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DrWatson

Electric Drive H28

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Re the batteries ( I didnt look at the links so might be a silly question ) but are these batteries able to be discharged down deep without damage?

 

If you _need_ 200Ah of capacity to do what you want, with lead acids you really want at an absolute minimum 400Ah of battery capacity to avoid damage to the bank, and 800ah, to get a good long lifespan from the batteries. Makes the weight of a small diesel electric setup look insignificant maybe?

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

 

 

Holy hemorrhoids batman, I just checked the price on those batteries - $5,000 for 500Ah at 12V!! - about 5 times the initial cost of lead acid.

 

I think I’ll wait till this stuff gets cheaper

 

Yeah but you only get 500-600 cycles our of a lead acid deep cycle battery assuming a depth of discharge (DOD) of 50%. You are meant to get 5000 cycles out of a LiFePO4 battery with a DOD of 80% i.e. 10 x the cycles for 5 x the price. You do need to factor in an upgrade to charging system if you want to maximise your benefits so its not quite that simple.

 

Also from what I understand the LiFePO4 batteries will accept near 100% charge up until full unlike lead acid batteries that tapper off. Your typical cruiser who is trying to maximise the life of his/her deep cycle battery will only use 30% of its capacity (50%-80% range) whereas the Lithium batteries can use up to 80% i.e. 50% more usable power for the same rated battery. What's better is that they generally are lighter than your nomal lead acid battery.

 

KM had a slightly less technical thread somewhere around on these batteries.

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Have a look at the link to AA Solar. Lots of stuff there and comparisons to lead acid.

Being able to charge at full speed would be great when you have 5 kilowatts coming out of the dc motor when running the diesel. I guess 100 amps at 48 volts so won't take long to re charge. Also with this amount of power available running the fridge won't be a big deal, maybe even air conditioner! Different world with this amount of power aboard.

The Lithium batteries are a bit less than 3 times the cost of sealed lead acid from AA Solar.

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I thought this was well priced. Providing it is a ligit battery.

http://www.trademe.co.nz/business-farmi ... 525147.htm

And their drive unit is pretty cheap too.

http://www.trademe.co.nz/business-farmi ... 525497.htm

In fact, even using that drive with a simple generating system would give you a light, simple and cheap drive system.

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Its a 100 amp 3.2 volt. So a bit more than $1000 per 100 amp hour at 12.8 volts. Saves quite a lot of weight and space! They have a hybrid system as well.

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Just found this on the Enertec website (Mastervolt)...."For six to eight hours sailing, you require 4.6 x kW capacity in kWh. Example: 4.6 x 3.5 kW = 16.1 kWh; this is the capacity required for six to eight hours sailing."

So for a 5 kilowatt motor......4.6 x 5 = 23kwh which at 48 volts is 23000 / 48 = 479 amp hours for 6 to 8 hours motoring.

With a hybrid setup I'd be happy with around 1 hours motoring because thats mostly what would be needed to get into and out of a harbour. So 480 / 6 = 80 amp hours. So 80 amp hours at 48 volts is 320 amp hours at 12 volts which is a bit light on for the house. Probably be ok if we went with the Lithium batteries.

With this setup one could motor electric sail say in light air or in a big swell and light air using very little throttle for considerably longer periods. This is one of the main attractions of electric drive for me.

http://www.mastervolt.com/marine/products/e-propulsion/

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So it is one hell of a lot of money to spend to get in and out of a Marina. You would be better off with a small outboard you could then remove and stow in a locker. For me (but remember we have a big Motor sailor) the engine is an important piece of equipment.

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Well $15 to $20 grand for a diesel is a big reach also. I understand your "floating palace" :thumbup: may be not suited to electric drive. Where I see a large advantage is in sailing in light winds with a bit of assist from the engine. In my current situation we could re charge the batteries with shore power and rarely need to use the diesel, though I reckon it would need to be run fairly regularly.

This is an interesting development......http://www.gizmag.com/mecc-bio-methanol ... der/23462/

maybe we can fill these tanks from a service station. We need something like this to make electric drive alone suitable for long range cruising.

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The more I read the more I am convinced the day of cheap fossil fuels is over and never coming back. Thus being able to regenerate under sail makes lots of sense.

Remember Wheels that is pretty much a one off cost vs buying diesel, oil , filters, fan belts, repairing pumps, replacing impellers ....... for a very long time.

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You'll like this Ogre from EV Concepts.....

"With good winds the system can regenerate power through the spinning prop. The regenerating system uses the power in the pop shaft to spin the electric motor to recharge the batteries. It takes about twice as long to recharge the batteries under sail as it does to drain them while under power. So motoring out of the harbor, sailing for four hours, then motoring back in for an hour would result in no overall change in the charge in the batteries. "

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