPD-48100D for ~$75.00
...but, it's max current is only listed as 35A peak (a tincy wincy bit better)
https://electricscooterparts.com/hookup/SPD-481000D.htm

Or the SPD-482000A for ~$100.00
...it's max current is only listed as 60A peak (a little better)
...but, this controller does not have a built in power relay to turn it on and off
...so, a heavy-duty switch & a power contactor is needed to turn this controller on and off ($19.95) http://<br /> http://www.electricsc...wer-contactors

Then, there is the Kelly KDS48100E for ~$90.00
...it's continous current is listed at 60A & 100A peak
http://kellycontroller.com/kds48100e...ler-p-285.html
...it too is supposed to be used with an on/off switch & a power contactor
...like the CZ 48DC 100A ($29.00)
http://kellycontroller.com/main-cont...mps-p-577.html

So, it looks like this Kelly controller can more than double the amps that are continuously available to my motor
...& provide almost 4x more peak amps for ~$120.00

Am I missin' anything?
...or is this the "best" way to go?
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Old 05-27-2018, 11:56 PM
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I wish I was electronically inclined. Sorry that I can't help you at all, but your logic does seem correct
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Old 05-28-2018, 12:23 AM
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you do in fact miss something very important...

Take your cutoff switch and wire it in series with
the batpack and the motor..
connect your shunt and the powermeter it came with..
hold on to your hat and close it...

See that on your Powermeter?...
Now... what do you think could a bigger controller do to change that value?

'sid
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Old 05-28-2018, 08:59 AM
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Quote:
Originally Posted by itsid View Post
you do in fact miss something very important...

Take your cutoff switch and wire it in series with
the batpack and the motor..
connect your shunt and the powermeter it came with..
hold on to your hat and close it...

See that on your Powermeter?...
Now... what do you think could a bigger controller do to change that value?

'sid
Is this a riddle?

What's your problem?

OK, then EXPLAIN it to us genius
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Old 05-28-2018, 09:18 AM
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If you want efficiency go with a 150A kelly. *They are overrated so figure the 150 will be good for about 100a. If you want raw power cheap go with the Chinese 24-60v YK43B. It supplies around 190a peak.
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Old 05-28-2018, 10:05 AM
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Kevin we've been through this already..

Remember how we measured the internal resistance of the me0909 clone you got from that fishy ebay-seller back then?

Remember how we calculated the maximum amperage that motor could draw from that resistance and the voltage you wanted to run it at,
to find a matching controller for it?

The controller is picked BY the current a motor could draw
since what the motor COULD draw is exactly the amount the motor WILL draw if it needs to.
(unloaded currents are slightly lower yadda yadda)

And this is a very important information you already have!
You know this already...

The controller is no limiting factor of a working setup. the motor is!
(yeah true you could ask a controller to stop at 75% PWM instead of going up to 100% cycles.. but apart from that.. nope if the controller doesn't overheat and die with the motor attached it is able to deliver all the current your motor is able to draw!)

So.. you motor can draw no more than 33Amps for all I know
(that's at it's stalling speed under full load at which it itself will selfdestruct in short order)

The yinlun controllers (I always get that name wrong.. I wonder how this time...)
are made specifically FOR the Unite my1020 motors.. so chances are it itself (rated at 27Amps) allows for a peak current of say 35Amps as well
(more likely 40 since generally MosFets peak in 20Amp steps)

Anywhoo.. your controller is no limiting factor, it's not, it wasn't ever and it'll never be!

And you can prove that yourself by cancelling out the controller from a bench-test equation...
(battery motor and measuring device and a beefy switch to turn in on and off an attached chain and gear for putting a load onto the motor)
you have all that's needed to quickly do so without a doubt...

AND THAT'S WHY I just asked you to do that.. hoping that as you read my previous reply,
you remember the things we already talked about a while ago,
and in case you wouldn't want to take my word for it
- I mean Quinc here certainly likes to state differently every chance he gets -

Just prove it to yourself with what you already got at home (nothing to buy just time to spend)

So, before you buy a kelly controller you don't need
Think, remember and when in doubt TEST!

