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locked Batteries starting to get weak - MMM - What to do -


Mark McGovern
 

Arno,

Voltage may not be as bad an indicator of SOC of LiFePO4 batteries as you might think.  Here's a quote from the owner of MV Tanglewood who has had his LiFePO4 bank in operation for about ~18 months now:

First, counter to what everyone says, I think battery bank voltage is a sufficiently close indicator of SOG.  People say it's a much worse indicator for LFP vs Lead, but I disagree.  My lead bank was 50.4 volts when fully charged, and 48.0V when is was 50% empty and the generator started.  That's a spread of 2.4 volts.  In contrast, my LPF bank is full at 53.6V, and ready for recharge at 50.4V.  That's a 3.2V spread and is 30% more voltage swing than lead.  The difference, though, is that in the mid area of charge, the LFP voltage doesn't vary much, so there isn't as much differentiation between 60% and 50%.

Granted, this 3.2v spread is for his nominal 48v system but even with our nominal 24v system it would be a 1.6v spread which is a significant enough spread to monitor and act on.  I am literally in the middle of installing my LiFePO4 system and I am not yet living full time on the boat so I don't have a ton of personal experience with it just yet.  However, the experience that I do have so far lines up with Tanglewood's experience.  I think that if you operated an LiFePO4 system simplistically such that it is assumed to be "full" at 26.8V (stop charging) and then "empty" at 25.2v (start charging), the battery bank would be quite happy and would give you many years of service.

Here is the full blog post:  http://www.mvtanglewood.com/search/label/Lithium%20Batteries  

Be sure to read his other LiFePO4 related posts.  They are full of great information.
 
--
Mark McGovern
SM #440 Cara
Deale, MD USA


Scott SV Tengah
 

Mark,

I looked at his first post and a few things he stated that is not consistent with the known characteristics of lithium:

1) Take a look at the voltage vs. SOC graph for a Lifepo4 battery. 
https://www.powerstream.com/lithium-phosphate-charge-voltage.htm

At 3.2v per cell or (3.2*8 = 25.8v) you are at around 3-8% state of charge.
At 3.3v per cell or (3.3*8 = 26.4v) you are at around 20-31% state of charge.
At 3.4v per cell or (3.4*8= 27.2v) you are at around 96-99% SOC. 

But it's not just the spread, it's the shape of the curve. The challenge is that the lithium curve, unlike lead, is NOT linear. The middle portion between say 10% and 90% has a very flat voltage curve.  See link above. I can attest that with my Mastervolt 110A charger set to 27.5v absorption, the alternator has stopped charging anywhere between 75-100%, averaging 85%.

If you set your charger to stop charging at 26.8v, you may be charging your batteries to only 40-50%.

And as you can see with lead, the voltage vs. SOC curve is quite linear, making it far more useful to determine SOC from voltage.
https://www.researchgate.net/profile/Jeff_Cherry2/publication/315847359/figure/fig2/AS:633864561106948@1528136496496/Typical-Open-Circuit-Voltage-OCV-of-12V-Lead-Acid-Battery.png

2) He stops charging at 3.45v per cell and has a high voltage alarm at 3.5v. His high voltage ALARM is below Victron's absorption voltage of 3.55v and below Mastervolt's absorption voltage of 3.6v. Keeping voltage low like that will help avoid high SOC induced imbalances but there are other sources of imbalance too, namely high load or imperfectly assembled batteries. And most cell balancing systems require you to charge to near full before they start balancing, as indicated by low charge current acceptance rate - namely because of the non-linear charge curve. I have had batteries that show perfect balance until you approach 3.5v+ and then one cell goes wildly out of balance.

By not charging your batteries fully every once in a while, you may end up prolonging a cell imbalance issue that, in the event that you need to draw the batteries quite deeply (big storm, can't run the genset because of sea state), could result in a cell LOW voltage problem that will destroy the battery or cause your BMS to disconnect your loads at the worst time. Further, most battery monitors determine state of charge based on calibrating to 100%. And 100% on my battery monitor is determined when charge current is below X for time period Y. That means the battery is full and no longer accepting charge. As such, Victron explicitly recommends charging fully once a month to recalibrate the SOC monitor.



