Jump to content

Electric Drive H28


DrWatson

Recommended Posts

Did anyone else note the Electric drive H28 which was up for sale on TM a few months back (might be 8-9 months, can't clearly remember).

 

If so, does anyone have any info on that particular setup?

 

Cheers

 

R

Link to post
Share on other sites

Not sure of that particular set up, but have a look at:

http://www.thunderstruck-ev.com/electri ... -kits.html

This is the system I've used on my electric boats over there. It is an obvious option to change to. Also try locally http://www.earthling.co.nz/marine-environ.html

It makes a lot of sense on a yacht, when you can regenerate power once you're sailing...

Link to post
Share on other sites

TimC, I had a look at those links, the exciting bit to me was the drive unit with a variable pitch prop. I love the idea of regenerating while sailing but still be able to get rid of the drag once the batteries are full.

But there wasn't a lot of info there. Do you know how many hours sailing for how many hours motoring? And they talk of a variable pitch prop but show a picture of a folding one (would that even work?)

Link to post
Share on other sites

I'm no expert but seems 500 watts per ton to drive to 70 % of hull speed so mine is 10 ton and hull speed is 7.2 knots so at 5 knots would draw 5000 watts so at 48 volt a ten kilowatt lithium type batteries may go for 2 hours.

In regards to re generation. May be good when there's enough wind to get to hull speed but when doing say 5 knots and having used the motor I'd be really keen to re charge so I think mostly a pain that is reducing my already slow light wind sailing speed.

I see Lithium batteries have come down in price so its tempting but still would need a diesel generator to ensure a charge is available. The immense power demands make a mockery of solar and wind generation I feel. Great for just going out and back from the marina but I think still hard to justify for cruising. That quiet is so appealing though!

Link to post
Share on other sites

To me it seems they might be ideal for getting in and out of a bay or marina. But for serious work like getting you off a lee shore or fighting into a strong wind or chop the small power of one of these installations won't cut it. So I'd want a boat which was very reliable sailing to windward.

 

I wonder how the powers that be would see one of these for meeting offshore rating requirements?

Link to post
Share on other sites

Correct Bogan. 500W/tonne maybe enough to propel you along in ideal conditions, or in and out of the Marina, but that',s about it. You need at least 2200W/tonne. At least.

BBay, the other thing to think about is how long it takes to get all that energy back into the Bank.

Link to post
Share on other sites

Depends on your expectations there Wheels.There are quite a few boats out there with electric drives and they are getting better.

Link to post
Share on other sites

Can't talk with any actual experience Wheels but have read that electric drives are pretty potent at least more than the shaft horsepower indicates probably due to high torque output. If just going daysailing and moored with 240 volts alongside then I believe these would be ideal and you would not need a huge amount of battery. You could have a genny onboard to enable slow motoring for longer distances as needed. At very slow speeds they don't draw a lot of current. I believe they are great for sneaking past your mates in light air! :D

Another aspect is that with the rather large batteries aboard the house loads become insignificant. Also, all those batteries will have to be supported well, would not like to be wrestling them in a storm.

I worked out that for 800 amp hours at 48 volts in lithium batteries would need a space 600 by 600 by 600mm. These batteries are getting smaller and much lighter. :thumbup:

Link to post
Share on other sites

Just to qualify my stand on Electric, my views are slowly changing over time, as they should due to advances in technology and it will continue to improve. But there are still some points that need to be clearly understood by anyone looking at Electric. The main point that will never change is that Power is Power. What goes out must go back in. The charging times have greatly improved. The batteries have become lighter, smaller and charge faster. But you still have to get the energy back in. We all know the pluses and minuses of the various generation methods, but few understand, or at least consider the time required. The time a prop would need to be dragged for, or a Wind gen spun, or a genset run for.

Re the Hp required. The benifits of Electric is that it has high torque over a wide range of RPM. The current drawn is in direct proportion to the load. So apart from the power required to turn the motor on it's own, the power is in direct relation to the load of pushing the boat. Where as a combustion engine will use a great deal of fuel just to run, with ruffly a 20% increase in consumption under load for a diesel and 80% increase for Petrol. Electric thus is the most economical for power required to load placed.

But Hp is Hp (or Kw's) and the figure of 3-5Hp per tonne is based on the requirement needed to safely control your boat in whatever situation. Torque is useless with out referenced to Hp. Hp is useless without reference to Torque. The both give you the actual power available to do something.

By the way, the electric saildrive and batteries are all listed for sail on trademe last night. Not bad for price actually. I was pleasantly surprised, especially the relative cheapness of the batteries. Pretty much on par with a really good quality deep cycle Lead Acid.

