Solar charging while also charging via shore power?

[Jarel Design]

Hello all,
Getting our C26 ready for a cruise and doing a lot of work (New custom made anchor roller, installed an anchorman manual windlass, New 25# Mantus with 5/16" chain and new braided nylon rode etc...) I may have read just about every thread in many of the forums here and have learned a lot!

Thank you to all!

I eventually will remove all electrical and start from scratch as I don't like how the previous owner had it set up, but we're leaving in July to spend a month cruising the San Juan islands and just had to change some of it before we leave (Added fuses, completely rewired our 120v system (double pole breaker, GFCIs etc.)

Just finished refitting our 12v and 120v electrical systems on our C26, tested them out and everything works great:

Two G27 batteries (I'll eventually change the house batteries to trojans)
On board 2-bank 8A Pro-mariner charger

I'm also adding two 100watt solar panels with a controller and I have a question (I know a LOT, but I also "know" that when I "think" I know a lot, the best approach is to do so as if I know nothing!

Here's my question:
While in a marina using shore power and our Pro-mariner charger, can I leave our solar panels connected?

My guess is, that the solar charger will recognize that additional charging is taking place and will limit the amount of amps it will send to the battery (I'm only solar charging our house battery because we plan to spend a lot of time on the hook and buoys.) I'm also thinking that the Pro-mariner will recognize the same and will limit the number of amps it sends to either battery.

Am I missing anything?

This comes from melting down our battery cables after connecting wires what the previous owner told me were positive... They turned out to be negative!

Changed all battery cables and battery selector switch with new, fused the "unknown" polarity wires and used my volt meter for confirmation... Still have images of melting wires and smoke in my head... As an ex-firefighter, this is not a good image to be carrying around in my head... But does add to my respect of what "electrickery" can do! LOL!

Thank you!

Richard

[msponer]

Originally Posted by Jarel Design

While in a marina using shore power and our Pro-mariner charger, can I leave our solar panels connected?

My guess is, that the solar charger will recognize that additional charging is taking place and will limit the amount of amps it will send to the battery (I'm only solar charging our house battery because we plan to spend a lot of time on the hook and buoys.) I'm also thinking that the Pro-mariner will recognize the same and will limit the number of amps it sends to either battery.

Yes, it's completely fine. Both will try to raise the voltage, which is fine, since both are programmed to not let the voltage get high enough to damage the batteries.

Your trip sounds super fun -- enjoy it!

PS -- About the melting cables -- if you are paranoid about an electrical fire (I am), when you replace your batteries with Trojons look into getting fuses that are on the battery terminals. Like these or another style.

[Jarel Design]

Thanks for the input.
That's what I figured... More amps the better as long as there aren't too many and both chargers putting in what the batteries will accept and then both cutting down their charging as the batteries come close to being fully charged.

With 200 watts of solar, we should be fine. Interior lighting is supplied by AA Nicad cells in converted "Harbor freight" lighting... These are charged via a smaller (1A) solar charger with it's own solar controller. Many of our "accessories" (Cameras etc) are powered with the same AA cells. We have a Garmin 640 with Vision blue chips for the area including canada, LOTS of paper charts for US and Canada, a hummingbird fish finder (visual (bottom condition), and back up for our installed digital depth. We also have knot meter and log, wind speed and direction...

As an ex firefighter, I'm always paranoid about fires! (We're carrying 5 extinguishers! LOL!) I was shocked (no pun intended), when I first hooked up my batteries to see my cables melting and smoke everywhere! Should have followed my gun safety etiquette: Ask if it's loaded and then make them open it up to hand it to you with the action open so you can see for yourself... Should not have guessed or assumed the polarity of the questionable wires! (My bad)

I've heard of battery fuses but your link didn't connect... They will be included in my complete re-wiring of our baby.

Been looking forward to our upcoming trip for a year! My wife and I both have blue water experience but are now only interested in coastal/Gunk-holing which is why we now have a trailer boat. Future plans include Sea of Cortez, ICW and the Bahamas...

Totally going bonkers on safety items and getting everything "perfect" (Ha!) My wife keeps reminding me that I sailed solo up there in a little San Juan 21 with only a handheld compass and handheld VHF using paper charts and a small danforth wanna-be (No GPS, No depth etc...) Old school back when Loran was popular (And I was a lot younger!). LOL!

