Lithium battery abuse

[Alan de Enfield]

1 minute ago, rusty69 said:

I only came here to bid on the mr grumpy mug in the auction, but I fear it may be out of my price range.

 

I'm still holding onto that engine you wanted 'years ago', your storage charges are now (probably) more than the price of the engine.

[MtB]

1 minute ago, Alan de Enfield said:

 

I'm still holding onto that engine you wanted 'years ago', your storage charges are now (probably) more than the price of the engine.

 

 

Ooh is there an engine available? 

 

I like engines. What is it? 

 

 

[rusty69]

2 minutes ago, Alan de Enfield said:

 

I'm still holding onto that engine you wanted 'years ago', your storage charges are now (probably) more than the price of the engine.

What? We didn't discuss storage charges. How much do I owe?

1 minute ago, MtB said:

 

 

Ooh is there an engine available? 

 

I like engines. What is it? 

 

 

Lister canalstar

 

ETA. You won't like it. Far too modern

Edited February 20, 2022 by rusty69

[MtB]

1 minute ago, rusty69 said:

What? We didn't discuss storage charges. How much do I owe?

Lister canalstar

 

ETA. You won't like it. Far too modern

 

 

Sounds HORRID!!

 

 

[Alan de Enfield]

2 minutes ago, rusty69 said:

What? We didn't discuss storage charges. How much do I owe?

Lister canalstar

 

ETA. You won't like it. Far too modern

 

 

Just now, MtB said:

 

 

Sounds HORRID!!

 

 

 

Lister LPWS4

 

Sounds sweet - not "clunk, clunk, wheeze, bang" of the old Listers et al.

[Dr Bob]

14 minutes ago, MtB said:

 

May I prevail upon you to refresh my memory?

 

What is this "Dr Bob theory" of which you write, exactly? I wonder if Dr Bob knows anything about it....

It was a long time ago!

I may be wrong but after I put together my hybrid system of old LA's plus Li's, I posted a thread wondering if you could just have a simple Li battery on top of your LA's and have a very simple and cheap system. I think that is what Biscuits is referring to.

Having now had the experience of running the hybrid system, the more simple system could work as in my summary to Rusty above, if it is big enough and you have some redundancy. It may be to expensive though if you have to buy B2Bs etc.

[nicknorman]

2 hours ago, Dr Bob said:

 

If an individual cell goes wonky, then one effect will be the capacity of that cell is likely to be different to the other 6 you have in parallel  which will bring down the capacity of the 'large 7 cell' unit. When you charge, then the 4 large cells will likely go well out of balance. Here's where I am at my pay grade limit - but would anticipate that 7 cell unit will hit the voltage knee first and likely overcharge if you charge to your normal voltage. I'm sure Nick will have the right answer.

Depends on what you mean by wonky. If capacity is lost due to ageing at a different rate from other cells, I would presume that top balancing would remain unaffected but bottom balancing would be out. If there was a slow internal discharge then presumably the top balancing would go out. But either way, this is why IMO cell level voltage monitoring is essential, with shutoffs for both high and low cell voltage.

[Naughty Cal]

5 minutes ago, nicknorman said:

Depends on what you mean by wonky. If capacity is lost due to ageing at a different rate from other cells, I would presume that top balancing would remain unaffected but bottom balancing would be out. If there was a slow internal discharge then presumably the top balancing would go out. But either way, this is why IMO cell level voltage monitoring is essential, with shutoffs for both high and low cell voltage.

The Daly BMS in our Sterling battery has a low and high cell voltage shutoff which can be user modified. We have left them as factory set.

 

Not seen that in action yet. It has not been needed.

 

Our cells are fairly balanced. (As said before the SOC gauge is useless!)

 

 

 

[MarkH2159]

On 19/02/2022 at 10:14, Dr Bob said:

 

You may have said that but you also said (see below)

 

 

 

I repeat again, this at best misleading and at worst DANGEROUS. If you are homebrewing a system, you need to be very careful if you are taking LiFePO4s up to 100% (or 99%). Once you are in the voltage knee (95%+) then you are in territory where you need to be in control of what is going on. Mark, you blindly tell the world that they are safe and happy in that regime. For newbies who dont understand, that is DANGEROUS.

