Re: [electricboats] Silly question - powering with a 120V AC motor?

There are several advantages to electric over an ICE:

Quiet - remember how it sounds when you have the sails up and you turn off the engine?

Water Pollution: you don't blow exhaust into the water

Torque at any prop speed:   can turn the prop really slow

Trim: position the battery to help trim the boat

Space and positioning:   electric motor is usually pretty easy to position and align.  Engine takes up little space 


Caveat Emptor

Not for everyone.   If you are cruising on engine for long periods of time ICE is more practical.  If you can't remember to keep batteries charged up then go ICE.

Peter S. Ford
petersford@hotmail.com

---

From: electricboats@groups.io <electricboats@groups.io> on behalf of julie Lynch <anthonyandjulielynch@gmail.com>
Sent: Monday, May 31, 2021 9:54 AM
To: electricboats@groups.io <electricboats@groups.io>
Subject: Re: [electricboats] Silly question - powering with a 120V AC motor?

 

Hi Mike et al.,

With regard to running a VFD straight off of a generator:

Generators are a bit spiky on voltage when they have no load. For instance, I fried the 12v dc power supply for my wifi receiver when I ran the house on a genny during a power cut. The man who supplied the wifi told me that having a 100 Watt bulb on the genny before you connect anything electronic would give it enough drain to let it regulate the voltage properly. 

A vfd is rectifying the input ac to a 330V ish DC bus and then chopping that into 3 230v ac phases. It may well be very tolerant of spikes, dumping it through a brake resistor if fitted. Also there is normally a slow start which slowly fills the dc bus at startup. You would have to have some other resistive load on the genny for when load comes off the vfd.

 I wouldn't chance it at sea. But they are so cheap now it might be an interesting experiment on a river. With an outboard handy. 

Bit circular though, using petrol to rotate a motor, 20% efficiency,

to rotate a generator to produce 230v ac, ~93% efficient

to power a VFD to rectify to 330v DC, ~98%

to produce 3 phase ac, ~95%

to drive a motor, ~87%

to rotate a propshaft.

Overall efficiency 15% to the gearbox, about half that of a diesel inboard, all the noise and smell.

Only advantages over an ICE inboard, you can use the genny for other stuff when not boating, no winterising and maintenance is easy, on the bench.

Anthony

On Mon, May 31, 2021 at 3:45 PM Mike hurley via groups.io <redwood1957=yahoo.com@groups.io> wrote:

Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor. 

You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor. 

I don't know how to calculate gearing or if you would need any. 

On Tue, May 25, 2021 at 10:21 PM, john via groups.io

<oak_box=yahoo.com@groups.io> wrote:

This is probably a really silly question, but....

Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?

For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?

We've discussed the efficiency gain of running off a higher voltage / lower current.

I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??

John

Re: [electricboats] Silly question - powering with a 120V AC motor?

Hi Mike et al.,

With regard to running a VFD straight off of a generator:

Generators are a bit spiky on voltage when they have no load. For instance, I fried the 12v dc power supply for my wifi receiver when I ran the house on a genny during a power cut. The man who supplied the wifi told me that having a 100 Watt bulb on the genny before you connect anything electronic would give it enough drain to let it regulate the voltage properly. 

A vfd is rectifying the input ac to a 330V ish DC bus and then chopping that into 3 230v ac phases. It may well be very tolerant of spikes, dumping it through a brake resistor if fitted. Also there is normally a slow start which slowly fills the dc bus at startup. You would have to have some other resistive load on the genny for when load comes off the vfd.

 I wouldn't chance it at sea. But they are so cheap now it might be an interesting experiment on a river. With an outboard handy. 

Bit circular though, using petrol to rotate a motor, 20% efficiency,

to rotate a generator to produce 230v ac, ~93% efficient

to power a VFD to rectify to 330v DC, ~98%

to produce 3 phase ac, ~95%

to drive a motor, ~87%

to rotate a propshaft.

Overall efficiency 15% to the gearbox, about half that of a diesel inboard, all the noise and smell.

Only advantages over an ICE inboard, you can use the genny for other stuff when not boating, no winterising and maintenance is easy, on the bench.

Anthony

On Mon, May 31, 2021 at 3:45 PM Mike hurley via groups.io <redwood1957=yahoo.com@groups.io> wrote:

Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor. 

You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor. 

I don't know how to calculate gearing or if you would need any. 

