Off Grid System on Houseboat Expand or what?

[Sam Caddle]

We have a houseboat with a solar system copied from one spec'd out by a local installer here in Northern California. It may be all wrong but I went with best information I had at the time. System is now almost 6 years old. In helping a friend with their system I "learned" their system was too small to support the battery bank so they were in deficit charge most of the time. The more I read about this the more I suspect I am in the same circumstance. My initial thought was to add more panels but after reading some stuff on this site I am confused and unsure what the best step would be so I thought I would describe my situation and toss it out there for ideas and critique. Here goes.

My houseboat has much of the stuff at 12 volts, and came with a 13.5kw generator to support the 110V stuff. I added the solar to become self sufficient without a generator except if I need to run my AC or Heat which s 220. For 110V stuff we have two refrigerators, microwave, coffee maker, 110V outlets for vacuum cleaner, fans, phone charging, etc. The system seems to work very well for our needs. I have six Kyocera 245W panels wired in pairs to a combiner box and then on to my Midnite Solar 150Amp Charge Controller. This charges my bank of six Decka L16 6V batteries. The batteries are wired in pairs then connected together to be one big 12 volt battery with quite a lot of amp hours. I have more battery questions but that later.

My system charges to 13.7v then goes into absorb mode at 14.3 or 14.4 (I forget) for 4 hours, then into float mode at 13.7. After sun goes down the system goes into resting mode and we are on batteries for the evening and night. When it goes into resting mode the battery voltage reading drops down to 12.5 usually. When the batteries were newer it was usually closer to 12.7 or 12.6. After reading some "SunKing" posts I even more firmly believe I am never getting to full charge (12.9?). My knee jerk reaction to this realization late in the summer was to lengthen the Absorb mode time to 5 hours and consider adding more panels. Before I read a couple SunKing posts I planned to add 4 more panels to give me ten, add another charge controller since my MS 150 would not handle more than my current six panels. But the more I read the more confused i got so here I am.

Is there a way to upgrade the system a bit to better charge my batteries on a daily basis? Is just adding the panels sufficient? From reading one post it sounds like I could cheat the system a bit by increasing my charge target voltage point to 13.9 or 14.something, thereby giving it more Bulk MPPT charge time before going into Absorb mode. Thoughts?

Additionally . . . my batteries are approaching 6 years old and showing some minor deterioration in performance (or ability to get as charged as when new) so at some point in a year or two, hopefully longer, I will need to replace them. At that time what would be my best setup? In reading SunKing it sounds like hooking up a bunch of 6 volt batteries to make a bigger 12 volt battery might not be the most efficient. No matter what I do I need to supply 12v to the house side of my houseboat system. A friend has six 2 volt batteries for his houseboat system, and I hear these have terrific amp hours so considering that route. Wire them into one big 12v battery. BTW, I am feeding a power panel with a 2800 watt Outback inverter. It has worked well for us. We just know we can't microwave, make coffee and run the hot water heater and blow dryer all at one time. )

If you are still with me then thanks for the time. If anyone wants to chime in I would appreciate it. SunKing, you out there? It's OK to call me a dummy. I clearly am no expert. Thanks, Sam

[Mike90250]

You are doing something right, 6 years is a pretty respectable life - what was the warranty period for them ?

Upping the Bulk & Absorb voltage might help, if you had enough solar, which I believe you don't. L-16 are about 450ah, so 3 pairs would be a bank of 1,350Ah which would want, idealy, about 130A of charge current.
So you either need another PV array and Charge Controller and stay with 12V
OR
More PV, rewire to 24V or 48V system and new inverter, when it's time to get new batteries.

What 12V appliances can you not do without ? Many LED lights have 3-30V versions available

Do you have a battery charger to connect to your generator ?

You CAN add more panels (that match your existing Vmp + Imp specs, the Classic will merely throttle back to safe operating conditions at noon for an hour or so, and you will gain more charge before & after noon.

[Sam Caddle]

I think the warranty on the batteries was only a year or two. I do have a 110v breaker in my panel I can switch on when operating off the generator that sends 110v to the inverter/charger which can charge my batteries if I have bad weather for awhile, or for some reason want to boost them in the evening. That is a bit more common in these winter months when we use the system and the days are so short. And made shorter when the lake water is lower at the end of the season so the sun sets behind the hills early. Not sure what my charge current amperage is when it's rolling good. One of my readout screens on the MS charge controller says 52+- volts in, around 15A, around 750W, 4.2 or 4.3 kwh. Not sure if this is what I need to look for.

Most of the lights and all the gauges, engine starting systems, electronic throttle controls, etc run off 12v so it would be hard to convert that side to a different voltage. I have switched out a lot of the lighting to LED but 12v led, and yes, I hear these will work with a a variety of voltages.

Any thoughts on a different type or size batteries when the time comes? I really appreciate your time and help. Sam

[Mike90250]

Most of the lights and all the gauges, engine starting systems, electronic throttle controls, etc run off 12v so it would be hard to convert that side to a different voltage. I have switched out a lot of the lighting to LED but 12v led, and yes, I hear these will work with a a variety of voltages.

You share the House battery with the Engine battery ? OK, that leaves you stuck at 12V

[Sam Caddle]

Are you a battery person too? What about 6v vs 2v bank when the time comes?

[Mike90250]

you ideally, buy cells in the Ah rating you need 2v @ 1,000ah 4v @ 500Ah or 6v @ 200ah, so you dont run parallel strings

[Sam Caddle]

My 6volt Decka's arre 370Ah wired in three 12 volt pairs then parallel together to stay at 12 volts but get the 370x3 for a little over 1000Ah. I think this is correct. So if i wanted similat Ah in 2volt batteries I would need each of the six to be the 1000Ah version. Correct? 2v would be more expensive but is there a benefit to one size over the other for longevity and/or performance?

[Mike90250]

2V cells, easy to replace if one dies, otherwise, you have to toss the good cells in the case, along with the bad one.

But, yes, if you need 1,000AH. 2V cells are the way to go. Fewer caps to check to add water too is a bonus

[Sam Caddle]

I got an email that "suprasoup" sent me a message or posted to this thread but when I click the link it says I ma not allowed to see it or something like that. If you are around Suprasoup then please reach out again.

[Suprasoup]

Sorry about that. Seems like every time I write a response 90% of what I typed disappears even after previewing. Lets see if this works any better.

Couple of things you might try:

Set your bulk=absorb=float. Its what folks around here refer to as max smoke. Since we dont have enough sun hours to do a proper float we turn our charge controller into a single stage charger to force as much available solar energy in to the batteries as we can. DEKA recommends for daily cycled systems setting bulk to 2.4-2.45vpc. Works out to 14.4-14.7v. Try bumping up the bulk to 14.7 and see if you end up with a higher SOC at the end of the day.

Since you also have a Generator you might try running the genny in the am to get your batteries through the bulk stage and have your solar finish the absorb and float stages.

Have you checked the SG of your cells lately?

Supra

[Sam Caddle]

Thanks Suprasoup. I will do this and give it a try. I have not checked my SG in a looong time. I am also having difficulty in how to have my Charge Controller perform a good equalize. I do use the generator when neccessary but try to avoid it as avoiding it was sort of the purpose of having solar system. )