How do you know you are not at 100% in one cell. You look at other forums and people will report their cell balance at 3.7V, 3.5V, 3.4V and 3.4V. Is that safe? Of course it isn't. Only someone who didnt have a clue, or a fool would operate like that. You say in one breath that you charge to 90% then in another you say to almost full. Almost full to most uninititated is 99%. In no posts do you say keep away from 100%.

Homebrewing an Li bank needs thought and consideration of what can go wrong and actions that keep the system safe. By buying a 'one stop shop' from a vendor it is different - they have responsibility - but homebrewing is different, you have responsibility.

I have read a previous post of your on another thread (which recieved 4 greenies - so it must be right???????????????) which suggests to me that you dont really understand the main issue with Li's. Can you remind us of how you avoid overcharging? I may have got it wrong and you do fully understand and if so, sorry I mentioned it.

 

 

 

Ah well, the safety is in the BMS settings and knowing how to read and adjust them.

I know I am not 100% in any single cell because the BMS is constantly monitoring and has an individual Cell High Voltage Disconnect.

It also has a Cell Low Voltage Disconnect, as well as a Pack Sum Voltage High/Low, Cell Differential Voltage Disconnect etc.

The only time I did take it all to 100% is when I was performing the initial Top Balancing.

So to remind you how I am able to avoid overcharging or any other 'dangerous' situations is by using a decent BMS with the correct settings which has safety features that cannot be exceeded.

 

Thanks for the insult that I 'blindly tell the world that they are safe and happy in that regime'

The fact is I am neither blind nor living dangerously.

I am just one of many who have self built Lithium Batteries quite successfully and we are all quite happy about them.

Now if that somehow scares you, then carry on and be scared, but do not try to tell others how wrong we are because the proof is in the pudding.

 

[nicknorman]

22 hours ago, Dr Bob said:

Fully agree with your comments on correlating charge voltage with SoC. I frequently charge at 90A with my 2 B2B's and 45A with one  B2B's. The voltage when I terminate is very different. My 13.8V target is with the 90A charge so the 45A would be 13.6-13.7A.  In my posts I do reinforce the point that peeps need to work out their own voltages. My 80-90% target is a point before the amps start dropping more quickly and hence well before the voltage knee. My biggest worry here is Mark saying its fine to charge to 95-99% (ie less than 100%) and peeps who dont understand accepting that fact.

 

I am not aware of examples of thermal runaway in LiFePO4 in the real world but we test them and they do fail. Of course the chemistry is safer and there is less energy density but internal shorts via defects/dendrites etc can trigger runaways. It is interesting in our work supporting the EU inititive of transporting Li cells on passenger planes, the relevant bodies made no differentiation between LiFePO4 and Li-ion cells (ie the regulations on transport will be the same from both). It's also interesting that all this air transport work is assuming the cells in transport are not on charge!!!! The relevant bodies see the risk of thermal runaway on just charged batteries rather than during the charging process. I dont know where the legislation will end up but may be set so the batteries will have to be less than 30% charged and in approved 'safe' packaging boxes. Also, we dont hear about many Li-ion batteries causing problems, likely as most vendors have well designed safety systems.

Is the main sudden failure mode Li dendrite formation that punctures the separator? Or something else? I’ve read of ceramic separators which are much more resistant to dendrite puncture.

 

One can get lifepo4 batteries for gliders that say they have some sort of capsule in them which, if the internal temperature gets above 60C, ruptures and releases a chemical that neutralises the battery. Do you know anything about how that works?

[Dr Bob]

10 minutes ago, nicknorman said:

Is the main sudden failure mode Li dendrite formation that punctures the separator? Or something else? I’ve read of ceramic separators which are much more resistant to dendrite puncture.

 

One can get lifepo4 batteries for gliders that say they have some sort of capsule in them which, if the internal temperature gets above 60C, ruptures and releases a chemical that neutralises the battery. Do you know anything about how that works?

