In spite of the extra complication, I have always thought that a CP prop and an electric motor would be an excellent match. With CP you could fully optimize load and RPM on the motor when motoring, and also optimize regen output to speed through the water, under sail.
A 10kw or 12kw BLDC/PMAC motor would be marginal for your boat but would be the choice of many e-boaters due to low cost and weight and just general DIY-friendliness. Or you could go with an AC motor from an electric car, along with the controller. Note that such systems usually run at high voltages, as high as 288v. The more typical 30' e-boat runs at 48v and operates under different set of electrical standards making DIY much easier. If you go over 48v, you may as well go high voltage because the cutoff between "lethal" and "nonlethal" voltage for wiring standards is 50v. So first of all you need to determine whether you need a lot of power or not. Myself, I would run a single 12kw BLDC motor and probably a 3:1 belt reduction gear and 96v or 120v from golf cart batteries for that size boat. Others will opine that you need more power. The problem is where are you getting the power? From batteries. How many tons of batteries can you carry? So I would be okay with the 15hp or so max from the BLDC motor, myself.
Most e-boaters do not even THINK about running hull speed. About 1/3 theoretical hull speed is a far more economical power level in terms of range, energy storage and usage. If you don't like to go slow, forget about cruising with electric. For short duration operation, just getting in and out of a marina or picking up a bouy, no big deal, run it wide open. The oft quoted hypothetical example of clawing off a lee shore is not going to happen all that well no matter how powerful your motor is, because you can't run full power for sustained periods without also running a diesel generator. More efficient to simply run a diesel engine coupled to the shaft. Electric is great for low speed or for short duration, superior to diesel. If you need long legs, go straight diesel or at least hybrid which is not cheap.
The 600lb gorilla in the room is batteries. Biggest bang for the buck is FLA golf cart batteries. Biggest bang for the pound (weight, that is) is definitely NOT FLA batteries, probably LiIon or possibly LiFePO4 but Li Ion have a lot of hazardous qualities to them and rely VERY heavily on a good BMS for safety, and either type will cost a bunch of $. So lots and lots of weight but not so much coin for a big bank, or lots and lots of coin but less weight for a big bank, take your pick. But either way, size of your bank is everything. Almost, anyway. Regardless, you MUST learn about your chosen battery type, maintenance, charge algorithms, charging and monitoring and control and management techniques and systems, etc. More important than motor, controller, reduction gear, ANYTHING else, is your batteries. Your propulsion system can have a complete failure, and your batteries are still very very useful. They are also the most expensive part of your system, and will most certainly need replacing within several to 10 years or so unless you go with Edison cells. In my opinion, the two big players worth considering are golf cart FLA batteries and large LiFePO4 prismatic cells, one or the other. Unless the only thing that matters is your batteries lasting 100 years, then Edison cells which underperform in nearly any property other than longevity and durability and overcharge tolerance.
Back to motor. A BLDC motor, BrushLess DC motor, is basically a PMAC or Permanent Magnet AC motor. It has no internal commutation. Commutation is achieved by the Motor Controller which accepts the input signal of a Hall Sensor Array or other position reporting system to tell it where the rotor is in it's rotation, and sends the appropriate polarity pulses to the appropriate stator coils to attract or repel the appropriate rotor magnets. There are also brushed DC motors but you must not use a brushed motor if you have gasoline or propane equipment or fuel aboard. The advantage of a brushed motor is if the controller fails, you can still limp home by connecting directly to the bank, perhaps tapping at some point along the series for lower voltage when less power is desired. This is only an emergency thing, BTW so don't imagine for a minute not having a controller. A decent motor of either type will cost way less than $1k, and controller a bit less than that. There are other types of motors, AC motors, worth considering at higher power levels. They are heavy and expensive. No, you can't use a big washing machine motor. I am talking about 30 to 100HP rated motors such as are used in electric cars. All of the various types of motors have their own type of controller.
Stick around and read the threads going back over the years. Do your homework. It will take you at least a year or two to reach the point where you can DIY your electric propulsion setup with a reasonable chance of success.
Then there are the turnkey packages installed by various vendors, which take all the engineering out of it other than managing your batteries and charging. Most are good. A few are excellent. Lesser known setups might be expensive garbage. Stick with vendors having a proven track record. It will cost a lot more than DIY but maybe less than DIY when you have to buy stuff twice LOL!
Last, you must educate yourself on proper operation of your electric drive, particularly its capabilities. Electric is a marvel for simply docking/undocking, locks, bridges, anchoring, etc where you need to maneuver for a short time. Power tacking is another opportunity to use the electric. Electric is very quiet, no fumes or smoke, (at least not normally!) and responds instantly with no warmup required. Charging from shore power is cheap. Charging from solar is cheaper, after paying for the panels and charge controllers. Charging via regen is cheap if you are going FAST and you don't mind a slight speed drop and a long time for charging. Electric can even be cheaper than ICE. My DIY setup cost less than 1/3 what a Beta diesel would have cost, including my batteries. The cons are simple. You get fair range, good speed, or small bank. Take your pick. Choose carefully because you only can have ONE of the above. Big bank and low power operation will give you a surprising range, The available torque is enough to nearly make the boat jump out of the water and you can achieve hull speed with the appropriate motor if for some reason that is what blows your skirt up. Or you can run slow and easy for an hour on a 48v ebike battery pack. You must be ever mindful of your SOC, at least in the ballpark.
So your diesel is in its end of days. Your boat loses resale value having no engine or a diesel in poor condition. Compared to the same boat with a good diesel, your electric conversion will lose resale value, But its resale value will still be higher than having no engine at all. This is one of the biggest arguments from the naysayers, that you lower the resale value by going electric. If you replace a perfectly good diesel with EP, yeah that is true. If you replace a broken down and unrepairable diesel with electric, no. A buyer who wants a diesel and wants your boat will be putting in a new diesel either way. In the meantime he can run with the electric, or some electric fanboy will snatch it up.
Think this over for a year or two as you educate yourself. Maybe it is just the thing for you. If you are doing it to save money and can't compromise on function, you might be disappointed. Try oars instead.
__._,_.___
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a New Topic | • | Messages in this topic (3) |
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.
SPONSORED LINKS
.
__,_._,___
No comments:
Post a Comment