On Tue, May 25, 2021 at 10:21 PM, john via groups.io

<oak_box=yahoo.com@groups.io> wrote:

This is probably a really silly question, but....

Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?

For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?

We've discussed the efficiency gain of running off a higher voltage / lower current.

I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??

John

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Re: [electricboats] Silly question - powering with a 120V AC motor?

Perhaps what might be a way to do this is use a 220 /240 volt generator run that into a VFD to make 3 phase to run a motor. 

You will need to calculate the KW or HP needed then double the size of the drive. An example would be a drive that's good for 5 hp would be able to run a 2.5 hp motor. 

I don't know how to calculate gearing or if you would need any. 

On Tue, May 25, 2021 at 10:21 PM, john via groups.io

<oak_box=yahoo.com@groups.io> wrote:

This is probably a really silly question, but....

Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?

For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?

We've discussed the efficiency gain of running off a higher voltage / lower current.

I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??

John

Re: [electricboats] Battery Fusing

On 28/5/21 2:56 pm, Kai wrote:
>
> This is largely an issue for Lithium chemistries, I don't believe that
> (most?) LA batteries are physically capable of generating the very
> intense short circuit currents which is necessary to overcome the
> interrupting capacity.
>
>
A Lead Acid battery bank can source some pretty fearsome fault currents
too. Just less likely to have the battery back burst into flames and
start and unstoppable fire, but overheated wiring is not friendly.

I have a 250amp fuse bolted directly to the positive battery terminal.
My motor is rated at 110amps short term and I set the controller current
limit at 60.

The fuse will only ever blow if a wire comes adrift and shorts or the
switching transistors in the controller have a catastrophic short
failure. And I suspect the transistor casing would blow and extinguish
the arc before the fuse blew anyway.

Even ignoring the battery, the wires to the battery could start a decent
fire on their own if there was short circuit current from my lead-acid
pack for any length of time.

In my city several months ago, a route bus caught on fire in service. No
injuries, every one baled out in good time, but the vehicle is a write
off. The fire started when the 'jump start' wiring to the jump start
socket shorted against some part of the body. There was no fuse at the
battery end on the jump start wiring between the battery and the socket
on the outside of the vehicle, so it's presumed the battery just dumped
all it's power into the wiring and something caught fire.











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Re: [electricboats] Battery Fusing

In any case, when your setups are done, perform a max stress test of the system at berth, or on the water, in good conditions.

Just to be safe.

Good luck !

Please post any experiences.

Carsten

On Sunday, 30 May 2021, 02:26:12 GMT+8, Randy Cain <randylcain@gmail.com> wrote:

I don't think the controller is at risk because it's the current sink, not source. Its fuse is there in case an overload occurs so that the controller might be saved from damage (like a motor winding short). My Sevcon Gen4 Size 6 controllers should never have to reach their maximum current (500A) as I'm running at the top of their voltage range (max 118vdc, 96vdc nominal).

Re: [electricboats] Silly question - powering with a 120V AC motor?

Thanks for the details.  Mine is all on manual mill and lathe as well.  I do have a DRO on the mill which I couldn't function without. 

My main bearing (5207) is clamped between a shoulder on the shaft and a threaded collar clamp on the other end.  The 2nd bearing (UCF205-16) is a pilot bearing that the forward end of the shaft fits in.  Photos are with a test shaft I made in aluminum.  It was only 1.5" dia so the big shoulder isn't there.  The final shaft is from 1.75" 304 SS.  I was going to use 4140 chrome moly as had been suggested but I could not get a good finish on it.  The SS is easier in that regard and cost about the same.  Not as strong but strong enough I think.  Min dia is 1.25 and  I thing it's stronger than what the Thunderstruck unit has and that seems to work.  I should finish turning that this weekend. 

The side mount was to leave room for a diesel gen set.  I hope the 50lb motor hanging off to the side is OK.  I can add a support mount with an isolation block if need be.   The belt is captive but it is not too difficult to remove the cover.   I added that to support the pilot bearing that I decided I wanted because of the mass of the drive pulley and to keep the shaft in column.  

Dan Pfeiffer

 

On 2021-05-29 10:34 am, julie Lynch wrote:

Hi Dan. That's nice work. Your motor being mounted to one side gives excellent access for checking or aligning the arrangement. Your belt is captive though. Someone suggested leaving the spare belt around the end of the shaft ready to in a hurry. I should be able to roll on my 20mm wide HTD8mm in a few seconds if the need arises. 

