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Old 21-03-2019, 13:21   #1
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Battery, Solar and Genset Options

I've been reading threads regarding battery replacement. I understand about guesstimating my daily power needs, but my questions are a little more basic. Most of them regard the LiFePO4s.

FWIW, I have maintained and replaced batteries, AGMs and LA, even completely rewired 2 boats. But after reading these threads, it seems technology has passed me by. I feel like the veritable fish out of water.

I read about these batteries. Quite honestly, for environmental, longevity and space to weight considerations, PLUS all the other benefits, they seem like a no-brainer, even at the hefty initial expense. Having dealt with 1000-1200 deep cycle batteries, I can't even imagine one with 5000.

1. Since most of the larger LiFePO4 are 3.2V, how are these calculated for a 12V or 24V system? Would I need 3 or 4 per 12V? Or is the 3.2V the charge voltage they need?

2. I'm looking at adding 24V solar as well, 24V so I have a smaller feed line, and less loss in the 25' to the MPPT and batteries. (I have thought about going the other way and mounting the MPPT on the panel, but I am still learning about what the best would be.)

3. Another possibility is to make the entire system 24V, with a 12V transformer to service everything, including a 12V watermaker. Is that practical?

4. The boat has a diesel generator and plan to remove it completely. In its place, I want a fast charging battery system, maintained by solar, alternator and possibly wind. Looking at the specs on the LiFePO4s, this seems a good possibility.

First and foremost, I have no desire to ever plug into shore power, which is a major design consideration.

I looked into the Integral System, but at $30,000 to $40,000, is absolutely cost prohibitive.

I have an $10,000 budget (with a slight possibility of more if I need it), hoping it will last 8 years. This is for solar, batteries, beefed up alternator, and possibly a wind generator (but one that DOESN'T make a lot of noise or vibration! I have been on 4 boats with them, and have yet to impressed, much less have on on my boat).

Seems the LiFePO4 batteries will do that, ....possibly even longer.

Am I on the right track with my overall design?

PS: I should add, the boat has shore power connections, so worse case, I can always add a charger. I just don't want to have to rely on plugging in, because once we get on anchor, we won't have that option anyway.
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Old 21-03-2019, 14:02   #2
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Re: Battery, Solar and Genset Options

I’ll be interested in this thread, but I’d be surprised if you could keep up with charging a big Li bank without access to the two big charging sources: shore power or generator. Distant Shores 3 has a setup as you suggest, but I would hate to think how much that would have cost if it weren’t sponsored. Certainly way over he budget you specify, although I guess that depends on your load requirements.

Making the whole system 24v is a possibility, but unless you intend to replace pretty much all of the pumps, windlass, water maker etc with 24v ones I’m not sure if you will get any significant benefit from it. The point of going 24v is to reduce current draw, which is defeated if you then convert it to 12v to power everything.

Removing a diesel generator is a very unusual step. I’ve not heard of anyone doing this, unless you have a truly ludicrous area of solar panels that would need a gigantic catamaran to mount. If you’re willing to do without high-draw luxuries such as a washing machine, AC, electric cooking then you’d be fine. But if you have a generator already then why wouldn’t you be installing these things? Personally I’m always looking for more charging options rather than fewer, so a generator is on my list to install rather than remove. Heck, some high users install two!

I’ve not yet come across a wind generator that’s not ugly, under-powered, or noisy. Or more than one of these.

Look forward with interest to how you get along.
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Old 21-03-2019, 17:11   #3
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Re: Battery, Solar and Genset Options

Two points I should clarify.

2 & 3. When I refer to making it a 24V system, I only mean making the battery bank 24V to match the solar, and since I will be upgrading the alternator, making it 24V too. Then I'd connect the bank to a 24V to 12V transformer, and wire it into the existing inverter.

Hmmmmm.... Writing that, ......that seems a tad convoluted. Guess I could keep everything at 12V, but use 24V for the solar panels to MPPT controller.

4. The genset is a 30yo Kohler 3Kw beast, with a the fuel economy of .....*starts laughing hysterically* ....yeah, right.
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Old 21-03-2019, 17:42   #4
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Re: Battery, Solar and Genset Options

Oh ok, if the genset is near the end of its life then you’re comparing replacing it with not having one, which is fair enough.

