Switch from AGM to Lith-ion

[Dockhead]

Originally Posted by Q Xopa

Being an aviation engineer I can say that most aircraft batteries, atleast larger turbine aircraft, are NiCads. These are known to have thermal runaways. But this risk is mitigated by proper maintenace practises.

Or I guess if your not comfortable how dangerous they can be then you can decline commercial air travel.

This hysteria over Lithium batteries, really needs to be kept in perspective.

You do realise that the car you ride in has an explosive gas tank in the back of it.

Maybe you are aware sailing can also be a dangerous pusuit.

Or that heart diesese, cancer and road accidents are by far the biggest killers in our society.

I dont see anyone advocating shunning flying, cars or McDonalds fast food.

As with NiCads, Sailing, cars, fast food indeed most things in life, it all comes down to knowing the dangers and managing the risks.

A bit of sensationalism and dramatic effect makes for good forum fodder.

Carry on.

So, if I understand what you're saying here -- you say that lithium batteries of whatever type are not that dangerous and not worth worrying about so much, right?


Fair enough, I guess. However, if we look at cars using lithium batteries (usually NOT LiFePo4, but some kind of cobalt based lithium batteries which are far more dangerous from a fire perspective):


https://en.wikipedia.org/wiki/Plug-i...fire_incidents


The risks seem non-trivial.


I think that's enough to make me prefer LiFePo4, personally.


Note that this is a real question, as some people are starting to use Tesla battery packs on boats, which ARE subject to a possibly small but real risk of thermal runaway, unlike LiFePo4.


And to keep it all in perspective -- LEAD batteries are subject to thermal runaway themselves, as I've experienced personally.


These are all probably fairly small risks, but significant enough to be worth thinking about in my opinion.

[Dockhead]

Originally Posted by FlyingScot

600 ah @ 24 v nominal is a lot compared to most cruising boats from what I see and read about.

Those are large numbers. I have 450ah @ 12v FF Oasis. When my 1440w solar is near max (90-100 amps charging), I barely reach the recommended minimum of 0.2C. We have a BD80 fridge, an Engel fridge, and we have a whole bunch of laptops, ipads, gadgets plugged in all the time. Two inverters, one always running. Of course, all lighting is LED, radar is new style, etc. We try to be efficient. Heating water is our indulgence.

Huge battery banks have to be recharged by something. Many forget this side of the equation. Our system is set up to for 20-40% DOD occasionally dipping below 50%.

Yes, but that's the beautiful thing about lithium -- you can put a huge amount of power into them and store a lot of power in a short period time, rather than grind, grind, grind, grind for hours trying to charge lead batteries.


I have now 70 amps of charging capacity (100 from the alternator), requiring about 2.2kW of power from the generator when on full chat. I would double that to 140, which is 4.4kW, a nice easy load for a heavy duty 6.5kW generator like mine.


With such a setup, I could store the entire usable capacity of my present battery bank in a little over an hour.


Also a large battery bank allows you to harvest basically free power off the alternator when you're motoring.





If you have a giant solar installation (1440 watts) and you are doing coastal cruising in a sunny place, then power storage is a completely different use case, than it is for those of use cruising far North (I'm above 60N as I write this) and without any solar. You know you will get x amount of power every day and you only need to store it long enough to cover the dark hours. Totally different situation. There's no point even to lithium batteries for a case like that, because with such solar production, you can provide the ideal working regime for lead batteries without any effort, topping them off every day.


My use case is just the opposite of this, and will quickly kill lead batteries if I don't make a big effort to get the batteries topped off, and what that means in remote places is a couple times a week simply running the generator all day long, which is truly awful.

[Dockhead]

Originally Posted by RaymondR

There could be another reason for the self certification trend.

An inquiry by the Brit government after the Piper Alpha oil platform disaster found many deficiencies in both design and operating procedures had contributed to the disaster. However the oil company was able to say they were innocent of any wrong doing as they had complied with all government requirements which were prescribed at that time and that if there was any fault it was in the inadequasy of the regulation.

