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Old 29-12-2015, 14:32   #211
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Re: Tug of War - Electric vs Diesel

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So, once you start to run an electric motor off a diesel genset, you get both the 35% losses of the diesel and the additional 8-15% losses of the electric motor, PLUS heat losses in the generator itself, and other losses in batteries and speed controllers etc...
That doesn't sound good.
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Old 29-12-2015, 17:30   #212
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Re: Tug of War - Electric vs Diesel

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No! Power <> Energy!

That 12 or 1000 Volt flashlight sized battery would be capable of producing the same power (Amps or Watts) as a huge battery bank of the same voltage (if you disregard factors such as internal resistance ).

The problem is that it can only do it for a tiny fraction of a second before its stored energy is depleted.

It's the lack of Amp hours or kWh (energy) stored in the battery that is the problem , not the number of Amps or Watts (power) that it can produce.
Yes, I am aware of that but was trying to put the example in the simplest possible terms to fit the context of the discussion.

I would have to point out, that 1000V in flashlight batteries in theory would spin a giant electric motor for some tiny fraction of a second but in the real world any power coming out of those batteries would be lost almost instantaneously when trying to energize the windings in the motor and the rotor would not turn at all, all power being dissipated as heat.

Skipmac, who long ago in a galaxy far away used to be an electrical expert (at least in 5V IC circuits with a slight nodding acquaintance with motors, power, signals and other arcane knowledge long since forgotten)
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Old 29-12-2015, 17:36   #213
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Re: Tug of War - Electric vs Diesel

Planet solar used 11 Tons of Lithium batteries (2910AH @ 388V - i.e. 1129KWH or about 17 times the total energy of your average Tesla battery) and 537m^2 of high efficiency solar panels.

On average they were able to generate about 20KW of power from the solar panels.

I think they would have done their trip a fair bit quicker if they had orientated the panels vertically in order to catch the trade winds, instead of horizontally to catch the sun

The boat cost 12.5 million euros. They could have made a much more comfortable and faster boat for 2.5million euros and had 10 million euros left over to buy some diesel.
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Old 29-12-2015, 18:01   #214
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Re: Tug of War - Electric vs Diesel

The boat cost 12.5 million euros. They could have made a much more comfortable and faster boat for 2.5million euros and had 10 million euros left over to buy some diesel.[/QUOTE]

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Old 29-12-2015, 19:04   #215
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Re: Tug of War - Electric vs Diesel

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Good point, flashlight batteries are probably not the way to go. Seriously though, I'm not trying to design a system here. Elco has already done that. I'm just saying what their system consists of & what they report for performance. If the consensus is that they are lying about the estimated performance possible I have a hard time believing that. That would not be a great business model.

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As with a lot of marketing, I'm sure they aren't outright lying. There is probably enough truth to keep them out of lawsuits.

What probably saves them from most of the bad publicity, is anyone who believes the marketing hype without independently checking the numbers is too embarrassed to speak up when they find their boat doesn't perform nearly as well as it would with a standard diesel.
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Old 29-12-2015, 19:35   #216
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Re: Tug of War - Electric vs Diesel

"flashlight batteries are probably not the way to go"

Reminded me of the Autosub:
Scientific expedition to the world's deepest undersea volcanic rift

Earlier Autosubs were powered by regular D-cell batteries - 5500 of them, which took half a day to change. But Autosub6000 instead uses up to twelve rechargeable lithium-ion polymer battery packs.
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Old 16-01-2016, 00:46   #217
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Re: Tug of War - Electric vs Diesel

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Of course assuming both diesel and electric motors are rated the same way, ....
Diesel engines and electric motors are not rated the same way. Power ratings for diesel engines are maximum power with no guarantee that it can be sustained for any period of time. Power ratings for electric motors are continuous power that can be sustained for days. Surge power of an electric motor is two or three times higher than the rated power.
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Old 16-01-2016, 00:52   #218
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Re: Tug of War - Electric vs Diesel

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Planet solar used 11 Tons of Lithium batteries (2910AH @ 388V - i.e. 1129KWH or about 17 times the total energy of your average Tesla battery) and 537m^2 of high efficiency solar panels.
That begs the question: Where does one find an MPPT controller to charge a 388V battery?
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Old 16-01-2016, 00:57   #219
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Re: Tug of War - Electric vs Diesel

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That begs the question: Where does one find an MPPT controller to charge a 388V battery?
Easiest solution is don't have a 388V battery, use a more practical voltage and step it up for the engine power. That way you can use the battery for all of your other power requirements simply.
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Old 16-01-2016, 01:04   #220
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Re: Tug of War - Electric vs Diesel

