yeah, Im inclined to agree. I think I’ll make up a watercooled mounting block to get a bit of the heat away. Thanks
This is what my burned up motor looks like inside. My plan is to rewind it. It is very difficult to get the wire off because it is coated with either epoxy or some type of super glue. If you soak it in acetone it will soften the glue, but it damages the green coating that is on the stator. So I don’t recommend it. It takes about a hour of hard work and some small hand tools to remove all the wire. Its a rats nest.
Each of the 3 motor phase leads contains 130 strands of wire. So 130/2=65 strands of wire are contained in each phase.
Update from 6/19/19 . I purchased another 80 KV 80100. I swapped modified parts form my burned up motor like prop shaft and fwd cover on to the new motor. Closed the motor up in the dry pod and ran it with no prop full speed. (No load, for a very short time). Then I added mineral oil. My mineral oil measurements are not perfect because of some mess and spillage.
Dry pod: Voltage =47.71, RPM=3830, AMP=5.1, WATTS =240
150 ml : Voltage =47.69, RPM=3750, AMP=9.9, WATTS =463
250 ml: Voltage =46.60, RPM=3700, AMP=13.54, WATTS =622
My goal was to understand how much power would be wasted adding oil to my dry pod to cool it.
I decided to go with 130 ml. If it does not burn up by the end of the year, I will probably reduce the amount of cooling oil.
130ml: Voltage =47.54, RPM=3770, AMP=19.09, WATTS =427
So the cooling oil is consuming 427-240= 187 WATTS at full speed.
First run with new motor. I took my E-foil out and it ran really well, It kept going, and going. Turns out on my new design it is much harder to hear the low battery voltage alarms when the batteries are in the board and behind you. I am still running the multi-star Lipos. When I fell I could hear all the alarms going off and I was a mile from my launch boat. So I slowly powered back until there was no power left. I found out it is awful hard to do the breast stroke in a wet suit. When I finally made it back my 6 S batteries were in the 18 volt range. After they cooled down several hours My charger was giving me cell voltage errors and would not charge the batteries.
After 8 hours they began to take a charge. They seem to have recovered completely from my mistake.
Second, third, and forth run have gone very well. I am improving but I still spend more time surfing than flying. I have been stopping before my alarms have sounded. Next I need to finish the 12P14S Samsung battery that I am build.
1 Like
Made some progress on the new battery today.
I am making the battery a small as possible so it fits.
2 Likes
I finished my batteries and they fit and work perfect. I have 9 runs now without a failure. I now can stay flying most of the time. As long as it keeps working I will put off any more improvements until the end of summer.
6 Likes
What size box are you using? Do you have a link to it?
1 Like
I down loaded a App on my phone to measure speed using GPS.I put my phone in a couple zip lock bags and taped it to the fwd end of the board. It worked great.
at 11-14 mph the board fly’s. 12 feels the best nice fun speed, 14 feels too fast. My top speed was 17 mph. I think my set up is capable of 20 mph, but at 17 the foil wants to leave the water.
I like how it rides, but I can’t leave well enough alone.I plan to add some shims to my tail to see if that changes things.
Could a drone near by screw up the communication between the Maytech and the receiver. I had a problem that I cant explain. It only occurred when a neighbor was trying to fly his drone in the same area I was.
I have had 18 rides without having to do much maintenance. Yesterday I tested the remote on shore as I always do. It worked good.
When I walked out to the water, and started to ride, my board did not move until my hand control indicated about 50%. I did this about 7 times before I gave up and returned to shore.
I took the board home and have done several tests. Including dunking the remote. Everything works as it should.
I am heading back to the water tomorrow, Currently I stumped.
I am using the skate remonte from maytech since last year and yes communication can be a problem , there is one spot I cannot use my efoil too much interference I loose communication while riding ( hit hard at 30km/h)
I just don’t to this place anymore
So yes WiFi … and high voltage area can screw reception
If the problem repeat itseft in the same condition here with the drone then it is probably it
You can try to put a magnet around the receiver wire as well
The problem never came back, The guy with the drone has not been around. All is good.
I know this is about 8 months late. but, I was updating my log for this build and I found this file I had recorded with the eagle tree data logger. The green trace shows the throttle and the red trace shows the current.
This is when I burned up the motor in May. This is in the test tank. You can see I hit the throttle a couple times before I realized my safety lanyard was not plugged in. Then there were several full throttle runs over 130 amps for several seconds. Then the current really peaks and drops off drastically. Was running 12S Lipo at the time.
After I burned up the first motor in May. I increased the amount of oil in the motor. I also have been running 14S 18650 batteries. Typically run at 65% as indicated on my Maytech control. When the batteries get low I will be in the 70% plus range. 27 rides with not much issue.
Now I am doing my winter service.I built this very simple shelf that sits on the foil, It makes servicing the motor much nicer.
1 Like
After siting for months on the garage floor I saw evidence the oil was leaking out of the motor. The aft dry pod cap has a ball bearing and 2 oil seals. The 2 oil seals are installed back to back so one keeps oil in, the other keeps water out. I replaced them both. The inside of the motor looks like new.
1 Like
