Lithiums only beat LA if you don't have enough solar

[nicknorman]

4 hours ago, peterboat said:

You have it right LAs take far more amps to charge as they give out...

Not really. Charge efficiency of a LA battery is in the low 90% area, say 93%. So if you take out 100AH you have to put back 107.5 AH. Which personally I wouldn’t describe as “far more”.

[peterboat]

13 minutes ago, nicknorman said:

Not really. Charge efficiency of a LA battery is in the low 90% area, say 93%. So if you take out 100AH you have to put back 107.5 AH. Which personally I wouldn’t describe as “far more”.

The trouble is Nick I found that my batteries charged fairly easily when new but as the years clocked on they didnt charge anywhere near as well, whereas my LifePo4s are already over 8 years old and charge like lightning

[peterboat]

20 minutes ago, ivan&alice said:

They are easy to do? I feel like I have read a number of people on this forum saying the exact opposite. I'd be willing to consider it but I am not sure it is a good idea given Li's volatility. Why are off the shelf systems so expensive? And what about these cheap Li's that @peterboat has with built in BMS?

 

Ok so you just manually flip on the immersion heater (through the inverter) when you have tons of sun. Yeah, I really like that idea.

 

 

This is an oversimplification. I think you are misunderstanding my argument. According to @WotEver the "throttling back" happens when the remaining Ah to be charged is less than the A coming in. My whole point is that the current from solar is going to be relatively low (maximum 50A). So, the batteries are going to be charging at full speed, i.e. almost as fast as Li; the only difference being any efficiency gain from Li technology over LA technology.

 

I'm not expecting max (or even high) current for 14 hours a day. I'm expecting a low current for 14 hours a day.

 

My point is exactly that with a charging current as low and extended as what you get from solar, the benefits of Li's diminish.

 

Also, a digression, but 500W is less than a third of what I'm talking about.

This is a valid point: when you are closing in on fully charged, you're going to "waste" some of the solar you get because LAs won't be able to take it all. However this will be a small proportion of the time, precisely because solar has such a low charging current, not in spite of it. In the 1000Ah battery / 1500W PV system I'm talking about, the batteries will not charge bulk in full sun only for the last 50Ah. That is 50Ah out of 500Ah usable capacity. So only a maximum of 10% of the charge I'm going to be wasting some proportion of the energy that falls on the PV panels.

 

That said, it will be hard to get the batteries to 100% daily, and therefore you are likely to still need to run your engine for an extended period once a week to clear sulfation. So I am happy to add this above argument as a "pro" for solar with Li's. So far we have:

1. Li's charge more efficiently, so you get somewhat more effective power generated for any given PV system.

2. Li's can charge at full speed right up to full, so you will not waste solar energy when nearing 100% (about 10% of the time you will waste some solar energy with LAs). This might necessitate running your engine for extended periods once a week.

 

For me, this simply isn't worth the extra hassle and cost of Li's. I need a better pro argument than this.

 

Which implies 150Ah from the system I'm proposing on what you admit is a bad day. I calculated 300Ah odd from the system on an average day in October, and I'm basing this on data from @Col_T not making it up. Furthermore if this is not enough, just add more panels. For the price of 138Ah of lithium (even at a frankly unbelievable 250 GBP) you can get at least a half a kW worth of panels. PV is so cheap compared to Li batteries that it doesn't make sense to create an expensive, fragile battery bank that can suck up more solar power, instead of just adding more solar power.

You have to realise that Li is just lithium batteries there are versions and on here we all have the safe LifePo4 version which isnt volatile.

Also my immersion heater just runs straight from the solar panels direct about 160 volts DC, why wear out the inverter when their is no need?

Dr Bob, MP and I are using these and so would mike if he could be bothered, So whilst you and others have google we have the real experience of them, 3 of my friends are also using them as well, they are using the same valence batteries as myself, and they are also having better results than they did with LAs. All our batteries are from smiths electric vans that were a bit of a mistake so we managed to get a load of batteries cheap whilst the going was good.

[jetzi]

12 minutes ago, peterboat said:

Also my immersion heater just runs straight from the solar panels direct about 160 volts DC, why wear out the inverter when their is no need?

