Solar Power Virgin - Be Gentle Please

[Dockhead]

Originally Posted by MarkJ

In England in winter to trickle charge a 440 amp hour bank at 24 volts.... sound like 150 watts to me, not 50. And then when you go to a marina you will never need to hook up again

Well, I think in winter I'll be somewhere with shore power -- to run electric heaters since I don't winterize my boat (I sail all year).

150 watts of solar will be a PITA, hard to find a place for, and expensive.

Yet another option is to just forget all about it. Let the batteries lose their 5% or whatever it is over a month, then just crank up the genset when I get to the boat.

[Aussie_Sequoia]

Like I said in my previous post. There's a big difference between trickle charging (maintaining a full charge when not in use) and RE-charging a discharged battery due to a load being placed on it in typical use.

If your batteries are full when you leave the boat (and they're not completely thrashed from hard cycling and over dis-charging on a load)... a much smaller solar panel just might keep the batteries high enough to curb or reduce your self discharge (even in the UK). It's certainly a cheaper option to try first. You'll need to wire two in series to achieve your 24 volts... but that's still ~$50 if you look around.

I think many of the other posters were thinking that you needed to charge your batteries after typical use.

Though it's probable that I misunderstood all together

[Pete7]

DH, the panel is permanently screwed down on the "garage" in front of the sprayhood which the companion way hatch slides under. This picture isn't my boat but gives the idea. Our panel covers the "garage" perfectly and since we have inmast reefing no one ever stands infront of the sprayhood, well apart from the dog.

I have to admit to probably spending more time googling solar panels than we took to choose the boat. I was looking for a frame for the stern, but in stainless steel they are +300. Add some big panels and the cost goes up even more. At the moment, a mixture of solar, engine and genny supply our needs quite well so it's difficult to justify the big investment especially as we need a new genoa this year, oh and some diesel heating is high on the list too.

The single panel is a nice to have, keeps the batteries in good condition and tops up any shortfall from a weekend.

Pete

[capn_billl]

TO those suggesting less than 50watts remember the batteries still have to run bilge pumps, and whatever incidental loads. In the UK for that big a battery bank I think 50 watts is just about right. With a small charge controller perfect.

If he had no choice he might be able to get by with a smaller cell for trickle only on a clear warm day with no clouds, or shade, ....maybe. Since he's not connected to shore power what are the odds the batteries will be perfectly topped off everytime he leaves the boat? A little extra for makeup id never a bad thing, that low a current worst case he will need to add a little water every couple of months.

[Bash]

Originally Posted by Dockhead

It's expensive and very little power! Maybe I should be thinking about wind . . .

An Air Breeze will produce 90Ah per day, according to Yachting Monthly. Or 45Ah per day at 24 volts. That's 10% of my total battery capacity or 20% of my usable capacity. I could almost live on that. Probably cut my generator runs in half, besides fulfilling the original purpose of keeping batts topped off when I'm not on board. Hmmmmmmm.

Cost not much more than two of those tiny solar panels, and easier to mount.

You might want to look into the Rutland wind generators first. They make smaller ones for similar applications. The 504 might be too small to trickle charge your bank, but the 913 would certainly suffice. These generators are more quiet than the Air Breeze, but are also rated at lower wattage.

[Dockhead]

Originally Posted by Bash

You might want to look into the Rutland wind generators first. They make smaller ones for similar applications. The 504 might be too small to trickle charge your bank, but the 913 would certainly suffice. These generators are more quiet than the Air Breeze, but are also rated at lower wattage.

There's an improved Rutland -- the 914i -- which produces 52 amp/hours a day according to YM. That's more than a trickle charge, I think -- would meaningfully extend time between generator runs.

It's cheaper than the Breeze too at 737 squids (on special from Force 4; about 1200 bucks) for the entire kit with controller, mast, mounting hardware.

There are two possible missions here, and I'm sure others have struggled with the same questions:

1. Trickle charge mostly charged batteries to keep them up while I'm away from the boat. I would hope that such a system would be able to slowly bring up, say, 80% charged batteries to 100%. I don't know what wattage would be required for that.

2. Make up some of our consumption and/or charge up partially discharged batteries.

The minimum requirement is (1). (2) would be nice to have but is probably not necessary.

Pete's solar installation looks very neat and uncluttered. I have a similar spot on the top of my own cabintop but I'm not sure what I can put there considering ropes running across from the mast.

[Bash]

Originally Posted by Dockhead

There's an improved Rutland -- the 914i -- which produces 52 amp/hours a day according to YM. That's more than a trickle charge, I think -- would meaningfully extend time between generator runs.

It's cheaper than the Breeze too at 737 squids (on special from Force 4; about 1200 bucks) for the entire kit with controller, mast, mounting hardware.

I just spent some time looking at the 914i specs. Wow. I wish that had been available back when I bought my Air Breeze. The old 913 didn't supply enough power for my application, but I think once I wear out the Air Breeze I'll be replacing it with something like this.

