Solar Panel Questions

[oneeyedjackass]

I've been trying to decide if I need to mount up some solar panels on our R-23 and have a few questions. I would rather not add the complexity if I can get by without. 🙂
How long does it take to charge battery bank by running volvo d-3 engine with the 115amp alternator?
If i'm using the engine to charge batteries at anchor, what would be the best RPM to run engine?
mark

 

[Chimo]

Can't answer your question(so why am I replying? :roll: ) except to ask how you know that the alternator is 115A? The latest spec. sheet shows 180A for our D3-150. I'm sure there will be an output/RPM curve for the alternator but it may not be public. I discovered this website http://boatdiesel.com recently. Haven't done much checking but they may be a good resource.

 

[wincrasher]

an hour or two idling the engine can give you far more amps to put into your batteries than an entire day of solar would give you.

The issue is you are not going to do the long cycle to top them to 100% thru engine idling. That requires quite a few hours to do that. So your engine alternator really is only good for the bulk phase.

That is where the solar could pay off - it will happily pump a few amps per hour over the whole day to get you thru the absorption phase. In storage, it will also keep you nicely topped off and float.

I'm happy with the single 160 watt panel my R-27 came with. On a sunny day, it's good for 5-7 amps continuous.

 

[Osprey]

Long periods of running a diesel at idle is not good for the engine . It is definitely not recommended. Keep in the cost of maintenance required at specified engine hours intervals. Yes, and the costs of repair are right out of sight.
Another aspect is the disturbance an idling diesel engine produces in a peaceful anchorage. Other boaters have to put up with both unnecessary noise and the stink of diesel fumes. This annoyance, in my view, is even greater than that caused by individuals racing their dinghies about the anchorage at full throttle. Call me cranky, but I am not alone in these views. Tugnuters are supposed to be good, considerate individuals (forum "handles" not withstanding)

 

[knotflying]

I have two questions. Why do you need to charge up your batteries? Is it because the boat is remaining unused for a long period of time? After a little more background info then I may be able to help with some guidance.

 

[oneeyedjackass]

The latest spec. sheet shows 180A for our D3-150

could you throw a link up for this? maybe I can find the output/rpm curve. good info to have.

The issue is you are not going to do the long cycle to top them to 100% thru engine idling. That requires quite a few hours to do that. So your engine alternator really is only good for the bulk phase.

That is where the solar could pay off - it will happily pump a few amps per hour over the whole day to get you thru the absorption phase. In storage, it will also keep you nicely topped off and float.

this sounds like a good reason to set up a solar panel

Another aspect is the disturbance an idling diesel engine produces in a peaceful anchorage

most definetly, we like to keep a low profile.

I have two questions. Why do you need to charge up your batteries? Is it because the boat is remaining unused for a long period of time? After a little more background info then I may be able to help with some guidance.

just our experience dry camping with our RV. we've found that using the inverter for any lenght of time can take the batteries down. boat camping is a whole new deal for us. heading to lake powell in a few weeks, that should be a good test on our system.
mark

 

[rpmerrill]

I think the big advantage is that you can leave the refrigerator running with food in it for (pretty much) ever.

 

[BradOwens]

The inverter will definitely draw the batteries down quickly. We run the engine any time we are using the inverter to power the microwave or 110v outlets. Other than that, we rely on the solar panel to keep the batteries charged for a day or two in a quiet anchorage, then motor on to the next spot. The batteries will be fully charged by the time we get there.

We feel the solar panels are well worth the money, and not too complicated.

 

[knotflying]

I have a 135 watt panel on my R-27. It works fine and I am good on the hook for three days. Power management is always important. We have all LED lighting and we charge all our phones, computer and other items via the small type 12v outlet inverters. The only time we use the promariner inverter is for the microwave or other large power hog and then we turn on the engine to supplement the power and not drain the batteries. We use an electric peculator and then i usually turn the engine on, power up the inverter, make coffee and then do all my personal morning wash up. By that time coffee is done and I turn off the engine and sip my nice cup of coffee. That also warms up the hot water in the tank so there is plenty of water after breakfast to clean up.
I have joined the Thruster battery to the house. In the morning the batteries are usually at an 80% charge. After the engine has run and the solar kicks in they are topped off by the end of the day and rady to carry me through the night. Since you have a generator you also have the bonus of using that in lieu of the engine.

PS. I also use a C-pap machine through the night using the small 12v inverter. Has been working great for 5 years.

 

[sleepyboat]

We knew the refrigerators were power hogs and a few years ago Knotflying actually did the math to confirm it. With one 135 watt solar panel you can get two days maybe three running JUST the fridge at a medium setting and sunny days.
When I ordered my 23 I wanted solar but it was not offered in the beginning of the run. So I ordered the 140 watt panel and had my dealer install it. It is larger than the 90 watt now offered. I count on it to keep the batteries topped off while away and turn off battery switches.
I try and limit going into the fridge and use a cooler for frosty beverages. I prefer to use the stove for hot water coffee and a french press as opposed to an electric peculator. Conservation is key.

 

[rpmerrill]

I don't know exactly what model Nova Kool refrigerator I have on my R27 but I looked on the Nova Kool web site and have estimated my fridge amp draw (based on catalog photos and dimensions) at 4.4 amps. At 12 volts, that is 50+ watts. Lets say 55.

Understand that the fridge would only be likely to run during a fraction of the day. Let's say 50% run time. That is only equivalent to a 27-1/2 watt continuous load. (A closed up boat in my neighborhood will easily get up to 100 degrees and that certainly adds a lot to the actual load as well as making the compressor work harder.) I didn't take that into account.

Even though that solar panel only works for part of the day. I should think that a 90 watt solar panel should be able to keep up fairly well. When I bought my boat (second hand) I was told it was a 180 watt panel (optional upsize).

My only experience so far this (my first) summer was when I left the boat at a boatyard for some service for 10 plus days without a shore power hook-up. All ran fine. Food in the fridge stayed cold. At least nothing I ate afterward killed me.

PS: I contend that opening the fridge is not a big part of the load. The only thing that spills out is air which carries almost no heat, when compared to the products inside.

 

[Sea Jo]

We have solar on truck camper,cant beat it. When we move up to a tug will get solar,if in a slip will keep batteries topped off if there is no power.