Ah thanks, that was the question I was asking - so your PV comes in at 160V?! I'm still struggling to picture your system, you have a flip switch before your charge controller and you can send the power to either your solar charge controller or your immersion heater once the batteries are full? Can an immersion heater run at any voltage you like - it's just a coil of high resistance wire after all?

 

 

12 minutes ago, peterboat said:

whilst you and others have google we have the real experience of them, 3 of my friends are also using them as well, they are using the same valence batteries as myself, and they are also having better results than they did with LAs.

Please understand, I know that I don't have experience here which is why I'm asking the question. I'm not trying to convince anyone of my opinion, I'm trying to understand the facts myself. People who have Li batteries love them, and I am trying to understand why because the facts as I understand them so far don't support it.

I'm sorry but the arguments presented so far are not enough to justify Li's, from my point of view. If they are better for me needs I really would love to be convinced - but I can't see it right now.

 

25 minutes ago, peterboat said:

The trouble is Nick I found that my batteries charged fairly easily when new but as the years clocked on they didnt charge anywhere near as well, whereas my LifePo4s are already over 8 years old and charge like lightning

Maybe this is a 3rd point? These batteries don't wear out so they give consistent and predictable performance?

 

12 minutes ago, peterboat said:

All our batteries are from smiths electric vans that were a bit of a mistake so we managed to get a load of batteries cheap whilst the going was good.

Ah, so you must see that this is a bit of an unfair advantage you have here. I don't "know a guy" that could organise me 250 GBP 138Ah LiFePO4s. So it's not really fair to compare these with 90 GBP 110Ah budget LAs. Any Li's I buy would be from a shop.

Edited September 29, 2019 by ivan&alice

[peterboat]

26 minutes ago, ivan&alice said:

Ah thanks, that was the question I was asking - so your PV comes in at 160V?! I'm still struggling to picture your system, you have a flip switch before your charge controller and you can send the power to either your solar charge controller or your immersion heater once the batteries are full? Can an immersion heater run at any voltage you like - it's just a coil of high resistance wire after all?

 

 

Please understand, I know that I don't have experience here which is why I'm asking the question. I'm not trying to convince anyone of my opinion, I'm trying to understand the facts myself. People who have Li batteries love them, and I am trying to understand why because the facts as I understand them so far don't support it.

I'm sorry but the arguments presented so far are not enough to justify Li's, from my point of view. If they are better for me needs I really would love to be convinced - but I can't see it right now.

 

Maybe this is a 3rd point? These batteries don't wear out so they give consistent and predictable performance?

 

Ah, so you must see that this is a bit of an unfair advantage you have here. I don't "know a guy" that could organise me 250 GBP 138Ah LiFePO4s. So it's not really fair to compare these with 90 GBP 110Ah budget LAs. Any Li's I buy would be from a shop.

No first contact was via ebay so its fair way of doing business, especially as I haggled the price down to what I paid so did Johnv who used to be on here, so we bought 18 batteries between us.

My immersion heater is a 3kw so its well under my maximum wattage [my drive solar is 2.5kw]

[nicknorman]

1 hour ago, peterboat said:

The trouble is Nick I found that my batteries charged fairly easily when new but as the years clocked on they didnt charge anywhere near as well, whereas my LifePo4s are already over 8 years old and charge like lightning

My batteries are coming up to 7 years old. The charge efficiency factor is calculated each time the batteries are fully charged, and is always between 92% and 94%. The figure hasn’t got any worse since they were new. If the CEF drops this means that the spare charge is going to gas the electrolyte in hydrogen and oxygen. So unless and until batteries start using a lot of water, the CEF is going to be in the low to mid 90s. Once batteries start using a lot of water, it is time to replace them.

[blackrose]

On a recent trip I was taking roughly 40 - 50ah/night out of my 450ah bank of Trojans. I have a gas fridge, LED lights and a 12v TV that draws about 2amps, so my consumption is low.  If I don't move the boat I can last at least 4 nights before I even have to think about re-charging, so I'm wondering if there's any real justification even in investing in solar panels, let alone Li-ion batteries and complex charging systems? I just can't see the point.

