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Old 02 April 2015, 04:33   #11
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Originally Posted by blueboy758 View Post
On our yacht we have a large solar panel fitted and it is amazing how much power it does actually put on over the course of the day.

I'm thinking about putting one on the rib, but not sure as to location and or if it were to be a permanent fix.
As the boat is out all day diving it does sit still for a couple of hours with a short sharp journey to collect divers then is sat again while having a chartplotter, echo sounder, VHF and a 12v charger for a phone buzzing away. would be nice knowing something is going back in.

Does anyone have one fitted or have had the same idea ?

Cheers Phil
When I bought my boat there was a solar panel fixed to the A frame connected to a dedicated battery driving a bilge pump. The boat stood on my drive for three years whilst I refurbed it and the bilge pump still kicked in every time it rained.
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Old 02 April 2015, 17:45   #12
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Thanks for all the replies.
I'll just put it on trickle charge for a day after I've been out.

Cheers.
Phil.
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Old 03 April 2015, 04:10   #13
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I can't see there being any harm in using a solar charger? I use 2x 4.8W Maplin Chargers for both my batteries over the winter period when I use the boat a lot less. With them fitted both batteries give a consistent 12.5Volts on power up... I am told the gel batteries for a Merc Verado do not like to be discharged....


I totally agree they are not going to overcome the output of day to day use without the alternator pumping. But it does give me comfort that if I do sit all day with the Fusion on or the deck LED's on at least the battery is getting something for nothing! I might be being delusional here but I take them with me on long trips so if I did break down on a summers day, I hopefully will have a ships radio for a lot longer than if they were not being trickle charged?!
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Old 03 April 2015, 06:50   #14
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Yup......delusional

Seriously, do the maths. You have 4.8w (not a chance you do BTW) assuming your in the med.

4.8w /12v (A=W/V) is 0.3 amps per hour. Indeed it is something for nothing.

Without getting too technical here and factoring in resistance of a flat battery,charging inefficiency etc. Most fixed VHF's use about 25w for emergency to get range. It will be in your manual should you need it and dont have the means to test it.

25/12 (A=W/V) is 2.03 amps.

So, in Lehman's terms, to get enough power to make that emergency call would take circa 8 hours if you were in the brightest of sunshine and you actually did get the rated wattage, realistically it is about half what they say.

The moral of the story is this, dont leave home with anything but good batts as solar power won't bail you out.

They will help keep topped up though if left on in storage.

Personally I'd take the money they cost and give it to shell and have a day out instead.

Cheers
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Old 03 April 2015, 11:07   #15
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Just keep it off concrete floors when at home and it is golden.
Old wives tale (based in fact though, so better than most):

ASK THE EXPERTS: Batteries on Concrete | Home Power Magazine

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Old 03 April 2015, 11:12   #16
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Yes it is kind of a non problem these days, certainly from a construction perspective. As i mentioned though, there are still good reasons for it. Read what I wrote post 9, pretty much covers that part...

Bring on the lithium!

Cheers
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Old 03 April 2015, 13:59   #17
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Id buy a second battery, cheaper than panels and just keep both on a trickle charger when at home.
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Old 03 April 2015, 14:12   #18
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I hate it when I get all poly-esq but I think your maths is flawed...
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4.8w /12v (A=W/V) is 0.3 amps per hour. Indeed it is something for nothing.

<snip>

25/12 (A=W/V) is 2.03 amps.

So, in Lehman's terms, to get enough power to make that emergency call would take circa 8 hours if you were in the brightest of sunshine
So you need to charge for 7-8 hours to transmit @25W for 1 hour. I'm kind of hoping that when the brown stuff hits the fan I'm not holding the PTT down for an hour...

It takes less than a 10sec to do a DSC mayday transmitting, plus probably a minute of being on flicking through menus etc if you wanted to send some info. 3mins for GPS to settle. Let's call it 6 mins... And you can get a voice call out. So 1/10th of the time you quoted. You quoted 8 hours so 480minutes, so you might get enough charge to power up a VHF + GPS and then transmit a voice call in under an hour. Sure I'd rather it worked the second I turned it on, but if it didn't I might prefer to be putting some juice in knowing in an hour i may be OK (especially as flat batteries often recover a bit after the drain has been isolated - ask any AA man how often they get to a car that wont start that starts after the hour it took them to respond) than remembering that great day out you used the solar panel money on the fuel for...

If there was a recent position known (e.g. you had VHF and GPS working when you arrived at anchor) you probably need less than 1minute of 25W transmit. Provided you genuinely were only going from just too low voltage / amps to just above (incandescent bulb will keep draining, starter motor will. Only electronics will tend to switch off when power low rather than just work less well so depends what drained battery) you might only need 1/60th of what you suggested. So 8mins of charging might get enough to send a DSC message... Granted that's in med conditions but in UK cloudy winter day you would get 40% of that.

But they also were not proposing the panel sat in a locker till the battery was flat. They were saying they would leave it as permenant fixing. So its charging when you anchor up and turn the engine off. At 0.3A/HR going in that's not really compensating for much use. But it probably covers leaving the VHF on *listening* or maybe not switching the plotter off depending on size and screen contrast etc. So when they ho to move off the engine still starts and there is no issue... But that's why I asked about kit and such like...
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Old 03 April 2015, 14:58   #19
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I hate it when I get all poly-esq but I think your maths is flawed...
That's Mister Poly to you, Bud...
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Old 03 April 2015, 15:42   #20
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Dubrus yup I did think I might be. But I didn't buy the chargers for that very purpose. They were bought to ensure my Verado Battery did not drop below 11V as was advised by my mercury agent. They do just that, and I like the fact that because my batteries are a bit awkward to get out and frankly I have no means at home to charge them, whilst I still use the boat from time to time over the winter - the charger wins hands down. And they do actually fit nicely on the radar arch pretty much out of sight to the passing eye.


For the sake of 48 I have two on board charging devices that work away in the background. The bonus being they give me a warm cosy feeling when I do sleep on the boat and use the domestic battery more aggressively.


Perhaps sleep on the boat is the delusional bit!!
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