Link to post
Share on other sites

This is fron Thundrstruck EV ( see link above in Ogres post)....."With a no-load speed of 1800rpm, the motor achieves peak output at 1,600rpm under load. Hull speed can require 2.5kW per ton of displacement, while 70% of hull speed requires just 500w per ton (credit to the Danes for the numbers)." The "Danes" don't get much wrong Wheels I know cause I'm one of them! 8)

Also...." This motor is rated to propel up to a 32’ sailboat and up to 15,000lbs of displacement, and offers 24v, 36v and 48v options at 3kw, 4kw and 5kw depending upon your needs for power."

Sort of a Toolman Tayler type hot up thing.

I've read these are great when sailing in large swells as they charge on the wave and propel the yacht in the slow part when set correctly. So making the power and then using it for a no loss help in certain conditions.

Link to post
Share on other sites
J

But Hp is Hp (or Kw's) and the figure of 3-5Hp per tonne is based on the requirement needed to safely control your boat in whatever situation.

 

Like I said - depends on your expectations, Hiscock said 1hp per tonne? . I had 13 hp in a Cav32 and was never disappointed, but I've heard others say that boat would need over 20hp. I think most modern auxiliaries are overpowered.

 

Agree I'd like to know how many hours to recharge after an hour motoring (6:1 or better would do me), can't find that, and I'd really want to be able to feather the prop or get it out of the water altogether once charged. Overcome those two and I am convinced.

Link to post
Share on other sites

Might be good to have a feathering prop and a water generator also. I don't believe the prop would be well set up for generating current. Probably do better with a towed generator or two.

A 9 kw motor will draw 180 amps so one hour of motoring will be recharged in about 4 hours with a 50 amp charger. this motor should be good for up to 34 foot yacht. Thats full throttle so you would do much better at say 4 or 5 knots.

Link to post
Share on other sites

These are interesting......http://www.hybrid-marine.co.uk/5.html

If you had one of these and you were berthed in a marina with 240 volts the engine would not need to be used. The electric motor would be enough to get out and back in to most berths with say 200 amp hours at 48 volts lead acid.

 

If cruising wind and solar would not be necessary, with 5 kilowatts of generator aboard I'd forego the eco trip.

 

With the above batteries house loads would be easily and quietly met, that is 800 amp hours at 12 volts would be plenty for us.

 

I'm guessing the diesel engine would last a lot longer due to the increased efficiency.

 

These batteries would be great for this http://www.aasolar.co.nz/AA%20Solar%20L ... eries.html

 

100 amp hours at 48 volts may be enough for a energy frugal couple due to the deeper cycling of the lithium batteries. Less than 0.2 cubic metres and 52 kg!

Link to post
Share on other sites
The way of the future, fossil fuels are on the way out.

 

I agree. But the price needs to come down considerably before the business case for ownership stacks up - hence my earlier thread on water as energy storage.

Link to post
Share on other sites

I think its more like twice the price of lead acid. The advantage is in the increased lifespan. They may outlast the diesel engine. With this setup it would be good to have batteries that accept a lot of current quickly so the charging time is reduced. Sealed lead acid at least. Coupled with a nice quiet Lombardini engine it would be a really sweet setup.

Link to post
Share on other sites

But Hp is Hp (or Kw's) and the figure of 3-5Hp per tonne is based on the requirement needed to safely control your boat in whatever situation.

 

 

Thats a figure which is often mentioned as being the "right" amount of hp for a yacht.

 

However - I do wonder if you have forgotten that 5hp at the motor does not equal 5hp being dissipated via the propeller. Can easily loose 20% through a transmission - not always, but power is easily lost there. Also, does the recommended 5hp include an allowance for battery replenishment, water pumping for cooling etc? I am not aware if it does or not, however, judging by the power most yachts have, this is allowed for in the "5hp/tonne" suggestion. Maybe by the time we have lost up to 50% of the total Hp/tonne into transmissions, generation of power, pumping water, etc, we can consider that the 1.5Kw/tonne dissipated by the propellor ( as an electric drive would achieve more or less ) to be not so incorrect. Thats around 2hp.

 

Also, another reason for the 5hp/tonne guideline, as noted by a few on this thread, yourself being one Wheels, is the efficiency of the internal combustion motors at moderate load vrs high load is dramatically better. And, the cooling characteristics of most diesels other than heavy industrial engines do not support 100% loading for extended periods - even if the water temperature is being correctly maintained, there can be localised hotspots in the engine which can cause issues. And electric motor is more immune to this - and will happily run to its maximum current all day long as long as its correctly specified, and has sufficient cooling ( which being immersed in water, I suspect it would have )

 

I like the idea in many ways. With a moderate sized diesel electric power generation setup. I suspect that there would be less to go wrong, and you are free to place the engine/generator in a sensible place, where access is easy and weight distribution is superior. If such a place exists!.

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.


×
×
  • Create New...