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


jetzi

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Inflammatory statement? Maybe. But I'd like to see if anyone can make a good pro-Li argument over LA's in this situation.

 

Say you have enough solar to generate 100% of your usage for 8 months of the year, and say the 4 darkest months you winterise your boat and live on land.

 

The main benefit of Li batteries is that they suck up all the charge you can throw at them and you don't need to ever go to 100%, meaning less running of your engine or genny. So if you are slow charging your battery bank all day from solar, that main benefit seems to be nullified.

Edited by ivan&alice
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Where to start? I have LifePo4s for over a year, they charge much faster than LAs so on poor summer/spring/autumn  days they work better, they are lighter and smaller and can be put where LAs cant, they last far longer than LAs in fact a set properly looked after would last a lifetime, saving much recycling and waste! Mine are secondhand and I would expect them to last another 20-30 years how much as that saved me in cost and effort changing them?

I think the tittle should be haw can you justify LAs over LifePo4s?

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12 minutes ago, peterboat said:

they charge much faster than LAs so on poor summer/spring/autumn  days they work better

But they don't charge faster than LAs when you're charging slowly over the whole day, right? If your solar is putting in 50A the LAs will be able to take it as bulk charge right up until you have only 50Ah remaining (for a 1000Ah bank, that's 95% of the charge). This is actually my whole point, so if I'm wrong about this I'll have to correct my position.

 

15 minutes ago, peterboat said:

they are lighter and smaller and can be put where LAs cant

Not usually a problem on a boat. Certainly not on my boat. In fact I drive around with a bilge full of concrete so putting a few LAs nice and low would if anything be a plus.

 

16 minutes ago, peterboat said:

they last far longer than LAs in fact a set properly looked after would last a lifetime, saving much recycling and waste!

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.
 

18 minutes ago, peterboat said:

Mine are secondhand and I would expect them to last another 20-30 years how much as that saved me in cost and effort changing them?

Well I hope you are right about that but it's certainly not what I hear. Li's last a long time but I've never heard anyone claim 20-30 years before. They're also more volatile so the chances of one accident destroying the bank is higher than with LAs.

 

I should also qualify that I'm thinking about this in terms of GBP/Ah/year, so yes you'll save the effort of physically replacing the batteries but Li's are widely recognised to be something like twice the price (GBP/Ah/year). So I'm not sure what you're referring to as saved cost. I'm trying to determine what advantage would justify the higher price of Li in my particular scenario, which is to run almost entirely off solar.

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37 minutes ago, ivan&alice said:

 

Well I hope you are right about that but it's certainly not what I hear. Li's last a long time but I've never heard anyone claim 20-30 years before. They're also more volatile so the chances of one accident destroying the bank is higher than with LAs.

 

 

....................  and destroying more than just the bank!

 

Unless a well-tested method of charging control is installed I understand that they can be lethal.  Perhaps someone with better knowledge than me could explain how this risk can be entirely eliminated.  My little electric launch has 660Ah of LA's installed under the bed and are routinely charged up with a 20A intelligent charger on a shore hook-up overnight when I am cruising.  I would hate to be roasted in bed.

Edited by Murflynn
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30 minutes ago, ivan&alice said:

But they don't charge faster than LAs when you're charging slowly over the whole day, right? If your solar is putting in 50A the LAs will be able to take it as bulk charge right up until you have only 50Ah remaining (for a 1000Ah bank, that's 95% of the charge). This is actually my whole point, so if I'm wrong about this I'll have to correct my position.

 

Not usually a problem on a boat. Certainly not on my boat. In fact I drive around with a bilge full of concrete so putting a few LAs nice and low would if anything be a plus.

 

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.
 

Well I hope you are right about that but it's certainly not what I hear. Li's last a long time but I've never heard anyone claim 20-30 years before. They're also more volatile so the chances of one accident destroying the bank is higher than with LAs.

 

I should also qualify that I'm thinking about this in terms of GBP/Ah/year, so yes you'll save the effort of physically replacing the batteries but Li's are widely recognised to be something like twice the price (GBP/Ah/year). So I'm not sure what you're referring to as saved cost. I'm trying to determine what advantage would justify the higher price of Li in my particular scenario, which is to run almost entirely off solar.

When I had my old full traction bank of LAs, I could notice a charging difference quite often, batteries charging I put kettle on and amp meter for solar doubles! so the answer is LifePo4s in my worlds always charge faster than LAs.

