Electric motors in karts: a simple guide

dcastillo

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Hi there,

I am a beginner in this kind of thing, so this might be a really simple question.

Does the voltage of the batteries need to match the voltage of the motor?

For example, could I use 2 12 volt batteries connected in series with a 36 volt 750 watt motor?

Thanks

short answer, yes, but youll lose power and speed...
next answer, definitely start a thread in the electric section
-Danny
 

Typa

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Great thread!! All the info i have been looking for, in one neat article. Thank you so much! I have embarked on building my 2 boys an electric cart. We live in a quiet street, but have alot of people ride motorbikes illegaly. So to avoid noise complaints im going electric. I am incorporating a solar panel and charger to get a few extra minutes and allow trickle charge when its not being used.. would this work? Any help will do.
 

Arlo1

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Great thread!! All the info i have been looking for, in one neat article. Thank you so much! I have embarked on building my 2 boys an electric cart. We live in a quiet street, but have alot of people ride motorbikes illegaly. So to avoid noise complaints im going electric. I am incorporating a solar panel and charger to get a few extra minutes and allow trickle charge when its not being used.. would this work? Any help will do.

Solar will take a lot of space. You can do it but if I was your I would install solar on your house or garage and position it to face the sun at peak hours I would not waste time putting it on the kart as it will not face the sun very often and even when it does it takes a huge panel to make any real amount of charge.
electric is my choice. I have 3 electric motorcycles. An 45 HP motard bike and a 54hp street fighter for my wife and a MX bike with 80+ hp that im just working on now. I also have a nice Kart chassis that I am putting a good electric power train on when I get time and a Nissan leaf motor Im putting in a Honda CRX. If money is an issue look for a cheep golf cart motor it should be a series wound DC motor and you can make crazy amounts of power with a low budget with them. You will need good batteries and a controller up to the task. Unless you want to scrap it in 3-5 years don't waste your time with lead. Use some sort of lithium battery and the performance will come from something with a high C rating.
 

nedfunnell

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Great thread!! All the info i have been looking for, in one neat article. Thank you so much! I have embarked on building my 2 boys an electric cart. We live in a quiet street, but have alot of people ride motorbikes illegaly. So to avoid noise complaints im going electric. I am incorporating a solar panel and charger to get a few extra minutes and allow trickle charge when its not being used.. would this work? Any help will do.

No problem. I know a guy in WI who has a solar panel on a power wheels jeep for his daughter. This works to recharge the battery between uses, but give no real additional usage time. You couldn't put more than about a 30 watt panel on a kart. Assuming you give it batteries that last for 30 minutes of use and used it with the panel constantly in direct sunlight, you'd pick up an extra 15 watt hours of energy. Batteries that'd last for 30 minutes of use would need to be at least 1500-2000 watt hours, so you can see that 15 Wh is not really much of an addition. If you really want a solar project, sure- leave it parked in the sun to recharge. I wouldn't bother, though, I'd just charge it from the wall.
 

ZanHara

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Hi, guys..I'm newbie and I just found this great thread recently. Firstly, thanks!!. I'm planning to make a simple DIY electric go kart. I have an idea to use 48W and 2000W brushed DC motor but I cannot find any brushed motor controller that suitable to the motor. The best controller I found was 48V-60V and 2000W brushless motor controller. Is it ok to use brushless controller with brushed motor? Any suggestion?

link for motor;
https://www.alibaba.com/product-det...60247895091.html?spm=a2700.7724838.0.0.WguqOH

link for controller;
https://www.alibaba.com/product-det...8209857.html?spm=a2700.7724838.4.2.fyDpec&s=p
 

Functional Artist

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Welcome! :welcome2:

From everything I have read, NO brushed motors & brushless controllers are NOT compatable. (or the other way around either)

But, don't be discouraged...

I've been looking at these, Golden Motors. :thumbsup:

http://www.goldenmotor.com/

On the left click on BLDC Motor.

They have small motors for Ebikes up to big liquid cooled motors.

They have a 48V 3KW (3,000 watt) Brushless Motor # HPM3000B (3,000-5,000 rpm) for $258.00 & a matching controller # VEC2000 for $260.00. (~$600.00 delivered)

...or if you want to go a little bigger, they have a 5KW Motor & Controller for ~ $850.00.

Either of these should move a kart quite nicely! :2guns:

For more info check out El Dingo, the Dingo I converted to electric this summer.

http://www.diygokarts.com/vb/showthread.php?t=33680

*You should probably start a new thread.
 

nemmi69

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I have also been looking at Goldenmotors, their 20kW BLDC Motor.

Model: HPM-20KW -- High Power BLDC Motor
Voltage:72V/96V/120V
1. Voltages: 72V-120Vdc
2. Rated power: 20-25KW
3. Peak power: 50KW
4. Speed: 3200-6000rpm
5. Rated torque: 80 Nm
6. Peak torque: 160 Nm
7. Efficiency: >90%
8. Dimensions: 30x30x25cm
9. Weight: 39kg(20KW),27kg(15KW)
10: Cooling: liquid cooling

I am aiming at 48V so if my maths is correct ( :idea2: ) the for normal running 21000W/48V means I need 438A :smiley_omg: and at peak 50kW 1042 :surrender:

Looking at 12V SLA batteries I have found a 85Ah one http://www.batterybayuk.com/batteri...s/lucas-12v-85ah-70ah-75ah-deep-cycle-battery which sort of leaves me a bit short unless I run with at least 12 x 4 of these batteries. :ack2:

Am I missing something (most likely) or is Lithium Ion the only route for me. :huh:
 

6.5hp

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I have also been looking at Goldenmotors, their 20kW BLDC Motor.

