LFP batteries

tiltrider1 · Aug 2, 2024

By dumb luck I met an engineer who does remote camp electrical systems. Most camps get their electricity from generators. Fuel is a big expense for them as is generator longevity.

He was explaining to me how they were using LFP batteries instead of small generators to run the camp at night. Charging was done on non peak times to keep the generator loaded. His oldest bank was 10 years old and he was still seeing 95% capacity from the batteries. His opinion was that the batteries should see 20 years but he was unaware of anyone having 20 years of experience with LFP so could not be sure that the batteries won’t fall off a cliff capacity wise.

He also made a very interesting comment. In his camps they use external BMS’s. In his opinion the BMS circuitry is the weak link in the system. He feels I will never reach the end of my batteries life but would eventually end up replacing them due to failed BMS’s. How long the BMS’s would last was anyone’s guess and wouldn’t be surprised if failure rates were totally random.

Interesting conversation and point of view.

SteveK · Aug 2, 2024

Interesting, Will Prowse compares BMS in every test he does. He has commented that an otherwise great storage system is run by a weak link BMS waiting to fail.

DavidM · Aug 2, 2024

SteveK said:
Interesting, Will Prowse compares BMS in every test he does. He has commented that an otherwise great storage system is run by a weak link BMS waiting to fail.

But the lack of a functioning overcurrent protection system- the BMS can be resolved with a simple fuse, so why the big deal about no or a poorly working BMS?

I would much rather depend on a fuse blowing to protect the wire and/or the battery than an electronic circuit- a BMS.

David

luna · Aug 2, 2024

Bms's do a lot more than that provided by a fuse.
Can a fuse warn you of imminent shut down due to overcharge, depletion, overtemp, undertemp, cell balance? Does the fuse monitor/control cell balancing?
I think a reasonably good BMS provides most if not all and maybe more of these functions.
Then, maybe I'm wrong.

Fuses I thought are a must for other, catastrophic failure reasons.

tiltrider1 · Aug 2, 2024

I used Will Prowse as one of many educational sources when educating myself on LFP. He even commented favorably on Eco-worthy batteries. Still, it’s not easy to grade the quality of a circuit board. I suspect as we all get better educated we will start to recognize the different BMS manufacturers and will have a better idea on which ones are quality builds.

There have been situations were I had 3 identical Raymarine MFD’s on the same dash. Over the course of ten years two of them partially failed. Each time it was a circuit board but, not the same circuit board.

It is speculation that this gentleman believes we will all suffer circuit board failures before actual battery failures. Certainly it’s not something to worry about but certainly something to be paid attention to.

tiltrider1 · Aug 2, 2024

DavidM said:
But the lack of a functioning overcurrent protection system- the BMS can be resolved with a simple fuse, so why the big deal about no or a poorly working BMS?

I would much rather depend on a fuse blowing to protect the wire and/or the battery than an electronic circuit- a BMS.

David

The BMS does a multiple of things. Over current protection is probably the least important. Turning off the current when the battery is fully charged is probably the most important. Then there is cell balancing and temperature monitoring just to mention a few items.

Barking Sands · Aug 2, 2024

DavidM said:
But the lack of a functioning overcurrent protection system- the BMS can be resolved with a simple fuse, so why the big deal about no or a poorly working BMS?

I would much rather depend on a fuse blowing to protect the wire and/or the battery than an electronic circuit- a BMS.

David

Its a pretty interesting topic. A very good BMS is pretty amazing, Coupled with a quality fuse and you have the best of both worlds. In most modern BMS's there are several layers of current protection. All deal with current over time. For instance on the Epoch 460 the Short Circuit Protection ( the last line of defense) is 1650A in 400uS (.0004 seconds). 9 times out of 10 that SC protect will cut current prior to the internal 500 amp class T fuse blowing since that class T fuse has its own current over time ratio. I was doing some reading on the characteristics of Class T fuses recently and they are amazing. But being able to plug in a current and a time scale into a couple of fields in an app is tough to beat. I know of at least 5 people who have gotten the SC prot with the Epoch 460 and other than the warning there was not even so much as a noticeable spark. Very anticlimactic. I do know of 1 that blew his class T fuse though. He ordered one and replaced it a few days later and all was well. To clear the SC protect all you do is disconnect the load and cycle the power. You dont want SC protect to auto reset with time of course. So given the choice...and paying for a BMS...it would be best for it to work as stated in the documentation. That way you can design your system appropriately or at least plan on a multilayered approach.

Jeff F · Aug 3, 2024

I have a couple of LI Time 300a batteries. If (when?) the internal BMS fails my plan is to cut open the battery and use the cells with an alternative protection. I don't see a BMS failure as necessarily being the end of the line for the battery.

