Electric standup jetski build

Boats, Jet Skis, Kayaks etc., including hovercrafts
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Quinc   100 W

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Electric standup jetski build

Post by Quinc » May 07 2022 10:16pm

Built this over the winter with my 8 year old. He took every nut and bolt off the ski and did the fiberglass! So please give him a like and sub on youtube. :)

Couple things I could use some help with. My Ant bms/battery only charges to 4.158 per cell. Any tips on getting it to charge up to the full 4.20v per cell? 20s2p SPIM08HP battery

I have read through the votol thread a few times now, but if anyone has any tips on how to get the absolute max power out of this thing that would be awesome. After the kids riding for around 15minutes and me trying for a few minutes she only used 2ah and the motor never got warm. So I am thinking she is no where near her potential.





Ski ready to ride weight is 226lbs. Battery weighs 35 pounds! Once I figure out if I want to stay with sprockets or swap to coupler I will shave some weight off or maybe go to aluminum. Also thinking I can cut out the hood liner for a few lbs.


Specs:

QS-120 motor 2000w / Maximum Torque: 20N.m to 49.6N.m.
Votol em-100 controller
Battery 20s2p 16ah SPIM08HP
ANT 300a bms


Ski 1986 300sx


Motor sprocket 14T Driveshaft sprocket 10T (Did this so I could adjust rpm/torque with sprockets)


Still trying to Figuring out the rpms Vs Torque for a jetski.. In the video I think the top speed was around 15mph.
Last edited by Quinc on May 10 2022 3:12pm, edited 2 times in total.

Hillhater   100 GW

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Re: Electric jetski build

Post by Hillhater » May 08 2022 2:26am

.My Ant bms/battery only charges to 4.158 per cell. Any tips on getting it to charge up to the full 4.20v per cell? 20s2p SPIM08HP battery.....
Seriously ?..why ?
There will be no noticeable change in performance from that 0.8 volt increase of pack voltage,..but you will likely seriously reduce the battery life.!
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4πr^2   1 W

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Re: Electric jetski build

Post by 4πr^2 » May 08 2022 8:44am

Interesting project!

Yes, I would second the post above - minimal gains in power or 'per charge' battery life from the 4.2V charge, and will most likely shorten the overall life of the battery by some amount. If you absolutely want to try it, there are likely some trim pots in your charger to control the stopping voltage. If your motor / controller can handle it, you could add more battery voltage and/or current. If you have the option, more voltage will generally get you more top speed and more current would get you a better hole shot / more torque.

Not sure on the chain/sprocket...seems like that would add a lot of weight/complexity and as you mention - gets hot, so a lot of energy wasted there. Any chance to run direct drive and make adjustments with different impeller pitches? For some skis you can also get different pump cones that help add torque or speed. Not sure on the 300, though.

Quinc   100 W

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Re: Electric jetski build

Post by Quinc » May 08 2022 11:40am

Hillhater wrote:
May 08 2022 2:26am
.My Ant bms/battery only charges to 4.158 per cell. Any tips on getting it to charge up to the full 4.20v per cell? 20s2p SPIM08HP battery.....
Seriously ?..why ?
There will be no noticeable change in performance from that 0.8 volt increase of pack voltage,..but you will likely seriously reduce the battery life.!
Good to know! Didn't realize it was a feature. I thought there was something wrong. :)

Quinc   100 W

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Re: Electric jetski build

Post by Quinc » May 08 2022 11:42am

4πr^2 wrote:
May 08 2022 8:44am
Interesting project!

Yes, I would second the post above - minimal gains in power or 'per charge' battery life from the 4.2V charge, and will most likely shorten the overall life of the battery by some amount. If you absolutely want to try it, there are likely some trim pots in your charger to control the stopping voltage. If your motor / controller can handle it, you could add more battery voltage and/or current. If you have the option, more voltage will generally get you more top speed and more current would get you a better hole shot / more torque.

Not sure on the chain/sprocket...seems like that would add a lot of weight/complexity and as you mention - gets hot, so a lot of energy wasted there. Any chance to run direct drive and make adjustments with different impeller pitches? For some skis you can also get different pump cones that help add torque or speed. Not sure on the 300, though.
I am still trying to figure out how to get the absolute max power/torque out of the votol settings. If anyone knows hows? :mrgreen:

My original plan was to go straight coupler but went with the sprockets so I could adjust rpms/torque when/if needed. I may still do the coupler but I need to figure out the motor settings first. I also have multiple pitch impellers to try.

Quinc   100 W

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Re: Electric jetski build

Post by Quinc » May 08 2022 9:16pm

Video of the motor out of the water. This is just over half throttle:

Quinc   100 W

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Re: Electric jetski first test ride

Post by Quinc » May 10 2022 3:12pm

Going to get some graphite into the rollers on the chain. Hopefully reduce the heat and noise some. Also working on figuring out the best way to attatch a coupler to the motor splines.