--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Mark McGovern
 
Edited

Scott,

Thanks for taking the time to reply.  I have read your posts with great interest and they have definitely helped me in planning and implementing my own system which shares many of the same components that you chose (i.e. I have lots of blue Victron stuff in my SM!).  

To be clear, I'm not saying that what the owner of MV Tanglewood is doing is the "correct" way to do it.  It certainly is not what most LiFePO4 manufacturers recommend.  I was simply stating that there does appear to be an observable and actionable correlation between voltage and State of Charge (SOC) with LiFePO4 batteries.  I totally agree that there is not a lot of "resolution" in the middle of the curve but there is enough resolution at the tail ends of the curve to take action before damage is done on either end of the curve.

Regarding the data posted that is posted here: https://www.powerstream.com/lithium-phosphate-charge-voltage.htm  you can see from the description of the test above the data that the test was done using very small batteries (less than 2.5 Ah capacity) and was done at over a 1C discharge rate (2.5 Amp discharge on 2.2 to 2.4 Ah batteries).  That is an extremely high discharge rate that is not really indicative of how we generally use our battery banks on our boats.  My normal "sitting at anchor" discharge rate is closer to 0.01C and I can even run one of the Air Conditioner units on the boat and still stay under 0.1C.  I think this high discharge rate has a significant impact on the Voltage vs. SOC results.

The data posted at the bottom of this article is from a test that I believe is much more indicative of how we use our battery banks:  https://marinehowto.com/lifepo4-batteries-on-boats/ and even this test is done at a relatively high discharge rate of about 0.075C.  Here is the chart of Voltage vs. Ah Discharged on the  772nd(!) Cycle on his ~11 year old LiFePO4 battery bank: https://marinehowto.com/wp-content/uploads/2015/09/34-LiFePO4-On-Boats.png


  


It's impossible to read the chart above but you can see the details in the links I that posted above.  I took the data from this 0.075C discharge test to get the following approximate Voltage vs. State of Charge %:

At 3.15v per cell or (3.15*4/8 = 12.6v/25.2v) you are at around ~15-18% SOC.
At 3.2v per cell or (3.2*4/8 = 12.8v/25.6v) you are at around ~30% SOC
At 3.3v per cell or (3.3*4/8 = 13.2v/26.4v) you are at around ~95% SOC
At 3.4v per cell or (3.4*4/8= 13.6v/27.2v) you are at around ~99-100% SOC

So on our nominal 24v boats there is a 1.2v difference from ~95%SOC to 15-18% SOC (26.4v-25.2v=1.2v).  That's not a huge difference, but it is easy to observe and use in decision making.

Other things to note in those test results:

  • He charges the bank to only 13.8v (3.45v per cell) with a 7.5amp tail current.  That's 27.6v on our 24v boat and is well below what most LiFePO4 battery manufacturers recommend. 
  • The battery bank reaches only 13.5v (3.37v per cell) at the start of the test with those charging parameters.
  • The voltage drops from 13.5v to 13.26v (3.32v per cell) after discharging only 6 Ah.
  • This data is from an eleven year old battery bank of LiFePO4 cells that has been in use in the lab and on a sailboat for and has had 773 cycles.  Most of those cycles have been to 80% depth of discharge or more.
  • This bank was rated at 400Ah when it was new but eleven years and almost 800 deep cycles later it still has MORE capacity than it was rated for when it was new.
Based on all of the above, Tanglewood's seemingly relatively simplistic scheme of charging to 3.45v per cell (but apparently only reaching 3.35v per cell or 26.8v on a 24v system), discharging normally, then charging again when the battery bank reaches 3.15v per cell (25.2v for Amels) seems pretty reasonable as it would cycle his batteries from 95% SOC to 15=18% SOC.  Only time will tell!  Hopefully he will continue to post his findings, good or bad. 

--
Mark McGovern
SM #440 Cara
Deale, MD USA


Arno Luijten
 

Mark, Scott,

Thanks for the links and additional information.  Very interesting and helpful.