I’m not sure what you mean by “24v solar to the mppt controller”. If I’m not mistaken, the panels produce all sorts of voltages and currents to the controller, and that’s the thing that converts it all to 12 or 24v as you require. Since the controllers are usually near your batteries, you get the mppt controller to provide what your batteries need. The supply wire at 12 or 24v is short.

I think you’re getting too concerned about the difference between 12 and 24v on a relatively low-current supply. 24v systems excel in the high current areas where you have real thick wiring: alternator, windlass, bowthruster, winches, inverter. You’re not going to have enough solar in one chunk to match anything like those situations unless you have 1000W+ of panels, in which case it would almost certainly be best split over more than one bank of panels and controllers surely?
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Old 21-03-2019, 19:15   #5
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Re: Battery, Solar and Genset Options

12V = 4S aka four cells in series, 13.2 nominal, 13.8-14V charging just right.

True for all LFP, chemistry is chemistry, cell Ah capacity irrelevant to voltage.

MPPT controller, needs to be close to the bank. High voltage panels will help increase efficiency, but keep VoC at 90% of the max rating.

Stick to 12V unless you've compelling reasons to go higher.

Think hard about getting rid of the genset if it's there and working IMO keep it. Need a quality shore charger for that.

With a limited budget - in what market? Also think hard about the risk of LFP, in the US well over a decade to get any ROI

Pass on wind power if you have solar + alternator + genset.
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Old 21-03-2019, 19:20   #6
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Re: Battery, Solar and Genset Options

Quote:
Originally Posted by CptCrunchie View Post
making the battery bank 24V to match the solar
An MPPT controller can use 40V or 65V whatever panels voltage, no reason whatsoever to "match" the bank voltage.

Of course alt output does need to match your 12V bank.

> genset is a 30yo Kohler 3Kw beast, with a the fuel economy of .....*starts laughing hysterically* ....yeah, right

never mind. You may only need it 20 days a year, total of 60 hours.

But I'd bet big you'll regret scrapping it.
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Old 21-03-2019, 19:58   #7
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Re: Battery, Solar and Genset Options

Quote:
Originally Posted by john61ct View Post
An MPPT controller can use 40V or 65V whatever panels voltage, no reason whatsoever to "match" the bank voltage.

Of course alt output does need to match your 12V bank.

> genset is a 30yo Kohler 3Kw beast, with a the fuel economy of .....*starts laughing hysterically* ....yeah, right

never mind. You may only need it 20 days a year, total of 60 hours.

But I'd bet big you'll regret scrapping it.
You make excellent points. Even though we would use the genset very little, it would make for the ultimate back-up.

I was planning on using the genset space for the LiFePO4's, but I will look for space elsewhere. This means I will likely have to put them in 3 different places. No matter, I have yards of 4/0 marine wire.

As to the 24V from the panels, I understand the voltage they run. I just see it as 12V for 2 in parallel and 24V for 2 in series. Over the same size wire, two panels in series over 25' of wire delivers slightly more power to the MPPT controller than 2 in parallel.
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Old 21-03-2019, 22:36   #8
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Re: Battery, Solar and Genset Options

Correct, but only if neither is shaded at all
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Old 22-03-2019, 10:10   #9
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Re: Battery, Solar and Genset Options

Quote:
Originally Posted by Tillsbury View Post
Removing a diesel generator is a very unusual step. Ive not heard of anyone doing this, unless you have a truly ludicrous area of solar panels that would need a gigantic catamaran to mount. If youre willing to do without high-draw luxuries such as a washing machine, AC, electric cooking then youd be fine. But if you have a generator already then why wouldnt you be installing these things? Personally Im always looking for more charging options rather than fewer, so a generator is on my list to install rather than remove. Heck, some high users install two!
One of the first steps after buying my boat was to remove the builtin washer/dryer. Within a year I pulled the 500 pound Onan 8.0 Genset, and later the dinghy davits exchanged for a windvane. Its a sailboat designed and built for adventure...not a luxury condo. To each his own.

