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

[mrm]

Originally Posted by FlyingCloud1937

No,

what is an inverter?

How much does it draw?

What is the heat?

just, FSAG's..I would love to see this technology, become real.

Lloyd

A DC/AC voltage/current converter.

A bunch'a Amps. (Pin = eta * Pout), eta >1.0

A form of energy.

Have serious doubts.


Ciao. (DNFTT)

PS: I also know what a windlass is, and a bow thruster. Impressive, isn't it?

[FlyingCloud1937]

Originally Posted by mcarling

I hope you're kidding. First, choose a manufacturer and a product. Then read the warranty.

No I'm not kidding!

Have you read the Winston Cell Battery Manual.

I have(I'll send anyone a copy) it states BMS Required, what is the definition of a BMS that meets Winston's requirements. It's not listed in the manual.

Is it the same for Bolqon??

Lloyd

sorry I forgot you timed out

[T1 Terry]

Originally Posted by FlyingCloud1937

No I'm not kidding!

Have you read the Winston Cell Battery Manual.

I have(I'll send anyone a copy) it states BMS Required, what is the definition of a BMS that meets Winston's requirements. It's not listed in the manual.

Is it the same for Bolqon??

Lloyd

sorry I forgot you timed out

Now you re talking complete B/S, they say no such thing in their manual. Can you give me the name of the BMS manufacturer that Winston, Sinopoly, CALB, recommend to protect their cells?
It's all fun and games till someone calls your bluff

[catakate]

MAYDAY MAYDAY MAYDAY
We have an emergency situation going on about an emerging technology here!
Let those who dare do the work, give a hand or duck!
Nobody here wants to know if somebody trusts this technology, those willing to discuss this are invited to open a new thread!

[Lagoon4us]

This fantastic thread will have to be swept clean every 24 due to one person who just delights in argument.

My supplier recommends a BMS, they have various boards, controllers and cutouts available to build one to their design, they will not recommend anyones particular BMS.

My thoughts are that a BMS is desirable on a yacht simply because it isn't manned 24/7, we spend at least 4 to 7 hrs ashore walking,fishing or exploring so we need to know there's some form of cutout if a cell went spacko.

Whilst i understand the chances are slim of this happening on a well balanced and settled unit it is still a possibility. We don't expect our seacock's/hoses to spring a leak BUT we have auto bilge pumps and alarms should this also happen, it's just the nature of boats.

Cheers all let's hope this thread doesn't degenerate into oblivion it's been extremely informative, highly technical with great explainers, love it

[mbianka]

Originally Posted by senormechanico

A typical 12 volt battery is just a bunch of 2 volt cells in series and I've never heard anyone worry about cell balancing or matching.
In the big picture, I don't see any problem slapping a minimal BMS on a set of lithiums.
It's working fine for me.

Senormechanico:

I think any type batteries set up in a series string should be kept in balanced. I make sure my 8A4D 210 amp AGM batteries that make up the 48 volts for my electric propulsion bank are kept in balance by a Pro Quad 4 charger. I first bulk charge them in series and then switch to the Pro Quad to finish topping them off. So far they have still working very well as I start my sixth season with electric propulsion. So my feeling is if it ain't broke don't fix it. But, I am enjoying the the discussion and Deckofficers and Maine Sail's testing and posts here but, still not convinced that I would go LifePo4 when this AGM bank gives up the ghost due to the complexity of the additional BMS circuitry involved and the sensitive voltage requirements/limits of the Lithium technology.

[Dockhead]

Following up on Deck Officers recommendation on a LiFePO4 battery for me to use as a power supply for a HF radio, I wrote to Balqon for information. My questions, and their answers follow:

I am interested in your 40 amp/hour 12 volt battery to use as a power supply for a marine HF radio on board a sailboat. Can you tell me:

1. Does this battery have an on-board BMS, and if so, can you please describe the functionality of it?

2. Can you ship to the UK, post code SO31 1ZL? Cost and time?

Thanks very much, Dockhead




Hi: These batteries do not have a BMS, they were made for a direct replacement. Balqon does not feel safe selling these batteries without some sort of minor BMS though. We opened up a 12v90ah battery and realized there was (4)-90ah batteries inside, no resistors or anything. So I would suggest a BMS or one of my options is to call China direct and ask one of their technicians.

Yes we can ship to the UK. How many were you looking for? I will set up a quote to show costs for this shipment, and to get approval from you to confirm purchase. Regards, Balqon."




So it looks like Balqon are just flogging something they get from China.


Is it worth messing with something like, do you think? The price is right.

[mcarling]

Originally Posted by senormechanico

A typical 12 volt battery is just a bunch of 2 volt cells in series and I've never heard anyone worry about cell balancing or matching.