If batteries last a lifetime you will have saved a massive amount of energy and valuable resources over LAs, As for safety I am quoting LifePo4s which are very safe and stable I have seen lots of pictures of exploded LAs and in my Army days have seen over 600 explode in one go! So I know which battery I want in my boat and it isnt LAs

Cost wise £250 for a nearly new 138ah LifePo4 is way better than over a £100 pound for a mediocre LA in my books. Also I need less LifePo4s to achieve the same as LAs about a third I would say because form the moment you use LAs the capacity drops quickly in normal boater use

5 minutes ago, Murflynn said:

....................  and destroying more than just the bank!

 

Unless a well-tested method of charging control is installed I understand that they can be lethal.  Perhaps someone with better knowledge than me could explain how this risk can be entirely eliminated.  My little electric launch has 660Ah of LA's installed under the bed and are routinely charged up with a 20A intelligent charger on a shore hook-up overnight when I am cruising.  I would hate to be roasted in bed.

LAs explode as well! LifePo4s dont I have seen well over charged LifePo4s destroyed but no fire or explosion

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1 minute ago, peterboat said:

When I had my old full traction bank of LAs, I could notice a charging difference quite often, batteries charging I put kettle on and amp meter for solar doubles! so the answer is LifePo4s in my worlds always charge faster than LAs.

Can you explain a bit more about what you mean by "charging faster"? Say you have 1.5kW of solar producing 50A current on a nice sunny day. 1000Ah LA battery bank at 50% SoC vs an empty 500Ah Li. Which will absorb 400Ah the quickest and why? Same setup except it is winter and we're only getting 10A from the solar for only 5 hours. Which will absorb that total 50Ah faster/more efficiently and why?

 

Reason I ask is because how I understand the theory, there should be very little difference as the LAs will be in bulk the whole time in both cases. Or is charging Li's more efficient - does the LA lose more of the charge or something?

 

6 minutes ago, peterboat said:

Cost wise £250 for a nearly new 138ah LifePo4 is way better than over a £100 pound for a mediocre LA in my books. Also I need less LifePo4s to achieve the same as LAs about a third I would say because form the moment you use LAs the capacity drops quickly in normal boater use

250 for 138Ah is much cheaper than I've generally seen - are these deals readily available? Does this include the cost of the charge controller or is that conveniently being left off? My mediocre 110Ah was 90 GBP, and I'd need 3 of them to match the 138Ah LiFePO4, so if those figures are accurate then my point may be wrong simply because Lithium is actually cheaper than LA in both absolute terms and over the lifetime of the battery. Which I'm really skeptical about...

(I'm ignoring the safety aspect for now, because I believe that both types can be used safely. I only brought it up because I'm skeptical of the "over 20-30 year life" claim. Even if they do last over 30 years, and LiFePO4 hasn't been around over 30 years yet so there's no proof of this, the chances that something will happen destroying the bank is high. If your LAs get destroyed, replacing them isn't as much of a hit because they are semi-disposable anyway)

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2 minutes ago, ivan&alice said:

Can you explain a bit more about what you mean by "charging faster"? Say you have 1.5kW of solar producing 50A current on a nice sunny day. 1000Ah LA battery bank at 50% SoC vs an empty 500Ah Li. Which will absorb 400Ah the quickest and why? Same setup except it is winter and we're only getting 10A from the solar for only 5 hours. Which will absorb that total 50Ah faster/more efficiently and why?

 

Reason I ask is because how I understand the theory, there should be very little difference as the LAs will be in bulk the whole time in both cases. Or is charging Li's more efficient - does the LA lose more of the charge or something?

 

250 for 138Ah is much cheaper than I've generally seen - are these deals readily available? Does this include the cost of the charge controller or is that conveniently being left off? My mediocre 110Ah was 90 GBP, and I'd need 3 of them to match the 138Ah LiFePO4, so if those figures are accurate then my point may be wrong simply because Lithium is actually cheaper than LA in both absolute terms and over the lifetime of the battery. Which I'm really skeptical about...

(I'm ignoring the safety aspect for now, because I believe that both types can be used safely. I only brought it up because I'm skeptical of the "over 20-30 year life" claim. Even if they do last over 30 years, and LiFePO4 hasn't been around over 30 years yet so there's no proof of this, the chances that something will happen destroying the bank is high. If your LAs get destroyed, replacing them isn't as much of a hit because they are semi-disposable anyway)

You have it right LAs take far more amps to charge as they give out, and LifePo4s really do take everything you can give them until they hit the voltage set to go to absorb.

I bought 14 of my original valence batteries at an average of 280 squids each, I have just sold 4 for 1000 squids.

I have paid for my replacement batteries 2500 squids for 30 of them which is a bargain but I could have had 60 of them if I wanted.