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Easiest solution is don't have a 388V battery, use a more practical voltage and step it up for the engine power. That way you can use the battery for all of your other power requirements simply.
The losses rise despite huge cables as one tries to put that much power through at lower voltages. The MPPT controllers can generally support a 48V battery bank. It would be inefficient and difficult to find a 60KW DC motor at 48V, so a buck-boost DC-DC converter would be needed. It would be simpler, cheaper, more efficient, and more reliable to have an MPPT controller that would accept 600V in and 400V out. I suspect that Planet Solar probably had their MPPT controllers custom made, but I don't know. They may have operated the battery at 48V.
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Old 16-01-2016, 01:06   #221
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Re: Tug of War - Electric vs Diesel

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Originally Posted by Scout 30 View Post
Good point, flashlight batteries are probably not the way to go. Seriously though, I'm not trying to design a system here. Elco has already done that. I'm just saying what their system consists of & what they report for performance. If the consensus is that they are lying about the estimated performance possible I have a hard time believing that. That would not be a great business model.

Electric Engines 101 | Inboard Boat Motors | Elco Motors
All looks very impressive. On paper. I was recently babysitting a craft which is new last year, cost an absolute bomb (50+ ft high performance cat), boasts a hybrid system which was supposed to be top drawer, and is currently awaiting total conversion either to diesel hydraulic, or just conventional diesels. The owner's preferred option, after spending a FORTUNE on the hybrid electrical system which took them around 1500 miles of coastal sailing with half a dozen emergencies and endless problems, is conversion of this brand new boat back to a simple old school twin diesel arrangement. The project was complete, took multiple years to build from a reputable "cutting edge" French outfit, and is an unusuable disaster. Owner is at his wits end. Just wants to go cruising and now looks like will be another six months to a year, with more enormous expense.
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Old 16-01-2016, 09:33   #222
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Re: Tug of War - Electric vs Diesel

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Diesel engines and electric motors are not rated the same way. Power ratings for diesel engines are maximum power with no guarantee that it can be sustained for any period of time. Power ratings for electric motors are continuous power that can be sustained for days. Surge power of an electric motor is two or three times higher than the rated power.
Sorry but both diesel and electric motor manufacturers rate the motors based on the maximum reliable power output they can be counted on.

It's disingenuous to imply a diesel ran at it's maximum rated output is likely to fail while at the same time implying that an electric motor ran at 2-3 times it's rated power is likely to survive any length of time.

You could add a big turbo and blast 2-3 times the power out of a diesel but just like you could hook up a big power supply to an electric motor, either will fail very in a short period of time. Stay within the ratings and either will last a long time.
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Old 16-01-2016, 09:46   #223
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Re: Tug of War - Electric vs Diesel

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Sorry but both diesel and electric motor manufacturers rate the motors based on the maximum reliable power output they can be counted on.

It's disingenuous to imply a diesel ran at it's maximum rated output is likely to fail while at the same time implying that an electric motor ran at 2-3 times it's rated power is likely to survive any length of time.

You could add a big turbo and blast 2-3 times the power out of a diesel but just like you could hook up a big power supply to an electric motor, either will fail very in a short period of time. Stay within the ratings and either will last a long time.
I've seen marine diesels fail because a skipper decided run a diesel engine at full throttle for a day or more. That's their rated power -- their rated maximum power, not continuous power.

An electric motor run at its rated power should be fine for months. However, it's possible to run an electric motor at 2 or 3 times its rated power for very brief periods, such as for the demonstration video at the beginning of this thread. Try that for an hour and the electric motor will fail. With a diesel, its not possible to substantially increase power beyond rated power the way it is with an electric motor -- except by making major modifications, like adding a turbocharger or nitrous oxide or something like that.

That's one of the often overlooked reasons why an electric motor will generally beat a diesel in a tractor-pull like competition such as the video at the beginning of this thread.
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Old 16-01-2016, 22:15   #224
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Re: Tug of War - Electric vs Diesel

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I've seen marine diesels fail because a skipper decided run a diesel engine at full throttle for a day or more. That's their rated power -- their rated maximum power, not continuous power.

An electric motor run at its rated power should be fine for months. However, it's possible to run an electric motor at 2 or 3 times its rated power for very brief periods, such as for the demonstration video at the beginning of this thread. Try that for an hour and the electric motor will fail. With a diesel, its not possible to substantially increase power beyond rated power the way it is with an electric motor -- except by making major modifications, like adding a turbocharger or nitrous oxide or something like that.

That's one of the often overlooked reasons why an electric motor will generally beat a diesel in a tractor-pull like competition such as the video at the beginning of this thread.
Good luck running your electric motor at 2-3 times the rated power for more than a few seconds. Come back and tell us if the manufacturer honors the warranty if you let them know what you are doing.

