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12 volt charging at marina

Oct 22, 2014
14,208
CAL 35 Cruiser moored EVERETT WA
Rick, @dlochner has given you good advice on solar in the PacificNW. Your 20 watt system barely is able to charge your cellphone on a clear sunshine day.

It is time to read the battery articles by MaineSail. Get clarity on the demands of batteries and what it takes to keep them healthy. It is easier to kill batteries then you might imagine. By kill I mean having to replace the battery in 6 months to a year because it will not hold a charge.

I have found success using the lead acid batteries produced in Seattle by Dyno Batteries. Specifically their 30TMX Dyno Battery - Premium Quality Battery Manufacturing - Made in the USA
which is a true deep cycle battery providing 135amp hours of power. At a little over $150 cost and picked up from their warehouse, they meet the economy value goal for a thrifty sailor.

Living on a mooring ball has challenges keeping batteries healthy will require some equipment and time investment.
 
Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
If the batteries are 100% charged when I move to the mooring, is the 1-2 amp (25 or 50w) panel with the regulator enough to meet the trickle charge and keep them at 100%? Something like this image?
Yes, 50 watt would be better, however you are not accounting for use of the battery. What every energy you use on weekend sailing adventures will need to be replaced and 50 watts probably won't do it, especially if you fire up the refrigerator. A 50 watt solar panel will produce about 4 amps at 12v. Using the estimate that Calder suggests in the earlier referenced article, you can expect 12 ah a day of output on average. There are formulas to make the actual calculation, however a perhaps only 9 or 10 ah a day will actually be returned to the battery. With this estimate only about 45 to 50 ah will be replaced or about 25% of the battery bank capacity. Bad weather and cloud cover will reduce the amount returned.

We have a blue-top AGM in a 20' Whaler that is going on 4 years old and we have taken pretty poor care of it based on what I have read here. At the marina it's had a AC trickle charger, but during the winter the battery was fully charged before storing it in my garage and then pulled out 6 months later - charged up and installed in the boat. Seems like it should be on the smart-charger all winter in the garage.
You may not be abusing those batteries as much as you think you are. The Optima probably has an capacity of about 50 ah and the alternator on the outboard probably puts out at least 6 amp or more. If that is the case, then the battery is being recharged at a rate of more than .1C. On the Whaler the engine will be running more than on the sail boat so there is more charging time at closer to an optimal charge rate. The one important variable that you didn't mention is how much energy is being used when the engine isn't running, or another way, how depleted is the battery when you head after a day on the water. Unless you have a mega stereo with huge speakers and several hundred watts of amplifier, you probably don't use much electricity. Thus when you get back to the dock, the battery is near a full charge and the trickle charger brings it the rest of the way up. Over the winter, a fully charged battery in a cold environment will have a limited self-discharge as cold reduces self-discharge rates.

It seems like my uneducated assumptions that the AGM was a better choice, was a fool's decision. Sounds like some basic flooded (cheap) batteries might have been a better choice given how the boat and it's batteries will be used.
If you read enough of MaineSail's articles you will learn lots and one thing you'll learn is that you are not the first (nor probably the last) to learn this the hard way. We learn best from our mistakes. ;)

Is spending $200 more for a solar system worth doing or should we just treat the 2 banks badly like the Whaler and hope we get 4+ years of use out of them by only charging when the Honda is running for the summer ?
In life there are seldom dichotomous choices. Without additional charging capacity, I doubt you will get 4 years out of the AGMS, if you use them much at all. There are some alternatives. It is essential to have a good idea of how much energy you actually use and and the current SOC of your batteries. Without this information, you will be guessing a lot and guessing induces errors and those can be costly. A battery monitor is essential for knowing the health and charge state of your batteries. Balmar makes a couple of good ones. Victron makes one that gives more information, however, it requires programming which can be a bit tricky. Check the HowtoMarine.com website for articles on battery monitoring.

Limit electricity use when you go sailing. The less you use, the less you have to put back.

Every few weeks sail to a marina and spend the night. Plug into shore power and get a good charge back into the battery. This will not be as good as a full charge every day, however, it should help extend the batteries life. Not as much fun as swinging on a hook in a quiet cove, but the crew might enough the marina's showers and nearby restaurants.

