Lithium fears

[Neeves]

In Australia one of the fears underlining Lithium uptake, or lack of uptake, in cars is the fear of there not being sufficient re-charging facilities. Its a big country, 1,000km between capital cities is 'normal'.

I see the advantage of Lithium in yachts, more amps for your kg (and Lithium prices, historically high have been falling). Lithium seems the ideal development, especially in Australia with its well know sunshine. Lithium is portrayed as much more efficient than Lead, negating the need for a gen set, no need for dangerous gas nor running the inboard diesel (and no longer upsetting the neighbours - and being environmentally unfriendly)

This thread is focussed at those who use Lithium as liveaboards for their practices of the amps they harvest from their solar.

Yesterday and the previous few days we enjoyed almost maximum sunshine, minimal clouds and (watching the forecasts, see below) all opportunity to fill the Lithium battery bank.

Today its effectively rained all day, rain fall on Pittwater has hovered around 20mm and the weather (defined by rainfall) and forecast for the next week is, and I average:

Tomorrow 10mm. worst case is 15mm
Day 2 10mm..............................15mm
Day 3 20mm..............................30mm
Day 4 30mm...............................50mm
Day 5 30mm...............................50mm
Day 6 20mm................................30mm

Now these are forecasts - not certainty.

Basically no sunshine.

What size of battery do you need to survive as a liveboard, relying on Lithium? No gas, no gen set - you do have a B2B of 40 amps. Pittwater is relatively civilised - Avalon (of Home and Away fame is a 20 minute walk)

My crude and uneducated guess is a 600 amp battery bank - or an inconvenient time under engine (shades of charging Lead batteries)

What is the reality?

Jonathan

 

[Sea Change]

"portrayed as more efficient". What an unusual choice of words. You sound sceptical. The indisputable facts are that lithium batteries have far higher round trip efficiency and much faster charging than lead acid. They also have almost all order of magnitude greater cycle life.

As to your question, we started out with a 280Ah bank and were very close to not needing gas or engine charging. We then added a second battery, bringing us up to 550Ah, and unless we go crazy with cooking this now makes us totally self sufficient for power. But the battery is only one side of the equation. The solar power is obviously critical too- we have 930w going in to the lithium. The other factors are usage (we almost always cook onboard from scratch, but we often cook pretty simple meals; baking or anything involving multiple rounds in the air fryer takes more power), and location (the Med was excellent for solar, the Caribbean a bit more varied, but still enough sun for us).

 

[vas]

Jonathan, it's a combo of solar size and lifepo4 size (I personally don't count on the engine's alternator as I tend to move for a few hours and then stay put for 4-5days).

I'm currently away from boat in Crete, checking remotely the stats and it seems with a "normal" overcast weather (not raining) I get 40% of max output compared to 70% for an April.
So if you overspecify solar panels (assuming you have somewhere to fit them that don't make the boat look crap...) you should be okay...

 

[geem]

A very odd choice of words. "Portrayed as more efficient" its is more efficient. I don't think anybody would dispute that. The hard facts are available for scrutiny.
You have options when your solar harvest is reduced. Don't use so much power or install a larger system. You can install more battery capacity to get you through the cloudy days and/or you can install more solar. Only you will know what your options are.
With lithium its not just a simple efficiency thing though. A good lithium battery will do far more cycles and have a longer calender life than lead. It doesn't care about sitting in a state of partial discharge ( something that will kill lead batteries in short order). They don't get as hot when being charged quickly, unlike lead. They can be charged often at their C rating with no harm unlike lead that is happier at far lower charge rates. They can be discharged at high rates with no ill effects so they can be used to power big inverters for cooking, making water, running the immersion heater, etc
I really get the impression you have a downer on lithium where as everybody we have met who has them uses phrases like "game changer"
I don't hear that from you. Why is that? I know you don't have them installed on a boat so maybe this is the difference

 

[stranded]

Lithium is brilliant, but it’s not magic - in itself it doesn’t negate the need to balance energy harvest, storage and usage.

I imagine the answer to your question very much depends on whether you are an old fashioned “live within your means” type of chap or a modern “I want it and I want it now” go getter (other descriptors are available).

We have planned around making hay when the sun shines. Even in this glum English spring we are already enjoying the benefits of our new lithium installation - using electric kettle, Nespresso machine, immersion heater much more than before. But only when we can. We are also happy to throttle back when we have forecasts like your example. The need to be more conscious of our use of resources when on board is an interesting contrast to the careless everything on tap attitude at home. So I reckon in basic but perfectly comfortable mode we can easily last a week without turning the engine on - we might whiff a bit by the end, and my wife may have to settle for Red wine, but there can be satisfaction in (mild) adversity. If you want it all, all the time, you are going to have to be rather more ambitious in your setup.

