A few questions about power on my new boat

ShamsB · #1 (**permalink**) 03-21-2011

I recently bought a San Juan 28. I has a power bank with 2 batteries. They are setup under the seat in the cockpit (access from the outside). The boat has outlets around the cabin but they only work while it is plugged into shore power. I would like to add an inverter and hook it up to the outlets so they work while away from the dock. Also I would like to add a solar panel to keep the batteries charged. I don't plan on using the power too much but would like to not need shore power to keep them charged and would like the outlets to work for small things (cell phone charger, laptop...). my questions:

1. Would you move the whole setup inside? I do have room under the seats to set this up.

2. Is my 2 battery setup enough? I think they are both deep cycle marine batteries. not sure about the rest of the stats but I could get them.

3. What size solar panel would I need to keep my setup charged when I get to the boat?

4. What size of inverter would I need?

5. What is the best order to set this up?

6. Anything I didn't ask that I should have =)

Thanks

ShamsB · #2 (**permalink**) 03-21-2011

Also i am on a budget so if the suggestions could be made with that in mind that would be great. i.e. the cheapest way to get this done while still doing it right. I don't want to setup a janky system but also don't need to overdo it.

rmeador · #3 (**permalink**) 03-21-2011

Find out what size batteries you have (their amp-hour rating). That, combined with how much power you plan on using (you'll need to do a detailed power budget) will tell you if they're big enough. I'd try to leave them where they are if possible, since all the wires already go to that location. If your only AC loads are going to be a cell charger and a laptop, you'll have a much easier time just getting DC adapters for both (usually sold as car adapters, your boat should have a cigarette lighter socket just like a car, or one can easily be added). If you want more complex AC stuff, figure out how much power it draws and whether it will tolerate a modified sine wave or if it needs pure sine wave (normal shore power is pure sine, modified sine wave inverters are cheaper though). Then post back with that info and we can go into more detail.

ShamsB · #4 (**permalink**) 03-21-2011

I will get the stats off the batteries over the next few days. The reason I don't want to just get DC chargers is because I would like guests to be able to use their chargers or any other small thing that may come up.

JKCatalina310 · #5 (**permalink**) 03-21-2011

I agree with rmeador. The inverters also use a lot of power just on their own. So you may end up with much more draw for the few things you want to run.

On my last boat, I installed a DC outlet (cigarette lighter) and purchased a small inverter (fits in a cup holder) to run and charge the lap top. The cell phone and Ipod had DC chargers. This worked really well. On my current boat, I have a built in inverter (relatively small) to power the TV. I don't know how much I will use it for that but plan to use it for the lab top.

ShamsB · #6 (**permalink**) 03-21-2011

The small things inverter is what I was thinking. I wouldn't keep it on but it would be nice to have wired in in case I wanted to use it. How large of an inverter would you need to run a small LCD TV?

JKCatalina310 · #7 (**permalink**) 03-21-2011

Not sure about the size of the inverter needed but I will look at what I have and let you know.

rmeador · #8 (**permalink**) 03-21-2011

I bought at 350W inverter for my car years ago at Sam's Club for about $30. I used that for a long time to charge my laptop and phone, since at the time I didn't have car chargers for either. That would be an economical way to go if you only need to run small appliances. I would imagine 350W would power any reasonable sized LCD. My entire desktop computer plus 22" LCD monitor only draws 220W.

nickmerc · #9 (**permalink**) 03-21-2011

Most cell phones and mp3 players have USB chargers that come with them. It will be much easier on the power budget to use a USB socket for charging than it will be to run an inverter. You can get cigarette lighter to USB adapters for pretty cheap.

Also, if you go this route you will not have to rewire every time a new configuration of charger plug comes to market. You will only have to buy the latest cigarette adapter. That was my plan when I rewired.
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sea_hunter · #10 (**permalink**) 03-21-2011

Quote:

Originally Posted by ShamsB

I recently bought a San Juan 28. I has a power bank with 2 batteries. They are setup under the seat in the cockpit (access from the outside). The boat has outlets around the cabin but they only work while it is plugged into shore power. I would like to add an inverter and hook it up to the outlets so they work while away from the dock. Also I would like to add a solar panel to keep the batteries charged.

1. Would you move the whole setup inside? I do have room under the seats to set this up.

No batteries are fine externally as long as they don't freeze, but I'd try and find a spot for a couple of more batteries as close as possible to the ones you have so as to balance the boat. A decision on the number of AMP/Hours you want-need as this is also going to effect the size of inverter and the number of batteries.

2. Is my 2 battery setup enough? I think they are both deep cycle marine batteries. not sure about the rest of the stats but I could get them.

It all depends on the total AMP/Hours you require or need.

3. What size solar panel would I need to keep my setup charged when I get to the boat?

People have a tendency to be drawn to "marine" 80W, but they overpriced in my opinion and you can get a 205W Sanyo for the same price. You'll again have to calculate the AMP/Hours you require or need. One thing everybody seems to forget is an MPPT charge controller. Don't cheap out here; a decent one runs between $300-$400 (forget those $20-$50 charge controllers, they not multipoint; ) and MPPT is required to maintain your batteries at optimal charge.

4. What size of inverter would I need?

Again this depends on the AMP/Hours you require or need. Based on the size of your boat I would say a 1000-2000W inverter/charger would be good.
Power Inverter, Pure Sine Wave Inverter, Marine Inverter
or
Inverter Charger | Freedom HF Inverter/Charger | Xantrex

5. What is the best order to set this up?

Inverter/charger - batteries - charge controller - solar cell(s).