Electric Cyclekart - Motor options at 52v

[Madmarcus]

I'm back with a question on an electric cyclekart. Think go kart crossed with old open wheel racing so I will be using CT90 17" motorcycle wheels. Around 200kg including the driver. Some very rough calculations says that I might be able to get around 40mph with 5kW of input power so I figure a 5kW motor that can surge above that at times should be suitable. It won't race with the really modified gas powered cyclekarts but I'm ok with that.

The battery is set at a nominal 48v. I'm leaning towards a pack of used Leaf cells giving 52v with Greentech Auto's 100A BMS. This isn't a great setup but it's easy and should feel safe enough that no one will question the 48v/52v issue. It's heavy but a homemade LiPo pack is going to get many more side eyed looks as well as take more work on my end. The BMS claims 150A for 30 seconds which should be enough. Which means I'm looking at a motor that can do 5kW at 48v peaking up to maybe 7.5kW.

I love the QS and similar motors but all of them are marketed as 72v motors. Are there any sold that are manufactured and sold as 48v models? Is there any reasonable way to get their specs at a lower voltage? Does anyone have good motor curves for them?

 

[Madmarcus]

I'm going to inflate my post count instead of editing.

I'm not wedded to a QS or similar motor but the other option looks to be running a mid drive bike motor well outside it's designed specs and without really improved cooling I don't trust that to work well.

 

[SlowCo]

A '72V' QS motor will run fine on 48V or 52V. You just need a programmable controller to match. A QS138 90H V3 with built in gear reduction would be ideal, I think. Contact QS to ask if they can make an offer for a kit that will run the voltage and amps you need. Although 72V or even higher would be even better of course. Then go to a QS180 90H watercooled and leave the gas powered cycle karts in the dust...

 

[Madmarcus]

A '72V' QS motor will run fine on 48V or 52V. You just need a programmable controller to match. A QS138 90H V3 with built in gear reduction would be ideal, I think. Contact QS to ask if they can make an offer for a kit that will run the voltage and amps you need. Although 72V or even higher would be even better of course. Then go to a QS180 90H watercooled and leave the gas powered cycle karts in the dust...

I know it will work but the tinkerer in me wants to have at least some idea of how it will work. As does the tightwad who looks at other similar motors and wants to comparison shop! That's an interesting idea to contact QS. I generally don't think of more or less asking for a one off but it's worth a shot.

The biggest question is what rpm I should expect so that I can plan the connection to the rear axle; chain drive with additional reduction like a go kart or geared motor directly connected to the right rear wheel without further reduction (it's open wheel racing so using a hub motor isn't straight forward)

72V might be really nice but I can live within that guideline/rule-that-isn't-called-a-rule.

 

[dominik h]

Golden Motor has an 48V Motor with 5kW