Thanks---you got me… my observations did not include measuring AC power to the chargers. I did measure a steady 40amps DC into the nom. 36v battery bank however (Link10 meter measurements). Likely I was pushing the EU2000i past its rated 1600w steady AC output since I don’t think the 20amp Lester and the 20amps from my Vicor Megapac were being generated with above 85% efficiency combined. I do know that the generator would not run continuous when I bumped the Megapac output up to 24amps for 44amps total---at 40amps, all was good for 17hours of 45-mile Columbia River upstream cruising over 2 days.
I suppose the genset was putting out about 1700w continuous on that trip.
-mt
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Eric
Sent: Friday, August 27, 2010 10:41 AM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] Re: battery bank upgrade
Myles,
While I'm not disputing your observations, I'd like to clarify some of the math. Assuming a maximum of 1600W in and 1440W out, the charger has to operate with at least 90% efficiency. There are some chargers that will do this, but many chargers like Zivans, Dual Pros and ProMariners are not that efficient.
Since charging voltages are higher than resting voltages, I think that a conservative average would be 13.8V per 12V battery (charging voltages are often higher), so 1440W divided by 55V is closer to 26A. I know that it is only 4A difference, but that is 13% less than quoted.
That said, I'm on your side. I think that a generator like a Honda EU2000i (mine is a Yamaha EF2000iS), matched with an appropriately sized efficient charger, is a reliable way to deliver between 20A and 25A into the batteries or drive system for as long as you've got fuel. Like you said, this can be used to "limp" home at slower speeds, or to extend the range of your existing battery capacity at somewhat higher speeds.
For me, that is my backup to my auxilliary.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Myles Twete" <matwete@...> wrote:
>
> DRMSUDO noted: "Yes, I own a honda 2000. In my experience the generator is
> only good for charging. I have tried to use it to drive the dc motor and it
> is just not powerful enough.. "
>
>
>
> The Honda EU2000i can continuously output up to 1.6kw. With enough charger
> onboard, I've successfully delivered 1.44kw into my pack for 17hours while
> cruising against the current. With a 48v pack as you have, this would be
> just about 30amps. This could double your range at 5knots or allow you to
> cruise indefinitely at up to 4knots. Attempting to draw any more than this
> power continuously will stop the generator, so you'd have to have a charger
> that is either adjustable or otherwise limited in the energy it draws. So
> YES, while the generator is only good for charging, that you can deliver up
> to 30amps into your battery bank with it means that you can draw up to
> 30amps less from your pack if you ran your generator and a properly sized
> charger while in a pinch.
>
>
>
> -Myles
>
>
>
> ._,___
>
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