Edited September 29, 2019 by blackrose

[Dr Bob]

2 hours ago, ivan&alice said:

They are easy to do? I feel like I have read a number of people on this forum saying the exact opposite. I'd be willing to consider it but I am not sure it is a good idea given Li's volatility. Why are off the shelf systems so expensive? And what about these cheap Li's that @peterboat has with built in BMS?

 

 

Who is saying the exact opposite? .....and what are they saying?

I think there are 4 people on here with LiFePo4s and simple home brew bms systems .....well MP's might be a bit more complex then the other 3. People who dont have Li systems will not know how they operate or what is needed to control them. They are very different to LA's.

Tom and Bex have a simple bms system that I copied. Peter has a simple system. LiFePo4s are very robust (they are not volatile)......there is a video of some chinese guys trying to set fire to some. They didnt explode.

Off the shelf systems are expensive as the batteries are mega bucks...so the bms system has to have many levels of redundancy so you dont wreck them. If you can control your charge sources then you dont need all those levels of safety. If you buy cheaper 2nd hand batteries then a simpler system works just fine. I spend far less time managing my Li's than I used to spend looking at my LA's. A lot less time.

Tom & Bex and MP got their 2nd hand batteries from Jeremy....a guy who builds EV's. They gave me his number. I contacted him and bought mine. The number is available. I am sure anyone can get them from him.

LiFePo4s are the future (well the short and medium term until someone comes up with something better). All 4 of us on here with them think they are fantastic and save lots of time that would be spent faffing with LA's. None of the 4 of us would switch back....ever? Tom (from T&B) told me last winter that the money he spent on Li's was far better than if he had invested in solar. Time will tell and after a few years others will follow and see the benefits.

This isnt about me trying to convince anyone to move to Li's. All I am trying to do is to relay the info I am getting from them so others can see exactly what they would be getting.

 

Just a question on your 3 times 500W. I have 4 panels on my 62' NB - total 500W. I couldnt fit anymore without restricting movement on the roof.....needed at locks.....or snagging centre lines etc. If you have a fat boat...then ok...but if it is a NB then how are you going to fit 1500W of panels? I would agree with you, if you have 1500W of solar then any battery system is going to work for 8 months of the year. Problem is, most of us dont have more than 500W on the roof so on days like today (not that bad by the way) you will only get a low % of your power (except MtB who is in camping mode if only using 30Ahr per day). I have always said, Li's are most use to CC'ers (or more specifically CM'ers).

[Dr Bob]

2 hours ago, Alan de Enfield said:

And, that's September.

 

Do you have plots on file of December / Jan / Feb ?

No, I didn't install the rasp Pi till march this year. I'll get the data over this winter.?

[jetzi]

41 minutes ago, blackrose said:

On a recent trip I was taking roughly 40 - 50ah/night out of my 450ah bank of Trojans. I have a gas fridge, LED lights and a 12v TV that draws about 2amps, so my consumption is low.  If I don't move the boat I can last at least 4 nights before I even have to think about re-charging, so I'm wondering if there's any real justification even in investing in solar panels, let alone Li-ion batteries and complex charging systems? I just can't see the point.

Sure, that's the other way you can do it - cut your consumption to near zero. As we need to be able to work from the boat this isn't really an option for us.

 

 

13 minutes ago, Dr Bob said:

I spend far less time managing my Li's than I used to spend looking at my LA's. A lot less time.

Point 4 for Li's then - less time mucking about with batteries is a fair pro.

 

15 minutes ago, Dr Bob said:

All 4 of us on here with them think they are fantastic

And I'm just trying to work out why, to see if they would be fantastic for me in my situation. I have 4 reasons so far, and none of them are enough to make Li's a go for me.

 

16 minutes ago, Dr Bob said:

This isnt about me trying to convince anyone to move to Li's. All I am trying to do is to relay the info I am getting from them so others can see exactly what they would be getting.

I know, and this isn't about me trying to convince anyone that Li's are worse than LAs. I just can't see why anyone with a big solar array and minimal usage in winter would need Li's, and if I'm wrong I want to know because I need to know what batteries to buy!!

