DougM's Puget Sound Build


I used the same one ( be carefull the quality Ones are not in plastic but “Bakélite”) in between my 4s pack to get 8s when switch on , worked well all last summer ,got the 200a , will still use it this year , but it gets a bit warm/hot after a long run

That is a way to keep the 6+6 for charging but 2 plugs will be left alone when running i didn’t like this idea …


@ Kappertz, @ Alexandre sounds like I might be under-amped. I haven’t ordered it yet - might bump up to 150A.



Last year I used this one. I am no longer using it. These are my observations. Many people on this forum are using it. It takes up too much space to fit in my enclosure. Never tripped even when I got in weeds which caused me to destroy my 200 AMP ESC. The XT90 connectors on my pair of multistar 20Ahr batteries started to melt first. I read somewhere that you need to go over 150 AMPs for quite while for it to trip. It works fine for a ON/OFF switch with no additional anti spark. Feels and looks high quality.


MAC you are correct it only trips-out after a long time ,its good to highlight this.
See trip time vs rated current.

I will be using one as a switch & a ANL fuse ( Have yet to determine the fuse size)


Shoulda stuck with the 80A :slight_smile:

I only expect this to work for catastrophic failures (dead shorts) but this is good to know - the one I got is unlikely to ever trip. When it gets here I’ll check the size and see if I can use it at all, then swap it for a smaller one.

If I blow up my driver I’ll probably replace it with a VESC6 since it’s a lot more configurable. However it tops out at 100A. Come to think of it I better start logging current draw (scope creep!).

Thanks for the input.


Maybe consider some of the designs based on the Vesc6 that run the same firmware if you choose to go this route. I only have experience with my diy vesc, but there are several to choose if you search the electric skateboard designs. E.g. A200S, there are also some ready to purchase with similar price.


@Flo thanks for the guidance - the A200S sounds like the perfect project for the fall…

When you say diy vesc did you design one from the ground up? You don’t happen to have a build log for that do you?


Ok, after 2 runs I got the battery box cutout cleaned out.

I did learn the wisdom of rough cutting vs. fine cutting. My original plan was 0.2" depth cuts with 0.3" stepover. If I had done that the thing would still be cutting. I roughed it out with 1" stepover and then went back and did a 0.3 stepover final.

I just need to router around the outside edges to give myself a roundover, then drill some drain holes and start drilling sideways to run lines between the battery box and the power box and the mast. So I guess the next step is to place the mast mount.

Then fiberglass these two openings in.

I liked @MAC’s idea of getting a big water trough for testing. I was originally going to just take it down to the lake and go for it, but I can see the wisdom of doing some actual load testing before committing to a large body of water.

Heading out to the Issaquah Grange tonight!


on top of looking at the amp, the voltage you’re using and the quality of your connection will matter a lot:

i started using that:
but it kept tripping, and to turn it back on you have to open the board on the water… and if you let a few drops in at the wrong place, you coulomb meter will literally take on fire… :slight_smile:

now i’m using:
and not a single issue, and even if it trips, it should auto-reset.

The difference was that the first one was rated for 12V and the second one is for 48V.
On top of that, it was much harder to get good connection for the wires in the first one, and i’m guessing the reduced area of contact made it heat even more.
I think in the end, it was never tripping due to high current, only due to heating up too much…

On the second one, you just solder ring terminal and the connection is much better.


Same here. The nuts need to be very tight or it will heat up a lot. I could smell the heat coming off the nut on my relay. Just had to touch it anyways. My finger made a sss noise.


A bit of forward movement, I got the edges of the cutouts rounded over and sanded down to the fiberglass around them. I figured out how I’m going to route the wires from one place to another, and I made the mount plate for the mast.

(If you look closely you can see where I screwed up the center when I started the cut on the CNC machine, but it doesn’t hurt anything)

Those tiny holes will get drilled out and threaded inserts will be pressed in, then the whole thing will be epoxied in place.

Also, following in @Mat’s footsteps I got a Stock Tank for testing.

The platform it’s sitting on was originally going to hold a hot tub, but that project did not make it past the “clear cedar is how much?” phase.

Next week I’m going to carve out the holes the wires run through, and actually put the motor assembly in the tub and spin it up. This assumes that the battery box somehow magically assembles itself between now and then.