Battery Charging - no engine

[surekandoo]

I have a 22' cruiser/racer with outboard. The outboard has no charging coil so I'm looking for the best way of charging the battery on the boat for extended cruising. Load will be fairly light - Handheld GPS, Depth Sounder, auto pilot + 12v fluorescent light say for 2 hours at night. Parrafin anchor light. Do not expect to be sailing at night much, if at all, so nav light demand not an issue. Do I go for solar panel (? wattage), wind generator, or buy small petrol genny?



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[charles_reed]

I'd favour, as the most certain, a solar panel or two - work out your 24-hr power consumption (include the navigation lights) and buy panels of sufficient wattage which will @60% efficiency, make up for that in 10 hours.
As a backup, when in a marina, have a pulse charger - a 10 amp one should be adequate.

My guess is that you'll need about 120 - 150 watts.

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[extravert]

120 to 150 Watts of solar power, crikey, that will cost.

Looking at the shopping link above a 30 Watt panel costs £300, so 150 Watts will require 5 and a regulator, over £1500 (and cover most of your deck).

If you cruise mostly during the day, mostly during summer, I would get...

a 30 Watt panel (£300)
a regulator (£30)
a second battery, switch, box and cables (£100)
a battery charger for when you are at marinas, and associated cables (£40)
a pair of 6V lantern batteries in case you ever run out completely, just to keep instruments going (£10)

Still not cheap, but at least you will get some deck to walk around on.

I'm on my second outboard powered boat, both with minimal charging output, with the above setup. I have only ever had to use the lantern batteries once, and that was during a trip with lots of night hours.

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[charles_reed]

Sorry to take exception to your suggestions:

1. 2 x 85 watt BP panels cost me €535, I'd actually suggest the flexible amorphous solar panels, you put them onto your spray-hood.
2. Get a regulator for £18 off Lumic
3. Your price is for an automobile trickle charger - a device guaranteed to shorten any battery's life - a pulse charger will be at least £80.

Obviously an optimist as well as an extravert. Your proposals would just about cover the domestics and totally ignore the autopilot.

The only safe way is to not guess but to work out the actual consumption and then adequate charging facilities. Adding a battery does nothing to recharge the existing one(s).

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[Alex_Blackwood]

What is wrong with a small wind generator and control panel. It will work all the time, at sea or alongside. You can get quite compact units these days.
I think that a company called Marlec of Corby Northants sell a system through RS Components. Cost around £500.00p If you look around there are probably second hand ones about.
I would certainly stay away from petrol genys-nasty imflamable stuff.

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[extravert]

My suggestions were based upon experience of cruising just such a small boat as surekandoo originally asked about. My first boat was an Extravert, a 7m cruiser/racer, which was outboard powered. Although surekandoo doesn't mention it, I expect he is in the same position as I was, ie on a tight budget, but prepared for some hardship in order to save money. surekandoo's Limbo 6.6 is unlikely to be crossing Biscay, more likely ditch crawling, as he says in his profile.

I haven't disregarded the autopilot, but small boats doing day cruising do not need to leave the autopilot on for hours at a time, even single handed. I used to switch mine on for minutes at a time, and hand steer the rest of the day. A fiddle and a faff, but it saves precious electricity.

Of course I realize that a second battery does not charge existing batteries, but what it does do is give you a greater time between having to recharge in a marina by shore power. I fitted a second battery to my Extravert for just this purpose, and it was a great help. My current Dragonfly also has a second battery for the same reason. It doesn't need this for engine starting as it is hand startable, but it still increases independant cruising range.

RS sell a small 3-stage charger for approx £40 - 301-4838.

I would be interested in a supplier of 2 85 Watt panels for £350. Can you post a link?

srekandoo now has 2 different opinions, one more convenient, one cheaper. Either will work.


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[ParaHandy]

might be worth looking at the very small upright vane wind generator - they generate small currents - 2amps - and you can mount them on the taf rail and they connect directly to the battery. Supplying power to an electronic autopilot will be a problem particularly with a Limbo which might be quite lively? Solar cells of the size extravert describes would seem more appropriate than 170w - I have not seen a Limbo with a sprayhood or the deck space ....

There is a Limbo web site on msn:
http://groups.msn.com/Limboyachts/general.msnw



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[extravert]

When I used to race my Extravert at Maryport, a Limbo 6.6 was my arch rival, although I cannot remember its name. The owner used to sail with his whole family sometimes, must have been a squash. It was cramped in my Extravert, and they are even smaller.

