Nice link Scott. Thanks for posting that.
Anne, I didn't see any mention of what size/type of boat and motor you've got. That will have a big effect on battery decisions.
I agree with Eric about adding a couple more wet cells as a cheap and dirty to way get started. Use a charger with separate outputs for each battery, and if you're going to use a small generator, make sure the charger(s) are sized so the generator can handle the load by a pretty good margin.
I've got two of these:
http://www.defender.com/product.jsp?path=-1|328|985|316471&id=88417
They do 10A per channel and my Honda 900W generator handles them just fine, which is why I picked that size. They'll charge a "typical" 110AH set of deep cycle batteries overnight on dock power. I use them on my 220AH bank of golf car batteries in my Albin 25 but it can take all day to charge if I've been using them hard.
Solar is a good option that can be added at any time, but it takes a lot of capacity ($) to make a dent in a large propulsion battery bank.
One of the neat things about electric drive systems is that you can start simple and add additional charging sources and storage capacity as you figure out what works for you.
Jim
--- In electricboats@yahoogroups.com, Q Scott Kaye <qskaye@...> wrote:
>
> http://explorersposts.grc.nasa.gov/post633/Explorer%20Post%20633%20-%202008-2009/Fuel%20Cell/Batteries_for_Dummies.pdf
>
>
> Since we are talking about batteries again, I found this PDF from NASA very informative as it has some of the basics about batteries as well as some very high tech info as well.
>
> Sent from my iPad
>
> On Feb 23, 2011, at 10:26 AM, "Eric" <ewdysar@...> wrote:
>
> > Hi Anne,
> >
> > I'll second the suggestion to not mix battery types. You can see a problem on any regular battery charger. Most chargers have a switch to set the charging voltages for flooded (FLA), AGM or Gel batteries. If you have 2 kinds of batteries in a string, what charging profile (voltage) should you charge them at?
> >
> > Steve's advice about how the different types of batteries discharge at different rates is also important. Since the FLA batteries drain faster, they will start to pull energy from the AGM as the string tries to stay at a single voltage. The FLAs don't really catch the voltage that gets pulled from the AGMs, it mostly gets lost as heat.
> >
> > So if you're trying to cut costs, just to get on the water and to work out the drive end of the system, I would buy 2 FLA batteries to match your existing ones. This should allow you to get operational for less money up front. If you do this, keep in mind that you'll want to install 4 new AGMs as soon as you can afford them, there are a number of reasons that AGM are better for electric drives, something called Peukert Effect is one reason. Buying 2 FLAs that you plan to replace fairly soon will drive up your overall project cost, it's your choice on handling your own cash flow.
> >
> > I believe that solar is more effective than wind for most of our boats. For a solar installation, you'll need panels that generate voltage similar to your battery bank, 48V will need 50 something volts, often done with two 28V+ panels in series. You'll also need a sophisticated solar charge controller to protect your batteries from the varying output from the panels. My boat has no good place to mount solar panels, other boats can add good size arrays fairly easily. But solar can be a fairly expensive proposition to get to reasonable output.
> >
> > Alternatively, a small Honda or Yamaha 2000W generator will drive most of the 48V chargers that are used in our boat conversions. These generators are about $1000 and you can leave them behind for a day sail. You will also find that they can be handy at home for various things. I've got a Yamaha, slightly narrower than the Honda, it fits in my rear lazerette, where the Honda got stuck. But they're basically the same generator, different colors.
> >
> > Without knowing your particular financial situation, I would buy 4 new AGMs and a portable generator later when you get to that stage. You could add solar later too if it makes sense in the way you use your boat.
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
> > --- In electricboats@yahoogroups.com, Steve Dolan <sdolan@> wrote:
> > >
> > >
> > > Anne it's not a good idea to mix battery types. There is plenty on the web to verify this. Cut from a site.
> > >
> > > "Different batteries (Brands/Types) use different chemical compounds. This means that some last longer then others. When one of the mixed batteries dies the other battery will continue discharging electricity. This may cause voltage reversal and can cause the batteries to leak and cause damage to sensitive electronics."
> > > It's really not a good idea especially different designs like AGM's and wet sells. I second the Genset over the solar for emergencies. You can always sell the Genset. The charger won't be happy either with a mixed set. :o) GOOD LUCK!!
> > >
> > > Steve in Solomons MD
> > >
> > >
> > > OK, I've made the plunge. The order is now in for my new electric engine. I need to buy the batteries and charger for it, and I'm looking to get solar panels to charge said batteries on those rare occasions when I venture far from my safe little harbor.
> > >
> > > Regarding batteries: I figured to get AGMs. I have 2 deep-cycle wet cells on board now that are still in good condition. Is there any reason why I can't save a bit of cost and get 2 AGMs and use them with the two wet cells I have on board now?
> > >
> > > I've been told by a 'green' friend of mine that there really isn't enough wind in our area to make a wind turbine worth the cost. So I'm thinking of picking up solar panels instead. What do I need in order to charge the batteries enough to not leave me stranded if I have a no wind day in the middle of nowhere? As I said, these occasions will be rare - maybe two or three times a season. So is the cost worth it or would it be better just a rent a generator?
> > >
> > > Anne
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Yahoo! Groups Links
> > >
> >
> >
>
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