Best batteries for $2k budget

[kmacdonald]

Originally Posted by Dockhead

As someone above said, few will care about efficiency, we care about speed -- because it's the hours of running the charge source, not the small incremental use of horsepower, which costs money and which bothers us. Right?

In your case that's right but not for people that use solar to charge batteries. It's the limited availability of solar power that is wasted in charge inefficiency that is troubling.

People often think it's charge inefficiency only that causes a LA battery to take a long time to fully charge but it's not. It's not even the primary reason. During absorption the charge source can supply the full acceptance current at CV. The current tapers off as the increased internal resistance of the battery limits charge current. The battery is considered full when the acceptance current drops to between 0.01C to 0.03C. For a 400 Ah battery that would be an acceptance current of 4 to 12 Amps. A properly sized charge system for a 400 Ah battery should be able to deliver between 40 and 52 Amps so a large portion of charge capacity is not usable past CC charging.

The second, but to a significantly less degree, reason for long charge times is high charge inefficiency at high SOC. Not all the energy put into the battery is stored by the battery. It's wasted watts. Charge efficiency = power stored divided by power delivered to the battery. It starts out high during CC and gradually drops during CV charging.

Those issues don't exist with Lithium. They will accept full charger capacity (if sized properly) right up to 100% SOC and will do so at close to 95% (WAG) efficiency. This, PSOC cycling ability, and cycle life make lithium very attractive. You can't charge them below freezing though.

[dfelsent]

I’m going on year two with three Firefly L16. My Merlin smart gauge (now Balmar) shows something but I’m not quite sure how accurate it is. It seems kind of right.
It’s complicated by the use of wind for the slow charging tail. The gauge has never seemed to read correctly with the constant low current from the wind gen.
This was the case with the gauge and fla as well.

The gauge does go up and down with charge and discharge. [emoji1]
Having the firefly bank has let me stop obsessing about PSOC though. That’s a win, at least for my head.

[Dockhead]

Originally Posted by dfelsent

I’m going on year two with three Firefly L16. My Merlin smart gauge (now Balmar) shows something but I’m not quite sure how accurate it is. It seems kind of right.
It’s complicated by the use of wind for the slow charging tail. The gauge has never seemed to read correctly with the constant low current from the wind gen.
This was the case with the gauge and fla as well.

The gauge does go up and down with charge and discharge. [emoji1]
Having the firefly bank has let me stop obsessing about PSOC though. That’s a win, at least for my head.

If we're now talking about battery monitors, I have and love the SG, which is far more accurate than any other battery monitor I've ever used under certain conditions, but one should understand its limitations:


1. It is useless for figuring out how far you get in a partial charging run, until the charge source has been off for a while.


2. It is useless if there is any charge source working, however small, at the same time you are discharging.



It is brilliant for determing DOD when there are no charge sources present.


I wouldn't have one on a boat with wind or solar.


But on my boat it's excellent.

[a64pilot]

Smart Gauge works great on my boat with 1000W of Solar and a 660AH bank.
You watch charge acceptance rate to get a feel for SOC during charging, the SG is in my opinion best for determining SOC first thing in the morning.
Wind I think is what could confuse it as of course it raises the voltage of the battery higher than actual during the discharge phase

[sailorboy1]

Originally Posted by kmacdonald

In your case that's right but not for people that use solar to charge batteries. It's the limited availability of solar power that is wasted in charge inefficiency that is troubling.

Doesn't bother me if the solar isn't getting fully used due to the charge efficiency. All that matter to me is the the batteries get charged! Why do people what to over think it and make it hard?

[Adventuresail]

I read something interesting on Emarine's website - That firefly batteries should regularly be charged at 0.4C.
So that means that a 180 amp charging source would be necessary to charge a modest 450ah bank of firefly batteries. Can you even achieve 180 amp charge rates without very expensive equipment? Starting the main engine with a very large alternator for an hour or two a day seems like the cheapest (still not that cheap) but also the least attractive when you are in a nice anchorage. You hardly want to listen to the 80hp, 1000lb diesel engine vibrating under your feet while you eat breakfast.

Comparatively, 900 ah of LA can be charged happily every day through a large solar array, silently and reasonably cheaply.

It is the extra costs around higher performance battery technologies that are keeping me with FLA batteries until I have a much bigger budget.

[Adventuresail]

https://www.emarineinc.com/Firefly-Group-31-FAQ

[kmacdonald]

Originally Posted by sailorboy1

Doesn't bother me if the solar isn't getting fully used due to the charge efficiency. All that matter to me is the the batteries get charged! Why do people what to over think it and make it hard?

Because it's a great profit center for marine service providers. Massive up-sells are the norm. It's certainly a buyer beware industry scattered with land mines. Personally I think it's hilarious. Reminds me of the Y2K software issue fear mongering. Caveat Emptor!!!!!!!!!!!

Sounds like you got plenty of solar.

[kmacdonald]

Originally Posted by Adventuresail

I read something interesting on Emarine's website - That firefly batteries should regularly be charged at 0.4C.
So that means that a 180 amp charging source would be necessary to charge a modest 450ah bank of firefly batteries. Can you even achieve 180 amp charge rates without very expensive equipment? Starting the main engine with a very large alternator for an hour or two a day seems like the cheapest (still not that cheap) but also the least attractive when you are in a nice anchorage. You hardly want to listen to the 80hp, 1000lb diesel engine vibrating under your feet while you eat breakfast.