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5 minutes ago, peterboat said:

You have it right LAs take far more amps to charge as they give out, and LifePo4s really do take everything you can give them until they hit the voltage set to go to absorb.

If 'everything you can give them' is 50A (maximum) what is the difference in time putting 100Ah into LI or 100Ah into LA (assuming a 1000Ah LA bank at 80% SoC)

 

If 'everything you can give them' is 10A (maximum) what is the difference in time putting 50Ah into LI or 50Ah into LA (assuming a 1000Ah LA bank at 80% SoC)

 

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1 minute ago, peterboat said:

LAs take far more amps to charge as they give out

Alright, this is potentially a big pro but I'd need to know numbers. @Tony Brooks suggests generating anything from 20% to 100% more than what you consume when you're using LAs. Any idea what the inefficiency of Li's is? Less than 20%?

If Li's say only lose around 10% of the charge, then that will also mean that you can size your generation systems smaller, so that saving will have to be factored in too. A quick look suggests that at that rate you could get 4 PV panels' worth with only 3 if you're using Li's, which means you can also get a smaller solar charge controller.

 

Still, I hear that the off-the-shelf Li battery management systems are very expensive unless you create your own DIY job (and I'm sure not prepared to do that given Li's safety reputation). So we're still not comparing apples with apples. At a guess the savings on the power generation side would be at least negated by the more expensive Li BMS.

I can't find prices anywhere near what you are quoting, I guess you must "know a guy". But OK I'll grant that this is a potentially significant pro for a mostly solar setup - but still, one that could be solved by adding more panels instead of switching Li for LA.

1 minute ago, Alan de Enfield said:

If 'everything you can give them' is 50A (maximum) what is the difference in time putting 100Ah into LI or 100Ah into LA (assuming a 1000Ah LA bank at 80% SoC)

 

If 'everything you can give them' is 10A (maximum) what is the difference in time putting 50Ah into LI or 50Ah into LA (assuming a 1000Ah LA bank at 80% SoC)

 

This is my original point. But @peterboat pointed out that 50Ah into Li is worth more than 50Ah into LA because Li are more efficient and lose less power in the charging process, which would indeed make the charging faster.

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2 hours ago, ivan&alice said:

Say you have enough solar to generate 100% of your usage for 8 months of the year, and say the 4 darkest months you winterise your boat and live on land.

 

 

Agreed they make no sense if you exclude the four months of the year when they are the most useful.

 

 

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1 minute ago, Mike the Boilerman said:

Agreed they make no sense if you exclude the four months of the year when they are the most useful.

That's good to know. People should make that point, then, in LA/Li debates, because a large number of people do not like to boat (as much) in the winter months and those people should not consider Li's, then.

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Ivan has however, homed in on something I discovered about them too. I bought my Li bank and never felt any need to install it as the solar keeps my LA batts fully charged all the time in spring/summer/autumn. 

 

In the dark months though I'm expecting to need to run the Whispergen for FAR less time than last winter, with significant fuel saving.

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9 minutes ago, Alan de Enfield said:
12 minutes ago, Mike the Boilerman said:

Agreed they make no sense if you exclude the four months of the year when they are the most useful.  you are living 'on land'

Amended to align with Ivan's question.

 

5 minutes ago, Mike the Boilerman said:

Ivan has however, homed in on something I discovered about them too. I bought my Li bank and never felt any need to install it as the solar keeps my LA batts fully charged all the time in spring/summer/autumn. 

 

In the dark months though I'm expecting to need to run the Whispergen for FAR less time than last winter, with significant fuel saving.

FWIW I actually do live on the boat year round, this was a hypothetical to get the facts on whether or not Li is actually a good idea on a boat for most of the year because it seems plain to me that it, in fact, isn't.

If you are someone who doesn't use their boat (much) in winter, you don't need Lis, you need LAs and lots of solar.

 

That's a really important point I've not seen articulated before.

 

For me, I am OK to rough it a bit in winter and not use the inverter - rather washing my clothes at the laundry. I'm also happier to spend out on lots of relatively cheap and hardy solar panels rather than relatively expensive and fragile batteries, so that I can live entirely on solar for as much of the year as possible.

 

I'm speccing my system to be 100% solar for 8 months of the year, but secretly I'm hoping that all my pessimistic calculations and overengineering will add up to a significant solar input in 2 more months (making 10). In real life I can be flexible, and combine high-power activities with crusing or save them for an unusually sunny November day. I'll also use that time to holiday in warmer climes. And don't tell anyone, but for the deepest darkest bit of winter, I'm going to drink a bottle of sherry and hibernate under my sofa and I won't need power at all!