~ ~ _/) ~ ~ MJH
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Old 22-03-2019, 12:01   #10
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Re: Battery, Solar and Genset Options

You haven't said what your daily power needs are, or how much solar you can mount.
Could you use higher efficiency solar and Firefly batteries to cram in enough of each?
88 usable amp hrs from each G31 and if you accidently drain them they bounce right back.
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Old 22-03-2019, 13:04   #11
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Re: Battery, Solar and Genset Options

Pull the old school Gen set , install a next gen with sound shield . Smaller lighter and quieter
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Old 22-03-2019, 17:17   #12
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Re: Battery, Solar and Genset Options

Keep it simple and what you're familiar with. Keep the voltages at 12, keep the generator as long as you can, put on a high output alternator, add a couple of solar panels and stick with the AGM's. I can recommend the Firefly batteries. They have a long life because they don't sulfate and absorb high levels of amps. They are expensive up front but in the long run they are cheaper.
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Old 22-03-2019, 17:51   #13
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Re: Battery, Solar and Genset Options

Quote:
Originally Posted by CptCrunchie View Post
I've been reading threads regarding battery replacement. I understand about guesstimating my daily power needs, but my questions are a little more basic. Most of them regard the LiFePO4s.

FWIW, I have maintained and replaced batteries, AGMs and LA, even completely rewired 2 boats. But after reading these threads, it seems technology has passed me by. I feel like the veritable fish out of water.

I read about these batteries. Quite honestly, for environmental, longevity and space to weight considerations, PLUS all the other benefits, they seem like a no-brainer, even at the hefty initial expense. Having dealt with 1000-1200 deep cycle batteries, I can't even imagine one with 5000.

1. Since most of the larger LiFePO4 are 3.2V, how are these calculated for a 12V or 24V system? Would I need 3 or 4 per 12V? Or is the 3.2V the charge voltage they need?

2. I'm looking at adding 24V solar as well, 24V so I have a smaller feed line, and less loss in the 25' to the MPPT and batteries. (I have thought about going the other way and mounting the MPPT on the panel, but I am still learning about what the best would be.)

3. Another possibility is to make the entire system 24V, with a 12V transformer to service everything, including a 12V watermaker. Is that practical?

4. The boat has a diesel generator and plan to remove it completely. In its place, I want a fast charging battery system, maintained by solar, alternator and possibly wind. Looking at the specs on the LiFePO4s, this seems a good possibility.

First and foremost, I have no desire to ever plug into shore power, which is a major design consideration.

I looked into the Integral System, but at $30,000 to $40,000, is absolutely cost prohibitive.

I have an $10,000 budget (with a slight possibility of more if I need it), hoping it will last 8 years. This is for solar, batteries, beefed up alternator, and possibly a wind generator (but one that DOESN'T make a lot of noise or vibration! I have been on 4 boats with them, and have yet to impressed, much less have on on my boat).

Seems the LiFePO4 batteries will do that, ....possibly even longer.

Am I on the right track with my overall design?

PS: I should add, the boat has shore power connections, so worse case, I can always add a charger. I just don't want to have to rely on plugging in, because once we get on anchor, we won't have that option anyway.
I see your near me . What boat are you doing the lfp install on ? What is the current battery setup and location ( you will be replacing them so use the same location )
Keep the genset you will be happy you did.
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Old 23-03-2019, 20:24   #14
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Re: Battery, Solar and Genset Options

Gentlemen, gentlemen,
Every time I read something with regard to batteries - or electrical equipment - it would appear that you have to have a degree in Electrical Engineering - to understand the jargon!
It isn't that I am slooowww - it is just that everyone else - is faaassttteerr - than I aammm!

ok. Boat sunk, generator U/S. Heard everything nowadays, done via battery charge to batteries and then onto inverters, but after asking ten different guys and getting ten different answers, wondering whether someone out there can suggest what way is best and not exorbitantly expensive (remember - am a retiree that worked a little too hard - saved a little too much - so now get nothing in return from my government).

Here in Australia, I currently have 240v fridges and microwave with 12v for lighting and 32v systems which I will convert 32 to 24v if i finally get motors rebuilt Detroit 8v71's. I have been told 32v winch - will work on 24v???

So, can someone please - in layman's terms - advise as to what i should do IE. type of inverter, batteries etc, that I will need?

Cheers

Gbmacca
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Old 23-03-2019, 20:36   #15
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Re: Battery, Solar and Genset Options



Since your configuration is completely different than what I am facing, please start your own thread. I'm still gradually putting mine together.
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