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[surekandoo]

Hmmmm! I was really trying to avoid spending £500!! I could trade my outboard in and get one with a charging coil for less than that. I've just sold an 80w solar panel which i bought v. cheaply from a business colleague - it was capable of producing 4 amps @ 18v in bright sunlight and would have been ideal except for it's size. I bought it sight unseen having no idea of the physical dimensions and when he delivered it I had a job to keep a look of horror off my face. Still I made a modest profit on the deal. I have 2 batteries but only have wiring and a compartment for one at the moment ( future winter mod). Shore power's fine when you're in a marina but I tend to prefer a quiet anchorage. The reason I mentioned the small petrol genny is that a firm is advertising 900w units for £125.00 new with warranty in July PBO. Anyone use a genny or similar??

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[andy01842]

I have read with much interest the answers to your question. I have just brought a 4hp outboard with 4amp 12volt output top up my battery. But am thinking about making my own genny as they seam vary expensive for what they are. I am a engineer and electronics are my hobby. Does anyone have experience of a water genny? It would seam to be the answer, works when under sail or outboard and if there is any current when moored. It also takes up vary little room

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[chippie]

I thought about a water generator but discarded the idea on the grounds of how much drag it would cause. I know a fellow who makes his own wind generators, I think I'll have a word with him.
It seems odd that so much electronic technology keeps getting cheaper but solar panels dont.

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[extravert]

Maybe trading in your outboard for one with charging output is the best option then. There are some old ones that have this capability. I used to have a Honda BF75 (what they called the 7.5 hp model ages ago) and this produced some, but not a lot, of electrical power. It produced 2 amps. It is still going at nearly 20 years of age with its new owner. My current 10hp Yamaha produces 6 amps, so things have improved with later models.

Although I have never used a small generator like you suggest, I guess these may be the problems...

- They are fairly heavy bulky lumps, and finding a secure space to store it on a Limbo 6.6 may be difficult.
- They contain petrol which may cause dangerous leaks of fumes if you take it inside the cabin.
- They will be vulberable to the salty environment and quickly corrode.
- You will not be able to run it safely while moving on anything other than the calmest of days.
- If they produce 240v AC, this may be dangerous in a sea water environment.

On the upside though...

- Cheap
- Uses a fuel you already carry
- Lots of power output

When cruising my Extravert for a couple of weeks I used to avoid marinas as well most of the time, visiting maybe once or twice a week. I made the most of electrical power at these opportunities. I understand the dilemma you are in, I was in exactly the same position with my Extravert.

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[surekandoo]

Morning all!

Have contacted cheap genny man - £125 900w model has no 12v circuit. Does a 600w model with 12v circuit (charging current unspecified) for £120 wieghs 21kg. "Honda type" 900w with 12v coil 53dB weighs 15kg for £340.
Am going for a look see next week - will report back.

Thansk for help

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[Gordonmc]

You have certainly had a range of replies, so I hope you find a solution that suits. I chuck in my own experience for what its worth.

If you can trade your outboard for one with a charging/lighting circuit fairly cheaply then fine, but I wouldn't regard it as a cure-all. On my former boat, a 22 footer I had a Suzuki 9hp with circuit and rectifier which I used to charge a domestic battery. In reality the output, around 2amp at cruising speed, was not up to it, especially as the motor only ran for short periods going in and out of the berth.
I mounted a boat jumble rigid solar panel, on the engine well hatch to supplement the engine and even in Scotland found it kept the battery well up. The yield may be small, but its more or less constant in daylight hours.
Finally, I got into the habit of taking the battery out for a slow charge at home the night before a cruise.
With draw from only autohelm, cabin lights and very occasional running lights I never ran the battery completely down. Ironically the first time I cruised on a 35 footer with inboard, petrol genny and windmill the domestic battery banks were flat after the first night.
The moral? Keep it simple and worry free!



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[NigeCh]

USF-11 (Flexible 11 watt solar panel) would seem to meet your needs. You just attach the cable to your battery and locate the panel somewhere convenient on your deck - You can even walk on it.

URL is : http://www.ampair.com/solar.htm

It's not cheap ie about £120 - 140 but you can get better deals at boatshows and by trawling the vendors on the web.


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