Are Lithium batteries becoming realistic?

[Colvic Watson]

Replacing every light with LED's has transformed our power use, especially with three children, three sleeping cabins, two heads, a saloon, galley and wheelhouse - how often were lights left on? Now I don't care! The fridge is a pain, draws an average of 1.7 amps - that's 40amps a day - which is an hour's motoring.

We put 200watts of solar on last year and that has been brilliant, so much so that I'm thinking of dropping the bank down to 330AH and saving a battery. It's irritating to think that 330AH, weighing about 140kg and costing about £330 only gives me 120AH or realistic usable power, a bit pathetic really.

 

[Blueboatman]

Not sure if this helps but my boatfridge came with a watercooled/heatexchanger compressor set up which to my surprise and delight seems to run fine on one 75W ' shade tolerant' solar panel, through day and night from 2 domestics. Everything else is , as you say, largely irrelevant though I haven't gone all LED except tricolour.

Perhaps have a look at the fridge set up b4 or until Li technology stabilises more?

Some 15 years ago in answer to the question how much solar array is required to run a fridge, the electrician would say: ''How big is yer Mainsail?''.

Technology has indeed moved forward, thank goodness!

 

[Greenheart]

Some 15 years ago in answer to the question how much solar array is required to run a fridge, the electrician would say: ''How big is yer Mainsail?''.

Why, what did he mean? Was he worried about shade, or did he plan on sewing panels into the main?

 

[Blueboatman]

My poor description. Panels required equal in area to a mainsail! Some fridge capacity eh?

Isn't there now technology that allows PVs toi be woven into sailcloth?

 

[Greenheart]

Isn't there now technology that allows PVs toi be woven into sailcloth?

I reckon we'd be hearing about it if it was available at more than development level. Very nice idea, although I don't want to imagine what 250sq ft of solar panelling would cost!

 

[pvb]

Boeings undoing was lithium polymer, along with sonylaptops.

Isn't the belief now that Boeing's problems were due to dendritic shorts caused by charging too rapidly? Their batteries used lithium cobalt oxide, I think, but all lithium-based batteries need very careful charging. Probably best to avoid for boat use unless you have sophisticated charging management.

 

[Robg71]

A blatant copy and paste......
Also, victron energy unlimited is well worth a read. Its not a sales brochure...


Lithium-iron-phosphate (LiFePO4 or LFP) is the safest of the mainstream li-ion battery types. The nominal
voltage of a LFP cell is 3,2V (lead-acid: 2V/cell). A 12,8V LFP battery therefore consists of 4 cells connected in
series; and a 25,6V battery consists of 8 cells connected in series.

Rugged
A lead-acid battery will fail prematurely due to sulfation if:
•
If it operates in deficit mode during long periods of time (i. e. if the battery is rarely, or never at all,
fully charged).
•
If it is left partially charged or worse, fully discharged (yacht or mobile home during winter time).

A LFP battery does not need to be fully charged. Service life even slightly improves in case of partial charge
instead of a full charge. This is a major advantage of LFP compared to lead-acid.
Other advantages are the wide operating temperature range, excellent cycling performance, low internal
resistance and high efficiency (see below).

LFP is therefore the chemistry of choice for very demanding applications.

Efficient
In several applications (especially off-grid solar and/or wind), energy efficiency can be of crucial importance.
The round trip energy efficiency (discharge from 100% t0 0% and back to 100% charged) of the average lead-
acid battery is 80%.
The round trip energy efficiency of a LFP battery is 92%.
The charge process of lead-acid batteries becomes particularly inefficient when the 80% state of charge has
been reached, resulting in efficiencies of 50% or even less in solar systems where several days of reserve energy
is required (battery operating in 70% to 100% charged state).
In contrast, a LFP battery will still achieve 90% efficiency under shallow discharge conditions.

Size and weight
Saves up to 70% in space
Saves up to 70% in weight

Expensive?
LFP batteries are expensive when compared to lead-acid. But in demanding applications, the high initial cost
will be more than compensated by longer service life, superior reliability and excellent efficiency.

Endless flexibility
LFP batteries are easier to charge than lead-acid batteries. The charge voltage may vary from 14V to 16V (as long
as no cell is subjected to more than 4,2V), and they do not need to be fully charged. Therefore several batteries
can be connected in parallel and no damage will occur if some batteries are less charged than others.