To avoid being held responsible in this manner the government changed the safety certification to one of self certification via the "safety case".

Under the safety case regime the oil company has to identify any safety related issues and their response thereto. If there is an incident from an unidentified source the government in then in a position to claim it was entirely the oil companies fault as they had failed to identify the problem in the safety case.

In this manner the bureaucrats authority is preserved without them having to bear any responsibility.

There is a lot of sense in self-certification of an extremely complex process like designing an aircraft. It is simply not possible for the bureaucrats to put the engineering resources on such a project to effectively check all the engineering solutions, or even all the main solutions, and so of course they don't. Self-certification allocates responsibility in the right place, which is key to getting good performance out of any complex team. I face similar issues in my own business, dealing with complicated buildings. Self-certification according to correct procedures AND WITH SELECTIVE AUDITS is the right way to do this. The aircraft manufacturers screw up once in a while, and it's always front page news, but the number of screwups is actually vanishingly small.



Commercial airliners are incredibly safe -- I guess the safest means of transport ever invented by mankind probably by a couple of orders of magnitude. This achievement is the result of really excellent engineering, on a level which I guess doesn't exist in almost any other field.

[Q Xopa]

Originally Posted by Kenomac

So, you guys think we’re living in the stone age here in our Oysters doing laundry in a bucket? I assure you, we’re not. The end result you desire can also be achieved much more cheaply via added efficiencies was the point I was trying to make. There’s no reason to mock those of us who are trying to help, some of us already have the answer you seek.

But it’s your money.... do what you like with it.

I didnt see anything like anyone mocking you on your Oyster or your attempts to help others.

Oyster 'stone age' hmmm. Id say that is the definition of contridiction of terms. I wish I was slumming it on an Oyster.

Pretty sure most here are singing the same chasing efficiency tune looking at heat pump dryers and other new fangeled devices.

Did I mention I was thinking to start a club for paranoids? But I thought everyone would be against me.

Some perceived conflict makes for interesting forum reading.

[Two Skippies]

Thanks BCBoomer.

Like the OP, I'm a dummy when it comes to tech stuff.

The picture associated with the Advt shows "LiFePO4 Battery Pack", so I assumed we are talking about the same batteries.
I messaged iTECHWORLD and they assured me I could just drop their batteries straight in without problem, and use my existing controller/charger.

[Time2Go]

Originally Posted by Kenomac

Our 53 remains in anchorages 4-5 months per year with a 400ah 24v bank and 450w of solar.and never drops below 80% on a daily basis. This covers all electric cooking, watermaking, laundry, coffee making, refrigeration, everything; and recovers to 100% daily. We may only burn 1 gallon of diesel per week to make hot water when used for four hours at 1 liter per hour.


Note: Sometimes it’s more cost effective to improve efficiency rather than throwing money at a larger bank. Here we are pictured at anchorage today with our boom out to eliminate sun shading of the solar and provide an attachment point for our stabilizer. Orinoco Flo did three loads of laundry today, and we’re presently at 91% SOC.

Could you post an energy audit
Device- A/hr - hours per day - total
I just helped a friend with one and can’t come close
Radar-Auto Pilot- Frig- Electronics- lights-
Noticed you are running 24 volts
Is there a big energy economy there?
How do you step down to 12 for most common gear?
Are you running an Inverter to charge any devices?
Always curious for a better way
Cheers
Neil

[Q Xopa]

Originally Posted by Dockhead

So, if I understand what you're saying here -- you say that lithium batteries of whatever type are not that dangerous and not worth worrying about so much, right?


Fair enough, I guess. However, if we look at cars using lithium batteries (usually NOT LiFePo4, but some kind of cobalt based lithium batteries which are far more dangerous from a fire perspective):


https://en.wikipedia.org/wiki/Plug-i...fire_incidents


The risks seem non-trivial.


I think that's enough to make me prefer LiFePo4, personally.


