Solar Upgrade verse Running the Generator

[Exile]

Originally Posted by Pizzazz

I have been in these threads for over a year and it is the same arguments over and over.

Golf carts cost $1/AHr and is the best value for money for wet cells. This is why golf carts and heavy equipment runs on them. Point me to a lithium system that costs significantly less than $7/AHr installed.

Some people pay for more expensive wet cells, some get AGMs. More power to them.

Lifeline AGM's can be had for about $2.55/AH these days, at least in an 8D. About the same as the same size battery in FLA from Rolls/Surrette. Does Trojan make a FLA 8D or just AGM in that size these days? If not, what's a decent quality FLA in an 8D?

[john61ct]

Why limit yourself to 8D?

Be very careful looking at 12V in automotive form factors, even from top notch vendors like Rolls.

Better to start with looking at their renewable energy or industrial line, most of which are 6V - 2v.

At least confirm they are specifically for deep cycling, should really be no mention of CCA/MCA ratings.

Get the DoD vs lifetime cycles chart and you'll see, rarely are the 12V models anywhere close.

I'm sure there are exceptions, and of course sometimes mods can't be made to the batt boxes.

And if you don't specifically **need** AGM, go FLA.

[a64pilot]

Originally Posted by Pizzazz

Regarding sizing of solar, I said 20% of battery capacity because you want to use solar charging in accept mode of charging. In the above example, you will switch off your generator at 80% SOC. The remaining 20% is approx. 80 AHrs. A 100W solar panel gives you around 30 AHrs per day. So you will need to have about 300 watts of solar to charge them to 100%. You do not need to go to 100% every day, may be twice a week would be fine.

.

Likely you will need quite a bit more than 300W, reason is you need 300W MORE than the house load. My typical daytime house load is about 15 amps, which I believe takes 200W to just break even, then of course you don't get rated power out of panels, so to get 200W you need say 400W of panels.
Don't forget the house load in calculations

[john61ct]

Plus you need to size for suboptimal conditions, on perfect days should have lots of "wasted" output.

[Pizzazz]

Are you guys for real? Of course, you need to size for the house load or you can run the genny for a few more minutes. 30AHr is the average, already taking into account cloudy days. Are you really telling the OP to install extra solar for a few rainy days, given he already has a generator as a backup. Lastly, if your day load is 15A, and you night load is half that, we are talking 300 AHr daily consumption so you need around 1,000 Ahr battery bank. Typical average cruising boat. Super relevant.

[foggysail]

Originally Posted by Pizzazz

I have been in these threads for over a year and it is the same arguments over and over.

Golf carts cost $1/AHr and is the best value for money for wet cells. This is why golf carts and heavy equipment runs on them. Point me to a lithium system that costs significantly less than $7/AHr installed.

Some people pay for more expensive wet cells, some get AGMs. More power to them.

My thoughts exactly

[foggysail]

Originally Posted by john61ct

Why limit yourself to 8D?

Be very careful looking at 12V in automotive form factors, even from top notch vendors like Rolls.

Better to start with looking at their renewable energy or industrial line, most of which are 6V - 2v.

At least confirm they are specifically for deep cycling, should really be no mention of CCA/MCA ratings.

Get the DoD vs lifetime cycles chart and you'll see, rarely are the 12V models anywhere close.

I'm sure there are exceptions, and of course sometimes mods can't be made to the batt boxes.

And if you don't specifically **need** AGM, go FLA.

Why even consider 4 or 8Ds unless you're young and in the gym 3 times a week.

And IMHO, physical sizes are important along with cost/AH....deep cycle of course for all applications. How many of you folks are planning to start boat engines at 0 degrees F???

[Exile]

Originally Posted by john61ct

Why limit yourself to 8D?

Be very careful looking at 12V in automotive form factors, even from top notch vendors like Rolls.

Better to start with looking at their renewable energy or industrial line, most of which are 6V - 2v.

At least confirm they are specifically for deep cycling, should really be no mention of CCA/MCA ratings.

Get the DoD vs lifetime cycles chart and you'll see, rarely are the 12V models anywhere close.

I'm sure there are exceptions, and of course sometimes mods can't be made to the batt boxes.

And if you don't specifically **need** AGM, go FLA.

All good points. Main reason for sticking with 8D's is fiberglass batt. boxes specifically made to fit. They were designed for the FLA 8D's the boat came with (along with a G24 for genset start). I know two 31's won't fit but haven't measured for smaller 12v's or 6v's. I think the 2v's I looked at were too tall. Went with Lifeline AGM's last go-around which have lasted 7 yrs. & still appear healthy, but I have (unfortunately) been plugged into shore power much of that time and I equalize (per Lifeline's instructions) several times/year. Once out cruising you may be right that FLA's might make more sense, although all the batts. live under the bed in the main (aft) cabin, and I like not having to mess with watering. Fwiw, Lifeline is almost all deep cycle and they all list CCA's. They only make a few designated 12v start batts. in sizes smaller than 8D (27 & 31 I think).

The FLA Rolls/Surrette's I've looked at were designed for land-based off grid solar so I assumed they were deep cycle. Some mixed reviews suggesting inconsistent QC which surprised me given the co. rep. I didn't see any FLA 8D's on the Trojan site so maybe it's AGM only in 8D size.

[Exile]

Originally Posted by foggysail

Why even consider 4 or 8Ds unless you're young and in the gym 3 times a week.

And IMHO, physical sizes are important along with cost/AH....deep cycle of course for all applications. How many of you folks are planning to start boat engines at 0 degrees F???

