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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Wed Mar 22, 2017 6:30 pm
by glossieblack
Now that I've got the air cooling of the e-motor sorted, I'm turning my attention to the other electrical component that needs to be kept cool if the e-motor drive is to perform as efficiently as possible.

The motor controller is the computer brain of the system, and controls the electricity being feed to the motor. The second picture below shows the back of the controller, and is a heat dissipater. I intend mounting the controller in a box fed by forced cool air from the same ducting system as the e-motor, and in a way that the cool air can flow over the dissipater. The box will have a computer fan outlet to assist air expulsion.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Wed Mar 22, 2017 6:53 pm
by Jaysen
Does the manufacturer sell a cast heatsink that you could install? If not you might want to consider attachment of metal channels using thermal compound to assist with heat dissipation. The mosfets in there will get very hot. The manufacturer should have a dissipation guide or recommendation. Should talk about surface area and min airflow. You can always exceed the recommendations but not meeting them will drastically shorten the life of the controller.

I need to find a reason for a business trip to you part of the world.

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Wed Mar 22, 2017 8:59 pm
by Fuzz
Jaysen wrote: ↑
Wed Mar 22, 2017 6:53 pm

I need to find a reason for a business trip to you part of the world.
You will need a helper :!: Take, take me :D

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Thu Mar 23, 2017 2:38 am
by glossieblack
Jaysen wrote: ↑
Wed Mar 22, 2017 6:53 pm
.... you might want to consider attachment of metal channels using thermal compound to assist with heat dissipation. The mosfets in there will get very hot.
Thanks for the advice to attach heat dissipation fins.

This afternoon I purchased four recycled aluminium heat sinks and a tube of thermal compound from the local computer repair guy, all for ten bucks :D

Tomorrow I'll clean them up and adhere them.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Thu Mar 23, 2017 6:48 am
by Jaysen
Those will be perfect. Just make sure the air flows thru the fins and not against. You'd be amazed how many times I've seen folks block an airway by putting the heatsink 90deg off.

You're going to love this once it's done.

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Thu Mar 23, 2017 7:16 pm
by glossieblack
Jaysen wrote: ↑
Thu Mar 23, 2017 6:48 am
Those will be perfect. Just make sure the air flows thru the fins and not against. You'd be amazed how many times I've seen folks block an airway by putting the heatsink 90deg off.
Thanks for the heads up. I hadn't considered fin orientation. I was going to construct the box around the fins big enough for air to flow around the external perimeter the block of fins. Is your inclination to restrict the forced air path to between individual fins only?

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Thu Mar 23, 2017 8:13 pm
by Jaysen
You don't want to restrict airflow as much as keep air moving over the fins. If you have limited space (and what space on a boat isn't limited?) allow at least 1" clearance around the cooling fins. Once you see it like that you'll understand the fin alignment issue.

One thing to keep in mind, that smaller the cross section the faster the air flow will need to be. Remember that the incoming cool air start taking heat at the first surface which reduces its heat dissipation later in the sequence. You'll know you have they right air speed when the exhaust is just a tad warm. If the air is hot increase the speed.

My guess is that with those heat sinks you won't need to huge volume through there. I would make sure they your thermal compound is "thermal adhesive" as the traditional compound is not designed to keep things in place.

My solution for this is water cooling. I'll be using larger motor and components most of which have water cooling be default. I've toyed with making my own motor and controller to allow for better air cooling options. Not sure I'm that ambitious.

Skinnydip is definitely a unique build. Can't wait to see how she performs.

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Fri Mar 24, 2017 7:04 pm
by glossieblack
I need to determine during sea trials the amounts of forced cool air that needs to be supplied to both the e-motor and the motor controller when the boat is being pushed hard on a hot day.

During the sea trials, I’ll be able to monitor the temperature of both components by going into the menu on the e-display pictured below, then mechanically adjust the forced air flow rates to achieve optimal settings for both the motor and controller.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Sat Mar 25, 2017 1:32 am
by TomW1
Hi guy don't over think this. You have an electric motor with a wide range of operating specifications. Set up the air flow to provide enough for the hottest days and you will be fine for the rest of the days. There is no real need to get paranoid about it just provide a good air flow to it and you should be fine.

Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Posted: Sat Mar 25, 2017 9:26 am
by peter-curacao
Hi Tom I don't know nothing about those electric motors, but as far as I know a hot day in the Smokey's and a hot day down under is a world of difference LOL :lol:
BTW I loved the Smokey mountains area, beautiful place 8)