Note that this is a real question, as some people are starting to use Tesla battery packs on boats, which ARE subject to a possibly small but real risk of thermal runaway, unlike LiFePo4.


And to keep it all in perspective -- LEAD batteries are subject to thermal runaway themselves, as I've experienced personally.


These are all probably fairly small risks, but significant enough to be worth thinking about in my opinion.

No thats not what I am saying that Lithium batteries of whatever type are not dangerous. Not sure how you got that.

My comment was in reply to others saying that all Lithium was dangerous.

As you say LFPs seem to be if not the safest then certainly one of the safest.

Ok perhaps I didnt articulate that clearly, my bad.

They can all, including as you say Lead and NiCad aircraft batts, be dangerous in different ways and to different extents. If you know how to mitgate those risks as much as possible then it is acceptable to most of us. Otherwise they would be banned etc.

I have previously had a Lead battery blow it's top clean off in a company truck in the Malaysian jungle. I can say it was impressive. Bad terminal sparking igniting hydrogen when I went to start the truck.

[Kenomac]

Originally Posted by Time2Go

Could you post an energy audit
Device- A/hr - hours per day - total
I just helped a friend with one and can’t come close
Radar-Auto Pilot- Frig- Electronics- lights-
Noticed you are running 24 volts
Is there a big energy economy there?
How do you step down to 12 for most common gear?
Are you running an Inverter to charge any devices?
Always curious for a better way
Cheers
Neil

Neil,

It might take a few days since we’ll have guests onboard beginning tomorrow, which will change everything. When they leave, I’ll start a new thread on the subject. Please remind me in 11 days time.

For openers, running 24 volts is primarily due to the increased length of the electrical wire runs on a 53ft boat. We use several Alfatronix Powerverters for items which don’t come in 24v, but most pumps and items which are DC come in either 12v or 24v.


Cheers

Ken

[bcboomer]

Originally Posted by Two Skippies

Thanks BCBoomer.


The picture associated with the Advt shows "LiFePO4 Battery Pack", so I assumed we are talking about the same batteries.
I messaged iTECHWORLD and they assured me I could just drop their batteries straight in without problem, and use my existing controller/charger.

Ah, I missed the label. Certainly seems like a heck of a deal, especially if that is in Australian dollars.

[FlyingScot]

Originally Posted by Dockhead

Yes, but that's the beautiful thing about lithium -- you can put a huge amount of power into them and store a lot of power in a short period time, rather than grind, grind, grind, grind for hours trying to charge lead batteries.
I have now 70 amps of charging capacity (100 from the alternator), requiring about 2.2kW of power from the generator when on full chat. I would double that to 140, which is 4.4kW, a nice easy load for a heavy duty 6.5kW generator like mine.
With such a setup, I could store the entire usable capacity of my present battery bank in a little over an hour.
Also a large battery bank allows you to harvest basically free power off the alternator when you're motoring.
If you have a giant solar installation (1440 watts) and you are doing coastal cruising in a sunny place, then power storage is a completely different use case, than it is for those of use cruising far North (I'm above 60N as I write this) and without any solar. You know you will get x amount of power every day and you only need to store it long enough to cover the dark hours. Totally different situation. There's no point even to lithium batteries for a case like that, because with such solar production, you can provide the ideal working regime for lead batteries without any effort, topping them off every day.
My use case is just the opposite of this, and will quickly kill lead batteries if I don't make a big effort to get the batteries topped off, and what that means in remote places is a couple times a week simply running the generator all day long, which is truly awful.

I agree that 'use case' is what matters.


Saying that you get 'basically free power' when motoring is akin to me saying that I get 'free' power from my solar. Sure we do, but after we both spent a lot of money first.


A normal sized LiFePO4 bank gets you almost all the same benefits at less upfront costs. I'd probably use the money saved to upgrade power hungry devices, if not already installed.