Dendrite formation is one of the routes but dendrites dont form suddenly. They grow slowly over time, possibly each time a cell get to a high voltage. In the link I posted earlier in the thread, I think there are some links to more detail on this. I am aware of one paper where it looked at dendrite growth over successive overcharges - ie dendrites were found after 10 excursions to 3.8V. It also can happen when charging below zero. If I was installing a system, I would be more woried about poor construction or contaminants in a new battery (again see links in the thread I referred to earlier), ie a 5mm length of wire nearly bridging across the anode/cathode. Is a cheap chinese battery going to be safe? Mine were in service in a van before I got them so I am fairly sure there are no 'manufacturing issues'. We are currently also involved in Li battery recycling and working with some of the new emerging gigafactories. One frightening statistic is that the biggest market for Li battery recycling is the waste from the manufacturing process itself. Typically you find 30-40% waste - and that is not just from floor sweepings! Their QC proceedures must be good. I hope they are spotting all the duff ones!

Most LiFePO4s sold as cells (ie my Thunderskys) have plugs in the top casing that blow when the temp reaches a certain point and the liquid between the anode and cathode is expelled thus isolating the plates so no route for the energy to short out and heat up. Just the venting of the liquid makes it safer. The problem is that the thermal runaway could be well on its way when the plugs blow. None of the 'extinguishing' chemicals ie Brominated or phosphated species would stop a themal runaway but may help surpress flames around the burning battery.

[nicknorman]

20 minutes ago, Dr Bob said:

Dendrite formation is one of the routes but dendrites dont form suddenly. They grow slowly over time, possibly each time a cell get to a high voltage. In the link I posted earlier in the thread, I think there are some links to more detail on this. I am aware of one paper where it looked at dendrite growth over successive overcharges - ie dendrites were found after 10 excursions to 3.8V. It also can happen when charging below zero. If I was installing a system, I would be more woried about poor construction or contaminants in a new battery (again see links in the thread I referred to earlier), ie a 5mm length of wire nearly bridging across the anode/cathode. Is a cheap chinese battery going to be safe? Mine were in service in a van before I got them so I am fairly sure there are no 'manufacturing issues'. We are currently also involved in Li battery recycling and working with some of the new emerging gigafactories. One frightening statistic is that the biggest market for Li battery recycling is the waste from the manufacturing process itself. Typically you find 30-40% waste - and that is not just from floor sweepings! Their QC proceedures must be good. I hope they are spotting all the duff ones!

Most LiFePO4s sold as cells (ie my Thunderskys) have plugs in the top casing that blow when the temp reaches a certain point and the liquid between the anode and cathode is expelled thus isolating the plates so no route for the energy to short out and heat up. Just the venting of the liquid makes it safer. The problem is that the thermal runaway could be well on its way when the plugs blow. None of the 'extinguishing' chemicals ie Brominated or phosphated species would stop a themal runaway but may help surpress flames around the burning battery.

Yes I meant sudden failure, not sudden growth. As far as I know all available prismatic cells have the blow-off vent thingy. Mine certainly do.

 

The batteries I mentioned (pbq) say this in the blurb, not sure what a PTC is?

 

”To avoid overheating of the battery, a special insertion, called PTC, is added to the electrolyte. This additive neutralizes the electrolyte and disables the battery permanently if the internal temperature exceeds 80C.”

 

(yes 80c no the 60c I mentioned earlier).

Edited February 21, 2022 by nicknorman

[Dr Bob]

14 hours ago, MarkH2159 said:

Ah well, the safety is in the BMS settings and knowing how to read and adjust them.

...........

So to remind you how I am able to avoid overcharging or any other 'dangerous' situations is by using a decent BMS with the correct settings which has safety features that cannot be exceeded.

 

...............

I am just one of many who have self built Lithium Batteries quite successfully and we are all quite happy about them.

Now if that somehow scares you, then carry on and be scared, but do not try to tell others how wrong we are because the proof is in the pudding.

 

 

Oh dear. Oh dear.

How the understanding of safety has fallen on this forum over the last 2 years.

Of course your system will work fine while the BMS works. Of course you are satisfied it is great after a few months. A few months of operation is not Proof. The issue is what happens if the BMS fails. Wake up and smell the coffee.