Replacing the controller to pump 2-3 times the HP out is almost exactly the same as strapping a big turbo so a 30hp engine pumps out 60hp. It's not something your average joe would take on and odds are both destroy the engine very quickly.

If you want to claim diesels can't be run at full throttle, give us specific examples with names, model numbers and the full situation. I've never had nor heard of a healthy engine failing from running at full throttle. Then again, I would rather have a 60hp diesel the keeps me moving for a day or more at full throttle before dying (not that I'm buying your story as anything but made up to prove your point) than a 30hp electric pumped up to 60hp that burns out in 5minutes.

As has been pointed out several times on this thread, peak HP for a cruising boat is needed driving into a heavy waves and/or a strong headwind...typically for an extended period of time (ie: 1/2hr to several hours). Tell us how running the electric motor at 2-3 times it's rated HP will do in those conditions.

Electric motors have a slight edge off the line because they generate maximum torque (not HP) from zero RPM. The original test shown had at least 2-3 additional issues unfairly giving the electric motor the advantage that could readily be seen and several others were the author never clarified as being kept fair. In a fair test where all other variables are kept equal, I would expect a slightly smaller electric motor to get a slight edge for a 2-3 seconds while the diesel spools up but before any noticeable momentum can be developd. Then the larger HP diesel would pull away.

For about the 10th time, HP is HP. There is nothing magical about electric HP.
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Old 17-01-2016, 00:15   #225
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Re: Tug of War - Electric vs Diesel

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Good luck running your electric motor at 2-3 times the rated power for more than a few seconds.
More like five minutes.

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Come back and tell us if the manufacturer honors the warranty if you let them know what you are doing.
Straw man argument. I never made any claims about warranties.

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If you want to claim diesels can't be run at full throttle, give us specific examples with names, model numbers and the full situation.
No problem. I'll even give you an example that's easy to verify. Sea Shepherd's MV Brigitte Bardot, formerly MV Cable and Wireless Adventurer designed by Nigel Irons blew up an engine by running several hours at full throttle playing cat and mouse with the Japanese whale poachers in the Southern Ocean Whale Sanctuary. Video recording of the event can be watched on Animal Planet's Whale Wars. While I have crewed with Sea Shepherd a couple of times, I was not onboard the Brigitte at the time.

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I've never had nor heard of a healthy engine failing from running at full throttle.
And that proves it doesn't happen???

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Originally Posted by valhalla360 View Post
Then again, I would rather have a 60hp diesel the keeps me moving for a day or more at full throttle before dying (not that I'm buying your story as anything but made up to prove your point) than a 30hp electric pumped up to 60hp that burns out in 5minutes.
You seem to think I've made some point, or tried to make some point, that I have neither made nor tried to make. Please reread or rethink.

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As has been pointed out several times on this thread, peak HP for a cruising boat is needed driving into a heavy waves and/or a strong headwind...typically for an extended period of time (ie: 1/2hr to several hours).
Yes, of course, and I've never suggested otherwise.

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Tell us how running the electric motor at 2-3 times it's rated HP will do in those conditions.
I've already clearly stated that it would burn up.

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Originally Posted by valhalla360 View Post
Electric motors have a slight edge off the line because they generate maximum torque (not HP) from zero RPM. The original test shown had at least 2-3 additional issues unfairly giving the electric motor the advantage that could readily be seen and several others were the author never clarified as being kept fair.
All of that is correct, but not the full story.

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In a fair test where all other variables are kept equal, I would expect a slightly smaller electric motor to get a slight edge for a 2-3 seconds while the diesel spools up but before any noticeable momentum can be developd. Then the larger HP diesel would pull away.
That's not what happens in real tractor pulls.

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For about the 10th time, HP is HP. There is nothing magical about electric HP.
I have not written anything contrary to that.

I'm going to try one last time to explain this at a third grade level, since what I previously wrote was unclear to at least one reader.

The difference between the maximum power than a diesel engine can produce for five minutes versus five days is roughly about 10%. The difference between the maximum power than an electric motor can produce for five minutes versus five days is about 2-3 times. These are facts that can be verified by anyone who knows about diesel engines and electric motors. The rated power of diesel engines is their maximum instantaneous power, which is not very different from their long-term sustainable power. The rated power of electric motors is their long-term sustainable power, which is very different from their maximum instantaneous power.

I have not claimed in this thread that electric motors have any advantage over diesel engines for any purpose other than tractor pull competitions, so please stop with the straw man arguments. If you still don't get it, please go ask an expert you trust.
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