Thanks again!
Richard

[msponer]

Yay. Have fun.

Our boat is in New Zealand, but our long term goal is to get her back to the Sea of Cortez. Because that's our happy place.

[basenay]

While not a problem leaving both on it makes sense to turn off shore charger during daylight & every 1-7 nights depending on number of panels, weather, etc turn shore charger while it is dark No use you or marina paying for what you can be getting for free.

[eMarineSystems]

Your assumption is completely correct! The charge controller from the solar system will work in harmony with the other charging systems on board, be it from your alternator, shore power battery charger or other charging devices. The controller will limit the charge current based on the voltage exceeds that it's terminals.

[CaptRory]

I agree with baseny. Last year, I stayed tied up all summer, with the battery selector switch on "both" and the charger on. The starting battery (significantly older) went bad and the charger attempted to charge it, burning itself out and the house bank trying to equalize with it didn't fare well either. This somehow caused the house bank to age prematurely (AGM's) because when I finally noticed it (I was in condo mode) they appeared topped off but seemed to decline too rapidly. An expensive mistake. Now I leave the switch on the house bank and turn the charger off. The solar panels have no trouble keeping the new ones topped off, ready to cruise. The charger sits at rest and I don't have to pay for shore power unless I use the A/C.

[ArmyDaveNY]

Good luck with your wiring. You have good reason to be concerned about boat fires. I have seen two and when they go they go quickly. Interestingly, according to some insurance figures, over half of all boat fires are proven to be electrical in origin. The figure is likely much higher but they cannot determine a cause in a large number of them. Of the ones that the can determine the origin, some 55% of the electrical fires originate in the shore power system.

There are a number of reasons for this. A major issue is that too often corrosion forms on the contacts and receptacles. As I'm sure you know, corrosion equals heat, which equals bad things. Another interesting thing is that the manufacturers recommend that you not draw more than 80% of the rated Amps. If you have a 30 amp cable, you should not draw more than 24 Amps on a steady basis. Many who really know electrical systems say don't draw more than 70% or 21 Amps.

The reason for so much trouble with shore power is the plug. It was designed in 1938 for building use, not for marine use. It was state of the art then but is seriously outdated now. The three prongs provide ONLY some 6 square mm or surface area! When you add this to corrosion, movement, moisture, and lots of juice, it's not hard to see why they can burn.

A much better solution is the smart plug. This provides a secure locking in place of the plug and most importantly, it has some 700 square mm of surface area.
Marine Market – Smart Plug

Full disclosure: I do NOT sell these. I just like them.

N.B. Plenty of people use the traditional shore power cables and have no issues. I myself had it connected for several years and had no issues. I also constantly unplugged it as I was sailing all the time. Once I learned about it, I stopped leaving it plugged in all the time. I only use it now for specific needs, such as doing work on the boat that requires more power than I can generate myself. I am going to change the plug after I finish a few other projects. Since I don't use shore power very much I am not in a rush. If I needed it regularly, I'd change it out ASAP. They're fairly comparable in price to traditional plugs and cords. I know Amazon has them.

Good luck with your project.

[Jarel Design]

Thanks everyone!

Our plan:

Leave Anacortes with fully charged batteries. Use solar to "hopefully" keep them charged while we're on the hook (I have a digital volt meter to monitor), reducing our consumption if needed.

We would "every once in a while" visit a marina (Trash, pump out, provisioning, fuel, water, sight seeing etc.). I figured our shore power charger would make up for what our solar power doesn't provide. Probably 24 to 48 hour stays with shore power. And then leave to go back on the hook for a week or so with our batteries topped off.

I was just concerned about leaving the solar connected while plugging in our 120v charger.

As for Sea of Cortez? Our absolute HAPPY PLACE!!! Been going down (when I lived in Los Angeles), since the road opened up (dirt at that time), in 1973! At LEAST 5 times per year towing smaller sailboat and aluminum fishing boat... =D

Thanks again!

Richard & Tresa

[Dave22q]

I suspect your 2 bank 8 amp promariner is very undersized. Have you figured the time to bring your bank from 50 % to near full assuming no sun? I believe that 2 bank units split the charge so it will only give 4 amps max to each bank regardless of their relative condition. You may be able to rewire it to act as a single bank charger.

