Electric Blackbird (Pericles)

[paladin]

It's a slow day in the bilge so after reading your interest in making a FL26 but with electrical power......and reading the lack of encouragement in the response......I doodled this up.....the numbers are based on the intended diesel for propulsion, one starting battery, at least one 4 d series house battery, and 40 gallons of fuel on board....

If we went to flashlight batteries......
Just as a fun excercise.....I checked the ratings of your proposed propulsion
unit.....72 volts at 200 amps....400 amps peak......

If you assembled the battery yourself, and without going into minute details about the fusing and temp controls for NmHydride batteries......
Imagine a "battery"...13 inches high, 8 inches wide and 24 inches long....weight 80 pounds (sorry)....current rated to 80% with 82.5 amperes.....that can be recharged with a small switching charger at a 2x rate for a complete recharge in 2 hours. This is your basic building block using off the shelf available today parts, total cost for batteries and thermistors/fuses about $250 U.S. Four such batteries would give you a flat out hours run with a little reserve, and since these are parallel-able packages use as many as you wish or can afford...
I forgot to mention the battery can be mounted on it's side or end and will work just as well......
Then for a bit more fun....Kyocera makes some very interesting solar panels these days...with high er than normal voltages output. If that output is run to a very high efficiency switching regulator (maybe 98%) and then to your charging system....you could make a rear deck aft about 16 inches in front of the transom, perhaps storage under, mount 4 of the new solar panels on the stern shelf and if the boat sat in the sun for a day or two you could have some respectable running time in the batteries, without plugging in. Jacques engine would weigh 500 pounds......plus the fuel and starting battery. The electric drive would weigh about the same as the starting battery and the fuel tanks, leaving the 500 pounds for the batteries......which in our case means at least 6 packages and we're still lighter because we have no fuel or fuel tanks....if we allow for 40 gallons of fuel at 8 pounds per gallon, that equates to 320 pounds or 4 more battery packs making our electric current capabilities now in excess of 820 amps, or four hours use without charging.....which also equates to 2400 dollars in batteries.....or an afternoon using a tank of diesel fuel would be about140 dollars and then you must buy more at $3.50 gallon, or more. The life expectancy of the batteries using the proper charger is 700 times...or the equivalent of $98,000 in diesel fuel.
System should be great for 4 hour trips before charging........quietly drifting along...some problems may apply....I suggest a propane or kerosene sea swing stove for cooking and coffee.....it will eat the batteries if electric......also consider adapting all lighting to LED. I am making LED adapters for all my lights.

compare all this against the cost of a 50 hp beta marine diesel and gear........

[JimConlin]

This could get interesting.

[paladin]

especially if you built a boat with a coachroof with room for solar panels instead of using an open launch like BlackBird...........The actual battery installation could come out much cheaper than a diesel but the limit would be the range before recharging....100 miles if carefull, 40-50 if you're in a big hurry

[willmarsh3]

Chuck, just think what the range would be if you used this kind of battery. The says up to 10 times the current lithium ion batteries that use carbon.

http://cosmiclog.msnbc.msn.com/archive/2008/01/17/586070.aspx

[paladin]

Will...it's only money.....the cells that I specified are a hair under $4 each wholesale, D sized solder tabs, 8.25 amps each.....the manuf. rates them at 700 recharge cycles when using the specified charger...I designed a different charger, a bit slower but the battery packs have the life more than doubled.....that's a lotta flashlight batteries....

[G. Schollmeier]

I like the battery pack idea. Another advantage would be the ability to fit them to the space you have. How realistic is this? I noticed some disclaimers, “without going into minute details about the fusing and temp controls for NmHydride batteries”, “some problems may apply”.
Gary

[paladin]

Nickle metal Hydride batteries can heat up when you charge them too fast or discharge them too fast. It is easy enough to design a system to work to 125 degrees C, but to obtain 72 volts for the motor specified, you need 60 batteries in series....as a flat pack it would be about 1.3 inches high by 8 inches by 24 inches.....when you series the batteries you need to add a thermistor and a series fuse to the pack.....you make 10 such packs and stack them flat to get the dimensions that I indicated. They could be stacked differently to fit a special place. This would give you the basic 72 volt, 82.5 ampere hour pack, then just make more packs as you need them....they can all be wired in parallel to get the reserve current that you need.

[mcdenny]

Chuck,

Can you give a little more specific info on the NMH battery idea?

I'm building another electric launch, this one needs 72 volts and 140 amp hours. The six deep cycle lead acid AGM batts I plan on using weigh about 540 pounds, occupy as much volume as three of your proposed D cell packs and cost $1800.

If I understood your first post correctly two of your packs would be 165 ah and weigh only 160 pounds and cost around $500. Can that be true?

Edited to say Oops - I did the math and the bank would cost $5000, not $500. A few spots on the web are charging about $8 per D cell.

[paladin]

Ya gotta buy wholesale.....didn't your pappy always tell ya to buy low sell high? :D You need the panasonic"D" cells 8250 mah, 1.2 volts, with solder tabs, a 10 k thermistor, fuse, a hair dryer or heat shrink gun or pc boards for the end mounts. There will be 60 cells in series in a zig zag pattern, 10 x 6 or 12 x 5 configuration so that you have a 72 volt, 8.25 amp pack, then stack 10 of them and wire the 2 system wires in parallel for an 80 pound box, 72 volts 82.5 amps.....then make as many as you require...the fast charger for one box would have to be 75 volts40 plus amps but that will fast charge the cells, probably cause some heating and reduce the number of cycles the batteries could be used....I prefer to charge at 75 volts with a current control sharp limited to about 20 amps to recharge at a slower rate. Then just add the extra current for each pack that you go up in size. I can supply a schematic diagram for the charger if needed, parts lists, sources etc.

[mcdenny]

Thanks, Chuck.

The lead acid option is (6) 12v 140 ah AGM batts = $1500 and 540#.

Comparable power in 60s17p Nimh 8.25 ah D cells @ $4 and 6 oz each = $4080 and 382#. Is the 6oz/cell weight right?

The 158 # weight difference would increase my top speed from 9.3 to 9.5 mph.

Not as economic as I first hoped.

[paladin]

Yup! That's about right....the only real advantage is buying at a cheaper rate and making the package fit in weird places, and possibly getting double the life out of the batteries with controlled charging.