 

[Sandy]

Out of interest what percentage of the time do most boats motor sail?

Last week I was crewing on the 'other boat' I regularly sail on out of Southampton. A few days of mixed wind from F1 – F6 where we spent 50% of our time motor sailing.

p.s. where was everybody it was really quiet on Lake Solent?

 

[dancrane]

It was foul and it felt freezing. So everyone was at home staring glumly out of the window, wishing they owned a boat they could steer from inside, especially since as you say, motorsailing dominates most people's use (not that any of them will admit it ).

 

[Neeves]

Lithium is brilliant, but it’s not magic - in itself it doesn’t negate the need to balance energy harvest, storage and usage.

I imagine the answer to your question very much depends on whether you are an old fashioned “live within your means” type of chap or a modern “I want it and I want it now” go getter (other descriptors are available).

We have planned around making hay when the sun shines. Even in this glum English spring we are already enjoying the benefits of our new lithium installation - using electric kettle, Nespresso machine, immersion heater much more than before. But only when we can. We are also happy to throttle back when we have forecasts like your example. The need to be more conscious of our use of resources when on board is an interesting contrast to the careless everything on tap attitude at home. So I reckon in basic but perfectly comfortable mode we can easily last a week without turning the engine on - we might whiff a bit by the end, and my wife may have to settle for Red wine, but there can be satisfaction in (mild) adversity. If you want it all, all the time, you are going to have to be rather more ambitious in your setup.

I was going to develop a spreadsheet based on Geem's last thread, house bank size vs solar display size for the various respondents but realised this was not too useful in itself - the spreadsheet needed more data, the worst case scenario. Which is actually occurring on Pittwater now (in sunny Sydney).

So looking at your usage and my weather forecast, and the latter is worst case scenario (I hope) - what is you actual usage of amps, say for a week, or averaged from that week. In my worst case scenario - assuming minimal or no solar input.

So what is:

'basic but perfectly comfortable mode we can easily last a week without turning the engine on' in terms of amps needed.

So data not words.

I can find the size of the batteries for most of the liveaboards, its in Geem's last (and valuable) thread. I can define the size of the solar display vs the size of the battery. Sadly that does not define usage of amps as many of those that post are doing so not 'in worst case scenario'. Most investors in Lithium have access to amps used - and farmed - but this is not defined.


So stranded, and to others, less of being defensive, or critical of my question (which seems fairly reasonable), less of the sarcasm - can you provide the data from those that use Lithium - to help those who do believe in Lithium and want some advice.

I appreciate this the 'how long is a piece of string' question - but anyone investing would want to do it once - and get it right. You would not want to have the need to buy a second, or third, or fourth battery - as that would need space that means rewiring what you have to fit in the extra.


"Portrayed as more efficient" - its only more efficient if it does what it says on the box (or on a forum). On the box it says (something like) 'with Lithium you can do without gas and a Lead bank, forum posts list the benefits of Lithium, more cycles, more amps/kg (but assuming the battery bank is big enough - its not efficient if you drain the bank) - but no-one has defined how big a Lithium bank you might need to replace gas (and maybe the alternator).

Jonathan

 

[Sandy]

@Neeves you pose an interesting question about data.

As I have said in other threads I am not convinced that Lithium is for most UK sailors. I am running a spreadsheet for my 200 watts of solar and 390 Ah of AGM house batteries this summer. While the boat will only be used hard for six weeks this year, for some reason work keeps piling in, it will be interesting to compare results.

 

[Tranona]

So what is:

'basic but perfectly comfortable mode we can easily last a week without turning the engine on' in terms of amps needed.

So data not words.


Jonathan

That is what makes your question almost unanswerable - very much an individual decision that may be data based or just reflecting your attitude. It is clear to me (as an observer) that what is valued most is the flexibility to adjust consumption to meet availability of power. Posts 2&5 reflect this very well and in a sense you don't need detailed data but an understanding in your individual case of how and when to make the necessary adjustments whether it be to reduce consumption or increase input by, for example running the engine/generator or popping into a marina for a quick burst of shorepower.

