Wind and Solar power

Wiring your boat, How to Wire Lights/Accessories, All things electrical other than actually powering your boat by electric motors.

Moderator: Bill Edmundson

efanton
Posts: 45
Joined: Sat Aug 11, 2012 7:46 am
Location: Co. Cork, Ireland

Wind and Solar power

Postby efanton » Sun Sep 02, 2012 5:03 pm

I am still researching ahead of my build.

Currently looking at electrical systems.

Ideally I would like on board the following

  • Nav Lights
  • Internal lighting
  • Small Stove
  • Shower
  • fishfinder/chart plotter
  • TV
  • Radio
  • electric sockets to run a small laptop

Obviously thats too much for one battery to handle so I was looking into setting up a battery bank. Not sure how many batteries would be required so your advice here would be welcome.

For the vast majority of the time all the above would not be in use while the boat is in use (except possibly the fishfinder/chartplotter and radio).
an obvious solution would be to have the battery bank being topped up on a constant basis by a small wind turbine and possibly a couple of solar panels. Would also be great to know that while the boat is not in use both the engine battery and the battery bank would be fully charged for the next time I take the boat out.

There seems to be lots of different products out there catering to this idea but to be honest I would be reluctant to start this project without the advice of a good electrician or someone who had already done something similar.
eg http://stores.ebay.ie/Flexienergy-di-Alex300000

Has anyone else done this, or does anyone have any advice on the matter?
"it's never too late to have a happy childhood"

User avatar
galamb
Posts: 809
Joined: Sat Jan 17, 2009 1:37 am
Location: Inverary, Ontario - Cuddy Sport (modified)
Contact:

Re: Wind and Solar power

Postby galamb » Sun Sep 02, 2012 8:16 pm

I'm definately not an expert but did research some of the same questions when trying to determine "what size battery bank" to put on my build. I was looking for "how much" to last a couple of days of cruising without having the option of plugging in somewhere to recharge.

You can keep your "needs" low with today's LED lighting. It's quite a bit more expensive, but all your nav/interior lights will draw next to nothing (like 1 or 2 amps total for the day).

Likewise, simply check the specs on your fishfinder/gps - probably draws about 1 amp max or so - so maybe 10 amps on a really long day out.

I would suspect the radio would have a similar power draw.

Other items are the "power hogs".

If you are talking an electric stove - you better add a barge for the batteries - just not practical - stick with alcohol or propane.

The shower - are you considering with "hot water"? A water heater needs generator power - you could run a waterpump on battery if you don't mind cold showers :)

And the plug for the laptop. Again, depending on it's requirements you could go with a simple up-converter (75-300 watts) from most automotive discount places. The thing to remember is when converting to AC from DC, you need 10X the DC.

So, to get 75 watts out @ 120, you need 750 watts in (that's 62.5 amps @ 12 volts) - however, since most laptops run on "converted" power anyhow, you could probably simply run a DC-DC adapter.

Ultimately you need to make up a chart of everything you plan to run and how long you think you will run them (then add 25%).

If you come up with say 100 amp hours for a 24 hour period (or 48 hours, or whatever until you can fully recharge), you almost want to call that 200 amps (so you don't overtax the batteries and really shorten their life - most mfg's don't recommend more than a 50% discharge on a regular basis).

I also took a hard look at "alternate" recharging sources. The bottom line is, unless your power usage is very very low, you probably can not recharge with wind or solar alone.

Take a fairly large (expensive) solar panel producing 100 watts (most produce quite a bit less). That's about 8 amps. So even under perfect conditions you might get 60 amp hours worth of charging from it.

Likewise, I priced out the portable wind Turbines that advertise 400 and 600 watts (33-50 amps). But that is running full tilt. At most cruising speeds, even into the wind, 200 watts was almost wishful thinking (15-20 amps). I tried to balance the almost 1000 dollar cost (turbine, mounts, controller etc) plus the "running" at 20 mph for 5 hours, to replentish the maybe 100 amps a day I would suck from the batteries.