Does LiFePO4 have minimum C requirements for charging? As you can see I'm a little limited in this area. If I doubled my AH capacity, then my max charge rate would be 0.1C. Shallower DOD would tend to lengthen battery life, yet slower charge rate would tend to shorten battery life. Not sure which matters more.

[Dockhead]

Originally Posted by Kenomac

. . . running 24 volts is primarily due to the increased length of the electrical wire runs on a 53ft boat. We use several Alfatronix Powerverters for items which don’t come in 24v, but most pumps and items which are DC come in either 12v or 24v.. .

24v is more or less universal in Europe for boats over 45 feet, at least the non-mass produced ones.


I don't think there is any measurable efficiency gain for low power items like lighting and pumps, but it makes a big difference for high power items like winches, windlasses, and bow thrusters, particularly the last of these. 24v is also significantly better for your alternators (half the amperage for the same power) and inverter (at least wiring it).



With 24v it is pleasant to be able to use quite light cable for almost everything. Also the higher voltage gear simply runs better. If you ever had a car with 6v power (like old VW's), you will know what I mean -- it's just like going from 6v to 12v on a car.


Like Ken said, nearly all DC gear on board is available in 24v (refrigeration, lighting, autopilot, toilets, pumps of all kinds, etc. etc.) and the few things which are not (navigation gear and radios, stereo system, TV antenna) are easily handled with Alfatronix droppers like the one Ken showed above.

[a64pilot]

I may be wrong, but don’t think an alternator can supply 24V more easily, with less heat than 12V.
Yes the amps are 1/2, but the total power as measured in Watts is the same.
I believe Ken is right, the biggest advantage is smaller wiring.
Many larger aircraft run most everything off of three phase 400Hz 115 VAC power, cause the weight difference in wiring is huge.
I don’t know why 400 Hz though.
Three phase is more efficient than single phase, but that’s another thing I know, but can’t explain, cause I don’t understand why well enough.

[hellosailor]

5-10 years ago the global auto industry was talking about converting from 12 to 48 VDC for everything, because of all the advantages of using 48VDC for electric power steering, electric everything instead of hydraulics...then someone figured out that all the really insignificant things like SWITCHES had to be massively upscaled to work reliably at 48VDC, and they whole concept was dumped as uneconomical.

A very different picture than boats, to be sure, but somewhere in between the two, the "best" working voltage changes as the situation does.

[Checkswrecks]

Originally Posted by carstenb

Ok, I'm not an electrical guru so everyone please keep your answers at the level of talking to a 10 year child (maybe I'll understand).

Our 600AH AGM house bank is on its final legs and i want to go with LITH-ion. I've stay clear of these before because I was always told you needed to be an outright expert to install one.

But here in the Marquesas, I meet 4 boats that have all told med the same thing. Buy the batteries (winston), make sure they are charged correctly, hook them up in series (4x3V=12V) then in parallel and don't worry about them.
My Sterling regulator has a setting for Lith-ion. I have a 160AH alternator on the boat.
Our normal needs for charging are met by our 700W solar array.

OK - so is what I've been told correct? all four of these guys were EE's so they should know what they are talking about.

Do I need a special charger to charge the cells the first time? If I use shore power through my Sterling charger - is that good enough?

thanks carsten

Carstenb -

There's a lot of wisdom and experience in what a number of folks have written. The Ytrium in the Winstons is a bit unusual and could be a small benefit, but the bottom line is to simply stay with a version of LiFePo4 and research the heck out of other people's experience with the brand you settle on. (Twoskippies - This applies to your itech120 question)

btw - There are a number of good "manufacturers" these days, so I don't recommend any one brand over another. The reason I've put "manufacturers" in quotes is because almost all of them are really assemblers and the assembly is their unique brand.

Anyway, largely just stay away from chemistries using Cobalt (look for Co in the name, such as LiCo) and stay away from the cheapest prices. Cobalt can pack in more power but as others mentioned, IF a cell fails the more energetic properties can lead to more energetic results. Cobalt is also MUCH less forgiving when overcharged. The problem with lowest price is that there are literally about 10,000 battery manufacturers in China and your cheapest batteries are assemblies of the least expensive cells to come out of them.

