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Drop In Lithiums


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On 15/01/2022 at 11:57 AM, Psyche said:

my existing system with a carbon foam LA

 

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I would be very surprised if your existing gear can be programmed to suit carbon foam batteries, and then not be programed or made to work with lithium.  Carbon Foam batteries do not share the same bulk, absorption, float voltages with any of the other LA batts.  What brand Carbon Foam are you looking at?

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Sorry my mistake not carbon foam, but lead carbon is the description of the battery. It is manufactured or at least branded by Remco. I am not sure of the differences but it appears the terms are often interchanged, the battery supplier said that the charging profile did not need to be altered.

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OK, further update. Now the batteries have done a months work over the holidays, a bit more info to work with.

1stly, I'd like to point out that I'm trying to figure out if this is a workable system for the average boatie to use. If it requires a programmable workbench power supply to top balance, or other specialist equipment, knowledge etc, then it's not what most users will want. Yes I have this gear, but most wont...

If you want to build a LiFePO4 batt with 3.2v cells and your own BMS, get into it, this is not what I'm looking for for customers. Simple and reliable without extensive processes or knowledge required is the aim.

Voltage. It's very different from lead acid. Here is a common basic chart of LiFePO4 battery voltages;

14.6V 100% (charging)
13.6V 100% (resting)
13.4V 99%
13.3V 90%
13.2V 70%
13.1V 40%
13.0V 30%
12.9V 20%
12.8V 17%

So, that is voltage for all 4 3.2v cells combined. At first, my batteries cells would differ by as much as 0.4v in each cel. Now, that does not sound like much, but consider this. On charge, max cell voltage before BMS cuts off charge (to the battery -  not the cell, so all charging stops) in my setup is 3.65v - that's 14.6v,  (3.65x4)right? Well, ideally yes, if all 4 cells are balanced. But if one cell is at 3.65v, and the others are all at 3.25v its 13.4v still on the above chart 99%, right? But what it really means is that 3 cells are at 30%, (3.25 x 4 =13v that's 30%) and one is full. Bad. These small voltage differences in a cell are very important to get the most out of the system. This is what the BMS balances cells for.

So the specific BMS is critical for this. My batts can be set to balance either at rest OR when charging. One that does both would be way better... Mine would charge and one cell would trigger overvolt charge cut off, and the balance would stop. 

In use over the last month, the balance has actually slowly improved, and now is often within 0.005v as the batts approach full charge. That's pretty cool :-) . I did see 3.5v in some cells and 3.3v in others after charge and rest before, now I don't normally see any more than about 0.08v. This is good!

The practical use of the batts. They can run the microwave, the anchor winch (both about 125a draw) without the alternator quite happily. They charge FAST - the Alternator will put out about 90-95a for an hour or more (most I've needed so far) The voltage is exceptionally stable, and the lowest I've seen so far is 13.1v. We have not run the engine for charging only at all. The solar has mostly been sufficient, and normal motor use has topped up when required. Unlike Lead acid (incl AGM, VSLA etc) there is no need to recharge ASAP, in fact LiFePO4 ideally likes to be down a bit.

The outstanding issues;

The NZ regs. (And USA and Ausy regs). They require audio and visual alarms to be triggered before the battery is shut down by the BMS. I have a battery computer that will alarm at 14.55v and also at 13.0v. This is a start, but the issue above - cell voltages can shut off battery - and this is currently not possible to monitor visually and audibly.

As the batts like to be stored at partially charged levels, this is quite hard to do. My boat has some 24hr services that always run - fan in the Airhead, a few LED's, battery computer, auto bilge etc. Total draw is about 0.5a, but even that would leave the batts flat after a while if solar or shore power is off. If it's on, the batts are filled to 100%, which apparently reduces their life expectancy. Still thinking about this...

The tech is moving pretty fast, and the alarm issue is likely to change. In the meantime, I have to say I'm pretty impressed so far.

 

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The only way to get an accurate SoC is with coulomb counting and even then you'll get drift over time.

You've identified the fundamental problem with drop-ins, they simply aren't drop and forget, they need watering and feeding. 

To maintain a safe SoC while away from the boat, you could set your solar to a cv of 3.3v/cell. 

Of course this then means that you need to do a balancing charge once a month and sync up the coloumb counter.  This could be done with a shore charger, the engine or by changing the solar settings. 