My point with using voltage to determine SOC is that the whole system on a boat in “action” is not stable. Your fridges turn on and off all the time. There is a cloud in front of your solar panel, a windgust for your windgenerator, you run a sheet winch, etc etc. So the voltage varies quite a bit because of fluctuating current draw and we just determined the voltage curve on Lithium is quite flat. How is your BMS to determine the SOC? This is why you really need a coulomb counter and some way to make it control your charging sources. Mastervolt has this mastershunt thing and some other stuff to make that happen but it quickly becomes very complex and maybe too complex for a bue water boat. I don’t know.
Anyway, for my usecase I think (as Scott rightfully says) it is not worth the trouble. I’m first going to try Firefly carbon foam batteries and in a few years we will see what the next best is. For those who spend most of the time off-grid lithium is much more attractive.

Regards,

Arno
SV Luna,
A54-121


Mark McGovern
 

Arno,

No problem.  That article that I linked to by Compass Marine is by far the most comprehensive that I have found regarding using LiFePO4 batteries in a marine electrical system.  I have read it many, many times and every time I re-read it I learn something new.

If I was not intending to move aboard full time and do extensive off-grid cruising, I would not have made the switch to LiFePO4.  The Firefly batteries you mentioned would be my choice for "part time" cruising.  They appear to have many of the same benefits of LiFePO4 regarding charge acceptance rate and Partial State of Charge use without the relative complexity and cost of installing a LiFePO system.

When thinking about SOC keep in mind that part of the beauty of LiFePO4 batteries is that, unlike Lead Acid batteries, they really don't care what the SOC is within a really wide range. They seem to be as happy at ~30% SOC as they are at ~90%.  They really just dislike the extremes, so the main job of the BMS (at least how Victron designs their BMS) is to keep the batteries from getting over-charged (over voltage) and getting over-discharged (under voltage) by cutting off charging source(s) or load(s).  Otherwise, the BMS doesn't really intervene in normal daily use (outside of intra-battery cell balancing which is a separate topic to itself and disallowing charging at temperatures below 5 deg C).

To give you some idea of the "new thinking" required with these batteries compared to Lead Acid when I took delivery of my batteries it was going to be several weeks before I could install them.  New batteries are delivered at about a 50% SOC.  When I asked my dealer how long I could leave them "as is" and what I needed to do to maintain them he said I could leave them that way for many months and probably years, and that I didn't need to do anything other than store them at a reasonable temperature.  Can you imagine what would happen to your Lead Acid batteries if they were left at 50% SOC for months?


--
Mark McGovern
SM #440 Cara
Deale, MD USA


Matt Salatino
 

Fire Fly doesn’t care if stored at 50% SOC

~~~⛵️~~~Matt

On Sep 12, 2020, at 3:29 PM, Mark McGovern <mfmcgovern@...> wrote:

Arno,

No problem.  That article that I linked to by Compass Marine is by far the most comprehensive that I have found regarding using LiFePO4 batteries in a marine electrical system.  I have read it many, many times and every time I re-read it I learn something new.

If I was not intending to move aboard full time and do extensive off-grid cruising, I would not have made the switch to LiFePO4.  The Firefly batteries you mentioned would be my choice for "part time" cruising.  They appear to have many of the same benefits of LiFePO4 regarding charge acceptance rate and Partial State of Charge use without the relative complexity and cost of installing a LiFePO system.

When thinking about SOC keep in mind that part of the beauty of LiFePO4 batteries is that, unlike Lead Acid batteries, they really don't care what the SOC is within a really wide range. They seem to be as happy at ~30% SOC as they are at ~90%.  They really just dislike the extremes, so the main job of the BMS (at least how Victron designs their BMS) is to keep the batteries from getting over-charged (over voltage) and getting over-discharged (under voltage) by cutting off charging source(s) or load(s).  Otherwise, the BMS doesn't really intervene in normal daily use (outside of intra-battery cell balancing which is a separate topic to itself and disallowing charging at temperatures below 5 deg C).

To give you some idea of the "new thinking" required with these batteries compared to Lead Acid when I took delivery of my batteries it was going to be several weeks before I could install them.  New batteries are delivered at about a 50% SOC.  When I asked my dealer how long I could leave them "as is" and what I needed to do to maintain them he said I could leave them that way for many months and probably years, and that I didn't need to do anything other than store them at a reasonable temperature.  Can you imagine what would happen to your Lead Acid batteries if they were left at 50% SOC for months?


--
Mark McGovern
SM #440 Cara
Deale, MD USA


Mark McGovern
 

Matt,

That is true and Firefly batteries are technically lead acid batteries.  They are just so unique and unlike "traditional" lead acid batteries that I put them in their own category.

--
Mark McGovern
SM #440 Cara
Deale, MD USA


Matt Salatino
 

Had them on my previous boat. Excellent!