With or without Battery Management System (BMS)?
Important facts:
1. A LFP cell will fail if the voltage over the cell falls to less than 2,5V.
2. A LFP cell will fail if the voltage over the cell increases to more than 4,2V.
Lead-acid batteries will eventually also be damaged when discharged too deeply or overcharged, but not
immediately. A lead-acid battery will recover from total discharge even after it has been left in discharged state
during days or weeks (depending on battery type and brand).
3. The cells of a LFP battery do not auto-balance at the end of the charge cycle.
The cells in a battery are not 100% identical. Therefore, when cycled, some cells will be fully charged or
discharged earlier than others. The differences will increase if the cells are not balanced/equalized from time to
time.
In a lead-acid battery a small current will continue to flow even after one or more cells are fully charged (the
main effect of this current is decomposition of water into hydrogen and oxygen). This current helps to fully
charge other cells that are lagging behind, thus equalizing the charge state of all cells.

The current through a LFP cell however, when fully charged, is nearly zero, and lagging cells will therefore not
be fully charged. The differences between cells may become some so extreme over time that, even though the
overall battery voltage is within limits, some cells will be destroyed due to over- or under-voltage. Cell balancing
is therefore highly recommended.

In addition to cell balancing, a BMS will:
- Prevent cell under voltage by timely disconnecting the load.
- Prevent cell overvoltage by reducing charge current or stopping the charge process.
- Shut down the system in case of over temperature.
A BMS is therefore indispensable to prevent damage to large LI-ion battery banks.

 

[Hadenough]

We put 200watts of solar on last year and that has been brilliant, so much so that I'm thinking of dropping the bank down to 330AH and saving a battery.

How does that work? I have 240w of solar and a 450AH bank. I've found that on even on an average sunny day the controller is dumping charge. Surely the bigger the bank the more you can benefit from solar charging.

 

[philld]

There have been several car fire incidents, but they tend not to make the news. If you look at this Wikipedia article you may decide to research nickel-metal hydride instead.

 

[DaveS]

My poor description. Panels required equal in area to a mainsail! Some fridge capacity eh?

Isn't there now technology that allows PVs toi be woven into sailcloth?

About 5 years ago I was at a new technology exhibition where Heriot-Watt University announced that they had got this to work. Their suggested application was tents for disaster relief - I immediately thought of sails!

 

[kentwhite30]

Good point! Lithium-ion batteries are on the rise and it is quickly becoming an efficient energy choice used to power the vehicles these days. Furthermore, the lithium-ion batteries used in electric and hybrid vehicles are secure, but do have some fire risk related to them. However, brand new research may create a better battery that creates an extended driving range by replacing liquid electrolytes with a solid form.

 

[Sailingsaves]

I think you are on to something. I like the idea of being able to drain batteries beyond the tiny amount that many batteries allow. Then again, deep cycle leisure batteries allow that don't they, so maybe you are not onto something, but worth experimenting to find out.

Now if you could afford it, it could become a winter experiment for you. Buy one of the batteries so if expt successful you only have to buy another one and not waste the test battery. Make a waterproof box for it and line it with Nomex or another fire proof material (cut up an old fire blanket), place it in the garden, wire up your solar panels and a load (lots of bulbs?).

If battery does not come with charging protection circuit sort that out so it is safe and cannot be overcharged. Wire up a heat detecting fire alarm (they sit on shelf next to smoke alarms). Wire up ammeters and voltmeters etc.

Even better, get PBO to do all of the above - make a great new article and they pay for all the experimentation. And I might buy that issue.

 

[Seajet]

LEDs certainly are great...I was reading earlier about the dim recesses of an engine-room that is now made bright by having one of those cheap strips of LEDs round all the corners.

As to how much power is really needed, the answer must certainly be almost nil...but as long as there are powered conveniences that forty-footers enjoy, their denial to 20-footers must relate to the unavailability of sufficient power, largely as a result of lead-acid batteries' massive weight.

I'm still fascinated by electric auxiliaries. I hold out hopes for diesel-electric propulsion in sailing boats - I reckon diesel experts will agree that many sailors' brief use of their engines while getting out of the marina, is not good for the unit's long-term health; but if you had 10kw to play with for fifteen or twenty minutes, you could get off the mooring without starting the diesel. I don't pretend to have worked out any solution to the problems involved, but undoubtedly weight was one of them, and lithium ion cells could be an answer.

Dan,

quite a few years ago when the ex-MD of Andersons and myself were seriously thinking of building new A22's, I REALLY fancied having electric propulsion.

I had some serious chats with the very clued up ( German, sadly ) chap from Torqeedo; it soon became clear that it's only viable if using a whole big v expensive load of Lithium batteries as at least part of the ballast; ie , still a U-Boat !

