LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[pacific_voyager]

Originally Posted by s/v Holiday

Hi all,

I would like to get some advise on adding to my existing LifePo4 batteries. I have 600ah LifePo4 battery bank and feel the need to add 200ah more capacity as I am headed across the pacific and beyond and my boat is a bit of a power hog.

I think it would be a bad idea to mix brands and age of batteries. With LA batteries you would never mix brands and ages. With LIFO batteries it might be different, but I would not bet on it.

You did not mention your net daily power consumption, but unless it is well over 200AH per day I would just keep the old bank and not do anything.

Another option is to install a second bank of 400-600AH that is independent of the first bank. Charge them separately on alternate days. I don't know what you could get selling the old batteries but this suggestion might prove less expensive and give you more power plus redundancy.

Good Luck

Jeff

[GoingWalkabout]

Hi,

I asked this question before. Perhaps I wasn't clear. I did get answers but none concerning what I actually asked.

The question is, is it better to have one large say 1,000 Mah. Battery rather than a BANK of batteries. One battery means no load balancing required. Could be more cost effective. Maybe even the total outlay could be less. Any thoughts would be appreciated.

Thanks,
Chaya

[darylat8750]

Originally Posted by GoingWalkabout

Hi,

I asked this question before. Perhaps I wasn't clear. I did get answers but none concerning what I actually asked.

The question is, is it better to have one large say 1,000 Mah. Battery rather than a BANK of batteries. One battery means no load balancing required. Could be more cost effective. Maybe even the total outlay could be less. Any thoughts would be appreciated.

Thanks,
Chaya

They come as 2 volt cells so you have to have at least 4 cells for a 12 volt system.

[kmacdonald]

Originally Posted by darylat8750

They come as 2 volt cells so you have to have at least 4 cells for a 12 volt system.

Last time I checked 2 X 4= 8

I think you would need 6, two volt cells if I'm not mistaken.

[darylat8750]

Post 5313 has bad numbers in it! Sorry...

Originally Posted by kmacdonald

Last time I checked 2 X 4= 8

I think you would need 6, two volt cells if I'm not mistaken.

OOF DA! Thanks. Dyslexia strikes again! :banged: 2 volts=lead acid Lithium Iron would be about 3.4V

[kmacdonald]

If you assume that the usable energy in a AGM battery is 35 or 40% of rating and lithium is 80% of rating then lithium is also a little cheaper if you don't have to change your charging system too much or have a BMS. With a little care you don't need the BMS but mistakes can be expensive. It's worked fine for me for years.

[GoingWalkabout]

Originally Posted by GoingWalkabout

Hi,

I asked this question before. Perhaps I wasn't clear. I did get answers but none concerning what I actually asked.

The question is, is it better to have one large say 1,000 Mah. Battery rather than a BANK of batteries. One battery means no load balancing required. Could be more cost effective. Maybe even the total outlay could be less. Any thoughts would be appreciated.

Thanks,
Chaya

Oooops. I meant 1000AH not MAH. Sorry but I work with MAH's in my day job

In other words. My question is what is better. A a bank of LifePo4 100 AH or 1 or 2 x 1,000 AH single batteries?

While I'm at it. How many 325W solar panels would I need to fill 1,000 AH battery daily? I realize the answer is a guestamet based on averages and assumptions. That is exactly why I'm asking cruisers here who have real life experience.

By the way you may will ask why am I looking at such a high power system. Simple. I want to run my AC without cranking a genset. I also like showering in hot water and would like to keep all the electronics running without having to choose between what I have on.

The reason also why I may over build the Amp Hour battery capacity it is simply to take in all of the sun and maybe wind power that I can. I see no good reason in having to shut down solar intake after just 2 hours in summer like those with small Amp Hour set ups do.

My philosophy on solar and wind is not to even look at the cost. For me it is infrastructure cost/investment. Those who have had to bring power lines onto a previous unnerved farm know the costs of doing this. They don't go and then calculate that cost into their electric bill over the next 10 years. No. It is a capital expenditure to achieve a lifestyle goal. I think it is the same for setting up your solar plant onboard. Do it the best way your budget can allow and best practises dictate. This is just my opinion.