Bearing block:

I don't have access to CNC machine tools. 

I just have a manual lathe and mill. I had a bar end of 2.5" 303 and I faced and bored it to the bearing OD. The length is the two bearing widths + the spacer ( another 6205 bearing without the cage and balls) - 0.5 or maybe 1mm. 

The PCS of M8 studs is a nice fit over the block but needn't be. The bearing outers are clamped axially between the I beam and the plate. This plate is relieved to clear the inner race. Therefore they can be a sliding fit.

The inner races are clamped by a screw in the end of the shaft against a shoulder at the prop shaft end. Order is 5205, spacer, 6205, spacer, taperlock hub for pulley, washer, lockwasher, M10 screw. Again should be an interference fit but bcause I am clamping them I left it a tight clearance fit. It was a couple of hours altogether. Shaft is 303 as well. It's what I had. I have a 3/4" bore the other end for the prop shaft. It is cross drilled. Was going to put in a shearpin but I think I'll split it and clamp it solid. 

If I had my time back I would have made it longer and gone s7205 2rs both ends with 2 spacer bearings, stainless as well if i can get them. 2 rolling elements would have less friction. 

Regards Anthony

 

On Fri 28 May 2021, 8:07 PM Dan Pfeiffer <dan@pfeiffer.net> wrote:

That looks great.  I like the way you used the I-beam section in the assembly along with the angles to give you pitch and yaw adjustment.    Well done.   I was going to use a C-channel for my mounting plate but it was not wide enough to accommodate the large belt pulley I needed for my 3:1 ratio.  The big pulley is 60 tooth and relatively heavy (16lbs/7kg) and is a bit of a flywheel. 

I'd like to see more of your bearing housing fabrication.   I used a 5207 double angular contact bearing and a UCF205-16 flange mount as a pilot bearing on the output shaft of my reduction gear.   I used a rubber sealed 5207 and made a housing from aluminum.  Not as robust as steel but ZF marine transmissions are aluminum and have to hold similar bearings to take similar loads so I am giving it a try. 

I have a soft mount by having my mounting flanges sit on rubber blocks that sandwich the fiberglass beds of the boat.  The equivalent place would be under your unistrut rails. 

I am at about the same state in my assembly.  Maybe a couple weeks from going in the water.   I am about to machine the output shaft of my reduction gear unit. 

I am sure you are correct about re-aligning in the water. 


Dan Pfeiffer

 

On 2021-05-26 12:13 pm, julie Lynch wrote:

Hi. I am in the process of building the suggested system.

 24v of leisure batteries 70Ah, 

24v to 230v a.c. inverter, 

230v single to 230v 3 phase variable frequency drive 

and standard 2.2kw 3 phase motor. 

It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft.

Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component. Cheap chinese components all. Nothing marine rated.

I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system. 

I have milled the motor mount to take a more proven bldc motor if I want to down the line.

I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches.

Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe.

Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September. 

Recharge via 270w solar.

Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator.

Worries:

Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts.

Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating.

Don't try this at home, kids.

Yet.

 

Anthony

 

On Wed 26 May 2021, 3:21 AM john via groups.io <oak_box=yahoo.com@groups.io> wrote:

 

 

This is probably a really silly question, but....

 

Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?

 

For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?

 

We've discussed the efficiency gain of running off a higher voltage / lower current.

I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??

 

John

 

Re: [electricboats] Silly question - powering with a 120V AC motor?

Hi Dan. That's nice work. Your motor being mounted to one side gives excellent access for checking or aligning the arrangement. Your belt is captive though. Someone suggested leaving the spare belt around the end of the shaft ready to in a hurry. I should be able to roll on my 20mm wide HTD8mm in a few seconds if the need arises. 

Bearing block:

I don't have access to CNC machine tools. 

I just have a manual lathe and mill. I had a bar end of 2.5" 303 and I faced and bored it to the bearing OD. The length is the two bearing widths + the spacer ( another 6205 bearing without the cage and balls) - 0.5 or maybe 1mm. 

The PCS of M8 studs is a nice fit over the block but needn't be. The bearing outers are clamped axially between the I beam and the plate. This plate is relieved to clear the inner race. Therefore they can be a sliding fit.