[wgoodbye]

Originally Posted by msponer

Yes, it's completely fine. Both will try to raise the voltage, which is fine, since both are programmed to not let the voltage get high enough to damage the batteries.

Your trip sounds super fun -- enjoy it!

PS -- About the melting cables -- if you are paranoid about an electrical fire (I am), when you replace your batteries with Trojons look into getting fuses that are on the battery terminals. Like these or another style.

I think your idea about fusing the batteries is a good one. How would you determine what size fuse to put on each battery terminal?

I'm using Oasis G31 batteries. Here are the specs:

Nominal Voltage
12V
Max Charge V
14.4V
Charge Current
Max 250A @25°C
Reserve Capacity
@25A
@75A
225 min
57min
Designed Cycle Life
50%
∿3600
Instantaneous P: CA/CCA
800/600
80%
∿1000
IR
3.8mΩ
Operating Temperature
-20°C to 50°C
(-4°F to 104°F)
Dimensions
Weight
13.4" x 9.4" x 6.7"
75lbs
Nominal Capacity
5hr
10hr
20hr
20.2A (101Ah)
11A (110Ah)
5.8A (116Ah)

[Jarel Design]

Group 27 batteries... Limited amp hours to begin with (Switching over to trojans when we get back and i re-wire EVERYTHING!). We should be fine with shore power charging and 200 watts of solar. Limited electical use on boat. All lighting is LED (Many are independently powered using AA Nicad cells solar charged on a separate smaller solar panel) With "short" sails between islands, instruments will be used for 3-4 hours.

Calculated boat's amperage usage at 17A/day with 6hours cruising. 200 watts @ 10A (max... LOL!) "should fill us back up in a couple of hours of good daylight (Days are also longer up there when we'll be there.)

Stereo (included in my amp hour calculations), will be the biggest draw, but we both play instruments and plan to play a lot!

So shore power will be used to supplement our solar. I'll keep the starter battery for engine starting only and if that fails, it's a newer 9.9 mercury electric start WITH hand start which works well.

Richard

[Sunsetrider]

Love the interior space in your boat - looks very comfortable for cruising. When you redo the electrics think about moving up to the 12A charger as a minimum. It isn't that costly. For stereo, I am using a rechargeable Sony Bluetooth speaker box playing music off my phone/iPad.

[Jarel Design]

Hi Sunsetrider,
Thanks for the kind words about our boat. It's weird as both Tresa and I come from living on a coast before we met 10 years ago and were used to boats much larger. We both have blue water experience, but when I moved from Los Angeles to Oregon (She was already living here), I thought my sailing days were over. Took a San Juan 21 to the San Juan islands and then it dawned on me: I could use a trailerable sailboat to get to the cruising grounds I was interested in exploring... (We both "Gunkholers" at heart.) I needed to find a boat that was much closer to blue water capable with larger "liveable" boat features.

Took me a year to discover that back in the day, Chrysler (of all companies), produced the C26 (Hershoff design). Slept 6, 6' standing headroom, wrap around galley, private head... Swing keel rests below the waterline in a sort of shoal draft long outer keel that was also weighted... Very stable! When I first shared this with my sailing buddies in Marina del Rey, they all replied: "Oh Richard... What have you done!?!?! After they saw it, they changed their tune... I get to go to the San Juans and Sea of Cortez, while they're still "day sailing" to Catalina.

When Tresa and I bought this boat, we took it up to a large lake not too far from here lake and spent a month on board just to see if we could really "live" aboard (size questions...too small?) It was wonderful! Especially for a trailer-boat.

As for a larger charger? I'm planning on adding 200 watts more (400watts total), instead of a larger charger... Not sure if we're keeping this boat for long term... If we fall in love with living aboard, we may just sell it all, move to the east coast (ICW, Florida keys, Bahamas, Caribbean), and buy a larger boat... I still want to re-do the electrical on this one for safety's sake and we're still planning to take this one to the Sea of Cortez.

OK... back to boat work... Installing water tanks with deck fills and a whole bunch more. Raising the mast tomorrow and going over all our rigging.

Best,
Richard