Comparatively, 900 ah of LA can be charged happily every day through a large solar array, silently and reasonably cheaply.

It is the extra costs around higher performance battery technologies that are keeping me with FLA batteries until I have a much bigger budget.

Sounds about right. Warranty void! Didn't follow manufacturers charge recommendations. Oh boy, I better be careful.

Salesman play book:
1) hype large output alternators and lead the unwary to believe a 150 amp (high performance no less) alternator will charge your LA batteries twice as fast as the stock 75 amp alternator. Stands to reason.
2) sell serpentine pulley kit when 3/8" belts are shredded by 150 amp (high performance) alternator.
3) When timing cover breaks (that diesel) or crank bearing are destroyed act like it's the first time you heard of that.
4) sell new diesel engine (cant get parts for old one BS)
5) oooops! you need new ancillary equipment also. SHAFT, cutlass bearing, gear, prop, exhaust, shop materials, etc.
6) cold call: How do you like your new charge system now?

Of course the marine industry is dying. They shot themselves in the head.

[sailorboy1]

Originally Posted by Adventuresail

I read something interesting on Emarine's website - That firefly batteries should regularly be charged at 0.4C.
So that means that a 180 amp charging source would be necessary to charge a modest 450ah bank of firefly batteries. Can you even achieve 180 amp charge rates without very expensive equipment?

Between my standard 100 amp alternator, 70 amp charger I can run off the Honda, solar that can do 45 amp, I can do over 0.4C if needed.

But FF says that 0.2C is enough and that happens if motoring while the sun is out.

I wouldn't let the high charge requirement of a "recovery" to offset that advantages of not having the everyday issue of PSOC.

[roland stockham]

You know the old adage that you should never discuss politics or religion on a boat? maybe we should add batteries and anchors...

[kmacdonald]

Originally Posted by roland stockham

You know the old adage that you should never discuss politics or religion on a boat? maybe we should add batteries and anchors...

My gosh, what would we want to do that for?

[a64pilot]

Originally Posted by sailorboy1

200AH in a 800AH bank is the last 25% and the bank starts at 75% SOC
200AH in a 600AH bank is the last 33.3%, and the ban starts at 66.6% SOC

Given a battery charger capable of putting out at 100% capacity 100 amps and that each bank could accept that till it reaches the mysterious 80% state of charge point. Then the battery acceptance just drops as a function of the internal resistance of the battery and varies as a % of capacity, which the bank doesn't matter.

800ah X (80-75%) = 40ah, divided by 100 amp = 0.4 hours = 24 minutes
600AH x 1(80-66.6%) =80.4ah, divided by 100 amp = 0.8 hours = 48 minutes

After that point it is assumed each battery bank will accept charge amps less than 100 amps and be self limiting and each will charge at the same rate. Let's say it takes 4 hours to go from 80% to 100%m that means the 880ah bank takes 4H 24m and the 600ah takes 4H 48m. So it takes longer to fully recharge the 600 ah bank to 100%.

Is it worth debating? You decide.

I just noticed this going back in the thread.
I’m not correcting anyone, however what wasn’t said was the comparison of the cycle life of the larger bank being discharged shallower is a lot longer then the smaller bank being discharged to a greater percentage.

Says the guy going from 660 AH to 450

What is also interesting to me is these totally unrealistic cycle lives given by most battery manufacturers.
But for instance a battery rated at 10,000 cycles should last a full time cruiser assuming 350 cycles a year, 28.5 years.
How often does that happen?

[a64pilot]

Originally Posted by Adventuresail

I read something interesting on Emarine's website - That firefly batteries should regularly be charged at 0.4C.
So that means that a 180 amp charging source would be necessary to charge a modest 450ah bank of firefly batteries. Can you even achieve 180 amp charge rates without very expensive equipment? Starting the main engine with a very large alternator for an hour or two a day seems like the cheapest (still not that cheap) but also the least attractive when you are in a nice anchorage. You hardly want to listen to the 80hp, 1000lb diesel engine vibrating under your feet while you eat breakfast.

Comparatively, 900 ah of LA can be charged happily every day through a large solar array, silently and reasonably cheaply.

It is the extra costs around higher performance battery technologies that are keeping me with FLA batteries until I have a much bigger budget.

I believe that high charge rates are good for AGM in general, but as SB says later on that .2c is acceptable.
I can do .4c as I have a 125 amp charger as part of my inverter and I have a 60 amp Sterling, so that’s 185 amps.
It takes about all my 3.5 KW generator can do to charge at 185 amps though, it also just about maxes out my 30 amp shorepower too. If my 660 AH Lifeline bank is representative and I assume it is, it will only accept that high a charge rate for 20 min if the bank is at 50% and I never actually pull my bank that low.
So I wouldn’t expect my 450 AH Firefly bank to accept .4c unless at a very low SOC.

I theorize that high charge rates raise plate temperature, and that may help reverse sulphation.
A question is does a Firefly actually reverse sulphation, prevent it? or do they just “deal” with it better?