Chris:
You hit the proverbial nail on the head! Solar Converters has a distributor here in Victoria so I can get the components easily. Thanks a million.
Victor
--- In electricboats@yahoogroups.com, chris Baker <chris@...> wrote:
>
> Hi Victor,
>
> Looks like I misunderstood your question entirely.
>
> I do use some stepup dc-dc converters on my boat to do something like what you have in mind. Because I use 12v solar panels to charge my house batteries at 12v, and then convert this to 48v for charging the engine batteries.
>
> When the house batteries are charged, which on sunny days around around the middle of the day, any excess power is then used to top up the engine batteries by way of a step-up dc converter.
>
> The converter I use is from Solar Converters Inc in Canada - you can check them out at http://www.solarconverters.com/product_frame.html
> Looks to be a similar company to David Zahn.
>
> My house batteries are AGMs and so the power that is used overnight for the fridge and lights etc needs to be put back first so they are not sitting partly charged. My engine batteries are Lithium and are quite happy about being left in a partially charged state, so they get second priority and are only charged after the house batteries are full.
>
> The AGMs are completely stuffed after about three years use. whereas the Liithiums are in good shape. I have taken delivery of some more lithium batteries which are to be used for the house pack soon.
>
> The interesting thing is that more energy is used by the house load than the engine load. Intuitively you'd think it the other way 'round cos the engine batteries are way bigger capacity than the house batteries. But because of more continous load of some sort on the 12v house batteries they need more energy - at least for my intermittent engine use.
>
> Cheers
>
> Chris
>
>
>
>
>
> On 31/01/2011, at 3:57 PM, vjmtymo wrote:
>
> > Chris:
> >
> > I get that part, thanks. What I'm after is something that takes the wattage from the source, high or low, and converts that output into a fixed voltage with varying current (within reason.) David Zahn makes a few interesting products you may want to look at http://www.zahninc.com/products.html
> > He's also working on another unit for wind turbines. I'd like to use my 12 wind turbine and step up the voltage for the batteries too.
> >
> > Victor
> >
> > --- In electricboats@yahoogroups.com, chris Baker <chris@> wrote:
> > >
> > > Hi Victor,
> > >
> > > The Xantrex does not convert the voltage in any way. Its not even in the line between the charge sources and the battery. So whatever voltage is available from the charge source will be seen by the battery.
> > >
> > > There'll be others here who understand the science behind this better than me, but to be going on with, I'll give you my take on it...
> > >
> > > The voltage produced by the charge source just needs to be higher than the battery voltage and the current will flow to the battery. In the case of a wind generator, the faster it spins, the higher is its voltage. So its voltage can get to be way higher than the battery. But the system voltage will be the voltage of the battery, depending on its state of charge. When you measure the voltage on the terminals it will be the voltage of the battery, as its charging. Even though if you measured the open circuit voltage of the wind generator it could be much higher. It kind of gets pulled down to the battery voltage.
> > >
> > > The Xantrex is also connected to the battery and just monitors the voltage. If it sees the voltage is above the set points for the various parts of the charge cycle it diverts current to the load. Just enough current to bring the battery voltage down to what is needed. Say 10 amps is coming to battery, but at its state of charge it can only take 2 amps without its voltage going high, the Xantrex would dump the other 8 amps into the water heater.
> > >
> > > You could actually simulate by hand and you'd get a good understanding of what the charge controller is doing. You could attach a charge source to the battery unregulated. Say a solar panel. Then have a load attached to the battery through a switch. Could be some lights. Then watch the voltage of the battery. You know from the battery specs what its maximum charge voltage is for the part of the cycle it is in. When it goes over the target voltage you switch on the lights. The voltage will immediately begin to drop. As soon as it goes under the target voltage you switch the lights off. And so on, switch on when the voltage is high and off when its low. In this way you'd be regulating the charge to the correct rate. The on-off cycle may be seconds apart, depending on how closely you follow the voltage.
> > >
> > > The charge controller does exactly this, but switching on and off at 20,000 times per second. or thereabouts. It uses pulse width modulation just as the speed controller of your motor does.
> > >
> > > Does that help?
> > >
> > > Cheers
> > >
> > > Chris
> > >
> > >
> > >
> > >
> > >
> > >
> > > On 31/01/2011, at 8:45 AM, vjmtymo wrote:
> > >
> > > > Are you saying that the outputs from the wind genny and the solar panels can be different system voltages and the Xantrex will convert them to 48v for charging?
> > > >
> > > > Victor
> > > >
> > > > --- In electricboats@yahoogroups.com, chris Baker <chris@> wrote:
> > > > >
> > > > > Hi Victor,
> > > > >
> > > > > There's also a way to do this using just one charge controller, such as a Xantrex C40 in load diversion mode. (Others such as Morningstar also have load diversion regulators)
> > > > >
> > > > > This is what i use on Current Sunshine, and whether the charging comes from solar, wind, regen or charger connected to the genset, the Xantrex is watching over it.
> > > > >
> > > > > The cool thing that I like about this kind of charge control is what you can do with the diverted power. I use a water heater element as the load and so whenever there is spare power it produces hot water for me.
> > > > >
> > > > > The way it works is that the solar, wind etc are all connected directly to the battery bank and they can just go ahead and deliver the maximum power that is available. And this is a good thing for wind generators because it keeps them fully loaded.
> > > > >
> > > > > And the Xantrex is also connected to the battery, and it just watches the voltage and keeps it to the required level by siphoning off power whenever its needed. Notice that the Xantrex is not between the charge source and the battery, as with the usual solar controllers, or some of the controllers on wind generators. The Xantrer is kind of off to the side, just watching over it all, dumping power when needed.
> > > > >
> > > > > For this to work you need to have a wind generator that is designed to use load diversion type regulator, such as Four Winds or Rutland or D400. I'm not sure what would happen with say an Airex which has a regulator built in to the unit.
> > > > >
> > > > > Cheers
> > > > >
> > > > > Chris
> > > > >
> > > > >
> > > > > On 30/01/2011, at 4:05 PM, vjmtymo wrote:
> > > > >
> > > > > > Any opinions about running several charging/regen sources into the batteries simultaneously? Is there any special management of solar panels, prop regen, and a wind turbine all at once? They will all be supplying slightly different voltages (albeit above the battery voltage for a charge) but does it all average out on the battery end of things or am I missing a detail here? If there is a previous post/string on the subject, I'd appreciate the reference, thanks.
> > > > > >
> > > > > > Victor
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
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