It wont be long before someone has a bad fire (likely not caused by the Li bank) but the insurance assessors will hold the owner responsible as he has been negligent in homebrewing his Li bank (even if the Li's had nothing to do with it). Then we will all come under the insurance industries spotlight. We, as a group, have to get this right and clearly you have not. I will keep calling people out when they are negligent as it will certainly come back to bite us in the future.

It's not just you though Mark. The other 'enquiry' from an LiFePO4 user - enquiring if taking his Li's to 16V was ok if an individual cell could be taken to nearly 4V - shows that the understanding of these systems is far from what is required.

Your peer group also has a lot to answer for in not curbing the urges of the clearly uninformed.

 

As they say on the telly, I'm out. Bye all.

[IanD]

3 minutes ago, Dr Bob said:

 

Oh dear. Oh dear.

How the understanding of safety has fallen on this forum over the last 2 years.

Of course your system will work fine while the BMS works. Of course you are satisfied it is great after a few months. A few months of operation is not Proof. The issue is what happens if the BMS fails. Wake up and smell the coffee.

It wont be long before someone has a bad fire (likely not caused by the Li bank) but the insurance assessors will hold the owner responsible as he has been negligent in homebrewing his Li bank (even if the Li's had nothing to do with it). Then we will all come under the insurance industries spotlight. We, as a group, have to get this right and clearly you have not. I will keep calling people out when they are negligent as it will certainly come back to bite us in the future.

It's not just you though Mark. The other 'enquiry' from an LiFePO4 user - enquiring if taking his Li's to 16V was ok if an individual cell could be taken to nearly 4V - shows that the understanding of these systems is far from what is required.

Your peer group also has a lot to answer for in not curbing the urges of the clearly uninformed.

 

As they say on the telly, I'm out. Bye all.

 

Which is of course equally true for commercial LFP, either "drop-in" batteries or using a bought-in BMS -- all circuits have a small chance of failing, regardless of who built them.

 

A shoddy home-brew system is likely to be less reliable and fail-safe, but then the same is likely for a cheap-as-chips-Chinese drop-in battery. A good quality commercial BMS (drop-in or not) should be much better. Somebody competent enough to design and build a home-brewed system is likely to take care about how it is designed and built, with multiple safeguards (like Nick did), and there's no reason to think that this will be any less safe or reliable than most off-the-shelf systems.

 

The only thing better -- the safest overall solution -- is if you buy in a big complete LFP battery system with integrated BMS (e.g. BYD LVL 15.4, includes cell monitoring/balancing, temperature control, disconnect relays, acts as "charging master") targeted at standby power systems, because there are thousands of these out in the field, which makes it more likely that any bugs or design faults have been corrected. But very few people do this for cost reasons... 😞

 

What is certainly true is what is said in the oft-referenced "LFP-on-boats bible" here:

 

https://marinehowto.com/lifepo4-batteries-on-boats/

 

"I do not believe LiFePO4 is ready for mass DIY prime time builds. Read with caution, and especially focus on the things that you don’t want to hear rather than only what you want to hear.

 

Since opening this article to the public we have now had what I consider a rather high number of LiFePO4 owners contact us who’ve ruined LiFePo4 batteries (not all marine based). In almost all of these cases of destroyed LiFePO4 batteries the resounding tone I hear come through is;

“But Rod, People on the internet made it sound so easy?“

Drop-in batteries will be a huge part of the future of LFP, and there are currently a few good manufacturers working to improve the marine specific shortcomings but, in my opinion, many of them are still not prime time ready, so purchase carefully. "

[Alan de Enfield]

43 minutes ago, Dr Bob said:

Mine were in service in a van before I got them so I am fairly sure there are no 'manufacturing issues'.

 

I'm getting even more confused .............

 

In another thread where I raised the question about 'car' lithiums being used in a boat, I was assured that they were not, and it was dangerous to do so.

 

People who really should know better are suggesting exactly that, and are either unaware of the consequences or are deliberately ignoring them 😞

I've pointed out before why this is not a sensible idea, not just because of safety issues but the fact that it may render their insurance invalid -- many marine insurers will cover boats with LFP but refuse to insure ones with NMC batteries (which is what almost all ex-car ones are).

