Electric motors in karts: a simple guide

[nedfunnell]

Don't buy the cheap high capacity 18650s unless you like house fires. They are fake.

 

[David Ham]

possibly the best source of cheap high rate cells would be RC suppliers such as hobby king.

yes I had been thinking about hobbyking and I think I found the best deal.
https://hobbyking.com/en_us/turnigy-5000mah-1s-20c-lipoly-single-cell.html
these 5000mah 20C batteries would be far more reliable and they're still very cheap.

 

[mgrzyb16]

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!

Those are fakes one for sure. "Real" 18650 capacity is 3400 mAh. I was thinking about this solution 'cause:
1. Tesla uses 18650 as power source for their cars.
2. They are quite cheap and easy to find (every laptop battery contains few 18650).
So.... I was thinking about getting some 18650s from laptop batteries and start with it.
ps. Even if laptop battery is "dead" few cells are for sure ready to recharge and reuse.
ps2. Be careful with them. I mean really careful.

 

[Krash]

18V liion battery drills typically use 18650's. They would be a handy source as they come pre packaged with battery management built in. They are a bit expensive per kWh, but the up side is they will probably have a much higher peak current rating than laptop cells and should be good quality if you buy a decent brand plus you can use them with your battery tools when not using the gokart.
I have also seen the a 40V whipper snipper, chainsaw, blower liion battery pack advertised at less than ½ the price per kWh of bigger brand 18V batteries.
Electric bike battery packs are cheaper still and also come with battery management built in.
Don't skimp on battery management or your cheap pack will become an expensive door stop.

 

[mgrzyb16]

I found in Poland 18650s with 10 amps peak and 2250 mAh measured minimum capacity for 1,5$. My source is telling me that this comes from "bigger pack that has some electronic issue" so they are not used but he can't sell them as new. Anyway - that's a very good price. Hobbyking 5k mAh comes for 7 bucks which is 2 times more expensive.

Wysłane z mojego LG-H850 przy użyciu Tapatalka

 

[pRoFiT]

I saw this at hf and was wondering, 40V Lithium 14 in. Cordless Chain Saw. Could it be used for a small electric go kart or mini bike? Not sure rpm or hp on it. But you would get battery charger and motor for ~$150. Only need controller? Maybe buy two, one for each tire

 

[nedfunnell]

I saw this at hf and was wondering, 40V Lithium 14 in. Cordless Chain Saw. Could it be used for a small electric go kart or mini bike? Not sure rpm or hp on it. But you would get battery charger and motor for ~$150. Only need controller? Maybe buy two, one for each tire

Here you go:

http://www.etotheipiplusone.net/?p=4187

 

[adr826]

Rectactor circuit

In addition to the three ways you have listed to throttle the kart there is a Rectactor circuit.

http://www.evdl.org/docs/rectactor.pdf

Its a way to progressively switch a motor that maintains the balance across the batteries. It uses 2 heavy diodes and 2 heavy duty switches to switch from 2 batteries in parallel at 12 volts to 2 batteries in series at 24 volts. This can be duplicated to use higher voltages at 24 v intervals. You can switch from 12 to 24 to 48 volts and so on using this scheme.

 

[bigblkblazin]

I just realized this post was from 2011..

 

[landuse]

I just realized this post was from 2011..

Still good info though

 

[fearthechilli]

Hi,

Know this is an old thread but hopefully some one can assist.

I'll be posting in more detail in the kart section with full step by step pictures but basically I'm taking a large and a small Kettcar and electrifying them..
Initially starting with a 250W 24V DC motor like the below on the small one.



i just want to know what the difference in the types of batteries below or are they basically the same.
Both are Sealed Lead units

The 2nd picture is the type you would use in a motorbike / scooter. The 1st is just a generic battery as far as I can tell.

I'm just thinking rather than buying one new - I have a scrap / breakers yard near me and could hopefully obtain them from motorbikes ?
Would these be ok to use from the motorbikes or do they need to be the below type ??



Also can they be recharged ?