[Eleven]

We had seven solar panels on my Cat (now sold) which kept a little fridge running as well as topping up the heavy house batteries. Night sailing on Autopilot did tend to run the batteries down though.
Go for the flexible panels, they charge from dawn 'till dusk and seem a lot less sensitive to angles and shadows.

[Dockhead]

Originally Posted by Bash

I just spent some time looking at the 914i specs. Wow. I wish that had been available back when I bought my Air Breeze. The old 913 didn't supply enough power for my application, but I think once I wear out the Air Breeze I'll be replacing it with something like this.

Why do you prefer it over the Air Breeze? Because it's smaller?

Have you been happy with your Air Breeze? Is it noisy?

[Dockhead]

Originally Posted by Eleven

We had seven solar panels on my Cat (now sold) which kept a little fridge running as well as topping up the heavy house batteries. .

Seven solar panels?! I'd never find room for that.

Originally Posted by Eleven

Night sailing on Autopilot did tend to run the batteries down though.

I don't really have that problem; there is enough battery capacity to run the autopilot, electronics and nav lights for days, I think. I have a 110amp * 24v school bus alternator on the main engine which will produce enough power for a whole night's consumption with just a little bit of motor sailing.

The problem is on the hook and when I leave the boat, since I don't have shore power on my new berth.

[Bash]

Originally Posted by Dockhead

Why do you prefer it over the Air Breeze? Because it's smaller?

Have you been happy with your Air Breeze? Is it noisy?

I'm about 90% happy. I've had mine for four years without incident. Indeed, it still has the original blades. While I wouldn't call it noisy, it's certainly not silent. The Rutland 913 is pretty much silent, and operates in lower wind speeds. Unfortunately, it doesn't produce half the power and it isn't self-regulating.

My biggest complaint about the Air Breeze is that it can be heard in the aft cabin below its mounting. We don't hear it sleeping in the forward cabin, but we've had guests in the aft cabin who have found it to trouble their sleep. I would change to the new Rutland for no other reason, even though I'd be losing power in the long run.

[MarkJ]

Originally Posted by Dockhead

Yet another option is to just forget all about it. Let the batteries lose their 5% or whatever it is over a month, then just crank up the genset when I get to the boat.

Even at 10% per month over 4 months you are still well above 50%.

And it could give you an excuse to get away from home every so often: "I jus hafta go to the boat for a night to charge me batteries! I betta take sum beer."

[Dockhead]

Originally Posted by MarkJ

Even at 10% per month over 4 months you are still well above 50%.

And it could give you an excuse to get away from home every so often: "I jus hafta go to the boat for a night to charge me batteries! I betta take sum beer."

Yes, but I never leave the boat for more than a month. I sail year round!

And to go to the boat for a night, I would have to get on a plane for a four-hour flight!

So the big question, I guess, is whether the occasional month without a trickle charge is harmful to the batteries.

If it's really not harmful, then maybe I'm solving a problem I don't have.

[S/V Alchemy]

Originally Posted by Dockhead

I'm taking up my mid-river mooring in the Hamble - hooray! But now I have to get used to life without shore power. I'm worried for my battery bank since the boat may be left alone for up to a month at a time.

I'm thinking about istalling a small solar panel just to keep the batteries up - what do you guys think? I always shut down refrigeration and basically everything except bilge pumps when I leave the boat, but the batteries self-discharge. Will a 50 watt panel be enough to trickle charge a 440ah by 24 volt battery bank?

No. You didn't say if the bank was AGM; I suspect not if self-discharge is a worry. I'll bet chafe gear is a worry, too, if it's alone on a mooring for month at a time.

I can't do the math at the moment, but I would suggest that an 80 or a 100 W panel would serve, and of course you'll need a 24 VDC output panel and an MPPT to regulate the input. You would also want to mount the panel with a clear shot at the south at the best angle for May-September sun.

In England, not to put too fine a point on it, I would think a regulated WIND generator and not a solar panel, would be the way to go. That way, shade from the boat drifting around the mooring isn't an issue...you get about the same input from any direction, and it's day or night. If the batteries are full, a "brake" can engage, and/or the power's dumped to a heat sink (the "brake" freewheel is better in my view for an untended boat).

Just some thoughts. The English make the DuoGen or AquaGen, which are towable and wind-driven generators, which might be very useful down the road, when the sun is short but there's plenty of wind to militate against the drag of the generator.

[S/V Alchemy]

Originally Posted by Bash

I'm about 90% happy. I've had mine for four years without incident. Indeed, it still has the original blades. While I wouldn't call it noisy, it's certainly not silent. The Rutland 913 is pretty much silent, and operates in lower wind speeds. Unfortunately, it doesn't produce half the power and it isn't self-regulating.

My biggest complaint about the Air Breeze is that it can be heard in the aft cabin below its mounting. We don't hear it sleeping in the forward cabin, but we've had guests in the aft cabin who have found it to trouble their sleep. I would change to the new Rutland for no other reason, even though I'd be losing power in the long run.

I have heard that various rubber mounting bases (including one the owner implied was cut out of a hockey puck!) can greatly reduce the "rumble".

I would also consider shooting a can of expanding foam up the pole to isolate the wiring from vibration as well.