Model: HPM-20KW -- High Power BLDC Motor
Voltage:72V/96V/120V
1. Voltages: 72V-120Vdc
2. Rated power: 20-25KW
3. Peak power: 50KW
4. Speed: 3200-6000rpm
5. Rated torque: 80 Nm
6. Peak torque: 160 Nm
7. Efficiency: >90%
8. Dimensions: 30x30x25cm
9. Weight: 39kg(20KW),27kg(15KW)
10: Cooling: liquid cooling

I am aiming at 48V so if my maths is correct ( :idea2: ) the for normal running 21000W/48V means I need 438A :smiley_omg: and at peak 50kW 1042 :surrender:

Looking at 12V SLA batteries I have found a 85Ah one http://www.batterybayuk.com/batteri...s/lucas-12v-85ah-70ah-75ah-deep-cycle-battery which sort of leaves me a bit short unless I run with at least 12 x 4 of these batteries. :ack2:

Am I missing something (most likely) or is Lithium Ion the only route for me. :huh:

Maybe think about something with a little less power...
Batterires will get VERY expensive if you go Lithium,
and especially for such a powerful motor.
 

Krash

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Hi Nemmie69,
No you won't be able to get the same power on a brushless motor by reducing the voltage and increasing the amps. The wiring in the motor will only have a certain amperage capacity. You can often get a bit more power out of a motor by increasing the voltage if the controller can take a higher voltage. This is one reason why high performance and commercial EV's all run relatively high DC voltages - maximum power for any given amperage.
There is nothing stopping you from using lead acid batteries, but the advantage of using lithium is that they can be run at much higher current draw for any given size cell, usually quoted as the C rating. The capacity of a lead acid battery will probably start to drop off at currents higher than 1C (capacity of the pack at a steady discharge for 1 hour) whereas a lithium pack might be able to routinely do 5C continuous and 20C peak discharge. In addition you can't fully discharge a lead acid cell without affecting long term performance, even a deep discharge lead acid cell might only be discharged to ½ of it's amphour capacity.
I wouldn't be discouraging using the 20kW motor, we've had a lot of fun on one with a 20kW motenergy motor. The build of this one including details of the controller and battery pack are written up at http://www.instructables.com/id/Gas-Beating-Electric-Race-Kart/
 

6.5hp

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Anyone tried 18650's as power source? Is it even worth considering?

wow I looked those up and they are so cheap!
10x single cell 4000mah for about $23.
for a small low power setup you could get maybe 4 lots of those to get a 37v, 16Ah setup. That would get you about half an hour running time at 1000watts, with more to spare.
so yeah, I might even get some of those!
Edit: I found some better value ones, 10x 3.7v 6000mah with a charger for $27. Thanks for pointing those out!
don't know about the quality or reliability though!
 
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itsid

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Edit: I found some better value ones, 10x 3.7v 6000mah with a charger for $27. Thanks for pointing those out!
don't know about the quality or reliability though!
check ebay lot # 191869744661 (10 for 11 ;) )

and at that price it's even worth a try indeed...
makes a 60Ah 37V batpack for 110 plus casing.. that's almost cheaper than a quality 12V 60Ah lead acid battery...

casing, tabbing and heatprotection should be around 40-50 bucks max...

If they hold up to their specs and there are less than 2 dead cells per pack of ten.... it'd still be decent (buying an extra set or two as spares)

Keep us informed 6.5 !

'sid
 

6.5hp

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es ist deutsch!
I might buy two or three of some various types and test them out with my rc battery charger. If these batteries are advertised as 6000mah and are the same size as 3400mah ones, then thats a bit sus...
https://www.youtube.com/watch?v=hWmy-MWRZZc
heres a review of some similar ones, but to get two or three would cost nothing just to test them out.
 

itsid

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japp ist es..
but just because the auction text was translated to german doesn't mean that HongKong seller won't ship to the Americas.. does it? ;)

But correct testing the cells is the ONLY way to know for sure what they're capable of..
unfortunately that still could be worst quality (dead after just a few cycles)


'sid
 

6.5hp

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japp ist es..
but just because the auction text was translated to german doesn't mean that HongKong seller won't ship to the Americas.. does it? ;)

But correct testing the cells is the ONLY way to know for sure what they're capable of..
unfortunately that still could be worst quality (dead after just a few cycles)


'sid

yes, but after seeing so many youtubes of these batteries I think they're probably not even worth buying to test them.

http://www.batteryspace.com/li-ionsinglecell.aspx
this page shows some categories of batteries and what they're capable of. If Nimh batteries are cheap (and reliable quality) they could be better than lead acid.
 

Krash

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It would be worth asking the maximum recommended discharge rate for the cells. You may find that the higher energy density cells have a lower maximum discharge rate and you should check what discharge rate you need from each cell for peak motor power. Sometimes you need to select a lower capacity battery to get the higher discharge capacity.
From what I've seen, alot of the high capacity cheap 18650's are designed for low peak power applications such as torches and electronics. If you use them in high rate applications such as RC aircraft and gokarts it may result in short lifespan. If you can get 18650's that are used in battery drill packs these are probably higher discharge rated, but possibly the best source of cheap high rate cells would be RC suppliers such as hobby king.
 
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