T-Pain Is On A Boat: Re: [Electric Boats] Re: Electric speedboat revisited

Thursday, January 27, 2011

Re: [Electric Boats] Re: Electric speedboat revisited

Certainly nice to have the likes of the Honda eu2000i for all kinds of general use benefits and home use in a pinch as well. But also noteworthy, if you just want the raw DC power out of a genny, I've noticed that even the tiniest (cheap) ones, putting out say 400w AC all seem to put out a direct current output of 8.3A. Presumably 8.3A was determined to be ideal for charging/jumping vehicle batteries, so even the tiniest (lightest, cheapest, quiet, and even more fuel efficient) are capable of that amperage output, though I don't know the conversion math to know if that fills the bill for on demand bypass power you reference below. I'd think that since the optimal use of the smallest gennys is to suck out that 8.3A/DC to charge into your bank directly and let you bank handle the high voltage needed for WOT high power needs for short periods. But again, I don't know how much that helps extend your WOT range, if at all, but at least you could jam for the aforementioned 10 minutes to drain your batteries to 20% capacity, but then, and perhaps somebody knowledgeable could calculate, how long would 8.3A/DC take to recharge the battery bank discussed in this user's setup to 80, 90 or 100% from 20%?

"The Framers [of the Constitution] knew that free speech is the friend of change and revolution. But they also knew that it is always the deadliest enemy of tyranny."

From: Steve Dolan <sdolan@scannersllc.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Thu, January 27, 2011 11:07:01 AM
Subject: RE: [Electric Boats] Re: Electric speedboat revisited

Let me ask this question.

Wouldn't it make more sense to output a genset to an inverter and take the normal 120v output to your usable motor requirements, most of you are running at 48v? You could split off before the inverter to maintain your 12v requirements and in the case of 48V motors have a long range directly of the genset rather than run a charger to recharge before continuing. I'm not good with the math but I would think in most cases 10A off the 2k genny at 12v would be more than enough to handle most needs so let's say you then would have 40A to run the motor as long as you want. Make sense?

Steve in Solomons

Is it feasible/advisable to entertain the idea of keeping a small 1,000 or 1,500w generator on board for emergency backup and also potentially the option to recharge batteries after a stretch of WOT motoring to help compensate for the massive and quick powerdrain. A rough guess I'd think would be 100 minutes of charging w/1500 watt gen would be needed after 10 minutes of WOT, but maybe if you only burned for say 3 or 4 minutes at a time and ran it for 30 or 40 minutes, then we'd be talking more realistically/practically/feasibly. Especially since efficient generators of that sort get over 8 hours of runtime per gallon, though maybe only at half power output, so maybe 4 hours to be more reasonable, but still gets you a lot more practical use cheaply out of such a setup, no? You can get a used honda eu2000i for under a thousand dollars USD (even more powerful for my very rough calculations), so maybe 30 minutes of runtime for 4-5 minutes of burn. Starts to sound a lot less daunting than riding the edge of oblivion for 10 minutes WOT max for the day's motoring IMHO, and you could probably get that generator for closer to $500 or $600 and these are super quiet and clean burning generators.

"The Framers [of the Constitution] knew that free speech is the friend of change and revolution. But they also knew that it is always the deadliest enemy of tyranny."