Power Supply's New To All Of This...

[Todd Jones]

Actually I am not working on an RC per se, but am building a kayak that will have 2 waterjets. I have a friend that is printing the jets for me and I will be using two SSS 56114/500kv motors with a 56mm impellers on them.

Max Amps for that motor is listed at 132 and max power is 13,000 watts.
I determined that I will need a 150a ESC for each motor but am stuck on the battery portion. Since this is a kayak and not a much smaller RC boat I want the motors to be able to run for at least an hour. I understand that I need batteries with the most mah that I can get. Where I'm getting stuck is exactly how many I will need, or if it's possible to run a motor that big off of a mower/motorcycle battery. Any advice would be greatly appreciated.

 

[Smoggie]

Need to wind back a little.

first of all what RPM do you need the impellers to run at?

This will determine the voltage you must run, which in turn selects the ESC you need. the motors are specified for 90V which is VERY high. that would be a 24S pack. there are very few ESC's that i know of that will work with 24S batteries, and they will be VERY expensive.

24S would give you around 45k RPM, if you need much less than that then a lower cell battery would do but then your power rating drops.

**EDIT*** so i did some Google research and it seems these jet propulsion systems are usually rated to run around 16,000RPM. That would mean with your 500kV motors probably a 10S LiPo pack ? This makes ESC choice much easier. A standard 'HV' (12S) ESC will do the job.

As for running for an hour, that's going to need a LOT of LiPo packs. How long a run time you get depends totally on how hard you use the motors. Getting 1 hour run is going to be very difficult. If each motor was cruising at (say as a guess) 25% power you would need 18 x 5S 5000mAh batteries. That's a LOT of batteries!

 

[Todd Jones]

Thank you for the info Smoggie. Maybe I'll start with one waterjet for now and see if I need to add the other one. I also went back and looked at the 3D plans and it's a 60mm impeller, which makes me feel a little better, although 4mm isn't a huge difference.

 

[Smoggie]

Sounds like a fun project. Did you have a specific ESC and battery in mind?

 

[Todd Jones]

I talked to the guy who created the waterjet plans and he used a YGE 200A watercooled ESC and 2x 6s 16Ah Lipo for only one waterjet but built a pack from 18650 cells.
I was looking at the Flycolor 150A ESC, but now I'm wondering if that's going to be enough. I'm thinking about building my own battery using used LIFEPO4's from batteryhookup. I may have to see how well one jet works though. This was supposed to be a cheap project. lol I am building the kayak from styrofoam and will create a 'skin" on it that can take the abuse and protect the foam. By time I'm done I'm going to have about $250 in yak materials and $1k in the propulsion system. This makes as much sense as the guys who put $10K rims on an '82 Caprice. lol

Here's the link to his boat in action if you care to see it.

 

[RandyDSok]

It just helps prove the saying... a boat is a hole in the water you throw your money into... lol

It probably doesn't help that you are entering into relatively new territory by trying to electrify a boat which is going to much less efficient to propel than an electric car.

PS... If you do make one... remember to make room for a paddle...

 

[Todd Jones]

Confirmed there is about a 72lb difference between the weight of my kayak with me and the weight of that boat with his daughter in that video. So looks like I will need 2 of everything if I want to make it fun. Time to start a youtube channel....