In my opinion the need for a BMS with a 12V lead acid battery (6 cells) is at least as great and probably much greater than the need for a BMS with a 12V LiFePO4 battery (4 cells). I would not put a BMS on either because I don't think the costs and risks are worth the benefit but, in my opinion, one can make a stronger case for a BMS with lead acid.

[catakate]

Given the shipping prices and the fact that I couldn't find any supplier in Eastern Europe, maybe we have a business opportunity in Europe here?

[diugo]

Again, a mountain is being made of a mole hill with regard to the need for a BMS.

It's very simple. Cells in series should be kept at the same state of charge. Especially when they are near full charge or near full discharge. For cells of identical capacity, that generally means the individual cells should always be nearly the same voltage.

Every LFP owner should invest in a $20 device that can monitor individual cell voltages and sound an alarm and/or operate a disconnect IF (and it's a big IF) the voltages ever get out of range. IF this happens, there are two straightforward options: the cells can be balanced manually---or they can be balanced automatically. The manual option requires time; the automatic option requires additional expense.

[ebaugh]

Originally Posted by catakate

Given the shipping prices and the fact that I couldn't find any supplier in Eastern Europe, maybe we have a business opportunity in Europe here?

These guys are a distributer is the Czech Republic...isn't that Eastern Europe? I've never done business with them....

http://www.ev-power.eu/

[mcarling]

Originally Posted by diugo

Every LFP owner should invest in a $20 device that can monitor individual cell voltages and sound an alarm and/or disconnect the battery IF (and it's a big IF) the voltages ever get out of range.

I don't share that opinion. I check cell balance once a year, manually, and see no reason to change. Historically, I did that with a hydrometer. With LiFePO4 cells, I'll be doing so with a handheld voltmeter.

How often did you check for balanced cells with lead acid batteries? Whatever the answer, that often or less often is how often you should check for balanced cells with LiFePO4. I have seen no reason to check for balance more frequently with LiFePO4 than with lead acid.

[hellosailor]

Gotta disagree, Terry.
"...unless you have a system in excess of 1.5kW an MPPT controller is a waste of good $$"
Whether it is a waste depends. If you consider that an MPPT controller, regardless of size and capacity, is going to pump juice into the batteries about 10-15% more effectively, that also means that if I'm trying to get a charge on one sunny day, in between cloudy days, that "wasted" controller is going to give me 10% more power, period. If I need that, the MPPT has given it to me, and the money was not wasted.
And again, if you are not on a ship and you have limited space for panels on your boat, the MPPT controller allows you to spend 10% less on panels, or to have 10% less space consumed by them. If you don't have unshaded space available for more panels, again, the MPPT pays for itself.
A waste? Only if you are in circumstances where there's another way to get power, or less power will do.

"if you have a system that uses more than one charging source at the same time, MPPT wouldn't work, they don't share well with others."
No no no, totally mis-stated. ANY regulated power source will have the same issue, this is nothing at all special aboiut MPPTs. Any engine-driven alternator with a regulator is going to respond in the same way, cutting back power when it sees high voltage at the battery. The MPPT is no different from a standard integral alternator in this sense.
The only chargers that will not suffer from seeing multiple charging sources, are the DUMB chargers that simply put out full unregulated power, or put out full power until they overproduce and dump.
That's not a problem with MPPT, that's a problem because there are apparently no "integrated charge combiners" on the market. There is no product, no solution, that combines multiple power sources and then moderates all of them in response to battery state.
And that also applies to all battery types, lithium, lead, nickel-cadmium, all of them.

You give folks the impression this is an MPPT problem or a battery type problem. It isn't. It is called "too many toys" and the different systems simply need human supervision when they are being used outside of their intended design. Which IS somewhat limited, but given all the options, not unreasonably so.

[mrm]

Originally Posted by catakate

Given the shipping prices and the fact that I couldn't find any supplier in Eastern Europe, maybe we have a business opportunity in Europe here?

Hmm, they are located in Czech Republic, I believe: EV-Power | About Us

and they are in Poland: Contact us

But competition is a good thing, go for it :-)

[diugo]

Originally Posted by mcarling

I don't share that opinion. I check cell balance once a year, manually, and see no reason to change. Historically, I did that with a hydrometer. With LiFePO4 cells, I'll be doing so with a handheld voltmeter.

Then you are operating recklessly. Cells could easily go out of balance (and then out of range), especially near full charge and near full discharge.

How often did you check for balanced cells with lead acid batteries? Whatever the answer, that often or less often is how often you should check for balanced cells with LiFePO4. I have seen no reason to check for balance more frequently with LiFePO4 than with lead acid.

The critical difference, of course, is that lead acid cells are much more tolerant of voltage excursions. That "opinion" should not be overlooked.