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liveforphysics   100 GW

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Re: Electric standup jetski build

Post by liveforphysics » May 10 2022 3:52pm

Ive made this mistake, its only fixed by making both sides sprockets larger in diameter is the way to make your chain more quiet. The link below shows the effect of tooth count vs chain vibration. It looks like you have room to package 2x the number of teeth at least, doing that will knock out most of that vibrational power.

http://chain-guide.com/basics/2-2-1-chordal-action.html
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DogDipstick   100 kW

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Re: Electric standup jetski build

Post by DogDipstick » May 10 2022 4:24pm

Quinc wrote:
May 07 2022 10:16pm

Motor sprocket 14T Driveshaft sprocket 10T (Did this so I could adjust rpm/torque with sprockets)


Even drive / Even driven.... sprockets... requires a chain with an ODD number of links or.... else your wear will be 2x faster, or even more. Just like if you have an even number of links, a even driving number of teeth, you need an odd number of teeth on the driven sprocket.. to keep the chain rolling around the sprockets and not wearing the chain prematurely. This keeps the same link from hitting the same spot on the same sprocket every time.

Most OEM manufacturers follow this pattern too. kawa, Honda, soozook, ect. Ducati, Ktm. Aprilla. Ect.
Well known by motorcycle mechanics. Often overlooked by motorcyclists.
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Quinc   100 W

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Re: Electric standup jetski build

Post by Quinc » May 11 2022 10:10am

DogDipstick wrote:
May 10 2022 4:24pm
Quinc wrote:
May 07 2022 10:16pm

Motor sprocket 14T Driveshaft sprocket 10T (Did this so I could adjust rpm/torque with sprockets)


Even drive / Even driven.... sprockets... requires a chain with an ODD number of links or.... else your wear will be 2x faster, or even more. Just like if you have an even number of links, a even driving number of teeth, you need an odd number of teeth on the driven sprocket.. to keep the chain rolling around the sprockets and not wearing the chain prematurely. This keeps the same link from hitting the same spot on the same sprocket every time.

Most OEM manufacturers follow this pattern too. kawa, Honda, soozook, ect. Ducati, Ktm. Aprilla. Ect.
Well known by motorcycle mechanics. Often overlooked by motorcyclists.
Very interesting! This is the first I have heard that information. However, shouldn't chain slack determine how many links you have? And if I throw a half link in there am I covered either way. :mrgreen:

Quinc   100 W

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Re: Electric standup jetski build

Post by Quinc » May 11 2022 10:12am

liveforphysics wrote:
May 10 2022 3:52pm
Ive made this mistake, its only fixed by making both sides sprockets larger in diameter is the way to make your chain more quiet. The link below shows the effect of tooth count vs chain vibration. It looks like you have room to package 2x the number of teeth at least, doing that will knock out most of that vibrational power.

http://chain-guide.com/basics/2-2-1-chordal-action.html
Thank you! Only thing is this QS motor has some oddball shaft size and after ordering multiple sprockets I cant find any that fit. Any chance do you have any tips on how to attach a coupler to a spline shaft? Right now I am thinking I will bolt the coupler to the sprocket that is on the motor shaft and run direct drive.

SlowCo   10 MW

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Re: Electric standup jetski build

Post by SlowCo » May 11 2022 1:26pm

Great build :thumb:
Weld a 20+ tooth sprocket on to the motor sprocket.

Quinc   100 W

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Re: Electric standup jetski build

Post by Quinc » May 20 2022 12:13pm

Worked with the ElectroBrapp guys yesterday and got the controller settings dialed in. 6500 rpms, instant power, (in the video it had soft start) and will hit the motors full power of 33ft\lbs of torque. If the motor can reach 6500rpms the impeller will be spinning around 9100rpms.

First video I had the controller maxed at 65amps. The controller is now set for 165amps.

Any guesses on top speed with a 75lb kid riding it? And will it get it my fat 230lb arse up out of the water?! =)

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liveforphysics   100 GW

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Re: Electric standup jetski build

Post by liveforphysics » May 21 2022 8:56pm

Quinc wrote:
May 20 2022 12:13pm
Worked with the ElectroBrapp guys yesterday and got the controller settings dialed in. 6500 rpms, instant power, (in the video it had soft start) and will hit the motors full power of 33ft\lbs of torque. If the motor can reach 6500rpms the impeller will be spinning around 9100rpms.

First video I had the controller maxed at 65amps. The controller is now set for 165amps.

Any guesses on top speed with a 75lb kid riding it? And will it get it my fat 230lb arse up out of the water?! =)
The easy way to find out is a test! Make sure you go above and beyond for corrosion protection on the pack and inverter.
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

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