T-Pain Is On A Boat: Re: [Electric Boats] Re: kill switch

Monday, January 25, 2010

Re: [Electric Boats] Re: kill switch

John, Your battery voltage drops as the battery discharges. As the volts go down the motor speed decreases, the boat slows and requires less power - thus the watts go down. You really want to monitor both volts and amps to test something like prop efficiency. This effect is very pronounced with a tired battery. I also found the cheesy auto parts store connectors I first used caused a lot of loss - the gold plated bullet connectors worked better.

Here is a pretty slick fuse idea, goes right on the battery terminal.

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/299119/377%20710%201629/0/Breakers%20And%20Circuit%20Prot/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710%201629&Ne=0&Ntt=Breakers%20And%20Circuit%20Prot&Ntx=mode%20matchallpartial&page=CategoryDisplayLevel1&isLTokenURL=true&storeNum=5002&subdeptNum=9&classNum=295

----- Original Message -----

From: john_casperson

To: electricboats@yahoogroups.com

Sent: Monday, January 25, 2010 11:37 AM

Subject: [Electric Boats] Re: kill switch

Thanks, Denny.

I've never had to wire anything where I didn't have instructions.

I was thinking about putting 100 amp resettables near each battery (+) terminal, the battery hot wires then leading to a 4 position (off, 1, 2, all) battery switch. A pair of hot wires (each protected by a 50 amp resettable) would lead from the battery switch, one to each of the controllers. I'll take a look inside the controllers to see if there is a light duty wire I can interrupt with a $10 kill switch.

I think I'll try making my fairing from plastic decking boards cut on a bandsaw.

I bought 4 APC props (10x6, 10x7, cw and cc) to test on a 30 pound thrust motor pushing the cat hulls but had not got around to it.
At the weight I was testing (about 650 pounds) each 50 pounds of weight took about .1mph off top speed. My recollection is that you had achieved 5.0 mph with a 300 pound canoe, and I was already achieving 4.3 mph with some setups, which is about what I would predict from your numbers. I was concerned that the big props have to be run deeper to avoid cavitation, and this may cause me problems running up on the beach or operating in shallow water.

My motors draw progressively less watts the longer (say, 15 minutes) that I run them, so it is difficult to say what is a faster setup unless I use a freshly charged hot battery, or normalize for watt draw. I don't know whether this is caused by motor, battery or leads. Everything I was using (ultimately) was new. If you figure it out, let me know.

John Casperson

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