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01-07-2009, 06:28
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#1
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Registered User
Join Date: Aug 2008
Posts: 39
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Basic Solar Hookup - Help!
Got a decent deal on a small Solar system to assist in keeping my batteries up and wantedd some advice. I currenlty have a group 29 deep cycle and a starting battery - 12 volt system. The system I got is a charge controller and a 20 watt solar panel (1.15 amps) . Am I correct that I hook the solar to the controller and the charger controller to the battery (deep cycle)? Positive to Positive, neg to neg? - The controller say it prevents drain and overchargeing...which I guess is what charge controllers do...correct? Anything else I should know? - Oh.....what gauge cables or wiring should I use?
Thanks
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01-07-2009, 07:20
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#2
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Registered User
Join Date: Jul 2006
Location: caribbean winter, Durango,CO summer
Boat: Nordhavn 5740
Posts: 455
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correct on the hookup of the wires. the controller will prevent drain and overcharging. i used 10 gauge for my setup; 10 gauge should work for you unless you have unusually long runs. you might want to consider a circuit breaker or fuse.
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01-07-2009, 08:06
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#3
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Marine Service Provider
Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,917
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You should have a fuse less and 9 inches or so from the battery going to the controller, and then one between the controller and the panel.
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01-07-2009, 10:41
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#4
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Registered User
Join Date: Aug 2008
Posts: 39
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so I should add a 2 fuses on the hot (red) lines? How do I gauge the fuse size? based on the panel amp capcity? I know it's a 20 watt with operating around 1.12 amps.
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01-07-2009, 11:14
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#5
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Senior Cruiser

Join Date: Apr 2008
Location: Punta Gorda, Fl
Boat: Endeavourcat Sailcat 44
Posts: 2,728
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Quote:
Originally Posted by corkscrew
so I should add a 2 fuses on the hot (red) lines? How do I gauge the fuse size? based on the panel amp capcity? I know it's a 20 watt with operating around 1.12 amps.
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If you're never going to upgrade to a high output solar system 10 guage wire is a big waste of money.
Referring to the following post:
http://www.cruisersforum.com/gallery...=500&userid=79
From the chart and doing the calculation for a 20 foot run 16 guage would be quite adequate. If you have to go a bit further 14 would handle it fine.
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02-07-2009, 12:00
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#6
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Senior Cruiser

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 36,581
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Quote:
Originally Posted by Captain Bill
If you're never going to upgrade to a high output solar system 10 guage wire is a big waste of money.
Referring to the following post:
http://www.cruisersforum.com/gallery...=500&userid=79
From the chart and doing the calculation for a 20 foot run 16 guage would be quite adequate. If you have to go a bit further 14 would handle it fine.
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Oddly enough, I agree.
While #16AWG may be electrically adequate (ampacity & voltage drop) when new; I'd also prefer #14 for mechanical (strength) reasons, and allowing for more leeway for inevitable electrical degradation.
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Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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06-07-2009, 11:06
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#7
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Registered User
Join Date: Aug 2008
Posts: 39
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So should I add a fuse? Maybe between panel and controller on the hot line? How should I choose the fuse size? Is it a certain size per watt or amp?
Also, with reference to amps and batteries and power consumption. My group 29 has like 125 or so AH. My understanding is that you simply add the amp draw up for all your stuff and that gives you the amps per hour you use. So if you have a stereo and a VHF radio that each draw 5 amps....that will be 10 amps an hour....so I could run them both for about 12 hours before my battery drained correct? The solar panel return amps to the batteries......extending my time. AM I on base here?
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06-07-2009, 13:34
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#8
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Moderator

Join Date: Jul 2007
Boat: Bestevaer.
Posts: 11,749
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Quote:
Originally Posted by corkscrew
So should I add a fuse? Maybe between panel and controller on the hot line? How should I choose the fuse size? Is it a certain size per watt or amp?
Its the Amps that are important for a fuse. A 2A fuse is correct for your 20w solar panel mounted close to the battery preferably fuse both + and -.
Also, with reference to amps and batteries and power consumption. My group 29 has like 125 or so AH. My understanding is that you simply add the amp draw up for all your stuff and that gives you the amps per hour you use. So if you have a stereo and a VHF radio that each draw 5 amps....that will be 10 amps an hour....so I could run them both for about 12 hours before my battery drained correct?
In theory to drain the battery completely yes, but the battery is not likely to be 100% charged and for various reasons it will not meet these theoretical claims. Its real capacity is probably 100AHRs, but for reasonable battery life it is better to restrict the discharge to 50%. So you have about 50AHrs to play with.
The good news is the power consumption of the VHF in recieve is only likely to about 1A and most "car "sterios are about 1 to 1.5A
The solar panel return amps to the batteries......extending my time. AM I on base here?
Yes . Depending on the time of year location etc the output will vary enourmously, but about 5Ahrs a day would be an average
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Cheers John
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06-07-2009, 15:41
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#9
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Senior Cruiser