The alternative is a proper bms that controls all the charge sources. And now you're no longer in the drop-in realm.

A lot of people seem to worry about the 100% SoC degradation issue. Ask yourself how many days a year you're actually going to be cycling the battery. A crappy Li battery will do 2500 cycles, an average quality 3500 and a decent one 5000+. Even at 2500,that's a ton of years based on most usage patterns. If you're living aboard, then you can manage it manually to 80% otherwise just don't worry about it... If you know you're going to be off the boat for more than a week leave the battery at 50%.

Personally, I wouldn't get to cycle the battery even 100 times a year. Something else is going to give before 25yrs is up... 

 

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Yep, I've got all that CD, but as I stated at the beginning of my previous post, I am looking to see if this can be a simple system for an average user. Many of my customers wont even keep wet cells full of water, so changing solar control parameters for on and off the boat, or resyncing battery computers is not likely to happen!

The BMS knows about current in/out and displays (via bluetooth) a SOC. How it actually goes about that is not programmable, or visible in this version.

I have adjusted my BEP battery computer to emulate closely that SOC figure - using a change in puerkets figure and the charge efficiency setting. I've also made it reset when the the voltage is over 14.2v and the charge current is less than 3 amps. This is not perfect, but it's pretty close. 

I would not, at this point, recommend drop ins without an external battery computer with programable features for batts and alarms, and a shunt to measure amps in/out. 

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I just thought, in view of potentially a fire being started by a direct short to a lithium bank, I should post something about AIC -Amperage Interrupt Current - of a fuse, esp a battery fuse. Yes, you should have a battery fuse on all your batts!

If you have changed to lifepo4, or are thinking of it, and have battery fuses, they may not be suitable for fusing this type of bank. ANL fuses, are not normally rated to a high enough AIC for lithium batts, but are good for lead Acid.

So, what is AIC? AIC is the amount of current that the fuse can interrupt - more than the AIC can set up an arc between the fuse contacts, and current will continue, with LOTS of heat, and probably a fire.

This is specifically an issue with Lithium Technologies, as, if shorted, they will produce 1000's of amps for a period. Yes, 1000's. Around 2800 is not uncommon, and I suggest a fuse with 10,000 AIC rating to be selected.

What can you use? This comes down really to 2 types. A class T fuse, or a MRBF fuses;

MRBF Terminal Fuse - 100A

This is an MRBF fuse, and although the one in the pic is only 75a, larger (up to 300a) is available.

Class T Fuse Holder with 2 Additional Studs

This is a class T fuse. Both of these have decent AIC ratings, and are good for all battery types. 

Please be careful out there, and check the ratings on your fuses to ensure suitability for your install.

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This was yesterday at Pine Harbour.  Apparently Lithium ion batteries.

How nervous should I be if i was buying a new boat with lithium  batteries?

Or is this just a bad setup?

 

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There is another thread on that here: https://crew.org.nz/forum/index.php?/forums/topic/20755-fire-at-pine-harbor/

Firstly it's possibly a rumor that this was caused by an Li-Ion battery installation.  It could have been caused by the battery in someone's phone, or an electric tool... and thus still be called a Li-Ion fire.

To your comment/question:

Your boat is probably coming with LiFePO4 cells?  If not, what is the chemistry?

Any amount of energy stored on your boat is a potential fire risk.  If that energy is escaping uncontrollably then it has to go somewhere and heat is the most likely place for it to end up.

The three things you need to worry about with any LiFePO4 battery setup on your boat are:

  • Puncture
  • Short Circuit
  • Over Charge

Of those three, short circuit is the only one likely to cause a fire, but it won't actually be the battery-cell that catches fire, it will be whatever is causing the short circuit, that thing will heat up and set something else on fire.

So the short-circuit risk is easily mitigated with appropriate fuses (see IT's post above).

LiFePO4 batteries are exceptionally safe.  And it's extremely unlikely that this was caused by the battery cell itself - although as always wait and see...

Here's a great video of GWL destroying some LiFePO4 cells:  

 

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1 hour ago, CarpeDiem said:

There is another thread on that here: https://crew.org.nz/forum/index.php?/forums/topic/20755-fire-at-pine-harbor/

Firstly it's possibly a rumor that this was caused by an Li-Ion battery installation.  It could have been caused by the battery in someone's phone, or an electric tool... and thus still be called a Li-Ion fire.