Chaya

[SV THIRD DAY]

Voltage...they don't make a nominal 12v single cell LiFePO4 battery.
So you need to put four 3.2v cells in series to get your needed 12v battery.

[snarron]

Originally Posted by GoingWalkabout

Hi,

I asked this question before. Perhaps I wasn't clear. I did get answers but none concerning what I actually asked.

The question is, is it better to have one large say 1,000 Mah. Battery rather than a BANK of batteries. One battery means no load balancing required. Could be more cost effective. Maybe even the total outlay could be less. Any thoughts would be appreciated.

Thanks,
Chaya

GoingWalkabout, Please don't take this the wrong way. But your question in and of it's self shows you need to really spend a good amount more time studying this subject. Please read this thread from the beginning and you will see just what I'm talking about. Please do this before you proceed or a real disaster is possible.

It's a chore, but well worth it! There is a great web site you should visit and my concerns will be made clear.

"LiFePO4 Batteries - Thoughts & Musings" by Compass Marine. It's about 3/4 way down the page.

Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com

It is directely referenced thru-out this thread several (Many) times. Best of luck!

[foojin]

I know it's rapidly advancing technology, and no doubt this has been discussed before, but....

Is there a book or website where LiFePO4 battery systems are explained?

[Jman]

Originally Posted by GoingWalkabout

Oooops. I meant 1000AH not MAH. Sorry but I work with MAH's in my day job

In other words. My question is what is better. A a bank of LifePo4 100 AH or 1 or 2 x 1,000 AH single batteries?

While I'm at it. How many 325W solar panels would I need to fill 1,000 AH battery daily? I realize the answer is a guestamet based on averages and assumptions. That is exactly why I'm asking cruisers here who have real life experience.

By the way you may will ask why am I looking at such a high power system. Simple. I want to run my AC without cranking a genset. I also like showering in hot water and would like to keep all the electronics running without having to choose between what I have on.

The reason also why I may over build the Amp Hour battery capacity it is simply to take in all of the sun and maybe wind power that I can. I see no good reason in having to shut down solar intake after just 2 hours in summer like those with small Amp Hour set ups do.

My philosophy on solar and wind is not to even look at the cost. For me it is infrastructure cost/investment. Those who have had to bring power lines onto a previous unnerved farm know the costs of doing this. They don't go and then calculate that cost into their electric bill over the next 10 years. No. It is a capital expenditure to achieve a lifestyle goal. I think it is the same for setting up your solar plant onboard. Do it the best way your budget can allow and best practises dictate. This is just my opinion.

Chaya

Really evident that you have not done any real research in this thread alone. Let alone other threads on energy usage.

You need multiples of 4 cells, to create a twelve volt system (battery). Whether that requires BMS if you choose 4 1000 ah cells, or not, is up for debate.

It is simple math to convert 325 watts to 14 volts = ~23 amps. How many panels you need depends on latitudes, ability to have all the panels in the sun at all daylight hours, cloud cover, charging efficiency, etc.

As to using solar power to generate electricity to generate heat to generate hot water... If you want to heat 5 gallons of water, 50 degrees Fahrenheit, you need over 600 watt hours, just for your hot water shower. Again not counting converting from sun to 12 volts, and back to AC through your inverter. And presuming you are will to wait for it to heat up, and then use immediately i.e. Not keeping it hot.

As to air conditioning - a 10000 btu air conditioner probably uses in the neighborhood 700 watts while running. Which will probably not even put a dent in the requirements to cool your proposed Lagoon 56.

Please do a little bit more research on your own before demanding answers from the group.




Sent from my iPhone using Cruisers Sailing Forum

[transmitterdan]

Originally Posted by GoingWalkabout

Oooops. I meant 1000AH not MAH. Sorry but I work with MAH's in my day job

Snip...

By the way you may will ask why am I looking at such a high power system. Simple. I want to run my AC without cranking a genset. I also like showering in hot water and would like to keep all the electronics running without having to choose between what I have on.