 

[Sea Change]

I'm not really sure what you're trying to find out, Jonathan. For any given amount of storage and solar, lithium will need a far smaller battery bank compared to lead acid, because you can use almost 100% of the capacity without any damage, and it charges faster and more efficiently, so less solar is needed.

It is not true to state that lithium suddenly lets you rip out your gas system, never alternator charge again, etc. Any electrical system could be built to do that if it's big enough, just you'd be a bit mad to try doing it with lead acid.

 

[Sea Change]

That is what makes your question almost unanswerable - very much an individual decision that may be data based or just reflecting your attitude. It is clear to me (as an observer) that what is valued most is the flexibility to adjust consumption to meet availability of power. Posts 2&5 reflect this very well and in a sense you don't need detailed data but an understanding in your individual case of how and when to make the necessary adjustments whether it be to reduce consumption or increase input by, for example running the engine/generator or popping into a marina for a quick burst of shorepower.

One way that we adjust consumption is to cook something different. If we're really struggling (doesn't happen now, with 550Ah) we will do a BBQ. Or a six minute pressure cooker risotto, takes probably less than 10Ah. On days when we are getting back to 100% easily, we can do what we like, which will include batch baking bread for the freezer. An unusual way to store solar energy but it works for us!

 

[vas]

Jonathan,
I agree with T & SC that it's unanswerable.
Keep in mind ambient temps (and fridge efficiency/performance) makes a great difference in overall system performance

 

[stranded]

I was going to develop a spreadsheet based on Geem's last thread, house bank size vs solar display size for the various respondents but realised this was not too useful in itself - the spreadsheet needed more data, the worst case scenario. Which is actually occurring on Pittwater now (in sunny Sydney).

So looking at your usage and my weather forecast, and the latter is worst case scenario (I hope) - what is you actual usage of amps, say for a week, or averaged from that week. In my worst case scenario - assuming minimal or no solar input.

So what is:

'basic but perfectly comfortable mode we can easily last a week without turning the engine on' in terms of amps needed.

So data not words.

I can find the size of the batteries for most of the liveaboards, its in Geem's last (and valuable) thread. I can define the size of the solar display vs the size of the battery. Sadly that does not define usage of amps as many of those that post are doing so not 'in worst case scenario'. Most investors in Lithium have access to amps used - and farmed - but this is not defined.


So stranded, and to others, less of being defensive, or critical of my question (which seems fairly reasonable), less of the sarcasm - can you provide the data from those that use Lithium - to help those who do believe in Lithium and want some advice.

I appreciate this the 'how long is a piece of string' question - but anyone investing would want to do it once - and get it right. You would not want to have the need to buy a second, or third, or fourth battery - as that would need space that means rewiring what you have to fit in the extra.


"Portrayed as more efficient" - its only more efficient if it does what it says on the box (or on a forum). On the box it says (something like) 'with Lithium you can do without gas and a Lead bank, forum posts list the benefits of Lithium, more cycles, more amps/kg (but assuming the battery bank is big enough - its not efficient if you drain the bank) - but no-one has defined how big a Lithium bank you might need to replace gas (and maybe the alternator).

Jonathan

I deliberately didn’t include numbers because they apply to me, my boat, our tolerance for occasional lack of luxuries, where and when we sail, whether the wind will be blowing when we are at sea, my attitude to running the engine just for charging. A spreadsheet isn’t going to capture that, you’ll need a fully evolved AI model. The sums are no different from those people have to make for other battery chemistries - there is no shortcut to doing your own energy audit or, as we have done, taken a stab at it accepting we may well need to adjust when the plan comes up against reality. I’m comfortable with that. Sounds like you wouldn’t be.

 

[Sea Change]

One other number to include- we have an 18A DC-DC charger, the smallest available. I only ended up fitting it because it became spare from another project.
I find that having such a miserly charger means that you never fall in to the habit of downing sail and motoring "because the batteries need a bit of a charge". But it's comforting to have it installed, as it means in extreme low power situations we'd be able to keep the freezer running. Haven't had to do that, we generally manage our power consumption well enough to avoid the need.

 

[Neeves]

There is currently no data, at all, (or nothing I have seen) on an all electric galley. Historically most people use gas and don't use Lead. I confess I don't know how to convert gas usage (and its wastefulness) to use of, say, an induction hob. I can find no basis to devise what might be a sensible Lithium Battery bank for a galley (as well as replacing a Lead house bank). I know what size of Lithium banks some have, its in Geem's last thread - but maybe some have Lithium banks that are a bit big or wish they were bigger.