 

 

18 minutes ago, Dr Bob said:

ust a question on your 3 times 500W. I have 4 panels on my 62' NB - total 500W. I couldnt fit anymore without restricting movement on the roof.....needed at locks.....or snagging centre lines etc. If you have a fat boat...then ok...but if it is a NB then how are you going to fit 1500W of panels? I would agree with you, if you have 1500W of solar then any battery system is going to work for 8 months of the year. Problem is, most of us dont have more than 500W on the roof

I haven't settled, but I planned to get four of these which are 1675x998. My boat would take up to 9 of these on the roof lengthwise (up to 3.6kW max), which would leave a strip either side a little wider than a gunwale. I haven't decided, but I'm thinking of hinging them on either side so I could lift them up almost vertical in one direction to make it easier to move on the roof. I have never needed to walk on the roof at locks even though it is sometimes helpful. I have a centre lines each which run in that little strip so I don't see them getting snagged. In fact having a continuous strip of solar panels would in my estimation make for less spots to snag.

[Dr Bob]

I use the roof a lot when going uphill at locks so Mrs Bob can go and set the next lock.  You couldn't hinge them up when moving which is when I need to use the roof. Everyone has their own way of doing things!!!

Best of luck in your decision but if you are having 1500w of solar then anything will do for most of the year. Your solar controller will not be cheap though.

Keep us posted on what you decide and how you are getting on with it when fitted.

Not sure if you want to monitor your power usage but if you are planning to get a victron BMV battery monitor, you can store all the data on a Rasp Pi and produce graphs like the one I put up earlier.....cost me about £50.

[peterboat]

4 minutes ago, Dr Bob said:

I use the roof a lot when going uphill at locks so Mrs Bob can go and set the next lock.  You couldn't hinge them up when moving which is when I need to use the roof. Everyone has their own way of doing things!!!

Best of luck in your decision but if you are having 1500w of solar then anything will do for most of the year. Your solar controller will not be cheap though.

Keep us posted on what you decide and how you are getting on with it when fitted.

Not sure if you want to monitor your power usage but if you are planning to get a victron BMV battery monitor, you can store all the data on a Rasp Pi and produce graphs like the one I put up earlier.....cost me about £50.

1200 watts isn't enough if you do no cruising,  when I had 2500watts it was enough just with my extravagant life style, this year it will be 3700watts through the winter and I hope not to need the whispergen at all. When not at the boat I do switch it to 1200 watts to domestic as I prefer the batteries not to be fully charged, and maybe get some hot water from the immersion heater 

[Dr Bob]

2 minutes ago, peterboat said:

1200 watts isn't enough if you do no cruising,  when I had 2500watts it was enough just with my extravagant life style, this year it will be 3700watts through the winter and I hope not to need the whispergen at all. When not at the boat I do switch it to 1200 watts to domestic as I prefer the batteries not to be fully charged, and maybe get some hot water from the immersion heater 

Yea, but you've got a super tanker with the roof space of a football pitch!

 

Us mortals only have a 7' wide sewer tube.

[jetzi]

7 hours ago, Dr Bob said:

I use the roof a lot when going uphill at locks so Mrs Bob can go and set the next lock.  You couldn't hinge them up when moving which is when I need to use the roof. Everyone has their own way of doing things!!!

I do most of the locking single handed and the only time I find the roof useful as a passageway is when I'm in a deep lock and the ladder is in an awkward position. Why can't Mrs Bob leave the boat at the bow?

 

I'm envisaging a mechanism where I can tilt all the panels together. My thinking would be that I could hinge up the panels as needed when arriving at a lock or other place I needed to use the roof.

 

The other option is to get a gangplank that you can place over the panels to protect them or the stick-on type that you can walk on. Of course these are less efficient, but the solar panels themselves are the cheapest component of the generation system, so it seems to me to make sense (if you have the space) to double or triple up on what you need so that you don't have to be as careful about squeezing every last drop out of them. In winter you can be more fastidious about angling them perfectly so you can maximise the energy.

 

7 hours ago, Dr Bob said:

Your solar controller will not be cheap though.

No, this is true. Around 700 GBP for a 100A Victron MPPT. 100A is loads though; perhaps to save money it might make sense to get only one smaller one for now and simply turn off solar panels when it gets too sunny. So in winter use 6 or even 8x 400W panels and then in summer just the 4 going through the 100A MPPT.