You have some time before the boat goes to a mooring, spend it learning about Solar power and electrical systems. In the spring, you can make a good informed decision and find a decent quality panel and controller. The Alt-E website has good information and products that are a good balance between cost and quality, MaineSail often recommends the company.
 
May 24, 2004
6,618
CC 30 South Florida
Now I'm thoroughly confused.

I don't need to run the cold-plate system. I don't need to run anything. The boat will have a float switch added to the bilge pump before it moves to the mooring, but since the bilge water level has not changed more than 1" in 2 months I'm not very worried about sinking on the mooring.


If the batteries are 100% charged when I move to the mooring, is the 1-2 amp (25 or 50w) panel with the regulator enough to meet the trickle charge and keep them at 100%? Something like this image?



It seems like my uneducated assumptions that the AGM was a better choice, was a fool's decision. Sounds like some basic flooded (cheap) batteries might have been a better choice given how the boat and it's batteries will be used.


Is spending $200 more for a solar system worth doing or should we just treat the 2 banks badly like the Whaler and hope we get 4+ years of use out of them by only charging when the Honda is running for the summer ?

Hard to answer your questions, but this is what I would do. I can get a pair of wet cell group 27 batteries at Walmart for under $200. To spend another $200 on a solar panel would not make sense to me unless I would have use for the charging power when cruising and not just for when batteries are stored. As far as battery upgrades, I consider them necessary when the electronics on your boat demand them. For a boat with basic electronics the cheap ones work well. Remember, there is more than one way to skin a cat; for long term storage I would remove the batteries from the boat and store them in my warm garage and trickle charge them with a smart 120V charger. When the boat is in a mooring it may not be practical to be loading and unloading them so a solar panel would be a solution but I would think a minimum of 100W with a charge controller. It is unlikely that you could keep the batteries charged to 100% so taking the batteries to shore and charging them periodically might be required or once a month tying up to a marina mainly to charge batteries could be helpful. I personally consider battery life to be expendable, so if I get three years use of cheap batteries I'm fine with it. There are no guarantees that the most expensive batteries with the best maintenance will outlive the cheap ones. In this fact is that the battery warranty market has grabbed root and developed. most of the time the best batteries merely carry the best warranty. Manufacturers really do not know which batteries will last 7 years and which will fail short of a month.
 
Dec 1, 2020
42
CAL Boats 2-27 Puget Sound (Kitsap)
What about buying a 200 ft (est) extension cord and running it from my dock (with flag) to the mooring (where the red star image is shown) and running the 20amp AC charger?

61929734292__E96AF632-4010-4588-8DEA-9B1425D47403 (1).JPG
 
Oct 22, 2014
14,208
CAL 35 Cruiser moored EVERETT WA
Rick that is an interesting idea. Granted limited folk might swim through the area. Perhaps you might find a few salmon float to the surface which would make interesting meal opportunities.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
What about buying a 200 ft (est) extension cord and running it from my dock (with flag) to the mooring (where the red star image is shown) and running the 20amp AC charger?
You are joking right?
 
Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
What about buying a 200 ft (est) extension cord and running it from my dock (with flag) to the mooring (where the red star image is shown) and running the 20amp AC charger?
Sounds good on paper, however, its implementation would be fraught with both danger and other problems. The consequences of an AC leak into water can be lethal. While AC lines are run under water to provide power to islands off shore, they are considerably more robust than an extension cord and their locations marked on charts.

Since the AGM batteries are pretty new, you might find someone in the marina who would buy them from you at a discount from the WM price. Then use the money to buy FLA batteries. Or take the extension cord money and purchase a larger solar panel.
 
Dec 1, 2020
42
CAL Boats 2-27 Puget Sound (Kitsap)
Yes. It was mostly a joke.

I'm still a bit confused.

The AGM's self-discharge very slowly. Say 2% per month, especially considering the batteries are inside the boat, below water line near the hull - how much "cooling" will these get with our 55deg water temp year-round. So 200 Ah batteries - 4 amps loss over 1 month.

A 50w solar charger will easily provide that 4 amps. Batteries are being treated reasonable well - correct?

Now when I use power. If it's light loads - no cold-plate, the solar will still restore the use but it might take a few days - so what, the boat is just sitting there.