'sid

[EDIT]
Oh look the my1020 48V 1000W power diagram:
Click image for larger version

Name:	1020-1000W48V.jpg
Views:	6
Size:	309.8 KB
ID:	97874
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Old 05-29-2018, 08:44 AM
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Quote:
Originally Posted by itsid View Post
Kevin we've been through this already..

Remember how we measured the internal resistance of the me0909 clone you got from that fishy ebay-seller back then?

Remember how we calculated the maximum amperage that motor could draw from that resistance and the voltage you wanted to run it at,
to find a matching controller for it?

The controller is picked BY the current a motor could draw
since what the motor COULD draw is exactly the amount the motor WILL draw if it needs to.
(unloaded currents are slightly lower yadda yadda)

And this is a very important information you already have!
You know this already...

The controller is no limiting factor of a working setup. the motor is!
(yeah true you could ask a controller to stop at 75% PWM instead of going up to 100% cycles.. but apart from that.. nope if the controller doesn't overheat and die with the motor attached it is able to deliver all the current your motor is able to draw!)

So.. you motor can draw no more than 33Amps for all I know
(that's at it's stalling speed under full load at which it itself will selfdestruct in short order)

The yinlun controllers (I always get that name wrong.. I wonder how this time...)
are made specifically FOR the Unite my1020 motors.. so chances are it itself (rated at 27Amps) allows for a peak current of say 35Amps as well
(more likely 40 since generally MosFets peak in 20Amp steps)

Anywhoo.. your controller is no limiting factor, it's not, it wasn't ever and it'll never be!

And you can prove that yourself by cancelling out the controller from a bench-test equation...
(battery motor and measuring device and a beefy switch to turn in on and off an attached chain and gear for putting a load onto the motor)
you have all that's needed to quickly do so without a doubt...

AND THAT'S WHY I just asked you to do that.. hoping that as you read my previous reply,
you remember the things we already talked about a while ago,
and in case you wouldn't want to take my word for it
- I mean Quinc here certainly likes to state differently every chance he gets -

Just prove it to yourself with what you already got at home (nothing to buy just time to spend)

So, before you buy a kelly controller you don't need
Think, remember and when in doubt TEST!

'sid

[EDIT]
Oh look the my1020 48V 1000W power diagram:
Attachment 97874
Yup, I remember
...& I reread the entire thread as a refresher
http://www.diygokarts.com/vb/showthread.php?t=33805


You said:
"So measure the internal resistance and go with that.
(cold and if possible after the motor ran for 5min under no load but at full speed)
BUT CAREFULL! since they disabled the temp fuse for some reason make sure the motor doesn't overheat from that... heat kills permanent magnets really quick;
if it's getting too hot to touch kill the powersupply and measure; no matter if only 1minute passed !!

the lower resistance value is the one you want (oh turn it slowly over by hand while measuring sometimes the commutator is not in perfect contact and turning will find you the best spot [least resistance])

divide 48 by that number and you'll get the max amperage

My const 165Amp guess was solely mathematical.. based on their claims...
10hp are 7457 Watts mechanical.
divided by 0.94 (efficiency rating)
7933 Watts electrical
divided by 48Volts... and you get ~165Amp.

So yeah if that's off... you know whom to blame
(not my math teacher )

Oh yeah.. you'll get the MAX rating not the constant rating
but you can choose the controller by that number if you overestimate by about 15% security margin.
(say max amp is 320Amps calculated.. pick a 370Amp max rated controller or bigger.)"



So, could you (please) explain (again) how you got to 320A MAX (I guess)
...from 165A continuous (I guess)

* I thought I was learnin' here

Sorry, didn't mean to be rude
...but, (sometimes) you make it sound like I don't know

I thought that W/V=A (Watts divided by Volts equals Amps)

So, for the ElDingo example it would be

8,000W (size of motor) / 48V (intended voltage) = 166.666A (constant amperage required?)