 

That's why I was so interested in the immersion heater idea, and why I was curious to understand @peterboat's wiring. If he needs an inverter/controller for the excess panels then this is going to raise the price substantially. If I can somehow switch the PV away from my precious MPPT and straight to the immersion heater, that would mean I'd need less MPPT.

 

7 hours ago, Dr Bob said:

Keep us posted on what you decide and how you are getting on with it when fitted.

Not sure if you want to monitor your power usage but if you are planning to get a victron BMV battery monitor, you can store all the data on a Rasp Pi and produce graphs like the one I put up earlier.....cost me about £50.

I certainly will, thanks! My install date is only 2020-04-01, I don't see there being any point in installing before spring and this will give me time to save and study. I'm definitely keen to hear more about the battery monitor but I'm going to get the basics down first before I ask a lot of questions about that.

[MtB]

11 hours ago, Dr Bob said:

(except MtB who is in camping mode if only using 30Ahr per day).

 

My 30AH/day is at 24V, as I never tire of pointing out 

 

So equivalent to 60AH/day for those with 12V banks.

 

And unlike you, there is only one of me on the boat consuming the leccy. A point often overlooked. 

[MoominPapa]

18 hours ago, ivan&alice said:

LAs are highly recyclable though and I understand that Li is considerably less so, so it is debatable that it is a more environmentally friendly option. Even if this is true it wouldn't be enough of a reason to swing me unless all else was equal.

Not clear to me why that would be. Apart from the plastic case, most of the weight of a Li battery is copper and aluminium foil. A process which minces that and then separates the Cu and Al based on density would seem to be perfectly practicable.  The weight of Li in a Li cell is quite small.

 

MP.

 

4 minutes ago, Mike the Boilerman said:

 

My 30AH/day is at 24V, as I never tire of pointing out 

 

So equivalent to 60AH/day for those with 12V banks.

 

And unlike you, there is only one of me on the boat consuming the leccy. A point often overlooked. 

Can we have new rule that electrical energy is always given in KWh and rate of use of EE in Watts? Maybe we should be purist, as insist on Joules instead of Kwh?

 

The first person to specify a volume of water in acre-feet gets lynched

 

MP.

 

[rusty69]

I am in the market for a new set of batteries.I am currently torn between trojan t105's or a small lithium bank, or my usual cheapies we have 1000W of solar. Decisions decisions..................

[peterboat]

2 hours ago, ivan&alice said:

I do most of the locking single handed and the only time I find the roof useful as a passageway is when I'm in a deep lock and the ladder is in an awkward position. Why can't Mrs Bob leave the boat at the bow?

 

I'm envisaging a mechanism where I can tilt all the panels together. My thinking would be that I could hinge up the panels as needed when arriving at a lock or other place I needed to use the roof.

 

The other option is to get a gangplank that you can place over the panels to protect them or the stick-on type that you can walk on. Of course these are less efficient, but the solar panels themselves are the cheapest component of the generation system, so it seems to me to make sense (if you have the space) to double or triple up on what you need so that you don't have to be as careful about squeezing every last drop out of them. In winter you can be more fastidious about angling them perfectly so you can maximise the energy.

 

No, this is true. Around 700 GBP for a 100A Victron MPPT. 100A is loads though; perhaps to save money it might make sense to get only one smaller one for now and simply turn off solar panels when it gets too sunny. So in winter use 6 or even 8x 400W panels and then in summer just the 4 going through the 100A MPPT.

 

That's why I was so interested in the immersion heater idea, and why I was curious to understand @peterboat's wiring. If he needs an inverter/controller for the excess panels then this is going to raise the price substantially. If I can somehow switch the PV away from my precious MPPT and straight to the immersion heater, that would mean I'd need less MPPT.

 

I certainly will, thanks! My install date is only 2020-04-01, I don't see there being any point in installing before spring and this will give me time to save and study. I'm definitely keen to hear more about the battery monitor but I'm going to get the basics down first before I ask a lot of questions about that.

