Solar battery charger/maintainer

[Cadeco]

I have a 168 Islander and would like to install a solar battery charger /maintainer. Does anyone here have one installed? How difficult was to install it? What brand would you recommend? Do they work fine?
Thanks.
PS: I'm thinking to install the solar panel on the hardtop .

 

[dogdoc]

The set up depends on your battery configuration. If you have multiple batteries which are charged independently ie "banks" it can be a problem. There are charge controllers that can handle multiple banks of batteries but reviews are iffy. If you are charging one battery or multiple wired parallel things are different. First you are really only talking about a maintainer as a charging array would most likely be to large for your situation. That said a 50-100 watt panel and charge controller will maintain your batteries fine. Maintaining a bank of batteries is a whole different discussion pertaining to voltage, state of charge, age, etc.... Currently I have 5 or 6 small solar maintainers going for various batteries which see long periods of time between use, or just get used a small amount at a time and all work great. Renogy is a good brand to look at.

 

[Cadeco]

The set up depends on your battery configuration. If you have multiple batteries which are charged independently ie "banks" it can be a problem. There are charge controllers that can handle multiple banks of batteries but reviews are iffy. If you are charging one battery or multiple wired parallel things are different. First you are really only talking about a maintainer as a charging array would most likely be to large for your situation. That said a 50-100 watt panel and charge controller will maintain your batteries fine. Maintaining a bank of batteries is a whole different discussion pertaining to voltage, state of charge, age, etc.... Currently I have 5 or 6 small solar maintainers going for various batteries which see long periods of time between use, or just get used a small amount at a time and all work great. Renogy is a good brand to look at.

Hi Dogdoc. Thanks for the reply. What I have is two(2) batteries (house/deep cycle and start) and the whole idea is to maintain the deep cycle charged because it gets very low due to the bilge pump and rain. the other situation is the distance between the batteries and the hardtop, what do you think?

 

[dogdoc]

The thought of snaking wires from the hard top to the batteries at the transom makes me queasy. The small 50 watt panel system would be fine for the starting battery and could easily be temporarily mounted with a rod holder bracket somehow and stowed when running. Thats a no brainer. The house/bilge battery is a horse of a different color. The pump/pumps (are there 2?) are potentially big current draws and may overwhelm the charging capability of a small rod holder system. Now you are talking 200 watt min (probably bigger) to be safe, which would deliver about 10 amp/hr under ideal daylight conditions. Thats a 5ftx2ft minimum panel and a hardtop mount? You may think, well my onboard charger is 10amp but that is a 24/7 charger. Solar is never there it seems when you really need it, ie 3 or 4 days of cloudy Florida rain. What you want to do is feasible but would require some engineering.

 

[Cadeco]

Thanks, so you understand my problem !!

 

[cosmic]

When I used to have my 18' cc in a non-electric slip a 50 watt panel kept it topped fine. Since the rain vs sun typically leans more on the sun side, the panel has plenty of time to restore what got used in the rain. Unless your bilge runs constantly don't overthink it. I used the Battery Tender 0211162 maintainer, under $30 on amazon.

 

[dogdoc]

That is true. The 50 watt system would keep batteries topped off. If it is the starting battery no problem with a failure to charge, a quick adjustment to battery switches or jumper cable and you are off and running. With an essential system (pumps) and a boat in the water failure to charge could be catastrophic. Most people design their solar system with a best case scenario in mind. In reality if essential it should be worst case scenario. That said even if at a slip with power a gfi could trip and lead to failure to charge and a bad problem. Saw it happen to a friend. There is no perfect answer. A pair of eyeballs on a regular basis is probably the best insurance.

 

[Cadeco]

When I used to have my 18' cc in a non-electric slip a 50 watt panel kept it topped fine. Since the rain vs sun typically leans more on the sun side, the panel has plenty of time to restore what got used in the rain. Unless your bilge runs constantly don't overthink it. I used the Battery Tender 0211162 maintainer, under $30 on amazon.

Hi . Went to look at the Battery Tender on Amazon and the reviews. are good. The only issue is: What panel should I buy for it ? Maybe that will be the solution.