To your comment/question:

Your boat is probably coming with LiFePO4 cells?  If not, what is the chemistry?

Any amount of energy stored on your boat is a potential fire risk.  If that energy is escaping uncontrollably then it has to go somewhere and heat is the most likely place for it to end up.

The three things you need to worry about with any LiFePO4 battery setup on your boat are:

  • Puncture
  • Short Circuit
  • Over Charge

Of those three, short circuit is the only one likely to cause a fire, but it won't actually be the battery-cell that catches fire, it will be whatever is causing the short circuit, that thing will heat up and set something else on fire.

So the short-circuit risk is easily mitigated with appropriate fuses (see IT's post above).

LiFePO4 batteries are exceptionally safe.  And it's extremely unlikely that this was caused by the battery cell itself - although as always wait and see...

Here's a great video of GWL destroying some LiFePO4 cells:  

 

Great Post CD, totally agree. LifePo4 is not a problem if correctly installed, incl fuses. Personally I'd be very wary of any other Lithium Chemistry in a boat.

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Do not assume all LiFePo4's are "bullet" proof. It depends purely on quality of manufacture whether the battery has potential of explosion/fire or not. Many Cars with this technology have burned to ash. Remember the early issues of Aircraft using these. The safety comes about from both the way the internals are made and the levels oif lithium and some other factors. So yes they can be made " bullet" proof, but those ones cost more as well. Cheap can be dangerous. 

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While that is true Wheels, anything with energy can be dangerous. LifePo4 is the safest lithium tech, with lower power density than some, and fairly high temps required for thermal runaway. Statistics are starting to show its less dangerous than AGM from what I've read so far...

 

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I am aware of three fires on kiwi boats that supposedly had all the safety systems yet the batteries started to run away...

And thus far there are not too many boats with Lithium batteries fitted in Auckland....

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4 hours ago, wheels said:

Do not assume all LiFePo4's are "bullet" proof. It depends purely on quality of manufacture whether the battery has potential of explosion/fire or not. Many Cars with this technology have burned to ash. Remember the early issues of Aircraft using these. The safety comes about from both the way the internals are made and the levels oif lithium and some other factors. So yes they can be made " bullet" proof, but those ones cost more as well. Cheap can be dangerous. 

Unless you have some actual evidence of LiFePO4, (LFP), cars turning to ash, or LFP batteries in airplanes causing problems, I have to take this with a grain of salt, or presume you're referring to completely different chemistries.

LFP in cars has only become mainstream since around 2020.  Prior to that manufacturers have mostly always opted for denser, lighter and higher delivery chemistry such as LiPo or NiCoMn.

Tesla announced the option of LFP in 2020, citing the significant safety benefits of LFP.  They have only done this in some markets and in some vehicles.  Their longest range and their performance vehicles do not use LFP, because if they did, they wouldn't be long range or performance.

Passenger aircraft never used LiFePO4 because of the associated weight issues.  The Boeing 787 fleet, which was grounded around 2013 because of a battery fire, was using Lithium Cobalt Oxide, the most flammable of the common Li chemistries.

Airbus very publicly dropped all Lithium batteries as a result.  While Boeing very publicly stated that they were backing Li batteries for the future and would continue to invest in R&D, despite the issues they were having at the time in the 787.  Since then Airbus have on the quiet reintroduced Lithium to their planes and now use them widely.

The Samsung Note7, which was banned from planes and blacklisted on all NZ mobile networks, because it would explode in your pocket, was also not LFP.

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I had provided a photo of a car on fire on the road between here and Nelson in the forum that no longer exists unfortunately. I will see if I can find the original and post it again. People fired that many fire extinguishers into it, yet it burned away unempeded. The car was nothing more than ashes and 4 shock struts sticking up.
How about the Cars onboard that Delivery Vessel. All $450 milion of them that are now with Ship at bottom of sea.
Boeing 787's had huge problems with the first lot of batteries on their aircraft. You only have to do a google of Aircraft and batteries fires to find all the stories on that.
Tesla has put a lot or work into making the banks safer. But not all Car or batteries are made by Tesla.

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