T-Pain Is On A Boat: Re: [Electric Boats] phasing into electric drive [1 Attachment]

Wednesday, July 2, 2014

Re: [Electric Boats] phasing into electric drive [1 Attachment]

[Attachment(s) from Yahzdi yahzdi@pointroberts.net [electricboats] included below]

Hi Art,

We created the attached circuit to switch from 48 to 72 volts when we wanted max power. It is before the controller in our case because the controller will support it. Perhaps you can adapt the idea for your needs. In case you are wondering, our motor does not do well with 72V in reverse (Perm 132) so we run in 48V mode except for an emergency.

Regards,

Yahzdi

To affect the quality of the day, that is the highest of arts. Thoreau

On 07/02/2014 03:59 PM, jortlif@msn.com [electricboats] wrote:

Hello group,

Have been reading these very interesting posts for the past couple of years and finally decided to break my silence to share and get ideas. I have a 38 FT sailboat with an aging and leaking Perkins 4-108 (called a 50 HP but probably only develops 40 hp). Even though it's a 1983, it still starts and runs well. In anticipation of the day it stops, over the past two years I have fitted a used Brushed DC ME0709 on top the transmission with vbelt drive to a pulley on the prop shaft. The ratio is about 3:1 reduction. It was originally a chain drive but the noise was unacceptable. If I really get serious I would go brushless but for now it's just trials on a low budget.

Not having a controller yet, I rigged up high current solenoids to provide 12 volts, 36 volts, and 60 volts as well as reverse. Because I was concerned about the high surge current, I have a home-made drop resistance coil which takes it initial surge and can the be shorted out. The voltages come from tapping into the battery bank at different places. Did my first test last weekend.

The ME0709 is rated at 24-72 volts.Still waiting for my digital ammeter but this is about what I found:

1. While sailing, with the transmission in neutral I start charging my 12 volt house battery at about 4 kts, and probably get up to 20 amps charging at 6 kts. This alone is a good outcome. Keeps my refrigeration going without depleting batteries.

2.With sails depowered, at 36 volts I can move this 20,000 lb boat at about 2 kts to 3.5 kts depending upon wind and sea conditions. Guessing amperage is about about 45 amps- (1600 watts or 2 hp???)

3. At 60 volts, really did not see much increase in speed, but I believe belt drive was slipping, Did not do it for very long due to mechanical and electrical concerns.

I do have a 5000 watt separate diesel genset (125vac @ 40 amps) which I could use if batteries run down. I also have lots of room for whatever batteries I need

Obviously, like most of you, I don't want to spend big bucks till I get good data. I purchased a used Kelly KDZ48200 controller so I can get rid of the drop resistor. It's pretty small for the motor, but the price was right. It is designed for 48 volts Max and 200 amps max- 80 continuous. It's called a 2KW rating but 80 amps and 48 volts is more like 4KW. 95% of the time I will only be running at low power, so no problem as back-up hobble-home power

Questions for the group:

1.Can I put an extra 12 volt battery into the output (motor circuit )of the kelly controller to get a 30 second surge (60 Volts) when and if I need it? provided I don't exceed the 200 amp limit.

2. Is the output of the MOSFET controllers such that two units can be paralleled for more current @ 48 v?

3. Is the output of the MOSFET controllers such that two units can be put in series for more for more voltage. example 36V + 36V = 72 volts

I really admire all the people on this website who have done interesting and innovated projects. Thanks for contributing you ideas.

Art

Sailing Barnegat Bay NJ