 

[Cadeco]

That is true. The 50 watt system would keep batteries topped off. If it is the starting battery no problem with a failure to charge, a quick adjustment to battery switches or jumper cable and you are off and running. With an essential system (pumps) and a boat in the water failure to charge could be catastrophic. Most people design their solar system with a best case scenario in mind. In reality if essential it should be worst case scenario. That said even if at a slip with power a gfi could trip and lead to failure to charge and a bad problem. Saw it happen to a friend. There is no perfect answer. A pair of eyeballs on a regular basis is probably the best insurance.

Understood, but my situation is a bit different. Boat stays on the trailer but at the location there is no way to keep a electrical extension feeding a maintainer; rain gets on the bilge and the pumps do their jobs, because of that , battery goes w/out charge. ( reason for a solar charger/maintainer).

 

[Halfhitch]

Boat stays on the trailer but at the location there is no way to keep a electrical extension feeding a maintainer; rain gets on the bilge and the pumps do their jobs

If your boat stays on a trailer, why do the pumps run? When the boat is not in the water the garboard plug should be removed. If you are worried about critters getting in, stick a piece of screen in the hole.

 

[dogdoc]

12V 30A Dual Battery Charging 100W Solar Flex Bundle

The Dual Battery Charging Solar Flex Bundle kit is the smart way to stay off the grid longer, giving you charging flexibility. Due to the MPPT solar input, the solution charges your house battery bank while parked or on the move.

www.renogy.com

look at this it is what you want to make.. no way i pay 450 though. the controller is the heart of the system. get a hard 100 watt panel, some 10ga landscape wire, heat shrink connectors and aluminum angle for the bracket and go to town. the charge controller and wire to the batteries mounted somewhere on boat probably the bilge or under gunnel on my boat. use 10 ga quick connect plugs for panel connection and stow panel when not in use.

 

[Cadeco]

If your boat stays on a trailer, why do the pumps run? When the boat is not in the water the garboard plug should be removed. If you are worried about critters getting in, stick a piece of screen in the hole.

I would agree w/ you if I used the boat a lot more. I'm looking for the "charger" to work during the periods when the boat is on trailer (3 months last time)) as well as the " few" times when we stay overnight (weekends) on board, that's why people use the maintainer, Right?

 

[Cadeco]

12V 30A Dual Battery Charging 100W Solar Flex Bundle

The Dual Battery Charging Solar Flex Bundle kit is the smart way to stay off the grid longer, giving you charging flexibility. Due to the MPPT solar input, the solution charges your house battery bank while parked or on the move.

www.renogy.com

look at this it is what you want to make.. no way i pay 450 though. the controller is the heart of the system. get a hard 100 watt panel, some 10ga landscape wire, heat shrink connectors and aluminum angle for the bracket and go to town. the charge controller and wire to the batteries mounted somewhere on boat probably the bilge or under gunnel on my boat. use 10 ga quick connect plugs for panel connection and stow panel when not in use.

So, if I don't get this, how would be the "system" w/out a controller?

 

[cosmic]

You don't need anything but the solar panel, charge controller, and enough wire to reach the battery. If there are separate batteries (not used together as one "bank") then an additional controller is needed for each. Multiple controllers can be powered from one panel.

Controllers are rated by power (wattage). You'll see the lowest power ones called maintainers because they are meant to keep a small maintenance charge under 5 Amps (which at 12V=60 Watts). The controller power rating should match or exceed the panel's.

For maintaining a single battery when not in use, like on the trailer, 10W panel would be more than enough. To recharge after a weekend stay and be at full charge by next weekend, that needs a bit more thought.

Ballpark: battery holds 100AH of charge and you use half of that over the weekend using the radio and a light, so you want to replace 50AH in 5 days or 10/day. Given 5 hours of full sun, you'd be getting twice what you need from a 50W panel. This is very rough and weather, efficiencies, etc. all play a role.

My suggestion: you can't go wrong with the Battery Tender and any brand 50W panel found on Amazon or wherever. Solar panels are relatively cheap, though, so if you want just get the biggest one that fits your boat and budget, wire it to a matching controller and be on your way.