 

We appear to have a conflict of information / expert advice (not unusual for the forum, but as I understand it - potentially life threatening advice is involved)

 

 

[IanD]

7 minutes ago, Alan de Enfield said:

 

I'm getting even more confused .............

 

In another thread where I raised the question about 'car' lithiums being used in a boat, I was assured that they were not, and it was dangerous to do so.

 

People who really should know better are suggesting exactly that, and are either unaware of the consequences or are deliberately ignoring them 😞

I've pointed out before why this is not a sensible idea, not just because of safety issues but the fact that it may render their insurance invalid -- many marine insurers will cover boats with LFP but refuse to insure ones with NMC batteries (which is what almost all ex-car ones are).

 

We appear to have a conflict of information / expert advice (not unusual for the forum, but as I understand it - potentially life threatening advice is involved)

 

 

 

If Dr. Bob's batteries are ex-van and they're LFP then he's no worse off than anyone else using them, maybe better since they're effectively worn-in to remove infant mortaility problems.

 

If they're not (e.g. NMC or NCA, which most vehicle batteries are) then this calls all his posting about safety and insurance into question, because he's already fallen at the first fence... 😉

 

I'll put this up again just to make clear why this is the case...

 

 

Edited February 21, 2022 by IanD

[nicknorman]

3 minutes ago, Alan de Enfield said:

 

I'm getting even more confused .............

 

In another thread where I raised the question about 'car' lithiums being used in a boat, I was assured that they were not, and it was dangerous to do so.

 

People who really should know better are suggesting exactly that, and are either unaware of the consequences or are deliberately ignoring them 😞

I've pointed out before why this is not a sensible idea, not just because of safety issues but the fact that it may render their insurance invalid -- many marine insurers will cover boats with LFP but refuse to insure ones with NMC batteries (which is what almost all ex-car ones are).

 

We appear to have a conflict of information / expert advice (not unusual for the forum, but as I understand it - potentially life threatening advice is involved)

 

 

The point is that most batteries used in cars these days are NMC (nickel manganese cobalt) which, whilst having much higher energy density by mass, are less stable and self-sustain combustion even under water. In Dr Bob’s case his ex-van batteries were LiFePO4. We come back to “all lithium batteries are not equal”.

[IanD]

12 minutes ago, nicknorman said:

The point is that most batteries used in cars these days are NMC (nickel manganese cobalt) which, whilst having much higher energy density by mass, are less stable and self-sustain combustion even under water. In Dr Bob’s case his ex-van batteries were LiFePO4. We come back to “all lithium batteries are not equal”.

 

What is certain is that all the secondhand lithium battery backs being sold today as "ex-car" (Tesla, BMW, Leaf, the Samsung cells that go into them) are NMC, and even though the cost and size look attractive -- and they may even have inbuilt or included BMS -- these should not be used on boats, for safety and insurance reasons.

 

This is not theoretical scaremongering; if things go wrong (even though this is rare) these batteries do sometimes catch fire, and the result is difficult enough to put out on the road where a fire engine (or other novel ways of putting out lithium battery fires) has access. On a boat on the canals there is pretty much zero chance of putting a battery fire like this out, and the likely consequence is a totally burned-out boat and possibly fatalities -- and almost certainly no insurance payout when they find out what caused the fire.

 

Please, please, only use "ex-vehicle" lithium batteries on boats if you're 100% certain they're LFP.

Edited February 21, 2022 by IanD

[Dr Bob]

1 hour ago, Alan de Enfield said:

 

I'm getting even more confused .............

 

In another thread where I raised the question about 'car' lithiums being used in a boat, I was assured that they were not, and it was dangerous to do so.

 

 

What on earth is a 'car' lithium?

 

The first adopters on here (Tom, MP and I) are all using LiFePO4s (thunderskys) ex vehicles. Peter is using LiFePO4s ex vehicle from Valance. These are the safest of the Li battery types around (but not fully safe).

 

It is crazy to assume 'car' lithiums cannot be used on a boat - its not where it came from, its the battery type that is important.

 

Too many peeps on here do not have a clue and certainly do not read what the people in the know are posting. I have mentioned likely a dozen times that mine are LiFePO4 yet a few posts ago someone questioned what type of batteries I have.