I have a large deck hatch over the batt. compartment and next time I'm going to use a block with a 3:1 purchase hooked to the end of the boom to get them in & out. But you're right in that smaller/lighter would be much easier to deal with. I suppose the upside with my 8D's is less cabling/fewer terminals, and thus fewer points for corrosion/resistance.

[sailcrazy]

Exile....your post is exactly why I redesigned our DC system and House battery-to 6 T-105s. We had 2-8Ds, one developed an internal short with the case getting so hot I could have fried an egg on it!. We tied a cradle around it, rigged a pair of fiddle blocks to the boom, had 1 guy below and I was up top pulling it up. Just as we got it high enough to swing over the companionway entrance.....the line broke-and 175lbs of battery and sulphuric acid went tumbling back down! Broke the foot of the guy below, and did other damage to the sole. I said never again.....I can easily pick up a T-105 and carry it out if I ever need to, but no more 8D's below deck! I'll gladly clean a few extra battery posts now and then.

[Exile]

Originally Posted by a64pilot

Likely you will need quite a bit more than 300W, reason is you need 300W MORE than the house load. My typical daytime house load is about 15 amps, which I believe takes 200W to just break even, then of course you don't get rated power out of panels, so to get 200W you need say 400W of panels.
Don't forget the house load in calculations

Is your 15 amps estimate while under sail or at anchor/mooring? This is why it doesn't make that much sense to me to install even a single 100w panel which is all I feel I have room for right now. Fine for leaving the boat at anchor to keep the batts. up after a full charge, but I'm not sure it would contribute enough to offset house loads (at anchor) to make it worthwhile, even though those loads are typically quite modest.

[daletournier]

Originally Posted by sailcrazy

Exile....your post is exactly why I redesigned our DC system and House battery-to 6 T-105s. We had 2-8Ds, one developed an internal short with the case getting so hot I could have fried an egg on it!. We tied a cradle around it, rigged a pair of fiddle blocks to the boom, had 1 guy below and I was up top pulling it up. Just as we got it high enough to swing over the companionway entrance.....the line broke-and 175lbs of battery and sulphuric acid went tumbling back down! Broke the foot of the guy below, and did other damage to the sole. I said never again.....I can easily pick up a T-105 and carry it out if I ever need to, but no more 8D's below deck! I'll gladly clean a few extra battery posts now and then.

Yep, the weight is crazy. I have three of them on my current boat, on previous boat I had 6v trojans, personally I believe its the way to go, I can change the 6v batteries by myself.

When it comes to changing these I'll be going back.

[Exile]

Originally Posted by sailcrazy

Exile....your post is exactly why I redesigned our DC system and House battery-to 6 T-105s. We had 2-8Ds, one developed an internal short with the case getting so hot I could have fried an egg on it!. We tied a cradle around it, rigged a pair of fiddle blocks to the boom, had 1 guy below and I was up top pulling it up. Just as we got it high enough to swing over the companionway entrance.....the line broke-and 175lbs of battery and sulphuric acid went tumbling back down! Broke the foot of the guy below, and did other damage to the sole. I said never again.....I can easily pick up a T-105 and carry it out if I ever need to, but no more 8D's below deck! I'll gladly clean a few extra battery posts now and then.

I hear ya, and certainly something I've thought about. So did your 6 T-105's fit inside a batt. box that held your old 8D? How does your rated ah capacity compare? I've also seen what looks like an AGM version of the T-105 (can't remember the model #) but may not be worth the added expense and probably won't perform as well off the dock.

Another potential plus using the 6v's is the way my boat's configured it has a 3rd 8D just for engine starting. More recently I wired a fuel polisher to it just so it sees more use, but still seems way overkill to use an 8D for starting my 80hp engine when some of that capacity could be devoted to the house bank. I think a G31 would be more than enough and maybe a 27. The genset uses a Lifeline deep cycle 24 for it's start batt. and that has always been fine.

[Exile]

Originally Posted by Exile

I hear ya, and certainly something I've thought about. So did your 6 T-105's fit inside a batt. box that held your old 8D? How does your rated ah capacity compare? I've also seen what looks like an AGM version of the T-105 (can't remember the model #) but may not be worth the added expense and probably won't perform as well off the dock.

Another potential plus using the 6v's is the way my boat's configured it has a 3rd 8D just for engine starting. More recently I wired a fuel polisher to it just so it sees more use, but still seems way overkill to use an 8D for starting my 80hp engine when some of that capacity could be devoted to the house bank. I think a G31 would be more than enough and maybe a 27. The genset uses a Lifeline deep cycle 24 for it's start batt. and that has always been fine.

Compared specs for my 8D's vs. T-105's and answered a few of my own questions. The T-105's are about the same length, slightly narrower, and slightly taller, so two 6v's should fit in each box made for my 8D's just fine. 225ah vs. 255ah for the Lifelines, although there is also a T-125 (240ah) & a T-145 (260ah) that are slightly heavier & taller (and presumably more expensive). Trojan also offers a "one point" watering system which sounds like a plus. I could potentially devote all 6 to the house bank (675ah vs. my current 510ah) and modify the box for the genset start batt. to accommodate a G31 for both genset & main engine starting.

Is my understanding correct about these so-called "golf cart" batts. that they can endure a lot more abuse, i.e. repeated charges to only 80%, etc.?

[Kenomac]

After reading all this, it seems that by chance and doing a little homework I got things right. Invisible 450w solar capable of charging 100% while at anchor, 10kw generator with two Mastervolt chargers 125w and an 85p extra 24v alternator, for a 450ah Trojan 105 bank.

When the time comes, the Trojans will be replaced with same. 'Just finishing up season six in three weeks.

WOW! Post #8000.