Electric Ferry

[portacruise]

Not a complete cycle from 0% to 100%. Probably just between 60% to 80% every 10 minutes or so, would be my guess...

P.

Originally Posted by philSweet

You plan to cycle this system every 6 minutes 7 days a week?

[portacruise]

This electric ferry type application is one of the niche uses where battery will clearly excel. Battery cycle life should be very high, probably over 3000 cycles with AGMs and even more with nicads or lithiums due to the shallow discharge/charge cycle. Also the maintenance/downtime on electric is much lower than diesel because of rotary drive having such few moving parts vs. hundreds/thousands in a diesel. Heavy cargo/low speed/short distance/opportunity charging- fits with electric motors better than fossil fuel motors. Some train locomotives/subs/military marine boats etc., take advantage of the high torque characteristics of electric motors rather than being driven directly by their fueled motors...

P.

[philSweet]

3000 cycles = 5 weeks. I think you can get 10,000 cycles with a bit of research with wet lead. Unless you plan to build the entire dock system at each end, I don't see this happening. The shoreside equipment will probably cost more than the ferry. How about mounting the batteries on a cart and swapping carts every few trips. A golfcart chassis carrying ten 8Ds. Hydraulics would be my first choice, but unattractive do to the risk of spillage. On the Rube Goldberg side of things, an 80' standpipe 8' in diameter feeding a 30KW trim pump would supply 20 cu ft/sec of lake water to a 6' Pelton wheel on the boat shafted to a genset. Tie up real good before you open her up. Just included the last to show you what sort of power we're talking about. Charging the batts is always the problem with electric drive. Continuous charging and a 5% duty cycle is probably doable. Dump charging and 50%+ operation is unattractive from a capital expense point of view.

And this inductive charger will weight what? 1500 pounds? How will you disipate the heat?

[portacruise]

How many start/run cycles on the Prius and other hybrids/EVs? There are reports of Prius going well over 300k miles without a battery failure, and the GM electric has 100k warranty even with deep discharges.... The original satelites used nicads designed for several hundred thousand cycles, some are probably still operating, maybe to millions of deep cycles....


Shoreside equipment with contacts should be low cost IF you employ a "bad boy" charger (no down or up on volts) at 600 volts. Only the contacts would have to be worked out and there some low cost possibilities.

That's what I see, anyway...

P.

Originally Posted by philSweet

3000 cycles = 5 weeks. I think you can get 10,000 cycles with a bit of research with wet lead. Unless you plan to build the entire dock system at each end, I don't see this happening. The shoreside equipment will probably cost more than the ferry. How about mounting the batteries on a cart and swapping carts every few trips. A golfcart chassis carrying ten 8Ds. Hydraulics would be my first choice, but unattractive do to the risk of spillage. On the Rube Goldberg side of things, an 80' standpipe 8' in diameter feeding a 30KW trim pump would supply 20 cu ft/sec of lake water to a 6' Pelton wheel on the boat shafted to a genset. Tie up real good before you open her up. Just included the last to show you what sort of power we're talking about. Charging the batts is always the problem with electric drive. Continuous charging and a 5% duty cycle is probably doable. Dump charging and 50%+ operation is unattractive from a capital expense point of view.

And this inductive charger will weight what? 1500 pounds? How will you disipate the heat?

[quicksail]

Thanks everyone for chiming in on this topic. I really appreciate the help as this is the one final step to making this operation as feasible success. From our calculations there is a significant savings to be had going to a electrical ferry. As has been mention previously cable ferries lend themselves to this type of technology due to their high efficiency drive systems.

The overhead cable solution would work great if we could block off traffic from using the channel. Unfortunately the odd sailboat might find this to be a shocking experience. We have also thought about a permanent cable that is deployed going in one direction and then retreived via a cable reel when going back. This system could work well but is unproven in our area and transport Canada would have a hard time dealing with this. So we must take baby steps in this relatively new area as our regulatory body is still stuck back in the 70's.

We are planning to use Lithium polymer batteries as they provide the highest energy density with high rechange rates (up to 4C) and long cylce life ( over 30000 @ 60% discharge).

At this point it comes down to making the operation as seemless as possible as in the service industry even if it is "green" technology no one wants to wait for the service due to that technology. Therefore if we can do automatic charging it would be great.

From your conversations I will look into the inductive contactors and contact some tranformer companies to see if they can develop something that suits our needs. Thanks again and let's keep this dialogue going as there is some good ideas being put out there.

Cheers,

Christian

[philSweet]

Well, keep us posted and let us know a bit more about the craft, its power requirements/duty cycle while enroute, and the sort of dock facilities you have and whether they are under your control or not. As a drop-in solution, its a tough one.

[portacruise]

Some more comments below, FWIW. Thoughts which might lead to something that can be of use or not. Specifics/scale of your setup would be useful as indicated by philSweet....

Porta

Originally Posted by quicksail

The overhead cable solution would work great if we could block off traffic from using the channel.

No batteries would be needed with an overhead cable.
The shoe/brush was suggested to show that high power can be transmitted through mechanical "whisker" arrangements with unsteady or complex moving contact conditions. There could be a spring loaded whisker poles on the boat and overhead strips of gridwork at the dock just as an example. That way charging could start while the ferry is still in approach and motion and while moving out. Stainless steel contacts are used in the streetcar contact to reduce pitting and would help with salt corrosion, and maybe magnetic arc suppression could be employed. Or maybe a cone and pole arrangement like is used in mid flight aircraft refueling, you get the idea of some possibilities.....





Unfortunately the odd sailboat might find this to be a shocking experience. We have also thought about a permanent cable that is deployed going in one direction and then retreived via a cable reel when going back.



Tangles, kinks, snagging, and wear on the cable, plus 600v under seawater resulting in corrosion and shock issues.....



We are planning to use Lithium polymer batteries as they provide the highest energy density with high rechange rates (up to 4C) and long cylce life ( over 30000 @ 60% discharge).


The specially developed Prius NiMH would be less costly and have a longer known history. Where did you find 30,000 cycle Lipoly?




From your conversations I will look into the inductive contactors and contact some tranformer companies to see if they can develop something that suits our needs.


Seems like at least one coil would have to be lightweight for alignment and close contact proximity required, as philSweet indicated about weight. I think magnetic effects decrease according to the cube of distance....



Thanks again and let's keep this dialogue going as there is some good ideas being put out there.



Just thought some of this would help, if not you can have a refund.

Cheers,

Christian

[Poida]

Oh no, it's me again. If induction charging can be used, could a cable on the waterbed be used. A cable from the boat would connect to the underwater cable with a roller set up that would allow the cable to roll through the connection providing an induction charge up to the boat.

It would work upside down to a tram system.

[SheetWise]

Originally Posted by Poida

Oh no, it's me again. If induction charging can be used, could a cable on the waterbed be used. A cable from the boat would connect to the underwater cable with a roller set up that would allow the cable to roll through the connection providing an induction charge up to the boat.

It would work upside down to a tram system.

If you can use a cable, just to move the ferry, it may provide other efficiencies that reduce your power requirements.