So wouldn't work for the A22, but might well go in a traditional long keel wineglass type hull.

I would be concerned about fires ( I take the trouble to have a proper hydrogen vent tube from the gel battery on my boat ) and remember, as is the achilles heel of electric cars at present, the whole battery pack has a life of only around 7 years, so ouchy expensive + hassle...

I'm sure it will happen within our lifetimes - I really like the idea of my boat on the French Canals with electric propulsion - but not really quite yet.

Fuel Cells do look good too and may well be the solution...

 

[Storyline]

.....
We put 200watts of solar on last year and that has been brilliant, so much so that I'm thinking of dropping the bank down to 330AH and saving a battery. It's irritating to think that 330AH, weighing about 140kg and costing about £330 only gives me 120AH or realistic usable power, a bit pathetic really.

Having read so much on here about solar that is what I would like to do but the problem we have is space. Storyline is not exactly small at 36' and nowadays that could be called average but with a centre cockpit there is nowhere really suitable to mount that amount. The only thing I can think of is to hang them off the guard wires but that will not give very good results.

Therefore some kind of battery that is physically smaller would be an attractive option.

 

[Greenheart]

Andy, I've spent years researching, sometimes attempting electric propulsion...the worst thing about it isn't inadequate power, it's how terrifying it becomes when there's a fault!

I too concluded that something like a sail-converted MFV (or other heavy hull, more easily driven), with tonnes of concreted scrap metal ballast in her bilges, could instead house a huge weight of batteries that might allow reasonable range at moderate speed. I still think the idea of silent auxiliary power is among the most exciting prospects in sailing today.

I had a look lately at the ups and downs of lithium batteries, and I wasn't very impressed. They don't seem that much lighter than lead-acid, and their cost is jaw-dropping.

Still, I recognise that having far more usable power per kilo in Li-ion cells is a huge plus.

The OP will laugh at my craziness...but I'd still been looking at the Heavenly Twins, not as a prospective purchase but as a bit of design I find very interesting...and I'd wondered about an electric auxiliary on her, too. Excess weight & overloading being really bad for the HT's limited performance, conventional battery-weight would be catastrophic...

...but solar cells & sound-proofed generator charging Li-ion batteries, powering Agni motors turning folding propellers...well, it mayn't be practical, but I'm excited by the concept.

 

[Colvic Watson]

The HT is perfect for electric propulsion - light displacement - put a 6HP pod under each hull, 300AH batteries to get you in and out of the marina or tick over to motor sail and a diesel genny to run a diesel electric system for long runs and all the power you'd want on board for cooking, lighting, heating, air con

 

[Saguday]

Interesting thread.

Another big thumbs up for solar panels here, never looked back since we put ours on. Just replaced our 10 year old AGM's, balked at the expected cost but got a deal and did it for a quarter the price I thought it was going to cost. I keep looking at lithium but share the safety concerns and they were still too expensive to tempt me this time round, especially at the price I got the AGMs. Time will tell how long they will last though.

Apropos of electric propulsion Island Packet in the US have in the last week or so released glimpses via the owners FB page of something new they're buidling at the moment, which looks like an all-electric boat. They've not said officially what it is yet, just teasers, but they did 'like' my comment suggesting that this was what it was. Seems to be using Mastervolt products. Bob Johnson is a clever bloke, be keen to see what they come up with.

 

[nimbusgb]

water. Lithium doesn't like it.


I spent a merry day on the M5 some time ago managing the emergency services response to a lithium battery fire in a batch of ex helicopter batteries from Yeovilton. It took a lot of persuading to stop the FB using hose reels.


They are a serious, very serious, fire hazard unless managed in a very technical way. I'd stick with familiar lead-acid, or AGM technology, and look at options for maximising your present battery-charging regime. You are unlikely to have the storage space or electrical capacity constraints which can justify lithium.

So many misconceptions in that post.

 

[Seajet]

So many misconceptions in that post.

Yes, it always amazes me that the people with hands on experience get it wrong compared to the theorists...

 

[charles_reed]

There is a dedicated thread, on Cruisers & Sailors forum, on Li batteries in cruising use.
There you'll find lots of people who are using them rather than a few with with little experience but bags of prejudices.
Of course lithium batteries are a potential fire-hazard (as can be lead-acid batteries), but charger manufacturers are already producing chargers which they claim are suitable for either lead-acid or LiFe Xxx.
Unfortunately suppliers of Li cells appear to be few and far between in Europe and all expect an enormous premium for dealing with such hazardous devices.