...or for the MY1020 example it would be

1,000W (motor)/48V (intended voltage) =20.83A (continuous?) & ~27A (peak?)

Sound right or still way off?

** I'm tryin' to understand this stuff
...& don't give up easily
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Old 05-29-2018, 10:49 AM
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Don't mess up MOTOR and CONTROLLER ratings.

What you want is a controller_continuous_ rating that's sufficient for the motors _continuous_ rating.. when in doubt (since the motor's power thirst can easily boil a controllers internals)
scale up so that the controllers _continuous_ rating matches the motors _MAX_ rating.

if a motor draws 165Amps as assumed, your controller then should handle that kind of current continuously.. thus ITS maxrating goes up a huuge amount (depending on the efforts the manufacturer spent on mosfet cooling)
THAT's what the 165 Amp motor could use a max rated 320 Amp controller (since the motor itself was of unknown values and every measurement has flaws and .. well better spend 10bucks on the bigger controller today than having to buy another 150dollar controller tomorrow because it was sized a hair to small at first)

Watts are NOT Watts!
Watts on one hand are VoltAMperes in which case your math is perfectly correct (R=U/I)
BUT motorwatts can be mechanical Watts (true watts) (efficiency and such comes in)

The 1000W my1020 is 1000W MECHANICAL power (1250 or such electrical Watts [VA])
just as it supposed to be for EV motors.

that's why it states 26.7Amps (@ 48 that's ~1282 Watts)
And since UNite was one of the better companies.. it's the CONTINUOUS rating

AS you can see from the diagram I posted above, it's able to draw 33.5 Amps max,
(but that rating is good for no more than 10 at best 20 seconds... then the coil insulation starts to boil off)

NOW.. again, that kind of current your controller is able to handle anyways..
you cannot (LUCKILY) push more currents through that motor,
otherwise ELDingos motor would've boiled off it's insulation long ago (320Amps peak remember )

But I can only repeat over and over again..
a motor will take as much currents as it needs and able to handle
the controller must only be able to handle that it can be bigger (even able to supply 10000 of amps if you like) the motor will still ONLY draw whatever it needs, never more.
So a bigger controller is due if you're unsure about the maximum amperage of a motor, but it doesn't ADD currents to a known motor.

'sid
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Old 05-29-2018, 12:06 PM
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Quote:
Originally Posted by itsid View Post
you do in fact miss something very important...

Take your cutoff switch and wire it in series with
the batpack and the motor..
connect your shunt and the powermeter it came with..
hold on to your hat and close it...

See that on your Powermeter?...
Now... what do you think could a bigger controller do to change that value?

'sid

Why couldn't u just say

What you want is a controller_continuous_ rating that's sufficient for the motors _continuous_ rating.. when in doubt (since the motor's power thirst can easily boil a controllers internals)
scale up so that the controllers _continuous_ rating matches the motors _MAX_ rating.

...the first time?

Short, sweet & to the point

Previously, you said,

"My const 165Amp guess was solely mathematical.. based on their claims...
10hp are 7457 Watts mechanical.
divided by 0.94 (efficiency rating)
7933 Watts electrical
divided by 48Volts... and you get ~165Amp."


So, doing it your way, you got 165A continuous & 320A max
...which isn't much different than the numbers I got

Doing it the way I did it

Manta (motor) listed @ 8,000W
...divided by the intended voltage - 48V
...equals ~166A (continuous)
...then roughly double it ~332A (max)

or

MY1020 (motor) listed @1,000W
...divided by 48V
...equals ~20.83A (cont.)
...doubled ~40A (max)

* I understand that your way is "by the book"
...but, there doesn't seem to be a very big difference between our final numbers

** Could you (please) explain (to us)
...the difference between mechanical & electrical watts
...& the details of the MY1020 diagram you posted
(it looks kool but, I don't understand everything)
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Old 05-29-2018, 12:33 PM
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Could one not have a "direct connect" between battery and motor? If top speed is all you want, you could have a controller for part throttle driving, and then the rare times when you want to wind it out, you have a mechanical relay or switch even that simply connects the battery to the motor and bypasses the controller?