Thanks in advance

 

[Liberty Karts]

Hi,

Know this is an old thread but hopefully some one can assist.

I'll be posting in more detail in the kart section with full step by step pictures but basically I'm taking a large and a small Kettcar and electrifying them..
Initially starting with a 250W 24V DC motor like the below on the small one.

View attachment 123492

i just want to know what the difference in the types of batteries below or are they basically the same.
Both are Sealed Lead units

The 2nd picture is the type you would use in a motorbike / scooter. The 1st is just a generic battery as far as I can tell.

I'm just thinking rather than buying one new - I have a scrap / breakers yard near me and could hopefully obtain them from motorbikes ?
Would these be ok to use from the motorbikes or do they need to be the below type ??

View attachment 123491
View attachment 123493
Also can they be recharged ?

Thanks in advance

Just be sure the batteries you get are deep cycle and not a battery for a starter motor. Starter motor batteries are only good for momentary use and don't handle being discharged very well. Deep cycle batteries are designed for continuous use and can be discharged to about 20% capacity before being recharged. If the scooter you get the battery from is electric powered it will have a deep cycle battery, if it's gas powered it will not be the correct type of battery.

 

[fearthechilli]

thank you - all components are coming together so will try and do step by step pics as I complete each step.

 

[Nitro1989]

I own a firm that makes DC motors Made In The USA for Electric Go Karts. D&D Motor Systems, Inc out of Syracuse New York. They have many low, medium, and high performance options. You may want to check them out at: Electric Go Kart Motors - MADE In The USA!!! 315-701-0635 Good Luck

 

[68pishta]

I make lipo battery packs and will add a few things about Lipos: Lipo battery manufacturers rate their batteries in C ratings. a C is a factor of how much current the battery can kick out when asked and stay safe. Laptop batteries are usually rated 1C as they are designed for capacity (time to discharge, ie 2500mah down to 2.5v) rather than current output. >3C rated batteries are found in Dewalt battery packs and are designed to start a hammer drill, ie max current NOW instead of capacity. Usually its a trade off of C rating and capacity but it has been getting better with battery chemistry. you can find the C rating in the battery part number, google it and you should find the battery and its performance specs. If you cant find the battery, use a cheap IR meter ($12 on Ebay) and test all your loose 18650 (or any under 36V battery) and look for an IR under 20 ohms, 10 being better with some larger 27mm batteries giving 6! SLA betteries have a terrible tendency to only put out about 60% of their rated capacity before they sag below the set limit of the BMS (mandatory on Lipo packs) Lipos have a very flat "torque curve" as they supply over 2.5v over a long period then drop off, causing the BMS to shut the pack down for safety of the cells as you don want the deplete any battery under its reccomended cut off voltage. I find old bike 36-48v packs at E-bike shops and ask to take them off their hands, They usually are glad someone is getting them out of their shop as they alsmost have to pay E-waste to come and get them otherwise. A guy gave me 16 E-bike packs for a 5th of tequila! He also offered me an E-bike mid drive for $25 (connects where the old cranks live, bottom bracket) , I may go back and get that. I can usually harvest 80% of the cells in these 70+ cell batteries by finding the dead P-group (4-6 batteries tied in parallel) and cutting them out to find most of them 0v or under 2.5v. The rest usually are good with the BMS shutting the entire pack down due to the 1 bad P-group. There are 10-14 p-groups in a 36-48v pack. I can replace the P-group and bring the battery up to voltage or scrap is and harvest the cells. These E-bike packs usually have cells in the IR range of 10-20ohm. Get yourself a cheap spot welder that runs off a car battery for <$30 and some nickle strips. you can buy battery frames, Hot glue them or make a wooden box for the battery array. Stay safe! Lipo batteries can catch fire if shorted but they usually just degass like a smoke bomb if seperate, still not fun to grab one and toss it out the garage door when its venting!

 

[68pishta]

check my write up above. 18650 UPS batteries are different than drill batteries even though they look identical. Check out larger 21+mm batteries, huge mah rating so less in parallel in your packs.

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

 

[samlevy0515]

Got it, thanks for the detailed info.