The inner races are clamped by a screw in the end of the shaft against a shoulder at the prop shaft end. Order is 5205, spacer, 6205, spacer, taperlock hub for pulley, washer, lockwasher, M10 screw. Again should be an interference fit but bcause I am clamping them I left it a tight clearance fit. It was a couple of hours altogether. Shaft is 303 as well. It's what I had. I have a 3/4" bore the other end for the prop shaft. It is cross drilled. Was going to put in a shearpin but I think I'll split it and clamp it solid. 

If I had my time back I would have made it longer and gone s7205 2rs both ends with 2 spacer bearings, stainless as well if i can get them. 2 rolling elements would have less friction. 

Regards Anthony

On Fri 28 May 2021, 8:07 PM Dan Pfeiffer <dan@pfeiffer.net> wrote:

That looks great.  I like the way you used the I-beam section in the assembly along with the angles to give you pitch and yaw adjustment.    Well done.   I was going to use a C-channel for my mounting plate but it was not wide enough to accommodate the large belt pulley I needed for my 3:1 ratio.  The big pulley is 60 tooth and relatively heavy (16lbs/7kg) and is a bit of a flywheel. 

I'd like to see more of your bearing housing fabrication.   I used a 5207 double angular contact bearing and a UCF205-16 flange mount as a pilot bearing on the output shaft of my reduction gear.   I used a rubber sealed 5207 and made a housing from aluminum.  Not as robust as steel but ZF marine transmissions are aluminum and have to hold similar bearings to take similar loads so I am giving it a try. 

I have a soft mount by having my mounting flanges sit on rubber blocks that sandwich the fiberglass beds of the boat.  The equivalent place would be under your unistrut rails. 

I am at about the same state in my assembly.  Maybe a couple weeks from going in the water.   I am about to machine the output shaft of my reduction gear unit. 

I am sure you are correct about re-aligning in the water. 


Dan Pfeiffer

 

On 2021-05-26 12:13 pm, julie Lynch wrote:

Hi. I am in the process of building the suggested system.

 24v of leisure batteries 70Ah, 

24v to 230v a.c. inverter, 

230v single to 230v 3 phase variable frequency drive 

and standard 2.2kw 3 phase motor. 

It is going into a Halcyon 23 sailing boat. 84lb thrust, 24v (Bison?) outboard, approx. 1kw as second auxiliary. Found it a bit weak against a headwind on a previous boat, 19ft.

Moored on a swinging mooring in a sparsely populated bay in West Cork, Ireland so very little motoring intended (minutes) so I can absorb the losses of all the electrical conversions. I have a backup so I can accept the increased risk of failure of a component. Cheap chinese components all. Nothing marine rated.

I wouldn't recommend this to anyone who was intending travelling too far or at all for a primary propulsion system. 

I have milled the motor mount to take a more proven bldc motor if I want to down the line.

I am running a 3 to 1 timing belt reduction to the 2 blade prop that was on the boat. I think it's 12d x 10p inches.

Original 3/4" bronze shaft to homemade bearing housing. 5206 double angular contact bearing for thrust and 6206 to take radial belt load. Spaced apart for radial stiffness. Probably should be using stainless bearings. Next year maybe.

Runs fine on the bench. Won't be in water for another month. I'll document and post it if it is still a success by September. 

Recharge via 270w solar.

Backup power is by Briggs and Stratton 3.5hp former lawnmower and 24v lorry alternator.

Worries:

Motor and bearing assembly is mounted hard on to unistrut rails on stringers. No flexible mounts.

Packing gland is hard mounted on stern tube. Essentially acts as a mid shaft bearing. Alignment has to be perfect! I think I may have to align the motor again when boat is floating.

Don't try this at home, kids.

Yet.

 

Anthony

 

On Wed 26 May 2021, 3:21 AM john via groups.io <oak_box=yahoo.com@groups.io> wrote:

 

 

This is probably a really silly question, but....

 

Is it possible to find a 120V AC motor that can be speed controlled (and maybe even reversed??) for at least a proof of concept on a boat?

 

For those of us that prefer electric motors to gas or diesel engines, but are challenged by the investment of a huge battery bank, wouldn't it be cool if we could run an AC motor off an inverter from whatever battery bank we have handy, and use a generator to supplement - or just run off the generator entirely at first?

 

We've discussed the efficiency gain of running off a higher voltage / lower current.

I'm guessing that there just isn't a suitable way to control and/or reverse an AC motor??

 

John

 

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