Along those lines, perhaps you do not need a completely new controller, but rather a "relay" after the controller to better handle the current of the larger motor. I say "relay" because I know if it not this simple, because it would have to be an H-bridge or some kind of PWM modifier. but it would be a dumb follower or repeater like a relay. Just a means to apply more power when the original source could not supply it.

There might even by some DIY project out there.

A quick google showed this:
http://www.greenfuelh2o.com/High_Pow...ler_p/hcpc.htm
pricey though.
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Old 05-29-2018, 06:45 PM
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Chinese 24-60v YK43B. I bought mine on ebay new for 45$. Use it and upgrade to something fancier later if you need it.
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Old 05-29-2018, 08:08 PM
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Quote:
Originally Posted by Functional Artist View Post
So, doing it your way, you got 165A continuous & 320A max
...which isn't much different than the numbers I got

Doing it the way I did it

Manta (motor) listed @ 8,000W
...divided by the intended voltage - 48V
...equals ~166A (continuous)
...then roughly double it ~332A (max)

or

MY1020 (motor) listed @1,000W
...divided by 48V
...equals ~20.83A (cont.)
...doubled ~40A (max)

* I understand that your way is "by the book"
...but, there doesn't seem to be a very big difference between our final numbers

** Could you (please) explain (to us)
...the difference between mechanical & electrical watts
...& the details of the MY1020 diagram you posted
(it looks kool but, I don't understand everything)
NOOOOO nononononooooo

you again mess up motor and controller rating and worse electrical and mechanical ratings...

the motor this topic is about has a
continuous rating of ~27Amps NOT 20 and a
max rating of ~35Amps not 50+!
BIG DIFFERENCE

the 1000Watts it says on it's label is MECHANICAL Watts NOT ELECTRICAL (electrically it draws 1280 VA! (watts) not just 1000)

Okay once more..you read this, didn't you?

A motor is a "converter"-unit..
it converts electrical power to mechanical power.

No converter is perfect (thermodynamics kick in)
that's why they usually have an efficiency rating.
(in case of the my1020 motor it's 'variable but around 80%)

the remaining 20% is the loss of power during conversion
(that's what heats up any converter... thermo-dynamics isn't drawn out of thin air )

The unit for power is Watts.. you still need to differentiate between mechanical, electrical or radiant power.. although it's always Watts..
One is VA (volt times amps = watts) [ELECTRICAL]
one Fv (Force times velocity = Watts) [MECHANICAL]
and the third
is Ir (Intensity times four Pi radius-squared = Watts) [RADIANT]

NOW, if you convert VA into Fv or vice versa you generate Ir as a side product (the heat loss)

You see that as P.in (VA) and P.out (Fv) in the diagram, the efficiency as n(the most curvy one)

motorspecs are no one-liner,
they are a plot like the one I posted above..
for every applied load the values will change slightly..
the important parts are the peaks mostly

And the more the efficiency drops at the upper (rightmost) end of such plot,
the more heat the motor generates... HEAT is a bad thing for coil insulation, magnets and bearings...
And that's the whole point.
At it's continuous rating of 27Amps the motor is efficient enough to not produce too much heat, it can cool itself with it's own movement enough,
to prevent the insulation from failing or the magnets from overheating.

Your coil can draw 30 something Amps w/o problem..
but since the efficiency drops at that point below it's critical point..
the amount of heat produced is big enough to heat up the small motor considerably.
do that for too long and the motor will heat up to a point where the insulation fails (or you cook the magnetic fieldstrength off the magnets) which will result in terrible powerloss (mechanical powerloss, electrical powerdraw could then again rise) or worse a complete failure (a shortened coil can smolder and humm but fail turn the motor over even once)

And that's the MAX rating of the motor

'sid
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Old 06-02-2018, 09:28 AM
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Yup, I read your motors essence thread several times back in 2016, a couple of times last year & a few more times in the last couple of days

…& yup, I'm still confused

That is great info & shows how to "do the numbers", "by the book"
...which is great for students or teachers

But, WOW

This isn't NASA
...it's Do-it-yourself Go Karts

&

Were not building a Mars rover
...just homemade go karts

I really appreciate your help/expertise & I'm glad you haven't given up on me (yet anyways)

but, come on, isn't there a simpler way?