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Right Mike how long did it take you to destroy your LA batteries?

I would think that in my case I would be losing a couple of percent charging my LifePo4s against at least 20% charging the Tractions they replaced, also I would say as time progressed the LAs took ever longer to charge and the capacity was reducing as well,

I have more solar than I need in summer so I use the excess to heat hot water via the immersion heater, In the winter I suspect for the most I will have enough solar to take care of my needs.

My batteries have internal BMSs which seem to work even though I am told they dont by forums, when I check them the cells are always balanced, now maybe this is because I only charge to 80% I dont know but its a fact.

I cant think if in circumstances that LAs are better than LifePo4s on the cut, some of my 36 volt batteries I have bought were down to 2.7 volts and yet they have fully recovered after charging so maybe they are stronger than we think?

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35 minutes ago, peterboat said:

I have more solar than I need in summer so I use the excess to heat hot water via the immersion heater, In the winter I suspect for the most I will have enough solar to take care of my needs.

May I ask how much solar you have and roughly how much power you use?

 

The immersion heater for excess solar energy is a really good idea - I think I might copy you on that. Do you manually switch it on or do you have a clever system that automatically switches it to the immersion heater?

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1 hour ago, ivan&alice said:

 

 

Still, I hear that the off-the-shelf Li battery management systems are very expensive unless you create your own DIY job (and I'm sure not prepared to do that given Li's safety reputation).

Dont even think about Li's if you are not prepared to do a diy BMS.

They are actually very easy to do.

 

On your question about charging Li's with solar, I have now had 6 months experience of charging in the summer. I agree with Peter.

Fact, my Li's charge far faster ....ie I get charge in far faster than I did with the LA's. Two reasons.

The first is that with Li's, you dont need to be up to 100% so you are always charging at max Amps in so 10A, 20A and even 50A. With LA's you need to get up to 100% at least a few times a week and once over 80%, your solar controller will be throttling back. At 90% it will be slow. You seem to be suggesting there will be loads of solar. In your spreadsheet you say 14 hrs a day in summmer. It just doesnt work like that. Yes, there is enough most of the time but what % of time will you get max power? We have 500W of panels but rarely get up to 100% after a night of 150Ahr out. Cloud, rain.....all restrict input. What do you do when it is hot....park under trees? That cuts the solar significantly.

The second reason ....you need a very good solar controller to maximise power in on LA's. I found my 2 controllers always went into float far too soon on my Lead acids and it was a real struggle to get the batteries up to 100%. I limited my 2 controllers back to just one and it was better but once over 90% it was a struggle to get the amps up.

Dont forget, once your batteries are up to 95%, they wont be taking more than 10A in on a 660Ahr bank. Mine will still be taking 25A (or 50A if I had the size of panels you are going to use).

 

Most of the above falls into the range at which you run the different types of batteries. On LA's you will be between 60 and 100% and so when over 90% will be limited on tail current.

On Li's you will be between 20% and 80% and charge will just pour in. That is why solar goes into Li's faster. Trust me. I'm a Dr.

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1 minute ago, ivan&alice said:

May I ask how much solar you have and roughly how much power you use?

 

The immersion heater for excess solar energy is a really good idea - I think I might copy you on that. Do you manually switch it on or do you have a clever system that automatically switches it to the immersion heater?

I currently have 3.7kw pf solar which will be rising to 4.6kw next year remember I have an electric drive motor so need lots of solar for it.

This means that for a lot of the time it does nothing so in the summer I just switch 2,5KWs to the immersion heater, it works very well to say the least

3 minutes ago, Dr Bob said:

Dont even think about Li's if you are not prepared to do a diy BMS.

They are actually very easy to do.

 

On your question about charging Li's with solar, I have now had 6 months experience of charging in the summer. I agree with Peter.

Fact, my Li's charge far faster ....ie I get charge in far faster than I did with the LA's. Two reasons.

The first is that with Li's, you dont need to be up to 100% so you are always charging at max Amps in so 10A, 20A and even 50A. With LA's you need to get up to 100% at least a few times a week and once over 80%, your solar controller will be throttling back. At 90% it will be slow. You seem to be suggesting there will be loads of solar. In your spreadsheet you say 14 hrs a day in summmer. It just doesnt work like that. Yes, there is enough most of the time but what % of time will you get max power? We have 500W of panels but rarely get up to 100% after a night of 150Ahr out. Cloud, rain.....all restrict input. What do you do when it is hot....park under trees? That cuts the solar significantly.