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 36,581
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Quote:
Originally Posted by corkscrew
So should I add a fuse? Maybe between panel and controller on the hot line? How should I choose the fuse size? Is it a certain size per watt or amp?
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A fuse protects downstream gear - primarily wire.
ie: #14 wire should be fused at 15A maximum.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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06-07-2009, 16:38
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#10
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Long Range Cruiser

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,827
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Quote:
Originally Posted by corkscrew
20 watt solar panel (1.15 amps) .
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Isn't the reality on a 20 watt panel that there is NO chance of overcharging a battery unless the boat is left unattended for months in the tropics?
Instead of wasting money on a regulator or fuses, wouldn’t it just be better to put in a diode to prevent night time discharge? Don’t most solar panels have that diode anyway?
So in a practice sense isnt it just better to put in the solar panel and stuff the rest of the expense?
Mark....
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06-07-2009, 17:00
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#11
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Registered User
Join Date: Dec 2004
Location: Deale, Maryland
Boat: SeaView - Privilege 37
Posts: 1,020
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Corkscrew;
Typically you only want to discharge your battery by half its available amps. So, with your 125 amp hour battery, you'd be better off with a 10 amp load for 6 hours. So your math is correct. If you start draining a Lead Acid battery by more than half you significantly shorten the life of the battery.
Mark is also correct, with that small a panel and that large a battery, you could do without the charge controller. But, it sounds like your controller has facilities for keeping the batteries from discharging to the panels at night (blocking diodes). So, since you already have it, I'd use it.
Keith
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06-07-2009, 17:07
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#12
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CF Adviser

Join Date: Dec 2008
Location: sausalito
Boat: 14 meter sloop
Posts: 7,260
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if you're anything like the rest of us...
...two weeks after you get that 20-watt panel fired up you'll decide that you need AT LEAST another hundred watts.
So go with the 10-gauge wire now so you don't have to upgrade the system when you add the next panel.
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cruising is entirely about showing up--in boat shoes.
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07-07-2009, 07:06
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#13
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Registered User
Join Date: Aug 2008
Posts: 39
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Well, the panel I have coming in is a simple 20 Watt (1.14 amps). I did get a controller...just to be safe and have a diode for reverse charging. Most of the time they won't even be in use as I'll be hooked to shore power, but the system is just going to be for overnights and long days out....to help keep the battery relativly up. If I like the panel I will add 1-2 more. If I add the second one I'll be at 40 watts (2.25 amps approx) - that should be fine for my needs. The only things I really have running all the time are (stereo, GPS/Depth/Alarm and VHF) - at night maybe a few lights, a fan.....etc. Now someone told me that stereos and VHF run like 5-10 amps each...is that true?
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07-07-2009, 08:15
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#14
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Moderator

Join Date: Jul 2007
Boat: Bestevaer.
Posts: 11,749
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Quote:
Originally Posted by corkscrew
The only things I really have running all the time are (stereo, GPS/Depth/Alarm and VHF) - at night maybe a few lights, a fan.....etc. Now someone told me that stereos and VHF run like 5-10 amps each...is that true?
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It is better to measure the consumption yourself as equipment does vary, but I think your energy budget would look something like this
stereo, GPS/Depth/Alarm and VHF about 2.5 A assuming they are on for 16hrs thats about 40AHrs (2.5 x 16)
3 lights and a fan say 4A over 5Hr gives 20Ahrs
Therfore 60Ahrs used. 5Ahrs from the solar pannel gives 55Ahrs taken from the battery. (assuming no input from engine charging)
Conclusion just OK for 24 hours away from shore power.
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07-07-2009, 08:18
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#15
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Registered User
Join Date: Aug 2008
Posts: 39
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And with a little trickle solar of maybe 2-3 amps...I should be very fine for 1-2 days....i expect.
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