Right Ivan, I have 2 Midnite classic 200s one is for leisure [24 volts] and one is for drive [72 volts] they are made in the USA and are maybe the best money can buy! I can give you where to buy them easily but you will need to do it now as its in Spain. I have 3 strings of solar 4 panels in series, in each string 8 of the panels are 310 watts, the 4 are 300 watts. The larger panels are paralleled together and feed the drive controller or can be switched to either the immersion heater or to the domestic controller. All the panels can also be switched to the drive controller, its complicated but very easy in the flesh.

Because my leisure system is 24 volts I can have more effective solar onto it

look at this chart

 

Classic Sizing Tool. - MidNite Solar

 

www.midnitesolar.com › sizingTool

 

Its very useful and will show you the problems of 12 volt systems and how you can normally only use 1100 ish watts of your 1500 watt solar system, some solar controllers are even less many are 720 watts!

If you have any more questions please ask

[cuthound]

I have worked with various types batteries all of my working life, but unfortunately not any of lithium ion types.

 

However I would be VERY wary of any claims of longevity for any battery type, including lithium ion. This is because they are all chemical devices, and temperature, charge and dischsrge rates significantly affects the chemical reactions. For example Tesla Superchargers revert to a much lower rate of charge once the battery has reached 80% Doc to ensure a reasonable balance between short charge time and battery life.

 

I have seen quality lead acid batteries, as used in the critical power industry,  last for 25 years (against an average life of  6-10 years) when the ambient temperature, charge parameters and discharge parameters have been carefully controlled. Conversely I have seen them wrecked in a few weeks.

[Dr Bob]

5 hours ago, rusty69 said:

I am in the market for a new set of batteries.I am currently torn between trojan t105's or a small lithium bank, or my usual cheapies we have 1000W of solar. Decisions decisions..................

I'd get an eco fan.

[peterboat]

1 hour ago, cuthound said:

I have worked with various types batteries all of my working life, but unfortunately not any of lithium ion types.

 

However I would be VERY wary of any claims of longevity for any battery type, including lithium ion. This is because they are all chemical devices, and temperature, charge and dischsrge rates significantly affects the chemical reactions. For example Tesla Superchargers revert to a much lower rate of charge once the battery has reached 80% Doc to ensure a reasonable balance between short charge time and battery life.

 

I have seen quality lead acid batteries, as used in the critical power industry,  last for 25 years (against an average life of  6-10 years) when the ambient temperature, charge parameters and discharge parameters have been carefully controlled. Conversely I have seen them wrecked in a few weeks.

Some Teslas have over half a million miles on their battery packs already! There is a Tesla for sale on ebay that has covered 266K miles and they want big money for it!! Its all about battery management and Teslas only fill up to 80% to give them their long life you can do 100% by pressing the screen but as you say that then cases issues later

[cuthound]

8 minutes ago, peterboat said:

Some Teslas have over half a million miles on their battery packs already! There is a Tesla for sale on ebay that has covered 266K miles and they want big money for it!! Its all about battery management and Teslas only fill up to 80% to give them their long life you can do 100% by pressing the screen but as you say that then cases issues later

 

Agreed, but Tesla use battery cooling and heating systems to keep their batteries in a relatively controlled temperature window.

 

I'll bet most installations don't have the sophistication of a Tesla.

[Dr Bob]

7 minutes ago, cuthound said:

 

Agreed, but Tesla use battery cooling and heating systems to keep their batteries in a relatively controlled temperature window.

 

I'll bet most installations don't have the sophistication of a Tesla.

Anyone got any good links to the new Tesla 3 ...to understand more about their batteries....ie forums etc.

Thinking about getting one. Not sure how many solar panels I will get on the roof though.

[peterboat]

59 minutes ago, Dr Bob said:

Anyone got any good links to the new Tesla 3 ...to understand more about their batteries....ie forums etc.

Thinking about getting one. Not sure how many solar panels I will get on the roof though.

Teslarati or summat like that

[cuthound]

1 hour ago, Dr Bob said:

Anyone got any good links to the new Tesla 3 ...to understand more about their batteries....ie forums etc.

Thinking about getting one. Not sure how many solar panels I will get on the roof though.

 

It would appear thst whilst the bstteries may last a million miles, the body won't. ?

 

https://insideevs.com/news/372613/tesla-model-3-new-kind-rust-problem/