Caveat: as mentioned earlier, care should be given to the power requirements of the bilge pump. If you use half the battery capacity Sat. and Sun. there won't be a lot of remaining capacity in case it rains Mon-Fri. If that's a concern then consider adding a second (house) battery instead of trying to compensate with more solar. Or just run the engine before leaving

[edit] I see you already have 2 batteries. 50W panel and 2 controllers is all you need. Re: the bilge, if you want real peace of mind add a second bilge pump powered from the other battery with its switch mounted a few inches higher than the other with an audible alarm. Multiple redundancies is always good.

 

[dogdoc]

respectfully disagree to using one panel and 2 charge controllers. a simple google query will explain the reasons why.

second your original post said 168 islander, i think you meant 268 correct. images of that boat show many with twin outboards, how is your boat set up? i only ask because a twin would have 2 start batteries normally, thus really 3 banks of batteries. if 2 start batteries they could be paralleled into one bank for charging if certain criteria are met.

last my post of the system on amazon was only to show the components needed for the system. i usually buy components individually and put together my own system to the specs i require.

https://www.amazon.com/EPEVER-Battery-Controller-Duo-Battery-Caravans/dp/B01N1ZL9EK/?_encoding=UTF8&pd_rd_w=pMOwl&content-id=amzn1.sym.bc5f3394-3b4c-4031-8ac0-18107ac75816&pf_rd_p=bc5f3394-3b4c-4031-8ac0-18107ac75816&pf_rd_r=25R90F5AJVFC0EJY2JY0&pd_rd_wg=ybUav&pd_rd_r=1c89b917-6e46-471a-b37e-8c585aa24aa5&ref_=pd_gw_ci_mcx_mr_hp_atf_m

 

[cosmic]

respectfully disagree to using one panel and 2 charge controllers. a simple google query will explain the reasons why.

https://electronics.stackexchange.c...le-charge-controllers-on-the-same-solar-panel

If you are thinking that when both batteries are low, both controllers will switch on together and that would somehow short both batteries, the Battery Tenders are reverse-polarity protected. You are right, though, if you do this with a cheap pwm from china add a diode or you risk burning it out. Mppt controllers will have their own issues, but we're not talking about those in a battery maintainer scenario.

 

[dogdoc]

nuff said, i'm out

 

[DennisG01]

I would agree w/ you if I used the boat a lot more. I'm looking for the "charger" to work during the periods when the boat is on trailer (3 months last time)) as well as the " few" times when we stay overnight (weekends) on board, that's why people use the maintainer, Right?

Yes, a maintainer is fine. But as noted, DO NOT leave the garboard drain plug in. Always take it out when you pull the boat out. Make sure you crank the tongue jack so it's bow high.

Sitting on a trailer, truth is, you don't even need 50W. 10W would be fine.

When you overnight, a solar maintainer isn't really needed (nor will it do much). During the day, the engine runs to charge the battery... at night... well... as you probably know, there's no sun!

 

[Fixit]

perhaps I can chime in on my setup. 270 islander. I used a renogy 100W flexible panel as I want to carry my tender on the roof occasionally and didn't want sharp edges of an aluminum frame. due to the curve, taper and shape of the roof a 100W flexible panel is all that will fit up there.
I ran some 10/2 tinned marine wire from the hard top, all the way back to the bilge where the PWM charge controller is mounted. My battery setup is 5x group 31 batteries: Port start, 3 deep cycle house batteries, and starboard start.
The solar keeps the house bank fully charged. a bilge pump running for ??? 10 seconds ?? every hour is not going to drain your battery when 100W of solar is pumping in 7A at 14.2v for 14 hours a day. Im not going to do the amp hour calculations for you, but ... your solar will keep it charged no problem
If you want to keep your starting battery(s?) charged too you should look into a blue sea add a battery kit. the combining relay will connect the house to the start battery, but disconnects when either battery voltage drops below 12.6V

every time I check on my house bank during the day its up at 13.8-14.2 volts. it might not keep batteries fully charged forever with the fridge and all 12v loads running at anchor but it does allow me three days before I need to start the engines.