If I use the cold plate, I'm now looking at 6 amps per hour. 50% of my bank capacity or 16 hours of use. If I can't access AC on a dock during this trip, wouldn't the 100 Ah of power used be returned after something like 1 week of mooring time (7 days x 2-3 amp x 6 hrs of useful sun from our 10-16 hrs/day in summer) ?

Or is the issue that the 100 Ah takes so long to restore at the low charge rate? And this is what is bad for the AGM's ?
 
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May 17, 2004
2,994
Beneteau Oceanis 37 LE Havre de Grace
wouldn't the 100 Ah of power used be returned after something like 1 week of mooring time (7 days x 2-3 amp x 6 hrs of useful sun from our 10-16 hrs/day in summer) ?

Or is the issue that the 100 Ah takes so long to restore at the low charge rate? And this is what is bad for the AGM's ?
I think you’re a little optimistic there. Calder recommends a factor of 3 to 4 for solar efficiency in the real world, and the PNW is on the low end of expectations. So your 50w panel would give 4.1 amps maximum, and if we assume a factor of 3.75 that gives us 15.7 aH of charging per day. At that rate it would take just over 7 days to restore your 100 aH of use, and for the entirety of the 7 days the AGM’s will be below full charge, which is where the potential damage comes in. The 50w panel is certainly plenty to keep the batteries charged - like you said AGM self discharge is very low, but recovering from usage will just take a detrimentally long time.
 
Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
If I use the cold plate, I'm now looking at 6 amps per hour. 50% of my bank capacity or 16 hours of use. If I can't access AC on a dock during this trip, wouldn't the 100 Ah of power used be returned after something like 1 week of mooring time (7 days x 2-3 amp x 6 hrs of useful sun from our 10-16 hrs/day in summer) ?

Or is the issue that the 100 Ah takes so long to restore at the low charge rate? And this is what is bad for the AGM's ?
@Davidasailor26's comments are correct. The value of AGMs is their ability to be rapidly recharged, i.e., the acceptance rate is higher than flooded batteries. Thus, long slow recharges are detrimental to the batteries.

Recharging batteries from any source is riddled with inefficiency and as the battery approaches 100% SOC the inefficiency increase. In the real world this means that the number amps required to recharge a battery is much higher than the number of amps taken out of the battery. As batteries age, the inefficiencies increase. This phenomena was first identified by Wilhem Peukert about 120 years ago and the inefficiencies can be calculated.


Long slow charging tends to cause the plates to sulfate, which reduces battery capacity. Rapid charging helps to de-sulfate the plates restoring their capacity. The only lead-acid batteries on the market that appear to be resistant to sulfating and can withstand longer periods of PSOC are Firefly batteries and they sell for about $550 a piece. Fireflies can also handle high charging rates and need high charging currents, as much as .4C with a minimum of 25 amps per Group 31 batteries (116 ah).

As you note, dealing with self-discharge is pretty easy, it doesn't take much to keep a fully charged battery at 100% especially in cold, below freezing, weather. The batteries on my boat stay on the boat all winter and do just fine, I'm in Upstate NY and most winters are pretty cold. In your case the problem isn't dealing with self-discharge, it is getting the batteries to 100% SOC quickly.

One solution that has not been mentioned is purchasing a small gas powered generator, like a Honda 2000 and using that to recharge the batteries while on a mooring. This not an ideal solution as there is carbon monoxide to deal with and the space it takes up. You probably would not want to row it out to the boat every week.

Before spending more money on solutions, install a good battery monitor, like the Balmar Smart Gauge. This will provide you with good information about the battery's SOC will guide you about when to get to an AC charger or when a small solar panel will do.
 
Jan 7, 2011
2,315
Oday 322 East Chicago, IN
Since the AGM batteries are pretty new, you might find someone in the marina who would buy them from you at a discount...
I was going to offer to swap him my 2 Group 27 FLA batts for his somewhat useless AGM’s...

PM me (I won’t hold my breath)

Greg
 
Dec 1, 2020
42
CAL Boats 2-27 Puget Sound (Kitsap)
Thanks to all for the education. To bad I didn't know about this forum BEFORE purchasing the sailboat...
 