Chaya,

The reality is that you would have to cover your boat entirely in solar panels to create enough energy in a 10 hour day to run air conditioning 24/7. Even to run AC at night requires an enormous solar array.

Battery bank required to run 20K BTUs of AC for 8-10 hours is about 10-15kW hours. For LiPo it would require about 1,200AH bank. And it would take 1000W of solar a couple days to fully charge.

For the vast majority of cruisers on 40-50 foot boats running AC from solar is still a futuristic endeavor. Someone will jump on and tell you they do it but for most of us it isn't practical.

[KASHMIR]

Originally Posted by foojin

I know it's rapidly advancing technology, and no doubt this has been discussed before, but....

Is there a book or website where LiFePO4 battery systems are explained?

Compass marine has a lot of info.LiFePO4 Batteries - Thoughts & Musings Photo Gallery by Compass Marine How To at pbase.com

We also have a bit here:
Lithium power
And in our back copy newsletters:
Lithium power

Admin, please remove if this is taken as advertising.

Peter

[Anjin]

I completed the testing of my new Lithium install today and thought I'd share the setup and a few photos with the folks here that provided me so much help and guidance.

So this is for my 2011 Lagoon 450. The boat was built for the charter trade and has extensive dc loads (2 not too well insulated fridges, a freezer, all electric winches, etc) and a large 13KW generator along with full air conditioning. In charter, the mode of operation was sail/motor during the day, run the generator (and air conditioning) all night which also recharged the 800 AH of AGM batteries. My wife and I will be living aboard in the Bahamas and did not want to be a slave to the generator and are willing to give up air conditioning (or at least cut back it's use to every other week or so). I bought the boat in March not in great shape; two years of charter and three years of utter neglect had taken its toll so I’ve been busy with restoration and repair since then but converting to a large Lithium bank and upgrading the solar have been high priorities.

So I started with the size and weight of the pre-existing batteries - they weighed about 520 lbs and fit under the berth in the master cabin along with a really disturbing rats nest of cables and wires that connected them and connected the master switches for the house batteries and starboard engine. I considered a 4P4S arrangement with CALB CA400AH (1600AH) cells but they were hard to get and seemed to be getting harder to get rather than easier. The 180AH cells were plentiful and I was told (and have since confirmed) that they actually have at least 200AH capacity. So I opted for an 8P4S configuration (1440AH). I got the cells from Kelly Larsen at the Electric Car Parts Company in Utah. They actually shipped from CALB USA in California and arrived at my local freight depot. I picked them up (not easy in a Subaru, but that’s another story) and moved them to my basement for few months to “get to know them.”

I followed Maine Sail’s advice and got a decent bench supply (0-60A, 015V) and top balanced them in groups and ultimately together (32P - takes time to top balance with 50 or so amps spread over 32 cells). I then configured them in the 8P4S setup and, using my new Victron Multi 3K inverter/charger started cycling them - charging and discharging all the while monitoring the stability, behavior, and performance. The Victron was a little tricky to program but I followed the general advice of Rolf Roetter and Rich Boren and tried to set it up for a consistent 13.8v in absorption with no float. BTW, this is also where I learned a valuable lesson - connections matter! (duh) After fooling with jumper cables and finally replacing them with cheap but decent automobile battery cables the charging and discharging behavior settled down and I started getting predictable and expected behaviors. I also started being careful in assembly of the configurations, polishing the terminals and using dielectric grease for all the bus bar connections.

I then added the components of a homegrown BMS. I used the Lightobject programmable voltmeter (discussed extensively in this thread) driving a pair of BlueSea 7713 remote battery switches. Programming the Lightobject was easy and I ultimately wired the on board relays in series with the manual remote switches that came with the 7713s and (on the boat) used those switches to replace the Battery Master switch. The Lightobject voltmeter has 4 programmable settings that translate to Charger cutoff (14.1v), Charger restart (13.6v), Load cutoff (12.6), Load restart (12.8). These are initial settings and may change as I gain more experience. I also purchased a Junsi 8s logger for cell level monitoring but have not yet decided whether I will install that on the boat - the 8P cells are just incredibly stable and with the careful top balancing I’ve done, they never seem to drift more than a couple of millivolts apart.