~~~⛵️~~~Matt

On Sep 12, 2020, at 5:08 PM, Mark McGovern <mfmcgovern@...> wrote:

Matt,

That is true and Firefly batteries are technically lead acid batteries.  They are just so unique and unlike "traditional" lead acid batteries that I put them in their own category.

--
Mark McGovern
SM #440 Cara
Deale, MD USA


Scott SV Tengah
 

Mark/Arno,

Arno pointed out one huge problem with using voltage as an indicator of SOC and a trigger to start charging. While lithium has a much flatter voltage profile than lead with respect to load, it still has a voltage drop under high loads. As mentioned, my bank drops into the mid 24v range when I'm running the bow thruster with engine/genset off. My load varies dramatically. We may be drawing only 60w but then suddenly the washer and dishwasher hit the heating part of their cycle and that is aligned with the misses using the microwave and we decide to run the water maker. Oh and the fridge compressors turn on. At that moment, we could easily go from 30w draw to 6000w draw. Additionally, you really need to monitor and act upon cell level voltage. You could easily have 26v at the battery/bank level but an imbalance has one cell at 4.2v, but unseen at the battery or bank voltage level. Keep feeding current and the battery is irreparably damaged.

Mark - you stated  "I think this high discharge rate has a significant impact on the Voltage vs. SOC results."  Based on this and our variable load, unless you are able to consistently let your batteries get to their resting voltage, I still think voltage is not useful for determining SOC. 

In my opinion, using voltage is a shortcut to try to make things easier. I am all for simplification as there is less to go wrong. But the manufacturers and the decades of academic research on lifepo4 all point to using a coulomb counter (like a BMV-712 or equivalent) to determine SOC and the target charging voltages are based on their research. Moreover, if I follow Victron's recommendations and a battery fails, they are on the warranty hook. They are incentivized to give you good information. It may be that the manufacturers and the decades of research and are wrong and that blogger and the MV guy is right, but I am not willing to risk my five figure lithium investment and my six figure boat on conclusions drawn from a sample size of two. I am certain the blogger wouldn't be providing warranty replacements if I tell him that I followed his advice and my batteries failed. :)

I am impressed that people are willing to go to the bleeding edge to save money. When I first started talking about installing a mostly-Victron system that was designed to work together, more than a few said that it was too risky to use "explosive" lithium. That was just two years ago. Now people are willing to mix and match batteries/chargers/BMS and trying non-standard charging routines. But I wouldn't be comfortable doing that on my boat on our intended, in-progress circumnavigation.

--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Joerg Esdorn
 

The discussion here is always interesting but I wonder about the following.  There are a lot of electric cars out there which are charged to 100% SOC every day, right?  How do their BMS deal with it?  How much of a problem is it really to charge to 100%?  Are we overthinking the issue?   I’ve posted elsewhere on this forum that I Have had installed an all Mastervolt system on my boat recently.  Mastervolt has certified that the installation conforms to their specs but I can’t try it out since I can’t get to the boat in Spain.  Based on the discussion here, I have told the boatyard not to plug the boat into shore power for now - SOC is 85% currently as shown on the MV Easyview Monitor.   I suspect this is unnecessary and will follow up with MV for their official view.   Will let you all know what I hear.   Cheers. Joerg 

A55 Kincsem
Vigo, Spain


Arno Luijten
 

Hi Joerg,

Actually these cars do not charge to 100% on daily basis. Other then Tesla you are not allowed the top 5 percent of the charge meaning you can only charge to 95%. Typically Supercharging only goes to 80% to preserve the batteries. Tesla advises to not use the top 10-20% of  the capacity for daily commuting and keep the SOC between 20 and 80%. Off topic : there is some data available that suggests that extensive supercharging affects battery life so that explains the advise of Tesla. Battery warranty is only for 70 or 80% of the capacity so if you loose 19% of the capacity it is on you.