Kinda like using the "Ball Park Equation" to help figure how fast a kart will go http://www.diygokarts.com/vb/showthread.php?t=38785

It doesn't factor in many variables like total weight or rolling resistance (on purpose-to keep it simple)
...but, if ya insert the "biggies" like motor speed (RPM's), gear ratio & the tire circumference IMHO it gives you an idea of how fast a kart can potentially go, using a given set up
...or at least it puts ya in the "Ball Park"

Ok, now I/we know,

That there are (3) different kind of watts
(VA-electrical watts, Fv-mechanical watts & IR-radiant watts)
...but, their not labled

Motors are rated in "Fv-mechanical" watts
...but, speed controllers are rated in "VA-electrical" watts

So, a motor labeled as 48V 1,000W(m) will "actually" draw 1,280W(e)

Can the 1,000W(m) = 1,280W(e) be used as a "Rule of Thumb"?

For scaling up, like
...a 2,000W(m) motor = 2,560W(e)
...a 5,000W(m) motor = 6,400W(e)
...or an 8,000W(m) = 10,240W(e)

* If over-volting isn't the answer
…& over-amping isn't the answer either

Maybe my original question should of been...

Sid, any suggestions on how to make a kart with a 48V 1,000W MY1020 motor go faster?
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Old 06-02-2018, 10:55 AM
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it is perfectly simple as long as you have a reliable source for the motor specs..
(which you have with above specsheet - for all I know it's the UNITE one aka manufacturer version of it)

So in order to get CORRECT values, you will need to find such reliable sources! (no exceptions!)

You can (which is what I do to ballpark electric setups) however
go by 'common' values instead..
commonly the efficiency of a modern good working condition motor is around 80% or better in it's optimal range.

And just assuming 1000W / 0.8 put's us to 1250 electrical Watts
(see? a rather close to real value)

The real problem is to know what's on the label.
Again good motors tell the continuous mechanical Watts..
bad motors (say RC stuff) not only always list electrical Watts but they tend to list the peak values..
If you don't know.. you can end up making wrong assumptions picking the wrong motor for your task.
So whenever possible ask for a sepcsheet, a power diagram etc.

Take larger scale industrial motors for example.. they more often then not come with a hp rating,
(electrical hp not combustion hp... 735Watts mostly but depends on continent )
Anyways, that's to tell you it talks about MECHANICAL Watts, it also mostly lists electrical Watts as well (as VA in 99% of all cases I've seen)

And if you compare the two you'll find that their efficiency is commonly lower than 80%..
due to more reliable but less powerfull ferro-ceramic magnets instead of neodymium ones for example.
Sep Ex, series wound .. brushless delty or Y config...
all have different characteristics.

And you cannot just assume things without knowing what you're dealing with.

it's like making an assumption about speed or hp from nothing but the combustion volume.
100cc makes 16 horses hitting 55mph on a prepped kart engine.
so a 200cc clone engine must be able to make 32horses and push me to 110mph...
(as we all know, NO! and NOOO!)

same thing.. you need to know the type of engine
(as you would need to know the type of motor)
to make an educated guess.

Anywhoo.. faster?
depends.. if you mean quicker, gear lower,
if you mean higher top speed, gear higher.
up to a point that'll produce the desired effect.

if still not what you've been after or the side effect is unacceptable..
the ONLY way is to scale the motor up (buy a bigger motor!)

that's the only reliable way I'm afraid.

unreliable is okay.. ?
put a fan on the end to force cool the coil as good as possible;
overvolt it and see how long it survives without boiling the magnetic field off the magnets or shorting the coil thanks to an insulation breakdown.
if you go gently on that a minimal gain might be viable...
if enough to compensate the additional weight of batteries I can't tell.. My guess is no tbh

IIRC MrGentry did 40-odd mph with his highschool my1020...
(on the race kart) I think it overheated slightly on the short runs and lacked a bit of acceleration,
but still an impressive result

'sid
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  #15  
Old 06-04-2018, 06:30 AM
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Quote:
Originally Posted by itsid View Post
you do in fact miss something very important...

