Sourcing Parts for Electric Drive

[pressuredrop]

i am going electric i have finally decided, while ive been romanticizing about cruising w/o an engine i realize im a few years away from that. electric is a good compromise in that i can only power for an hour or two at a time, but much longer at 2kts...

anyways,i really like the Electric Yacht 130ib system, do not like the price tag one bit though, what else is new

so id like to build my own system, and my questions pertain to finding a few of the key compononets

motor will be an etek 5hp (9 peak hp) 48v., battery bank will be 8 t-105's,
the reduction assembly i can fabricate in the machine shop at school, as well as the shaft collar, no problem

the 3 things i need help with are, motor controller, battery monitor, and throttle assembly...

motor controller, i for sure want regen abilities and have been looking at the sevcon controllers, any idea what these cost?

battery monitor, are there special ones made for 48v systems, can a link be used on 48v system, or even better, are there any dual bank monitors that can monitor a the 48v bank and 12v house bank?

source for throttle?

this is going to be a fun summer project, thanks for any and all advice

[klem]

I don't have any experience with 48V systems, only 118V and up so I can't really help you with specific controllers. As a general rule, DC systems do not do regen nearly as well as AC systems. In a DC system, you can separately select a motor and controller but AC systems come as packages. Also, whether you have a permanent magnet motor or an induction motor matters for regen, some controllers don't support induction motors.

For throttles, they are usually inductors and can often be bought from the controller company. If not, they will give you the specs and you can buy an inductor and make a linkage for it. Some newer controllers no longer use inductors.

I have always used E meters (early version of the Link 10) for battery monitoring. Some controllers come with simplified battery monitors (curtis for example).

Good luck.

[s/v Thea]

These guys sell parts for DIY electric vehicles and may have some parts you need:

EV Components

[pressuredrop]

think i found the one,

klem, are you firmilliar with the mar electric brushless d/c motors?
i really like this 8.5kw kit from thunderstruck motors
Thunderstruck Motors - Electric Sailboat motor Kit. Mars Brusless motor with Sevcon PMAC millipak regen controller.
contains:
-Mars Brushless Motor
-Controller: Sevcon 250A w/ regen
-Throttle: PB-6 pot box
-Fwd/Rev toggle switch -Key Switch
-Contactor
-Fuse w/ holder
-Complete wire harness and instructions.
for $1450... about 1/3rd the price of the electric yacht systems...

so all that leaves up to the imagination is batteries and monitoring...

[klem]

I have never personally used a Mars Electric motor I have definitely seen small electric vehicles with them. I don't know of anything horror stories but I do know that you need a decent controller, the kelly units have a triangular wave which doesn't work well with them. There really isn't too much to go wrong in a motor like this. The only way that it should mechanically fail is if you overheat it and running a temp gauge on it is definitely in order. I do not believe that the Sevcon controller supports a temperature sensor input so it won't automatically shut you down. Since the motor shaft is quite short, you shouldn't have any problems with the shaft bearings. Since this is a 3 phase DC motor, it has hall sensors which have been a little problematic in my experience. The biggest problem with them is figuring out what exactly is wrong and takes a pretty good electrical background. The rated motor efficiency is 90% which is okay but not great. It won't make an enormous difference in terms of range but it does means that you need to dissipate a lot of heat. If you are running at 5kw, you need to dissipate 500W of heat which is very significant so airflow and temp monitoring are going to be very important.

It should be noted that the Sevcon controller is not 8.5kw, it is 6.5kw max and you will be very lucky to ever see that. The only was to get 8.5 is to run 80V which is not supported by the motor. I did not see any efficiency numbers on this controller. What would be especially telling is what the regen efficiency is.

I have used that exact throttle before a few times and it seems to work just fine. The only problems I have ever had were with how we interfaced the pedals to it and that was a design issue on our part.

If you decide to go with this system, definitely go 48V. The higher the voltage, the better your efficiency. Also, if you want to get anywhere near the rated output, you will need to be at the highest voltage possible since your controller is current limited, not power limited.

Have you figured out how you would do gear reduction? Or would you run a prop with very little pitch?

[Rising Star]

Pressuredrop,

I built my first electric system from components (including an Etek 48v motor). I hope you have a good engineering background. I discovered the hard way I wasn't up to the engineering challenge!

I had a working system, but the balance of motor, controller, gearing, and prop was never quite right. I scrapped the first homemade system and bought the Electric Yacht package and have been happy since.

I am now in Dinner Key (coconut Grove FL) if you want to see my setup.

[sandy daugherty]

Reduction gearing will seriously overburden any system when being water-driven for regeneration, especially since the prop (with the foil oriented for efficient drive) will be poorly shaped to be driven.

[glenn.225]

Pressuredrop

Did you get an electric drive yet?

I have been considering the same system, yes you would have to build a reduction gear but a belt drive should not be too difficult. But I really don't have much experience with electric motors other than starters.

I read some of the EV forums and it seems like they are getting their act together and most DIYers are producing working vehicles, although range is a problem. I would think a sailboat would be the perfect craft for an electric drive, you usually don't need to motor too much, you could repower your batteries by Regen and if you really needed it you could carry a generator for long distance motoring.

Glenn

[Juniper]

If you have not bought the motor yet, look around for a motor you do not need a reduction for,or as little as needed, my diesel (3600 ) with reduction (2.63:1 ) spins the shaft at 1300rpm, find a 1200 rpm motor and no reduction, or if you really want regeneration look at sep-ex motors, then you can control the field to almost any voltage/rpm, I'm thinking of using a pair of Elec Trak motors they will require a reduction or as I have a Max Prop repitch, but with the Max Prop no regen, I plan on not using a sand controler, just voltage switch, using 6 volt batteries I'll have 6, 12, 18, and 36 volts, as these are 36 volt motors, just using contactors, parallal all at 6 volts = long slow cruise/steerage, parallal pairs at 12 volts = slow cruise, split in half 18 volts = normal cruise, all in sieries 36 volt = full power, drop the field volts = max speed.

[glenn.225]

Juniper

Do you have a lot of experience with electric drives, the switching voltage seems like a good way to go without a controller but what are efficiencies like at lower voltage? Would it be less than a controller?

I was looking at Sep-ex but aren’t they brushed?

I'm going through a large learning curve with this and only finding our how much I don't know.

Glenn

[chris07732]

I abandonded my electric drive project due to non delivery of electonic components from ASMO, Copenhagen, Denmark. After 18 months of "it will be there soon", "maybe next month", I bailed. In retrospect, I'm glad I did, because I grew increasingly suspicious that the end result would be to much of a compromise for a coastal cruiser with aspirations for longer range.

That said, I ended up with the only component ASMO shipped me, the cadillac of electric drive motors, a 17.5kw Lynch permanent magnet motor, 96 VDC, with belt drive reduction gearing to give shaft rpm 0 to 1230RPM, designed for a 18x12 prop. This unit is for sale, I would love for it to go to someone who's more motivated to convert to electric drive. I have full documentation of my project, available free to anyone interested.

[capn_billl]

I've used a sep-ex for my electric car conversion with a kelly controller. Yes it does have brushes, but they haven't been much of a problem and are easily replaced. I used a 48 volt forklift motor, I bought for a couple of hundred dollars. Solomon electric wheel is a good brushless motor designed for marine. I've found regen is somewhat over-rated.