ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

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lelandtampa
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by lelandtampa » Sun Feb 16, 2020 4:38 pm

Could you not just duct a bilge blower into the enclosure and one out the other side.? Or perhaps an enclosure air conditioner that is used on large control panels?

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Mon Feb 17, 2020 4:04 am

Rickk wrote:
Sat Feb 15, 2020 4:54 pm
How hot are we talking here GB?
Not sure Rick. I've gone back through my rat rod test run notes, and alas, I didn't record the temp when the e-motor (or was it the controller?) shut the system down.
lelandtampa wrote:
Sun Feb 16, 2020 4:38 pm
Could you not just duct a bilge blower into the enclosure and one out the other side.? Or perhaps an enclosure air conditioner that is used on large control panels?
Alas, there are severe spatial restrictions to using additional ducting to the enclosure, or attaching a thermoelectric cooling assembly to it.

This is why in the first instance I'm concentrating on tweaking the existing air supply ducting system. This afternoon I test fitted the new shroud. So far so good. :D

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Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by OrangeQuest » Mon Feb 17, 2020 3:42 pm

glossieblack wrote:
Mon Feb 17, 2020 4:04 am
This is why in the first instance I'm concentrating on tweaking the existing air supply ducting system. This afternoon I test fitted the new shroud. So far so good.
I agree this is the best place to start. I would think the next, if still having issues, would be to trade out the diameters of those two pulleys.

Hope the box cures your issue.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Wed Feb 19, 2020 4:41 am

Thanks OQ. :D

I've not been paying sufficient attention to your comments over recent weeks about perhaps needing to change the diameter of one or both of the pulleys.

I've been naively assuming that the power required for the e-motor to spin the new 10 x 12 prop at 2000 rpm will be the same as it was to spin the old 10 x 10 at 3000 rpm, and that as heat generated is proportional to power, the heat generated would be the same. So I've been vaguely wondering why the pulleys would need to be re-sized.

Your prodding has caused me, as a complete dill in electrics, to do a bit of 101 homework, and I now tentatively think that for the new 10 x 12 prop, more torque and hence more amps will be required at each point up the rpm chain, and that means more heat, because heat generated is proportional to amps, not power. Have I got this right?

If so, I'm assuming that because the new prop is optimised for a 1:1.5 step-down diesel transmission, I'll need a new pulley setup that produces a 1:1.5 step-up, if the e-motor is to draw the same amps and hence generate the same heat as in the old setup? Is this right? :help:
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Thu Feb 20, 2020 3:18 am

As I was about to reconnect the e-drive motor to its three main cable terminals - U, W and V in the pic - I noticed a loose smaller cable.

Which terminal had it been connected to before disassembly? I had to do this partly by feel, and I hadn't noticed the small cable, or that it had fallen of its terminal.

I sent the pic below to a number of people asking which terminal to connect the small cable to, without initial success.

Then one rang back. He'd taken a closer look, and realised it was not any old electrical connection, it was a heat sensor, and it should be connected to W. Phew! :D

The cables connected to the terminal in the pic are from within the motor itself. The connection cables will be bolted above them.

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Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Jaysen » Thu Feb 20, 2020 5:10 am

That’s a 2wire sensor with a single connection terminal? What else is connecting to W? Ground? V+, V-?
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I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by OrangeQuest » Thu Feb 20, 2020 5:15 am

glossieblack wrote:
Wed Feb 19, 2020 4:41 am
I'm assuming that because the new prop is optimised for a 1:1.5 step-down diesel transmission, I'll need a new pulley setup that produces a 1:1.5 step-up, if the e-motor is to draw the same amps and hence generate the same heat as in the old setup? Is this right?
From the looks of your e-motor set up you have the opposite ratio as the diesel motor transmission of 1:1.5. The e-drive looks like it is close to a 1.2:1.
Meaning the e-motor rotates once but the prop turns 1.2 times.

To make it simple the 1:1.5 ratio (increases torque of the motor output but less rpms than the diesel is turning) for the diesel is like having a 45hp motor turning the shaft that is why you put the bigger, more pitch prop.
To increase the torque of the e-motor you also need to change the ratio. Having A smaller diameter pulley on the motor will increase torque but reduce rpm, just like in the diesel drive. Changing the diameter to a bigger pulley on the prop shaft will also increase torque and decrease the rpm.

Since the picture looks like the dia. of the prop shaft looks smaller than the motor pulley maybe trading places with them will give you the extra torque the e-motor needs to turn the bigger prop (at a reduced rpm) but will be less load on the electrics and keep things cooler.

Hope that makes sense. :)
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
A. A. Milne

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Heimfried » Thu Feb 20, 2020 3:53 pm

Hello GB,
points you should consider are:
- a larger prop pitch means normally to increase the needed torque - that will slow down the motor rpm
- the build in cooling ventilator will blow a smaller air stream with less rpm so the cooling effect decreases
- the efficiency of the motor will (in most cases) decrease also, that means a larger part of its intake of electric energy will be transformed in thermal heating

Look at the attached curve, which is quite typical for BLDC motors (I don't know your motors data.)
This is why I bought water cooled motors. (I'm the guy with the solar electric katamaran build - not finished yet.)
Attachments
HPM3000-48V3KW Curve.pdf
Typical curves for BLDC Motors
(90.11 KiB) Downloaded 4 times

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Fri Feb 21, 2020 3:08 am

Thanks Jaysen, OQ and Heimfried. All understood and most helpful. :D

The new shroud box is ready for installation. Oyster reef restoration politics is taking up a lot of time at the moment, so I've only been able to squeeze in small jobs on Skinnydip.

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Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Sat Feb 22, 2020 6:34 pm

For some time the plan has been to get a full set of storm covers built, as Skinnydip will be permanently in the Noosa River.

But as she's likely to be used fairly often in coming months by others as well as myself, removing and re-installing a full set of covers each time will be a pita, and probably not done correctly at times.

So I've decided to go minimal for the time being, covering only the rear deck hatches as an added precaution against leaks. Initially I'm experimenting with a 4' x 6' of-the-shelf canvas tarpaulin.

If the cover works well, a custom- shaped one will follow, which could form the aft panel of an eventual full storm covers setup.

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Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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