Take your cutoff switch and wire it in series with
the batpack and the motor..
connect your shunt and the powermeter it came with..
hold on to your hat and close it...

See that on your Powermeter?...
Now... what do you think could a bigger controller do to change that value?

'sid
I did some "load" testing this weekend (as you suggested)

I mounted a 48V 1,000W ZY1020
...a 12V 100A contactor
...(5) 12V 12AH batteries (4-for the propulsion system & 1 to power the contactor)
...a momentary switch
...& a 40A fuse on e-Lemon-aid

Then, put the kart on a big rubber mat with the front up against a block wall

For a "warm up" I put the rear of the kart on a jack stand
...hooked up (1) 12V battery & ran 'er "unloaded" for a few minutes
...the powermeter did not show an amp reading

First "load" test (kart sitting firmly on the ground/against wall)
@ 12V the kart lurched but, the motor or rear wheel did NOT turn
...the meter peaked ~50A

Second test
...@ 24V the motor & rear wheel turned but, not super fast
...the meter peaked ~64A

Third test
@36V the motor & rear wheel turned faster (burnin' a little rubber)
...the meter peaked ~75A

Fourth test
@ 48V the motor & rear wheel turned much faster (burnin' a lot more rubber)
but, then blew the 40A fuse

"On with the show"

I was out of 40A blade fuses
...so, I replaced it with a 50A circuit breaker (off of the !Arriba! kart-temporarily)

Then, I did the 48V test again
...the breaker did not "trip" (burnt a lot of rubber)
& the meter peaked ~80A

I video taped the tests but, having issues with "Movie Maker" (it's showing an upright version & a sideways version at the same time)
I don't know what that's about but, I wanted to share these results

What's up with these Amp readings?

TBH I was kinda expecting a bit more than a 30A max Amp draw
...but, WOW

*Still workin' on a video to help document this data

I'll do the same tests on the 48V 1,000W MY1020 next
...for comparison
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Old 06-04-2018, 09:23 AM
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I went ahead & assembled a video
...it was half upright & half sideways (on my computer)

But, YouTube seemed to have fixed it

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Old 06-04-2018, 05:35 PM
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impressive results...


that voltage drop is insane I hope your batteries survived that!
And more importantly, I hope you haven't made any test longer than 10seconds roughly and allowed the motor to cool back down for at least a minute between tests...
since stall speeds and heat is not nice treatment..
as I said above, overheating can cook magnetive flux out of magnets
(lowering efficiency and requiring more amps to get the same mechanical power in the end)

Anywhoo
80Amps at 40Volts (reading at the 48-52Volt run) is still 3200 VA (e-Watts)
which frankly I wouldn't have assumed the motor will be able to tolerate at all
it likely ran at no more than maybe 50% efficient.. which STILL resulted in a
mechanical power advantage of 600Watts (or 60% of the nominal power!)

THAT is INDEED impressive!

better built than I expected..
but can you make use of it?

you cannot stall the motor while driving of course..
maybe on a steep incline, but certainly not on flat ground
(since stalling means close to zero rpm .. and that's unlikely of any use for you, right?)

So it's back to gearing (as mentioned above) gear to your desired speed...
and see what it'll do for you (This thing can do about 30mph on a light kart)
but it's a tailchase.. you can only have ONE quick acceleration or top speed.. not both!
so all you can do is settle at a midpoint (your gearing looks fine to me tbh)

IIRC MrGentry geared his up to 3:1 or such and it still moved...