Also cars use a different chemistry (Li-ion instead of LiFePO4)  and are not kept at 100% SOC for extended periods of time. Lithium does not like to be KEPT (as in days or weeks) at 100% but if you start draining shortly after charge the impact is not so great.
The use case for cars is very different from boats. Most people don't stay in their car when not driving, so everything is switched off. No so for a boat. So a car can sit without charging for some time but on your boat (when in use) you are constantly draining the batteries.

Cheers,

Arno Luijten
SV Luna,
A54-121


Mark McGovern
 

Joerg,

I think you ask a great question.   The only information that I have been able to find regarding anything remotely close to answering the question of what actually happens if you keep LiFePO4 batteries at a 100% SOC is from Rod Collins at Compass Marine.  He has been researching, using, experimenting on, and installing LiFePO4 batteries on boats since 2008 both on his personal sailboat and professionally as a marine electrician.  He is also part of the committee that is writing the ABYC safety standard for Li-Ion batteries. His extremely long and detailed treatise on LiFEPO4 batteries in marine systems is here: https://marinehowto.com/lifepo4-batteries-on-boats/

Below is the excerpt on the two long-term experiments that he has conducted on what happens if you leave LiFePO4 batteries at a 100% SOC for a long period of time:

STORAGE SOC EXPERIMENT: We recently ended a very expensive experiment regarding storage at 100% SOC. The test duration wound up being 12 1/2 months using four 100Ah CALB SE cells where they were charged to 100% SOC and then left to sit idle with no connections to a BMS or other parasitic loads. The low temp recorded over the 12 1/2 months was 46°F and the high temp was 87°F. This test was meant to be a representation of the real wold.
 
A min/max capture thermometer was used to record the peaks. The cells, prior to letting them sit at 100% SOC for 12 1/2 months, were regularly testing at 101.2 to 101.3 Ah’s of capacity (previous 6 Ah capacity tests) as a 12V nominal bank. After 12 1/2 months the cells were discharged to a cut off voltage of 2.9V for the lowest cell. After 12 1/2 months of doing nothing but sitting there, at 100% SOC, the cells had lost 11.6% of their previous rigorously confirmed Ah capacity. Now imagine if you additionally stressed the cells by continually float charging them. Ouch!!!!
 
“The cells lost 11.6% of their confirmed capacity just sitting at 100% SOC”
 
UPDATE: We have now completed a second round of this type of testing with a brand new prismatic cell. The difference was rather dramatic and I have no explanation as to why? The second test we did went for 13 months, under identical testing criteria, and this cell only lost 3.8% of previously verified Ah capacity. While this is quite a bit less capacity loss it still lost capacity.
 
How can LFP cell manufacturers suggest that the mere act of storage, at 100% SOC, is bad for the cells, which we have physically tested and confirmed is degrading them, and then suggest it is okay to float? How can they say “store at 50-60% SOC” yet then give you a “float” voltage?
 
I can sum up my feelings on the cell manufacturers, and their charge voltage guidance, like this:
 
They figured out a great recipe, they can repeatably make the recipe, but they have no idea why it tastes so good.
Once again, I will ask any and all Li-Ion battery researchers or scientists (I know many of you are reading this because I have your emails) to please send me any credible data to suggest a “need” for such high voltage charging guidance for the proposed use as a marine house bank.

I have not found any other source that has conducted a similar experiment and published the results.  If anyone else has, please post a link as I would love to read it.

--
Mark McGovern
SM #440 Cara
Deale, MD USA


Sheriffdep
 

Thank you Scott for the additional information!!!!!

