12v 400ah battery bank

Nuno

New Member
Hello all.

I'm new to the world of solar and batteries.
I need to make a 12v 400 Ah house battery bank for a boat and I have a few questions, please.
Are CALB cells up to the job in marine environment?
Since 200ah CALB cells cost aproximately 25% of the 400Ah ones, do anyone see any problem in making a parallel and series 8 dell battery instead of a series only 4 cell battery?
What BMS should I use, 4s or 8s? Any reccomendation on model?

Many thanks in advance.
Nuno

 
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SolarRat

Photon Sorcerer
Are CALB cells up to the job in marine environment?
Since 200ah CALB cells cost aproximately 25% of the 400Ah ones, do anyone see any problem in making a parallel and series 8 dell battery instead of a series only 4 cell battery?
What BMS should I use, 4s or 8s?

CALBs should be good. There's no problem going with a 2p4s setup, with a 4s BMS. Posters here seem to like Daly BMS's.
 

grizzzman

Some say "Why" and some say "Why not?"
Will tested one that was a newer unit with a external temp sensor. It failed the test.(Daly)
The specs look good. Use the enterprise version of the software for the one you posted.
 

Nuno

New Member
Another question, please.
The seller states the following:

Nominal Capacity200Ah
Nominal Voltage3.2V
Impedance0.2~0.4mΩ
Standard discharge current200A
Standard Charge Current40A
Max.charge voltage3.65V
Discharge cut-off voltage2.5V
Charge working temp.0ºC~45ºC
Discharge working temp.-20ºC~55ºC
Charge methodCC/CV


Can I assume that in 2P4S (8cells, 12V, 400Ah) I can charge them with a current up to 80A?

Thanks in advance for your help.
 

Sojourner1

Itinerant
40a/ 200ah is .20c charge rate (or 80a/ 400ah) .5c seems to the recommended by manufacturer so if you could charge at 200a on 400ah batteries you would be fine.
 

Sojourner1

Itinerant
Never heard of "standard" charge current before but ok if that's the new wording for what ever that means... and standard compared to what???

From Calbs site, max 1C so anything less is fine, if using a motor to charge why limit the current if you can safely add more for less charge time, less wear and tear, less fuel cost.

Screenshot_20200113-191519_Chrome.jpg
 

SolarRat

Photon Sorcerer
Never heard of "standard" charge current before but ok if that's the new wording for what ever that means... and standard compared to what???

From Calbs site, max 1C so anything less is fine, if using a motor to charge why limit the current if you can safely add more for less charge time, less wear and tear, less fuel cost.

Standard is the recommended charge rate. 1C is MAX, for fast charging. Batteries will last longer at the standard charge. A lot longer in hot climates. If there's no reason to push it, don't. If you have no choice, go ahead and use max charge, but I'd recommend keeping an eye on temps.
 

Nuno

New Member
I'm still procuring the different parts.
I'll need 16 Calb 200ah cells.
A 200 amp bms.
I only have room for two300w solar panels.
I have a 70 amp alternator and I'm probably buying a 60 amp Sterling battery to battery charger, conecting the starboard fla starter battery with the house battery.
I'll probably need a genset... Next years investment. A marine genstet doesn't come cheap...
Still in doubt regarding mppt controller and inverter.
 

nosys70

Solar Addict
well you should ask yourself how you will charge this battery then.
because it take one hour to charge a 400A battery with a 400A source, but since you PV are 600W (50A under 12V AT BEST!) , they will hardly charge anything.
(well i mean if you have the need for a 400A battery it means you have a pretty solid load too).
so you will need to run your 70A alternator for 400/70 =6 hours a day just to charge the battery (let alone you are using the 600w PV to fullfill the eventual load)
 

Nuno

New Member
Good point!
One of the possible solutions is a genset, working when the largest loads are present and taking the opportunity to charge the batteries.
Another one is... A larger boat!
In fact I could instal some 600w more but that would mean getting rid of a lot of the living space outside.
Thanks for the input!
 

nosys70

Solar Addict
the easiest way to plan capacity is to plan without battery in the equation.
power in, power out. the battery will just be calculated as an extra load.
Then you add the battery for 2 reasons.
1- you need electricity when other sources are not possible (PV at night for example).
2- you need to level some short power surge (a starting fridge)
For short power surge a small battery is enough and require only to add the enough power to charge.
for delayed capacity, this is another problem because it depends a lot from how long you need to delay (a few hours in the evening or morning or all night long) and how much to delay (just the TV set and a few lights, or the AC all night long).
But keep in mind that draining a battery is usually easier and faster than charging it, ,so increasing the battery size is usually playing against you.
 
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SolarRat

Photon Sorcerer
There's nothing wrong with oversizing an LFP battery bank. It's a whole lot better than undersizing. Your batteries will last longer and you'll have the extra capacity if you need it. As long as you know you might have to give it help charging on the days following using the "extra". <That can be as simple as shutting off the loads and spending the day at the beach, instead of staying home and consuming sun power.
 

nosys70

Solar Addict
yes, but it all depends on your lifestyle.
Personnaly , i am looking for backup, so the Grid should be there most of the time, keeping the battery fully charged.
Then When Grid goes off, you switch to PV and battery.
With that scenario, you are looking for a huge battery because you know that if the grid goes off for 3 days, you expect your batteries to be empty at the end of the 3rd day. The PV are here just to slow down the battery drain, and you will not change your habits (like if you were still living on the grid).
But for a day to day all year long off-grid life, you will have to change some habits, forget about huge fridge, AC running all day and night long unless you can afford a huge array of PV.
So a 400A battery is not a bad idea, but not on a boat , where room is limited and Pv exposure not always optimal. 200A should be ok and a genset would be welcome (because you can run it at anytime you really need power).
 
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