I still doubt you'd benefit from a bigger controller...
so next step IYAM is this:
refit the controller, change the ratio to your desired speed
test the setup and read the amps while doing so..
if you go beyond the 40Amp line more/longer than for split seconds..
I might have been wrong and you do indeed would benefit from a bigger controller.
but keep in mind that at such violent gear ratios you MUST force cool the motor as good as you can,
an external heat sink, a fan mounted to the rotor so that it forces air through the can...
maybe a tightly wound copper tubing coil and a waterpump even...
Once the magnets overheated you no longer have something to enjoy.
(it's drawing more and more amps getting slower and weaker mechanically)

'sid
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Old 06-04-2018, 06:30 PM
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That was cool!

Another option is to take the controller and try to get more heat out of it. Be sure it has good air flow while riding. Perhaps add a computer tower fan and a separate switch?


Also keep in mind for your experiment that as the tire heats up, the traction increases, the load increases and the current increases 1 for 1.

Same for the wires. As they heat up their resistance increases and you end up with a voltage divider of sorts.

Those batteries have a rated maximum cranking amps as well. Push them and they will heat up. I think that spec rating has a duration. Like 200 amps for 2 seconds, 100 amps for 4 seconds, and so on.
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Old 06-04-2018, 09:27 PM
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I did some more 48V 1,000W ZY1020 testing

Same set up as yesterday
...but, this time it's a road test-load test

Lots more fun

While watching the video, I noticed that the meter showed 97A @ ~3:30 when I was climbing an incline going up the drive way to put 'er away

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Old 06-05-2018, 09:07 AM
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Quote:
Originally Posted by itsid View Post
impressive results...


that voltage drop is insane I hope your batteries survived that!
And more importantly, I hope you haven't made any test longer than 10seconds roughly and allowed the motor to cool back down for at least a minute between tests...
since stall speeds and heat is not nice treatment..
as I said above, overheating can cook magnetive flux out of magnets
(lowering efficiency and requiring more amps to get the same mechanical power in the end)

Anywhoo
80Amps at 40Volts (reading at the 48-52Volt run) is still 3200 VA (e-Watts)
which frankly I wouldn't have assumed the motor will be able to tolerate at all
it likely ran at no more than maybe 50% efficient.. which STILL resulted in a
mechanical power advantage of 600Watts (or 60% of the nominal power!)

THAT is INDEED impressive!

better built than I expected..
but can you make use of it?

you cannot stall the motor while driving of course..
maybe on a steep incline, but certainly not on flat ground
(since stalling means close to zero rpm .. and that's unlikely of any use for you, right?)

So it's back to gearing (as mentioned above) gear to your desired speed...
and see what it'll do for you (This thing can do about 30mph on a light kart)
but it's a tailchase.. you can only have ONE quick acceleration or top speed.. not both!
so all you can do is settle at a midpoint (your gearing looks fine to me tbh)

IIRC MrGentry geared his up to 3:1 or such and it still moved...

I still doubt you'd benefit from a bigger controller...
so next step IYAM is this:
refit the controller, change the ratio to your desired speed
test the setup and read the amps while doing so..
if you go beyond the 40Amp line more/longer than for split seconds..
I might have been wrong and you do indeed would benefit from a bigger controller.
but keep in mind that at such violent gear ratios you MUST force cool the motor as good as you can,
an external heat sink, a fan mounted to the rotor so that it forces air through the can...
maybe a tightly wound copper tubing coil and a waterpump even...
Once the magnets overheated you no longer have something to enjoy.
(it's drawing more and more amps getting slower and weaker mechanically)

'sid
Teamwork
...that's why I like runnin' this stuff by you!

I was concentrating on the Amp draw & didn't even notice the huge voltage drop
...is that a.k.a. voltage sag or is that something different?

Larger AH (amp hour) batteries should handle that (voltage drop) better?

Gearing? which gearing?

The motors, I'm using have 10t "Power Curve" drive sprockets
...e-Lemon-aid has an 84t driven sprocket for an 8.4:1 ratio (low)
& !Arriba! (we were discussing previously) has a 72t driven sprocket for a 7.2:1 ratio (mid)
& the Torsk kart will have a 60t driven sprocket for a 6:1 ratio (higher)
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