Battery/Solar Arrangement Questions

[DDabs]

I am currently outfitting my 40 ft. sailboat, and I am having a tough time putting together a system for the solar/batteries. I know this is a super broad area, but I am just looking for a nudge in the right direction.

The boat currently has two brand new AGM house batteries (100ah each) and a starting battery. I want to increase the house bank a little bit to be able to have a comfort zone running my refrigeration 24/7 and some electronics.

This is what I have put together for solar:

3 Kyocera KD140SX panels (will be mounted on an arch, mounted above dinghy davits)
Tristar 45 Amp MPPT controller
10-2 and 8-2 wiring for panels and controller

Now concerning the batteries... the two AGM batteries on the boat are brand new, so I am debating if I should just buy a few more AGM batteries and make the entire system AGM, or put together a LA bank. Lithium has me intrigued, but I just don't know if it's worth the price for me. I have a 200ah bank right now, and I would ideally want to have somewhere around 500-600ah.

Thoughts? Ideas? Anything. Thanks so much.

David

[sailorboy1]

Originally Posted by DDabs

Thoughts? Ideas? Anything. Thanks so much.

David

You want all the batteries to be the same type or your charging setup will not be correct. So for you it sounds as the new batteries need to be AGMs. But you may want to consider if adding batteries to changing ALL to 6V golf cart type batteries as it may be more cost effective getting a larger bank that way than the adding of 2 more AGMs (my 460AH bank of 4 6V batteries was less than $500)

[DDabs]

Would it be an option to have the 2 AGM batteries be one bank, and then have a second bank with a setup like yours- 4 6V batteries? I am going to be installing a windlass and that needs a battery as well, correct? I guess I could use the AGM batteries for the windlass? And just create a new house bank?

[F51]

Do you have a battery monitor? I find mine invaluable in showing what my real-world amp-hour usage is. I have started with a fully charged house bank and turned off all charging for 24 hours. I thus established what a typical daily draw is for my system (about 86 ah). Once you have that knowledge, you can calculate how much solar panel to buy. I suggest that you don't skimp--electrical loads always seem to increase but not decrease. I have never heard anyone complaining that they installed "too much solar." I am very pleased with mine. My battery chargers have not been energized once since the solar panels went online. I'm usually at 100% charge by early afternoon, even on cloudy days.

[MarkJ]

I would add extra AGMs similar to what you already have. (I dont like golf cart batteries, but lots do. They need to be accessible to check water where agms dont)
The wattage of the solar panels are too small. put in the three biggest you can fit. Try for 200 wats each.

Run the windlass off the main bank, but always with the engine on.

You cant have too much electricity.


Mark

[sailorboy1]

Originally Posted by DDabs

Would it be an option to have the 2 AGM batteries be one bank, and then have a second bank with a setup like yours- 4 6V batteries? I am going to be installing a windlass and that needs a battery as well, correct? I guess I could use the AGM batteries for the windlass? And just create a new house bank?

NO the charging voltages for the AGMs and the 6V standard lead acid are different. (it of course is possible but is just going to cost more in the needed controllers etc)

I don't have a separate battery for my windlass. In fact mine comes off the start battery that gets charged from the house system. The main reason for having a separate battery for a windlass is so the battery can be closer and not need a large gage wire due to the distance and voltage drop. As long as the cabling is sizing correct it doesn't matter where the battery is and you can run it off your house bank if you want to.

BTW - in my mind if you are going to be off the grid and using solar for charging AGM isn't a great choice as they don't really like not getting fully charged all the time.

[sailorboy1]

Originally Posted by MarkJ

I would add extra AGMs similar to what you already have. (I dont like golf cart batteries, but lots do. They need to be accessible to check water where agms dont)
The wattage of the solar panels are too small. put in the three biggest you can fit. Try for 200 wats each.

Of course the choice of batteries does need to consider location factors. Mine are easy to get to and even though I checked them probably 6 times last year they only needed water once. I would bet it could be a lot different in hotter weather locations and if you run your absorption phase a lot longer than I do.

Far as wattage goes, you never feel you have enough. But my 290W panel more than keeps up with my anchorage loads with power to spare. But I sized the controller and wiring for 2 panels in case I want to later instead a second panel.

[DDabs]

F51, that's another thing I just noticed I will need. I have heard alot of good reviews of the Victron monitor from forum members here. Will I need a display for the solar panels to view the MPPT information, or as long as I have a battery monitor to view the battery information will I be OK.

Mark, when the welder at the yard and I designed the arch, we measured that we would most likely only be able to fit three 140W panels on the arch sideways. I could probably add another panel on top of the dodger or bimini at some later point in time, but I don't like the idea of solar panels on top of the bimini's flimsy structure. For now I think I'm going to have to get away with three. Is 420W not enough to just run refrigeration and perhaps the electronics/autopilot for a day?

[DDabs]

sailorboy1, my batteries are all positioned directly behind the engine in a huge crawl space, so I can get to them very, very easily. The only thing about going with a LA system seems to be I'm forced to ditch my two new AGM batteries.

[sailorboy1]

Originally Posted by DDabs

sailorboy1, my batteries are all positioned directly behind the engine in a huge crawl space, so I can get to them very, very easily. The only thing about going with a LA system seems to be I'm forced to ditch my two new AGM batteries.

an emotional decision I understand

but it was just something consider, if 2 new AGMs to match what you currently have are less money I would go that way and reevalute it when replacement time comes

[DDabs]

I think that may be the way I end up going for now. For the next year, the boat will just be doing east coast cruising and hops to the Bahamas/Upper Carib. Perhaps when I push further offshore I will replace the system with a significantly larger LA bank.

So in addition to the 3 panels and charge controller, will a single battery monitor suffice for monitoring levels, or should I have a monitor for the solar panels as well?

[Scott Berg]

A bit more than a nit to pick: all the batteries being discussed are Lead Acid (LA). They may be Flooded, Gelled, or Absorbed in a Glass Mat, but are all LA.

Electrolyte behaves differently in different states but they're still lead acid batteries. Lithium ion are a different chemistry altogether... But that's another thread :-)

[DDabs]

Scott Berg, thanks, I was actually just going to post that and make sure. So for example, 6V Trojan T-105's and a 12V AGM battery are both going to be LA?

[DDabs]

Looking at prices, I think sailorboy1 might be right. For the price of adding two more AGM batteries to my house bank, which would give me around 400-450 total, would be just as or more expensive than having an entirely new bank of four 6V 225AH golf cart batteries. A 450AH bank seems like it would be decent enough size for coastal cruising and if I need more I can always add two more or four more 6V and have up to a 900AH bank. Thoughts?

[sailorboy1]

450AH of batteries for a 40' boat with 420W solar is more than enough power for coastal cruising