If you can keep your power requirements to an absolute minimum and you have deep pokets to buy the best solar/wind products currently available, you probably can do it.

However, at the current time, it's still tough to beat a super low end 200 dollar gas generator and a couple bucks worth of gas. It can recharge a 200 ah battery bank in a few hours and it doesn't care if the sun is shining or the wind is blowing when it does...
Graham

Yes, Plywood is "real" wood :)

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

User avatar
svenole
Posts: 999
Joined: Mon Sep 21, 2009 7:49 am
Location: WISCONSIN
Contact:

Re: Wind and Solar power

Postby svenole » Sun Sep 02, 2012 9:09 pm

How about a small Honda generator?

efanton
Posts: 45
Joined: Sat Aug 11, 2012 7:46 am
Location: Co. Cork, Ireland

Re: Wind and Solar power

Postby efanton » Sun Sep 02, 2012 11:11 pm

Thanks Graham, that was a really useful reply.

With regards to the stove I was trying to avoid gas if at all possible. The stove would rarely be used, just to heat up a tin of beans or soup now and again or reheat a meal I had previously prepared at home. I know it would be heavy on the batteries but was thinking along the lines that it would be turned on for only about 10 minutes at a time. Doesnt seem like a great idea to be having gas on a wooden boat and I'm sure the insurance premium will be affected by having gas.

The shower would definitely not be a cold one, even if I had had a few too many the night before :lol: Was hoping to heat just enough water for a shower and as It would not need to be even close to boiling, here again was thinking that although it sounds like a big drain for the time it would be on I might be able to do it. Also saw this article and thought it was a great idea. Basically you heat the the water from the mains before leaving the dock and then have a feed from the engine that pumps the coolant water through a worm in the tank to act as a heat exchanger to keep the water warm. Have a read here http://www.boatus.com/boattech/casey/boat-plumbing.asp

I am aware that I could not generate enough power to replenish the batteries at the same rate as they will be discharged, but as I would only be using the boat at weekends I was hoping to have a battery bank that could supply my power needs for the two days and then rely on the wind turbine to recharge the battery bank over the weekdays when the boat would not be in use. I was trying to avoid a petrol generator for a couple of reasons, theft, wanting to free up as much space in the cockpit, and the noise.

I can pick up two 100 ah gel batteries for about 230 euro which I am hoping would be sufficient for a battery bank but like you said until I have calculated my total usage over the weekend I dont know if that would be sufficient.

Have been looking at various wind turbines, and although there is never a shortage of wind (or rain :( ) here in Ireland I have been going on the assumption that I would get about 30% of what is claimed for the turbine. I would think that over the week days while not on board the boat it would be very possible to fully charge the batteries.
"it's never too late to have a happy childhood"

User avatar
galamb
Posts: 809
Joined: Sat Jan 17, 2009 1:37 am
Location: Inverary, Ontario - Cuddy Sport (modified)
Contact:

Re: Wind and Solar power

Postby galamb » Mon Sep 03, 2012 2:54 pm

Take a look at the small, single burner butane stoves (take the small, portable, butane cylinder about the size of a can of hairspray). They are portable and would probably suit your needs without the requirement of a propane locker, relay cutoofs, gas detectors etc.

And yes, as far as the hotwater goes, if you have an inboard or an I/O there are water heaters that scavenge heat from the cooling system - so as long as you got your shower after running for a bit, you could get by with just enough power to run the pressure pump. But then again, if you have this set-up you can recharge your battery bank from the alternator (or fit a larger one and do the job for sure).

Now, if you are looking simply to recharge your battery bank say between Monday-Friday if the boat isn't in use, then that can easily be accomplished with a solar charger.

A 30 watt charger (about a 2'x2' square in size) would give you (ideally) 2.5 amps per hour x say 8 hours a day for maybe 20 amp/h a day - which should pretty much ensure, that even if you come in with only a 50% charge left, that they would be ready to go the next weekend...
Graham

Yes, Plywood is "real" wood :)

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)


Return to “Electric Power & Systems”

Who is online

Users browsing this forum: No registered users and 2 guests