SeaMaster101 · Aug 19, 2024

Well designed lithium battery system will not depend on the BMS to be cutting off for over voltage and under voltage. The charging system should be well within the limits and there should be way to automatically start generator or solar to recharge the batteries if they go down below certain voltage, the BMS is not considered a switch. It is final level of protection and yes, it is designed to be able to cut full of its rated current but that should not be happening often or ever.
Needless to remind you that those BMS from 10 years ago were very early age BMS, therefore BMS exceed by factor of 10 the capabilities and the reliability of the early BMS

BILL GOOD1 · Aug 19, 2024

SeaMaster101 said:
Well designed lithium battery system will not depend on the BMS to be cutting off for over voltage and under voltage. The charging system should be well within the limits and there should be way to automatically start generator or solar to recharge the batteries if they go down below certain voltage, the BMS is not considered a switch. It is final level of protection and yes, it is designed to be able to cut full of its rated current but that should not be happening often or ever.
Needless to remind you that those BMS from 10 years ago were very early age BMS, therefore BMS exceed by factor of 10 the capabilities and the reliability of the early BMS

Which has raised (for me on reflection) how will the BMS work if a cell within the battery fails? I will modify my install to ensure the BMS disconnect power will not rely on the battery in use but will obtain the power from an external battery i.e. the starter battery to ensure a proper disconnect. (the BMS & balance boards cost more than the cells on this install compared to the first LIFEPO4 done over 12yrs on my sailboat)

tpbrady · Aug 19, 2024

I have drawn on paper my LFP upgrade architecture with the only missing part being the battery I want to select. With the ABYC recommendation for using UL1642/1673 tested batteries, that is what I am focusing on. The problem is the Chinese battery manufacturers don't seem to advertise their UL certification well and bury it way down in their specifications. In addition they apparently only test some of their batteries but not all. Does anyone know of a list of UL tested LFP batteries?

Tom

BILL GOOD1 · Aug 19, 2024

Further you may have to look into what is the real specs on DIY installations as I found out too late that the cells for solar installs are reject cells from Chinese manufactures that fail the requirements for heavy EV use in China. We just do not why they failed the required QA. 15yrs ago I used CALB cells & was assured of specs & they did last but now buyer beware is the new rule. Try to get cells with serial numbers that are following from the manufacturer direct even if you have to pay more!

dhays · Aug 19, 2024

Over the years I have learned to defer to Rod Collins/MaineSail/CMS on anything related to electric systems. He really likes Epoch batteries. He also has some recommended "budget" batteries available on Amazon.

Barking Sands · Aug 19, 2024

dhays said:
Over the years I have learned to defer to Rod Collins/MaineSail/CMS on anything related to electric systems. He really likes Epoch batteries. He also has some recommended "budget" batteries available on Amazon.

They continue to move forward as well. They just dropped a 300ah dual purpose cranking battery. In several months they will have additional large 24 and 48 volt batteries as well. They aren't without a few quirks, but the battery and performance is great. A new tear down video just came out which has a teardown of their Essentials budget battery side by side with the 460 Marine battery. The Essentials battery uses a JBD BMS and has good performance and heating etc. But when he opens the 460 Marine...its on another engineering level. it uses their own proprietary BMS coupled in a slick way to some buss bars and has a big heat sink that is open to the outside of the case. Its clear these batts are a complete engineering effort from case to cells to hardware to BMS, not just a box with cells, bms and foam/tape. It does have its quirks though from a software and app standpoint. The price of the 460 Marine is now down to $1799 and its easy to get 10% off that.

READY · Aug 19, 2024

I am probably going to go with MG Energy brand batteries for my new to me 2011 Greenline GL33. They built the Victron batteries (2013) that I am replacing. It currently has 2x 24V 190 AH. They still work but seem to have lost significant capacity and at 11 years they are at the end of expected life. The new MG Energy batts are 24v 305 AH. Same case size so easy retrofit. Probably 2x the price of Epoch but overall the easy path forward. Over what I hope is a 10 year life the cost/year premium is not life changing.

Barking Sands · Aug 19, 2024

READY said:
I am probably going to go with MG Energy brand batteries for my new to me 2011 Greenline GL33. They built the Victron batteries (2013) that I am replacing. It currently has 2x 24V 190 AH. They still work but seem to have lost significant capacity and at 11 years they are at the end of expected life. The new MG Energy batts are 24v 305 AH. Same case size so easy retrofit. Probably 2x the price of Epoch but overall the easy path forward. Over what I hope is a 10 year life the cost/year premium is not life changing.

