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Old 07-09-2017, 05:59   #1
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Solar trickle charging through the cig lighter?

Wintering for 9 months in Greece on the hard next month. They just informed me that no power will be available over the winter (long story).

I have a large 12volt GELL battery HOUSE bank (800 amps) and can link my starter battery to it via a switch. I have a 5watt (24volt it says on the label so I guest that means 10watts at 12volts) 1'X1' portable solar panel with a cigarette lighter plug. If I leave the 12v outlet breaker 'on', will it be OK to use this as to keep the batteries full? (I also have alligator clips that I could easily connect to a linked battery also)

The only 'direct to the batteries wired' parasitic load I have on during the winter is a CO2 monitor alarm and a couple small 'breaker on' LED's bulbs.

1) Is the cig lighter safe for this?
2) Will this panel be enough to keep up with my GELL battery loses?

Thanks for the help!

Mark
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Old 07-09-2017, 08:13   #2
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Re: Solar trickle charging through the cig lighter?

Two thing that I can think of that you need to consider; does the solar charger have a blocking diode built in? If not, from what I understand, the batteries can discharge out through the panel at night. Also, is the wire from the cigarette lighter sufficiently sized to accept the charging load? I assume that it is as the load is less than an amp. Finally, your panel output is less than an amp, take away what your LED's are using up and your other dormant stuff and I doubt that you will have any left over to make any input whatsoever on such a large battery bank.
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Old 07-09-2017, 15:12   #3
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Re: Solar trickle charging through the cig lighter?

Quote:
Originally Posted by tulsag View Post
Wintering for 9 months in Greece on the hard next month. They just informed me that no power will be available over the winter (long story).

I have a large 12volt GELL battery HOUSE bank (800 amps) and can link my starter battery to it via a switch. I have a 5watt (24volt it says on the label so I guest that means 10watts at 12volts)
May I politely suggest you learn the basics of electricity before messing about with any electrical systems, At least learn the difference between Amps, Amp hours, Watts and Volts. You may like to read this: Amps v Amp hours v Amps/Hr

Just to keep the terminology straight - your house bank capacity is 800 Amp hours - not Amps.

More importantly, Watts is Watts, regardless of Volts.
If it's 5 Watts @ 24V, it's still 5 Watts @ 12V. The only difference is that it will deliver twice as many Amps at 12V. It will still only put up to 5 Watts into your system.


Quote:
1'X1' portable solar panel with a cigarette lighter plug. If I leave the 12v outlet breaker 'on', will it be OK to use this as to keep the batteries full? (I also have alligator clips that I could easily connect to a linked battery also)

The only 'direct to the batteries wired' parasitic load I have on during the winter is a CO2 monitor alarm and a couple small 'breaker on' LED's bulbs.

1) Is the cig lighter safe for this?
2) Will this panel be enough to keep up with my GELL battery loses?

Thanks for the help!

Mark
1. In terms of current, it is safe. 5 Watts is less than 1/2 an Amp on a 12V circuit, so would be quite acceptable. BUT: I wouldn't use this unless I knew a lot more about the panel. Especially, what its actual output voltage is. When a panel is rated at 12 or 24V, that generally means that it is intended for charging a nominally 12V or 24V system. A 24V panel is likely to put out around 35V in practice and that is far too high to plug directly into your 12V circuit.

2. An 800 Ah Gel bank could well have a self discharge rate of 2-3% per month, which means you need to put back about 24 Amp hours per month. Call it 1 Amp hour per day with the small parasitic loads. 5 Watts in winter will give you maybe 15 - 20 Watt hours per day. That is a little over 1 Amp hour per day at 12V nominal, so it would be sufficient if it could be safely connected to your batteries
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Old 08-09-2017, 14:26   #4
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Re: Solar trickle charging through the cig lighter?

With an expensive bank like that, I'd spend a bit extra to do it right. Bigger panel, say $100 for a 35-50w, that 24V is good to look for, and a good controller, like Victron 75/15 also around $100.
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Old 08-09-2017, 14:35   #5
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Re: Solar trickle charging through the cig lighter?

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With an expensive bank like that, I'd spend a bit extra to do it right. Bigger panel, say $100 for a 35-50w, that 24V is good to look for, and a good controller, like Victron 75/15 also around $100.
I agree with this post. Remember that in Greece in the winter time, the sun will be pretty low in the sky even at noon, and there will be periods of cloud cover to additionally reduce solar panel output. Then there is the issue of shading from your won rig as well as neighboring boats'. So, you will need a considerable cushion of extra panel capacity to take care of those decrements, and then the need for a controller to limit charge on the good days.

If you skimp here, you may find a seriously degraded battery bank on your return.

Jim
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Old 08-09-2017, 15:06   #6
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Re: Solar trickle charging through the cig lighter?

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Remember that in Greece in the winter time, the sun will be pretty low in the sky even at noon, and there will be periods of cloud cover to additionally reduce solar panel output.
What sun? Winter in Greece is wet and messy. At least the winters out boo hat spent in the Ionian.

Get a decent solar panel and charger, or better yet get the yard to provide power. And then get a decent electrical low temperature dehumidifier, like Meaco DD8L.

It Really is wet there. Any small leaks will see your boat grow mildew.
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Old 08-09-2017, 15:20   #7
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Re: Solar trickle charging through the cig lighter?

Lived in the Peloponnesus in an ancient leaky stone house, no electricity, only heat the hearth and a cooker in the kitchen, we had to break the ice some mornings to get water from the well.

Was actually a wonderful time.

But yes, point being it can be miserable weather right through March, much more pleasant winters up in the Alps, at least they prepare properly!
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