After finding a brand people are having good experience with, it's the details of the BMS that you want to really research the details of. This is what people don't discuss enough while they are going on about which chemistry is best. Your post mentions a mixed parallel/series installation, which can be done. However, series cell installations creates problems unless the charger and BMS are addressing cells individually for balance. Even then, there are cars which do this and specific cells at the end of the series strings are always the first to drag the pack down. If you do run cells in series, plan to check voltages occasionally in case you need to swap cells.

The next item is to make sure the batteries are protected physically, plus from heat and vibration. While everybody correctly talks about how bad cold charging is, testing in a calorimetry chamber (ARC) revealed that there is a fundamental difference between breakdown and max operating temps. While max operating temp is a limit the battery can function at, we found these are NOT for sustained periods and that the actual breakdown/degradation of the cell chemistry can begin 20 degrees C less than the max operating temp. I mention this because of all the people who put batteries into engine compartments then wonder why they don't last.

The physical protection largely relates to handling during installation and removal. Jarring the case hard can be enough to damage separator material between anode and cathode windings. This has repeatedly led to fires, and is one of the biggest problems at shipping company terminals.

jtsailjt - A lot of this also applies to your concerns. And it's not too hard to parse the people here with long personal experience from those who don't. Note my forum name, as I led part of the 787 investigation and wrote some of what you were trying to cite. While LiFePo4 can have hazards, it's not in the same league as what is in the 787, Tesla cars, hover boards, or a lot of other consumer products.

To the question about why Boeing stayed with the LiCo chemistry after 2006, (A) the chemistry was the most energy possible when the certification began and LiFePo4 was not as well developed at that point, plus had lower energy density. In essence, using LiCo was actually avoiding unknowns then, meant that a certain (proprietary) number of more people could be carried per flight, and carrying paying passengers is how transport airplanes make their money in operation. Plus (B) the battery was a certified part of the entire Thales/GS-Yuasa subcontracts for the DC power system on the airplane by the time final testing was being conducted. Changing the battery properties would have led to huge expenses and possibly years of time delays due to the amount of re-testing required since 2006.

The final 787 report went into extensive detail about how Boeing/Thales/GSY addressed what their combined experience (which had big assumptions) felt was the assumed worst case failure mode (overcharge), while they missed the importance of something as simple as mitigating initial cell failures in an assembly.

Hope this helps.

[tanglewood]

Originally Posted by mbartosch

This is not correct. The Boeing incident involved LiCoO2 cells which are in fact susceptible to thermal runaway.
The LiFePO4 chemistry we use on our boats does not have this problem and can be considered as safe or even safer than lead acid chemistries.
It is also not correct that LiFePO4 „requires better care“ and is „less forgiving“ than lead acid. Having 4 years if experience with a LiFePO4 bank I can say that it requires almost zero attention. The most important thing to take care of is literally not depleting them beyond 0 % SoC or below 11.9 V pack voltage.

I agree. I find LFP to be much easier to manage on a day to day basis, because you can just ignore them. No worries about partial state of charge, no worries about when you last got to a full recharge, no worries about when you will next get to a full recharge, no worries about how sulfated your batteries are, no worries about when and how long to equalize, no worries about absorption time, no worries about shutting off the generator before full charge. None of that. Just ignore them


All the work is in setting things up, and it's no harder than tuning your chargers for AGMs. Set the max voltages, set the max absorb times, set the float voltage, and you are done. If something starts to run out of bounds, you will get a warning from your BMS. Note that "your BMS" could be an electronic device, or it could be you keeping an eye on things.


And unlike AGMs, if you try to run your batteries into the ground, the BMS will disconnect to protect the batteries from you. Your AGMs don't do that, and will happily let you ruin them. And if your LFP batteries are overcharging for whatever reason, your BMS will disconnect them to protect themselves and your boat from you. AGMs will happily let you cook them to a crisp.