The battery charger on my outboard is a waste of space and I think I need a solar panel. By all accounts a simple 5W panel will top the battery up between weekends away but I'd like something powerful enough to replace the charge I use on a day to day basis so I can go away for a week or more without having to seek out shore power.
Am I right to think 5W will not be enough (I'm thinking 20W would be nearer the mark)? and if so can anyone recommend a good system ?
Thanks for any help.

Mike P235 #47

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I had a 10w panel on my 21. The first season it seemed to work fine but I found at the end that it had boiled away all the liquid from the battery. I got a regulator from Maplin and that solved that problem as well as telling you what it was thinking (orange charging, green fully charged)
Elec was only used for GPS (all the time) and the Autohelm (when pulling up and taking down the main). so maybe not very typical!

Geoff ex P21/30 Cygnus

Yes, I think anything bigger than 5W needs a regulator.

I will have GPS, Radio (quite a big drain I believe) and in due course an Autohelm plus of course cabin lights, phones, etc.

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Having used a 10W panel plus regulator (flexible Spectra plus Solsum)with an 80AH battery for occasional nav lights,LED anchorlight ,more frequent use of the autohelm,vhf standby,I would next time get a 20W panel,which is very little larger than a 10W.So on the mooring you will get back to square 1 quicker.But the major draw of power has to be the autohelm plus any tungsten lamps,assuming no fridge.
A modest solar panel won't keep up with daily demand over say a week because inevitably the orientation/shading will limit output when you are 'underway'.
So I think the limiting factor will be the battery capacity rather than the panel.
I also found that renewing the cable and clean connections through to the outboard charging point (on a Honda 5) was worthwhile as it seemed to produce enough juice to simultaneously run the autohelm during motoring.