Looking over the MG batteries they look like higher end batteries, probably better than Epoch and most others. Hard to say what glitches and anomalies the package may have but a 300ah x 24 volt is nice.

READY · Aug 19, 2024

If it were just a house battery setup I probably would not spend the extra money on the mg batteries. But since it's a key part of the propulsion system and also supplies my inverter with no generator to charge them up I will rest a little easier knowing they are top of the line and that fully integrates into the rest of the victron system. Mg energy makes some massive batteries for much higher voltages and capacities so I suspect they have a very rigorous quality control and Manufacturing process. I really do like the Epoch and that latest review where they took apart the professional model showed it an extremely well-constructed battery. That would save me probably 2 to $3,000 but it's a different form factor and I don't think they have a 24 volt Victron Comms version shipping yet I am purchasing them through our local Victron distributor so I also have his backing if I run into any issues. I am normally the guy who is always looking for a deal and getting the best bargain but I decided to bite the bullet on this one.

tiltrider1 · Aug 20, 2024

I always bought my lead acid batteries from a local manufacturer who built for the railroads and commercial fishing fleet. I knew their batteries were built to the highest standards.

With LFP, they all come out of China. There is little ability to know which batteries are quality and which ones are not. I’ve seen all the YouTube video’s and there isn’t any consistency between expensive batteries and inexpensive batteries.

I understand why some buy the expensive brands hoping there is a difference and why some buy the inexpensive ones believing they are just as good as the cheap ones.

Hopefully we will all keep reporting our experience with different brands over the next 10 years.

Comodave · Aug 20, 2024

Nothing says that from year to year there will be a consistency of quality with batteries from China…

twistedtree · Aug 20, 2024

READY said:
I am probably going to go with MG Energy brand batteries for my new to me 2011 Greenline GL33. They built the Victron batteries (2013) that I am replacing. It currently has 2x 24V 190 AH. They still work but seem to have lost significant capacity and at 11 years they are at the end of expected life. The new MG Energy batts are 24v 305 AH. Same case size so easy retrofit. Probably 2x the price of Epoch but overall the easy path forward. Over what I hope is a 10 year life the cost/year premium is not life changing.

I'm using MG Energy both in my boat and home. They are really first rate, include control signals for shutting down alternators, etc, support DVCC, and integrate well with Victron inverters. I've helped several other people get set up with them as well.

rslifkin · Aug 20, 2024

tiltrider1 said:
I always bought my lead acid batteries from a local manufacturer who built for the railroads and commercial fishing fleet. I knew their batteries were built to the highest standards.

With LFP, they all come out of China. There is little ability to know which batteries are quality and which ones are not. I’ve seen all the YouTube video’s and there isn’t any consistency between expensive batteries and inexpensive batteries.

I understand why some buy the expensive brands hoping there is a difference and why some buy the inexpensive ones believing they are just as good as the cheap ones.

Hopefully we will all keep reporting our experience with different brands over the next 10 years.

Even with lead there are a few decent manufacturers in China (and plenty of crappy ones). With LFP, there are only a few cell manufacturers, so most of the batteries out there are using cells from only a couple of sources, the differences between manufacturers is down to the BMS they choose, quality of their interconnects, and how they package the whole thing. So if they give info on what cells they use, etc. and the rest checks out when someone digs into it, then I'd consider them an acceptable source.

dannc · Aug 20, 2024

rslifkin said:
Even with lead there are a few decent manufacturers in China (and plenty of crappy ones). With LFP, there are only a few cell manufacturers, so most of the batteries out there are using cells from only a couple of sources, the differences between manufacturers is down to the BMS they choose, quality of their interconnects, and how they package the whole thing.

And how well the battery manufacturers test the cells and battery. The manufacturer would be tracking cell quality since they are going to be responsible for the warranty. For instance, Praxis is a commercial marine systems manufacturer that builds LiFePo batteries and they would have to stand behind their batteries. Praxis batteries are similar to the higher end MG batteries that are mounted in racks and can have water cooling.

tiltrider1 · Aug 20, 2024

Eco worthy just released a new battery. 280 Ah 12v with low temp cut off sensor and Bluetooth for $520.

Just shows what a moving target the LFP market is.

Barking Sands · Aug 20, 2024

I just bought a Chin's 48 volt 100ah battery right off Amazon for $799 on sale for my Electric Zero turn mower. Been using if for a month now. All works great.

The lead acid agm replacements would have cost $100 more. And the cheap Chins batt can probably mow 3 times as much (maybe 2.5 to 3 acres) because there is so little voltage sag. When the AGM reported 50% on the stock meter the cutting motors would die randomly, almost certainly due to voltage sag.

What a time to be alive! LOL.

LFP batteries

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