Going back to basics for this topic:

1. Building a bank out of cells - from what I can see the really good cells that can be bought and put together (Will Prowse website) costs are around 1k for a 24v 100ah battery. However not sure how things add up with other cells. Plus adding a good BMS and a separate Battery Conditioner to wire to the investor for higher amp loads etc... price seems to be about half of the BB 400ah 24v setup. 

Questions for that - is it worth doing all the setup yourself and not entirely having the warranty for 10yrs to save maybe half or less? I am all for DIY and can learn to do it but my goal would be to get much more amp hr's for less or similar money but have at least the same known reliability. 

2. I am understanding the LFEPO4 batts should be kept between 80% and 30%. so that turns a 400ah bank into a 200ah useful plus whatever solar you may have. From my calculations on a SM2k I would be using at anchor without using the AC around 200ah per day.  It seems with the electronics running for passage you would add another 150ah + to your daily use. (chart plotter is 5ah so 2x of them would be 100ah for the day). Also if you increase the bank size you then would be using less cycles than if you didn't increase it. 

The LFEPO4 batteries claim 80%SOC at the end of 3K cycles +.  From several YouTube boats showing a year on the LFEPO4 batts and having around 1k solar watts they showed using approximately 115 cycles for that year. That would mean 10yrs or so for 1k cycles. Batts mathematically should last at least 30yrs at the same rate. 

Ok we don't trust them that much and they haven't been around long enough but doing the math nothing even comes close to comparing. It seems a no brainer to go with them but now the choice for most of us is whether we DIY a bank or go the BB route. 


Elja Röllinghoff Balu SM 222
 

He good morning
You use 200 AH at ancor ? It ist too much we need 120 Ah in summer in greece .
What yo have running ?
When i at see i woud take a hydro generator .

Best Elja
SM Balu 222





Von meinem iPhone gesendet


Joerg Esdorn
 

Following up on my post further up this chain:  I received word back from Mastervolt tech support whether it is safe to leave the boat plugged into shore support and connected to the Mastervolt smart charger.   The response came both from Spain and the US:  yes, no problem leaving the boat plugged in.  The Spanish MV technician recommended turning off the charger once a month and putting a load on the battery (i.e. turn on some electrical loads) for 30-45 minutes and then reconnect the charger.   Since the Spanish dealer has also certified the installation, I will not worry too much about running the batteries at 100%.   

Joerg Esdorn
A55 #53 Kincsem
Vigo, Spain


Arno Luijten
 

Hi Joerg,

I don't want to annoy you but how long is the warranty on your installation? This whole "do leave the batteries at 100% for extended periods" is to preserve the batteries in 5-8 years time, not next year. So unless you get 10 years of warranty for more then 80% of the original capacity, they can say whatever they want.
My point is that I have a hard time believing these batteries will last for such a long time. And even Tesla with their 8 year warranty tells you to refrain from keeping the batteries at 100% SOC. They do have some experience in this field, more then Mastervolt for sure.

Regards,

Arno Luijten
SV Luna,
A54-121


Teun BAAS
 

In addition, in general, what good is a “warranty” if you are in several years 500NM to 5000Nm away from the “installer”. I have had problems getting people to back up their warranty while still being in the same location; they promise to come on board and don’t show up etc. etc.

Likely a reputable manufacturer will blame/question the installer and if not a factory affiliated installer you are “up the creek” in the “blaming game”.

 

Although not boat related, I am currently in something similar between a truly first rate USA insurance company and the official ASTON MARTIN dealer; both holding their grounds but I am stuck in the middle.

 

Best Regards Teun

 

A54 2009 #128

September 18, 2020 09:28:26

 

 

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Arno Luijten via groups.io
Sent: Friday, September 18, 2020 09:13
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Batteries starting to get weak - MMM - What to do -

 

Hi Joerg,

I don't want to annoy you but how long is the warranty on your installation? This whole "do leave the batteries at 100% for extended periods" is to preserve the batteries in 5-8 years time, not next year. So unless you get 10 years of warranty for more then 80% of the original capacity, they can say whatever they want.
My point is that I have a hard time believing these batteries will last for such a long time. And even Tesla with their 8 year warranty tells you to refrain from keeping the batteries at 100% SOC. They do have some experience in this field, more then Mastervolt for sure.