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Sep 24, 2018
1,221
O'Day 25 Chicago
What about buying a 200 ft (est) extension cord and running it from my dock (with flag) to the mooring (where the red star image is shown) and running the 20amp AC charger?

View attachment 189137
My dock neighbor did this, not with one cord but multiple 12awg plugged into one another. He did the best he could to seal the connectors. I still shook my head and vowed to never swim in that part of the marina
 
Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
My dock neighbor did this, not with one cord but multiple 12awg plugged into one another. He did the best he could to seal the connectors. I still shook my head and vowed to never swim in that part of the marina
And the marina didn't throw him out? Electricity in fresh water is very deadly, a little less so in salt water.
 
Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
Thanks to all for the education. To bad I didn't know about this forum BEFORE purchasing the sailboat...
I'm a little surprised the yard didn't give you better information and explain the issues with different batteries.

If you should decide to go back to FLA batteries, there are battery caps that recapture water that would otherwise boil away. They reduce the number of trips to awkward places to check the batteries.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
Thanks to all for the education. To bad I didn't know about this forum BEFORE purchasing the sailboat...
I would offer a suggestion of stepping back a bit and re-consider your choice to moor vs slip. Perhaps you should just enjoy the first year of having your boat free from some of these complexities. :)
 
Jan 22, 2008
180
Macgregor Venture of Newport 23, Montgomery 17, Mirror sailing dinghy, El Toro sailing dinghy Mound, MN -- Lake Minnetonka
FWIW, I have kept my boat on a mooring not too far from my home for many years. I have an AGM battery that I keep topped up with a 15W solar panel and small Morningstar controller. The boat sits on the mooring from early May to late October with no other means of battery charging. I sail her 2 to 4 times a week. I usually have just the depth sounder and VHF on during these sails. Running lights and cabin lights are LEDs, but I rarely sail at night. I do, however, have an automatic (LED) anchor light at the masthead that comes on at dusk every single night and turns off at dawn. ( I decided to add the anchor light after the boat was rammed and dismasted at the mooring in the middle of the night by a drunken power boater. But that’s another story.) The 15W panel has done a great job of keeping the battery charged. I would probably add another 20W panel if I did much night sailing.
 
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Jan 11, 2014
6,812
Sabre 362 113 Fair Haven, NY
FWIW, I have kept my boat on a mooring not too far from my home for many years. I have an AGM battery that I keep topped up with a 15W solar panel and small Morningstar controller. The boat sits on the mooring from early May to late October with no other means of battery charging. I sail her 2 to 4 times a week. I usually have just the depth sounder and VHF on during these sails. Running lights and cabin lights are LEDs, but I rarely sail at night. I do, however, have an automatic (LED) anchor light at the masthead that comes on at dusk every single night and turns off at dawn. ( I decided to add the anchor light after the boat was rammed and dismasted at the mooring in the middle of the night by a drunken power boater. But that’s another story.) The 15W panel has done a great job of keeping the battery charged. I would probably add another 20W panel if I did much night sailing.
When batteries age the voltage does not drop, the capacity drops, meaning if a new battery (of any type) starts at 60 ah capacity over time that capacity drops, to 50 ah, 40 ah, and so on. When the loads on the battery are low the loss of capacity is barely noticeable unless a 20 hour capacity test is conducted. Depth sounders and VHF (on receive) draw very little current however, combined with the anchor light they probably draw more than a 15 watt panel can recharge. Since you seldom if every place a heavy load on the battery the capacity loss isn't easily discernible.

Loss of capacity is much more noticeable when a heavy current draw is applied. Last year I had to replace my start/reserve battery. When I checked the voltage it looked fine and when I started the motor right after unplugging from shore power, the motor would start. However after a day of sailing, there wasn't enough capacity to start the motor, although the voltage looked fine and had I connected devices with a low current draw they would have run fine, but trying to take a couple hundred amps out to start the diesel, it was no go.
 
Sep 24, 2018
1,221
O'Day 25 Chicago
And the marina didn't throw him out? Electricity in fresh water is very deadly, a little less so in salt water.
This end of the marina is like the wild west. They don't seem to care what you do but dont don't expect them to actually fix anything. They're floating docks that require a dinghy to get to