While still set up in my basement I also wired up (and got to know) a Victron BMV 700 battery monitor - a marvel of a device that has really helped me understand and anticipate the behavior of the bank. It also drives alarms for high and low voltage (inside the range of the HVC/LVC) as well as for low capacity. It has much more capability that I’m just beginning to explore but I can’t say enough good about this product. Peter Kennedy (Peter Kennedy Yacht Services - Marine Electrical Systems) helped with all the products I wound up buying - all the Victron and Blusea stuff I’ve mentioned plus busbars, fuses, remotes, etc.

Once I started moving the setup from my basement to the boat, things got serious and I sought some advice and help. I had all the pieces and parts (charge bus, load bus, ground bus, remote switches, shunts, etc) but was unsure about where to put everything. Andy and Rouric from Yacht Electronic Systems suggested a layout for all the components and offered to help with the recabling. I installed everything the way Andy suggested and then gladly accepted their help in removing the old batteries and untangling the rat’s nest of cables in the existing setup. They did beautiful work and when that was completed I did the actual installation of the batteries. They are installed carefully inside a frame I designed and built and that also accommodated full length ratcheting hold down straps.

I also reprogrammed the existing Cristec chargers to 13.8 volts and use them primarily as back up to the Victron Multi Charger. When it has external power (shoreside or generator), the Victron will throw 120 Amps non-stop at the new batteries until they reach 13.8v at which point it will switch to absorption and rapidly tail off current and eventually float (which I’ve programmed to be effectively off).

I also replaced the crappy controller that came with the pre-existing solar panels mounted over the davits as practice for my upcoming solar upgrade (also another story).

I completely sidestepped the (seemingly endless) debates about the best approach to deal with the alternators. I view the alternators as a backup to the solar (primary) and the Victron (primary when the generator is on or when docked with shore power and backed up by the Cristecs). We also don’t motor very much - it’s a sail boat ya know. Anyway, I didn’t have the money to upgrade the rudimentary hitachi 80 amp alternators so I just left them attached to the starter batteries and ran the house bank connections to a switch that allows me to turn them on as chargers when I need to and have the time to monitor them and turn them off when I don’t.

Finally, I also had to cut back the drawer that fits under the berth to accomodate the Victron. That space is pretty tight now and I'll probably have to add better ventilation but for now am just monitoring the temperature in there.

Anyway, we’re just getting used to the new setup and I still have to tackle the solar upgrade. But I’m pretty proud of the way it turned out and attached some photos of the install for anyone whose interested. Happy to answer any questions or provide more photos if anyone is curious about the details.

And a big thanks to all of you for your help and advice!

[GoingWalkabout]

Originally Posted by Jman

Really evident that you have not done any real research in this thread alone. Let alone other threads on energy usage.

You need multiples of 4 cells, to create a twelve volt system (battery). Whether that requires BMS if you choose 4 1000 ah cells, or not, is up for debate.

It is simple math to convert 325 watts to 14 volts = ~23 amps. How many panels you need depends on latitudes, ability to have all the panels in the sun at all daylight hours, cloud cover, charging efficiency, etc.

As to using solar power to generate electricity to generate heat to generate hot water... If you want to heat 5 gallons of water, 50 degrees Fahrenheit, you need over 600 watt hours, just for your hot water shower. Again not counting converting from sun to 12 volts, and back to AC through your inverter. And presuming you are will to wait for it to heat up, and then use immediately i.e. Not keeping it hot.

As to air conditioning - a 10000 btu air conditioner probably uses in the neighborhood 700 watts while running. Which will probably not even put a dent in the requirements to cool your proposed Lagoon 56.

Please do a little bit more research on your own before demanding answers from the group.




Sent from my iPhone using Cruisers Sailing Forum

I humbly apologize. I didn't think I was demanding anything from anyone.