Regards,

Arno Luijten
SV Luna,
A54-121


Porter McRoberts
 

Not that I’ve got lithium’s, but will hopefully at some point. Why not ask the battery manufacturer how to park the batteries?  Surely they have a recommendation?  Interesting thread. Thanks. 
Porter

Porter McRoberts 
S/V IBIS A54-152
WhatsApp:+1 754 265 2206
Www.fouribis.net

On Sep 18, 2020, at 6:29 AM, Teun BAAS <teun@...> wrote:



In addition, in general, what good is a “warranty” if you are in several years 500NM to 5000Nm away from the “installer”. I have had problems getting people to back up their warranty while still being in the same location; they promise to come on board and don’t show up etc. etc.

Likely a reputable manufacturer will blame/question the installer and if not a factory affiliated installer you are “up the creek” in the “blaming game”.

 

Although not boat related, I am currently in something similar between a truly first rate USA insurance company and the official ASTON MARTIN dealer; both holding their grounds but I am stuck in the middle.

 

Best Regards Teun

 

A54 2009 #128

September 18, 2020 09:28:26

 

 

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Arno Luijten via groups.io
Sent: Friday, September 18, 2020 09:13
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Batteries starting to get weak - MMM - What to do -

 

Hi Joerg,

I don't want to annoy you but how long is the warranty on your installation? This whole "do leave the batteries at 100% for extended periods" is to preserve the batteries in 5-8 years time, not next year. So unless you get 10 years of warranty for more then 80% of the original capacity, they can say whatever they want.
My point is that I have a hard time believing these batteries will last for such a long time. And even Tesla with their 8 year warranty tells you to refrain from keeping the batteries at 100% SOC. They do have some experience in this field, more then Mastervolt for sure.

Regards,

Arno Luijten
SV Luna,
A54-121


Joerg Esdorn
 

A couple of points here.  Sure, the duration of the warranty ( 2 years) is not a guarantee that the batteries will hold up long enough to amortize the much higher cost vs. gels or   AGM.  However, the advice I received from the US dealer was in response to my inquiry to MV head office.  Head office forwarded my question to the US dealer since I had indicated that I lived in the US.  So this is in fact official advice, not advice from some installer.   If you think about it, the people who sail their boats less than full time must be in the 99% majority vs. live aboards who are off the grid all the time.  So given that demographic, a technology which does not solve the obvious issue of how to park your boat for the off periods is not going to go anywhere.  I simply don‘t believe that MV would risk its excellent reputation by putting out a product that self destructs after a few years of totally normal use.   For another reality check, I just put LiFePO4 batteries (KiloVault) on my solar system on my house.  There is no mention in the manual that they should be kept at less than 100% SOC.  Of course it is understood that they will be at 100% almost 100% of the time since the batteries are just for backup in case of a power outage.  

I am aware that Telsa‘s default charge is to 90%, not 100%.  But that’s not 80% as suggested here and most importantly, Telsa‘s batteries are a different chemistry from LiFePO4 so I‘m not putting much weight on the comparison.  

I hope this helps others.  Cheers Joerg

Joerg Esdorn
Amel 55 #53 Kincsem
Vigo, Spain


Denis Foster
 

Hello,

what I understood is that these LiFePO4 batteries don’t like to be for days, weeks ...months at 100%SOC. Where the 50-60% is preferable for storage. A little of a few % charge once a month looks the ideal procedure.

It seems Ok to charge to 100% or 95% then start discharging like a typical live aboard cycle.

Am I correct?

On the brand debate, of course the Battle Born, Mastervolt etc.. Haven’t heard about Lithionics that comes with a smart dual channel BMS that distinguishes for shut off charge and discharge circuits.

An other concern is to be sure the BMS tolerate high discharges like a bow thruster < 2 minutes.

Thank s for your helpful thoughts.

Denis
ex Meltem 32