 

For Christ's sake guys. Get a grip.

[nicknorman]

Another thing about Li NMC is that the cell voltage is not convenient for 12v systems. 4 cells is too much, requiring up to 16v charge voltage, too much for connected 12v equipment not to mention incompatibility with alternators, and 3 cells is not enough. LiFePO4 very conveniently has a cell voltage such that 4 cells are pretty compatible with existing 12v systems.

[peterboat]

15 minutes ago, nicknorman said:

Another thing about Li NMC is that the cell voltage is not convenient for 12v systems. 4 cells is too much, requiring up to 16v charge voltage, too much for connected 12v equipment not to mention incompatibility with alternators, and 3 cells is not enough. LiFePO4 very conveniently has a cell voltage such that 4 cells are pretty compatible with existing 12v systems.

I have built 3 x 48 volts packs using Lithium polymer and 12 volts didn't work for it

[IanD]

2 hours ago, Dr Bob said:

 

What on earth is a 'car' lithium?

 

The first adopters on here (Tom, MP and I) are all using LiFePO4s (thunderskys) ex vehicles. Peter is using LiFePO4s ex vehicle from Valance. These are the safest of the Li battery types around (but not fully safe).

 

It is crazy to assume 'car' lithiums cannot be used on a boat - its not where it came from, its the battery type that is important.

 

Too many peeps on here do not have a clue and certainly do not read what the people in the know are posting. I have mentioned likely a dozen times that mine are LiFePO4 yet a few posts ago someone questioned what type of batteries I have.

 

For Christ's sake guys. Get a grip.

 

A "car" lithium battery/pack is one removed from a car... 😉

 

As you say (and I agreed with) it's the battery type that is important. But if you go and look on the sites reselling used lithium batteries from cars today they're all from BMW/Tesla/Nissan/VW, and they're all NMC.

 

Maybe this was different several years ago when you bought yours because initial lithium installations were in buses and vans and these did use LFP (Thundersky/Valence), but cars nowadays certainly don't -- and these are where most of the secondhand batteries come from today.

 

And you're the one who said your batteries were ex-van without saying they were LFP, so don't blame people for assuming otherwise given the above facts... 😉

 

 

Edited February 21, 2022 by IanD

[peterboat]

1 minute ago, IanD said:

 

A "car" lithium battery/pack is one removed from a car... 😉

 

As you say (and I agreed with) it's the battery type that is important. But if you go and look on the sites reselling used lithium batteries from cars today they're all from BMW/Tesla/Nissan/VW, and they're all NMC.

 

Maybe this was different several years ago when you bought yours because initial lithium installations were in buses and vans and these did use LFP (Thundersky/Valence), but cars nowadays don't -- and these are where most of the secondhand batteries come from today.

 

And you're the one who said your batteries were ex-van without saying they were LFP, so don't blame people for assuming otherwise given the above facts... 😉

 

 

Mine are ex Smith's electric van, Bob I thought had car ones but LifePo4s 

[IanD]

9 minutes ago, peterboat said:

Mine are ex Smith's electric van, Bob I thought had car ones but LifePo4s 

Yes, they're all several years old from when the only ex-vehicle lithiums around were LFPs from vans and buses. Now they're all NMCs from cars -- at least, that's the case for every single website selling them I could find... 😉

 

And many of the websites do promote these batteries as a low-cost alternative to buying new -- in fact I know some people have suggested using them on boats for this reason -- but are coy about saying what the chemistry is.

 

Don't do it; LFP batteries are fine for use on boats, NMC batteries aren't... 😞

 

[yes I know you and Bob know this, but plenty of "lithium newbies" don't -- and for sure the websites selling them are not going to point this out because they'll lose a sale]

Edited February 21, 2022 by IanD

[Dr Bob]

36 minutes ago, IanD said:

Maybe this was different several years ago when you bought yours because initial lithium installations were in buses and vans and these did use LFP (Thundersky/Valence), but cars nowadays certainly don't

 

 

 

 

Tesla now use LiFePO4s in some models ie the M3 SR+. They introduced them almost a year ago.

 

Please attempt to be more accurate in what you say.