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Cigarette Electric 42' Raceboat

Discussion in 'Technical Discussion' started by Capt J, Aug 19, 2013.

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  1. Capt J

    Capt J Senior Member

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    I have seen several of the new technology regarding diesel electric and etc. and figured I'd post about this since it hasn't been mentioned. Cigarette and AMG Mercedes partnered together to make this happen. This is full electric and don't know why they didn't put a small diesel generator and diesel tank to charge the batteries and extend the range, but the technology is pretty impressive. Judging by the specs a 8KW generator should charge the batteries fast enough to extend the range at least 4x and all they'd need is a 20 gallon diesel tank and burn about 3/4 of an hour to recharge itself. 2220hp and 2200lbs of torque, it can be recharged fully in as little as 3 hrs with a 250v/50amp shorepower connection. In a 38' Cigarette, it will do over 100mph and can do 70mph for an hour straight with enough power to make it back to the dock to recharge or cruise at 50mph much longer with it's lithium ion batteries. But it shows how quickly technology is moving foward. The big problem is the buyers can't figure out how many speakers they need on the transom to make the fake annoying raceboat noise to piss everyone off!!!!!!!!!!!!

    I didn't post a link, but you can google it and get some good articles.
  2. deckofficer

    deckofficer New Member

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    2220 hp electric is 1656 KW, so if they had batteries to run it full bore for 15 minutes, at 100% conversion efficiency would be 414 KWhr bank. 3 hours charging at 250v/50amp again with 100% conversion efficiency would put 37.5 KWhr back in the battery.

    An 8 KW genny would maybe allow 5 kt of speed at best.
  3. Capt J

    Capt J Senior Member

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    True, but if you're running at 50 mph which would be 50% or less an 8kw generator would probably keep up with the electric demand. There are several articles that are on the web on it. One article states 9 minutes WOT with enough capacity to cruise back to the dock, an hour at 70 mph, and over double that at 50 mph which would be a realistic cruise speed in a boat like that. I could see blasting down to Miami at 70 mph from Ft. Laud, stopping for lunch at Bayside or Miami Beach Marina while the generator recharges the battery.....But then you're getting into the weight of the generator.
  4. deckofficer

    deckofficer New Member

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    It has 240 kWhr lithium-ion battery packs that tip the scales at 4,840 lbs Typically for each doubling of speed requires an 8 fold increase in power. That boat takes 1200 hp for 100 mph, so 50 mph would still require 150 hp or 112 KW. Don't think 8 KW genny will cut it, but it is cool tech.
  5. Fishtigua

    Fishtigua Senior Member

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  6. Capt J

    Capt J Senior Member

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    Something is wrong with your math. A 250volt/50amp shorepower connection will charge the batteries in 3 hours. An 8-10KW generator will put out 50amps at 250volts....If the boat can cruise at 50 mph for over 2 hours, then technically the charger should extend the range by an hour or so, but also allow it to recharge itself......It takes 2200hp to achieve 100mph. 50mph should then be 275KW but the motors run at 400 volts.
  7. deckofficer

    deckofficer New Member

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  8. deckofficer

    deckofficer New Member

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    The batteries are 240 kwhr so charging at 8 kw will take 30 hours.
  9. Capt J

    Capt J Senior Member

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    You're not taking voltage into the equation and that they're converting DC power to 3 phase AC power for the motors. The electrical on this is a little out of my league. However, I do know that a 8-10KW diesel generator will put out 50amps at 240 volts. The batteries in the boat hold 240 KWH of electricity. The published data says that a 240volt-50amp shorepower connection will fully charge the batteries in 3 hours. The published Data says that the 2-220KW chargers on the boat use 44amps at 240volts. So if the engines are using 275KWH at 50mph, then technically a 8kw generator that will run the 44amp 2-220KW chargers, than the boat can run at 50 mph until you run out of diesel for the generator. This is all based upon published material on the boat itself.

    I also know a Newmar 24volt 95amp battery charger will use a maximum of 16amps at 240volts.
  10. deckofficer

    deckofficer New Member

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    Think in terms of energy storage. Voltage and amps isn't involved in storage but volts X amps = watts. The boat's battery has a capacity (storage) of 240 kwhr. Your diesel generator produces 8 kw and after one hour has outputted 8 kwhr. If run for 10 hours puts out 80 kwhr and in the case of this battery "fills" it to 1/3 its capacity. Hence 30 hours to fully charge this bank.

    On the Newmar, it probably charges at 28 volts X 95 amps so its output is 2660 watts. The input from the grid is 240 volts X 16 amps, = 3840 watts which means the charger is 69% efficient, which isn't too good. If the charging output is 29.6 volts that would be 2812 watts, eff 73%, still not too good.
  11. Capt J

    Capt J Senior Member

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    Well, if that is true. Why do all of the websites say that you can fully charge the batteries with a 240volt-50amp shorepower cord in 3 hours?????? A 8kw generator will put out 50amps at 240 volts. So somehow your math for recharge time is not correct.
  12. deckofficer

    deckofficer New Member

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    The website is wrong by a factor of 10. I'll try and find it if you don't have a link for me.

    This is what the web site said....

    "....The boat has two chargers providing a total charging rate of 44 kW, taking about seven hours for a full charge."

    44 X 7 hours = 308 kwhr so a charging efficiency of 78%. But a lithium should only be run to 80% DOD (depth of discharge) for good cycle life.
  13. Capt J

    Capt J Senior Member

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    The other website says 3 hours to full charge, that aside.

    It is deriving all of it's energy to run those battery chargers from a 240volt-50amp shorepower cord. An 8-10kw generator puts out right around 50amps at 240 volts, so the input power for the chargers would be the same.

    "the powerboat is fitted with two 22-kilowatt on-board chargers from the 'SLS AMG' coupé electric
    drive as standard - fully charging in approximately seven hours, with additional options to reduce
    charging to less than three hours."
  14. deckofficer

    deckofficer New Member

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    How does a charger input 8 kw and outputs 44 kw? And that output is required for a 7 hour, not 3 hour charge.

    A 10 kw generator would be 40 amps @ 240 volts.
  15. deckofficer

    deckofficer New Member

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    additional options like maybe 3 more of those 22 kw chargers. That is the only way to charge in 3 hours. 308 kwhr / 3 hours = 103 kw and if the input voltage is 240 volts, then 103,000 / 240 = 429 amps / .79 eff = 543 amp circuit. To charge that battery in 3 hours on 240 volts would require a 543 amp circuit.
  16. deckofficer

    deckofficer New Member

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    I'm new to this forum, but I would think the membership isn't all deckies like me. Where are the engineers that can shine some light on P= I X E and the above discussion?
  17. Marmot

    Marmot Senior Member

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    It is relatively irrelevant ... your magic boat is not driven by a resistive load.
  18. Marmot

    Marmot Senior Member

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    If the breaker fails it may do that until all the smoke leaks out.
  19. jhall767

    jhall767 Senior Member

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    Didn't you read what CaptJ said - It is on the websites that they can recharge the boat in 3 hours.

    AND you should know they can't put anything on the internet that isn't true....

    I think people get confused because you can step the voltage up or down and vise versa for the amperage but wattage is wattage. You can only lose it during conversions. Maybe the engineer's get tired of pointing out the obvious?
  20. deckofficer

    deckofficer New Member

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    As one deckie to another, I felt like I was spinning my wheels trying to tell CaptJ, that you weren't going fill a 240 kwhr battery in 3 hours with a 8 kw source and just was hoping for some collaboration from the engineering side.