The second reason ....you need a very good solar controller to maximise power in on LA's. I found my 2 controllers always went into float far too soon on my Lead acids and it was a real struggle to get the batteries up to 100%. I limited my 2 controllers back to just one and it was better but once over 90% it was a struggle to get the amps up.

Dont forget, once your batteries are up to 95%, they wont be taking more than 10A in on a 660Ahr bank. Mine will still be taking 25A (or 50A if I had the size of panels you are going to use).

 

Most of the above falls into the range at which you run the different types of batteries. On LA's you will be between 60 and 100% and so when over 90% will be limited on tail current.

On Li's you will be between 20% and 80% and charge will just pour in. That is why solar goes into Li's faster. Trust me. I'm a Dr.

Virtual greenie Bob for saying it better than I can

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20 minutes ago, peterboat said:

I currently have 3.7kw pf solar which will be rising to 4.6kw next year remember I have an electric drive motor so need lots of solar for it.

This means that for a lot of the time it does nothing so in the summer I just switch 2,5KWs to the immersion heater, it works very well to say the least

Virtual greenie Bob for saying it better than I can

What do I have to do to get a real greenie?:)

Your giving too many away on the brexit thread!!!?

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Just now, Dr Bob said:

What do I have to do to get a real greenie?:)

Your giving too many away on the brexit thread!!!?

True Bob, I do hand them out to you though, did you read I have sold four of my 12 volt batteries to a mate and they are working great with his alternator which pumps out 13.9volts he has kept the LA starter battery on a relay which seems to work. We might fit an over under voltage cut out but that will be next year as he has finished cruising for the year

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4 hours ago, ivan&alice said:

 

 

Say you have enough solar to generate 100% of your usage for 8 months of the year, and say the 4 darkest months you winterise your boat and live on land.

 

.

We are a month away from the 4 darkest months. I think you are over egging what you will get out of your solar.

Below is a plot of Amps (in orange) and voltage (in blue) today from the sun (only charging source). Parked up all day on shore power so the Amps are purely the solar, less water pump.

I reckon we got 50Ahrs in from our 500W array in the 10 hours they were active (maybe a bit low in the first few hours as I couldnt be bothered to swing the panels into the sun before the rugby finished. I think that is pretty typical of a day with sun and cloud and rain and wind and............

 

I reckon we use circa 150Ahr per day so that was about 30%.  Pretty typical with naff weather or if you park under trees to keep  the boat cool in the summer.

Screen Shot 2019-09-29 at 18.23.22.png

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2 hours ago, ivan&alice said:

If you are someone who doesn't use their boat (much) in winter, you don't need Lis, you need LAs and lots of solar.

 

That's a really important point I've not seen articulated before.

 

 

I agree.

 

I have 560W of solar and use about 30AH per day (at 24v) and the solar keeps the batts at 100% all the time for 8 months of the year so why would I need lithiums?

 

The rest of the time I run the Whispergen for 90 mins when I get home if the batts are looking low and this works really well too. So Lis are still  pretty superfluous I now realise, having bought them!

 

<Awaits incoming>

 

 

 

 

 

 

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1 hour ago, Dr Bob said:

Below is a plot of Amps (in orange) and voltage (in blue) today from the sun (only charging source). Parked up all day on shore power so the Amps are purely the solar, less water pump.

I reckon we got 50Ahrs in from our 500W array in the 10 hours they were active

And, that's September.

 

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

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1 hour ago, Dr Bob said:

Dont even think about Li's if you are not prepared to do a diy BMS.They are actually very easy to do.

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?

 

1 hour ago, peterboat said:

I just switch 2,5KWs to the immersion heater, it works very well to say the least

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.

 

 

1 hour ago, Dr Bob said:

once over 80%, your solar controller will be throttling back. At 90% it will be slow. You seem to be suggesting there will be loads of solar. In your spreadsheet you say 14 hrs a day in summmer. It just doesnt work like that. Yes, there is enough most of the time but what % of time will you get max power? We have 500W of panels but rarely get up to 100% after a night of 150Ahr out.

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.

1 hour ago, Dr Bob said:

Dont forget, once your batteries are up to 95%, they wont be taking more than 10A in on a 660Ahr bank. Mine will still be taking 25A (or 50A if I had the size of panels you are going to use).

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.

 

1 hour ago, Dr Bob said:

We are a month away from the 4 darkest months. I think you are over egging what you will get out of your solar...I reckon we got 50Ahrs in from our 500W array in the 10 hours they were active (maybe a bit low in the first few hours as I couldnt be bothered to swing the panels into the sun before the rugby finished. I think that is pretty typical of a day with sun and cloud and rain and wind and............

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.

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