My current conclusion is that people buy or build a Lithium battery and once it is in service they decide to build/buy (or not) another battery - and then find their inverter is too small and the B2B totally inadequate. If one knew that a 400amp Lithium bank could be used frugally for a week (worst case scenario) one might then plan for a 600amp bank.

I'm puzzled at the, complete, lack of data - and the apparent reluctance to offer same. Sea Change/aka Kelpie - has provided some data - its a good start

What's wrong with.... "we are a cruising couple and we consume about 25amps or 64 amps a day on average (that's amps used, whether from solar or the battery, at anchor in the Caribbean (but we often use a gas BBQ - maybe 3 times a week". Others might suggest they use more or less - currently there is no data - at all.

My understanding is that Victron devices can devine exactly what is being harvested and used - but maybe I have that wrong. The lack of data would then be simple - its too difficult to abstract.

Obviously we all use our energy resources differently - but a response from those few with Lithium house banks would be a basis from which to start - and the more people who respond will make the data more robust.

Why am I asking - simply so that I can buy once and buy right - to make my purchase - efficient. Hopefully a cross section of amps used would also be invaluable to anyone else interested in a Lithium house bank and an all electric galley.

Or is the all electric galley a pipe dream - to vulnerable to the vagaries of the weather.

Jonathan

 

[Sea Change]

I wouldn't call it a pipe dream at all, we've been running an electric galley for nearly three years and it's easily the best upgrade we have made to the boat. At Martinique gas prices it's probably paid for itself already, which is remarkable given I didn't expect to ever see a return on investment like that. I primarily wanted to minimise heat inside the boat, and also avoid the hassle of hunting for gas bottles as we moved from country to county.

I'm not sure what numbers I can provide you with other than those already given.
A cup of tea takes about 2-3Ah, most meals where we're not trying to save energy are around 70Ah. Our background running (mostly fridge and freezer) sits at about 8-10A.

Our Epever MPPTs don't log solar input so I don't have an easy way to tell you how much we generate or use. In practise, I glance at the battery monitor in the morning and we cook appropriately that day in the hope of being at the same SOC or higher the following morning. Or look at the weather forecast and if the next few days look good, we can be a bit more generous with power consumption.

 

[geem]

If you invested in Victron MPPTs they would give you upto 30 days of data logging. The unit of measure for energy harvested is kWh not amps. The Victron kit logs the daily kWh harvested. For us our solar provides about 3kWh on cloudy days and upto 4.3kWh on sunny days at the moment. If its nice and windy we get about another 0.5kWh per day from the wind turbine. On a cloudy day we will decide what not to use. We always cook electrically regardless of the cloud conditions as it keeps the galley cool. We may not make water for the day if the tank level is high. Water making uses 0.5kWh per day. A tank of hot water is another 0.5kWh. The batteries are rarely less than 75% charged by the end of the day even on cloudy days

 

[rogerthebodger]

Jonathan

I have been looking to converting my setup to lithium for sone time but due to lack of data I am confused to what I really need as my battries are getting to end of life

I currently have a 12 VDC system with 12 x 105 Ah lead acid domestic bank that I can separate into 2 sections. charged from 8 80w 12vdc solar panels
I have a 150 Ah engine start battery. charged from a separate 50 w solar.

I have a 120 Amp engine driven charging the domestic and a 70 Amp engine driven alternator charging the engine start battery.

I also have a mains battery charger charging the batteries via a selector switch not used much as solar kept batteries in order.

Anyone has recommendations for equipment and suppliers for my setup.

I have a 12 vdc bow thruster powered from the domestic battery with very large buss bars between battery and bow to power windlass and bow thruster

Inverter is 2500 watt for power tools and microwave cooking is by gas and we will keep gas for time being

 

[Sea Change]

If you invested in Victron MPPTs they would give you upto 30 days of data logging. The unit of measure for energy harvested is kWh not amps. The Victron kit logs the daily kWh harvested. For us our solar provides about 3kWh on cloudy days and upto 4.3kWh on sunny days at the moment. If its nice and windy we get about another 0.5kWh per day from the wind turbine. On a cloudy day we will decide what not to use. We always cook electrically regardless of the cloud conditions as it keeps the galley cool. We may not make water for the day if the tank level is high. Water making uses 0.5kWh per day. A tank of hot water is another 0.5kWh. The batteries are rarely less than 75% charged by the end of the day even on cloudy days

At the time I built my system, there was a substantial price difference and Victron was out of budget. They appear to have come down quite a lot now, I might make the switch and leave my Epevers as spares.