Solar dump.

[Psychalist]

5 minutes ago, David Mack said:

f intended for street lights then the load terminals must be powered from the battery, as there will be no solar output when the street lights are on!

Exactly, but if solar is providing 10A to the battery and the load is taking 5A, then 5A will go into the battery. If both 10A, then the battery current will show 0 (the tipping point) and if the load current is greater than the solar say 10A load, 5A solar, then the battery current shows -5A. This information can be used to control the load and match it to what's available from the solar. This might be Epever specific behaviour though.

[IanD]

8 minutes ago, Psychalist said:

Exactly, but if solar is providing 10A to the battery and the load is taking 5A, then 5A will go into the battery. If both 10A, then the battery current will show 0 (the tipping point) and if the load current is greater than the solar say 10A load, 5A solar, then the battery current shows -5A. This information can be used to control the load and match it to what's available from the solar. This might be Epever specific behaviour though.

That's what I meant when I said "spare output from the panels" earlier.

[DShK]

30 minutes ago, Psychalist said:

Exactly, but if solar is providing 10A to the battery and the load is taking 5A, then 5A will go into the battery. If both 10A, then the battery current will show 0 (the tipping point) and if the load current is greater than the solar say 10A load, 5A solar, then the battery current shows -5A. This information can be used to control the load and match it to what's available from the solar. This might be Epever specific behaviour though.

 

This is just how DC systems work generally is it not? Battery essentially uses "excess" current (the current not used directly by loads) to charge. I think your logic is that you turn on the dump instead of charging the batteries. When the batteries are fully charged, this figure won't be useful as the batteries won't be able to take much charge (and thus the reading from the solar output being low - the panels can't communicate how much they "could" output). So you'd need batteries not fully charged to do this. As immersion heaters aren't variable in their output (afaik?) you'd either need to only keep this on when solar is over the value of the immersion heater (quite an ask, mine is 1300W) or toggle it on and off based on SoC, to stop it draining too far. Not sure how healthy this would be for batteries. I don't think LA would appreciate the large current pull, and LFP the micro-cycling.

 

So yes, it's possible if your batteries aren't full and you have a solar array much larger than the rating of your immersion heater. I don't think this is the case for most people....

Edited July 18, 2023 by DShK

[Swanky pirate]

Thanks for all the information guys iam not tha technical iam lucky a friend is on the YouTube blog I watch he set it so when his leisure battery dropped to a certain level that was set it automatically stopped heating the emerson so not to drain them will look into it more.

[IanD]

22 minutes ago, DShK said:

 

This is just how DC systems work generally is it not? Battery essentially uses "excess" current (the current not used directly by loads) to charge. I think your logic is that you turn on the dump instead of charging the batteries. When the batteries are fully charged, this figure won't be useful as the batteries won't be able to take much charge (and thus the reading from the solar output being low - the panels can't communicate how much they "could" output). So you'd need batteries not fully charged to do this. As immersion heaters aren't variable in their output (afaik?) you'd either need to only keep this on when solar is over the value of the immersion heater (quite an ask, mine is 1300W) or toggle it on and off based on SoC, to stop it draining too far. Not sure how healthy this would be for batteries. I don't think LA would appreciate the large current pull, and LFP the micro-cycling.

 

So yes, it's possible if your batteries aren't full and you have a solar array much larger than the rating of your immersion heater. I don't think this is the case for most people....

 

Toggling the immersion heater on and off is what would happen in most cases, because you want it to have similar power to the solar array peak power so it can absorb all the "free" energy even when it's sunny. This is absolutely fine with LFP batteries, probably cycling between something like 80% and 90% SoC which they'll happily do tens of thousands of times. You need to watch the currents though, 1300W is about 100A -- better to have a big LFP house battery bank, or maybe even a 24V one.

 

With LA batteries, forget the whole idea, the "free" power won't pay for the cost of replacing the batteries when they die prematurely under the strain... 😉

[DShK]

6 minutes ago, IanD said:

 

Toggling the immersion heater on and off is what would happen in most cases, because you want it to have similar power to the solar array peak power so it can absorb all the "free" energy even when it's sunny. This is absolutely fine with LFP batteries, probably cycling between something like 80% and 90% SoC which they'll happily do tens of thousands of times. You need to watch the currents though, 1300W is about 100A -- better to have a big LFP house battery bank, or maybe even a 24V one.

 

With LA batteries, forget the whole idea, the "free" power won't pay for the cost of replacing the batteries when they die prematurely under the strain... 😉

I had assumed LFP would not like this method as I understood that repeatedly undercharging them to the same SoC (as would happen with an algorithmic approach) would result in a memory effect, reducing their capacity over time. I guess you could maybe use a random number in a range to charge to each time...

[IanD]

9 minutes ago, DShK said:

I had assumed LFP would not like this method as I understood that repeatedly undercharging them to the same SoC (as would happen with an algorithmic approach) would result in a memory effect, reducing their capacity over time. I guess you could maybe use a random number in a range to charge to each time...

 

AFAIK there's no evidence that LFP suffer from memory effect in this way, even if chemistries like NMC (which also have shorter lifetime) do. Like fire risk, I suspect that people are failing to distinguish between the two... 😞

Edited July 18, 2023 by IanD

[Tony1]

1 hour ago, IanD said:

 

All fine until the ISO specification makes it into the RCD and then presumably into BSS, which seems very likely.

 

But at least then they should then hopefully be clear, not "anti-LFP" or left to the discretion (or over-zealousness) of the BSS inspector... 😉

 

However the bit about being "installed, operated, and maintained according to manufacturers’ recommendations" -- and needing a BMS which including a warning of disconnection audible to the steerer -- may cause some difficulties for those with DIY installations, unless they can find a friendly BSS inspector who will turn a blind eye... 😉

 

 

I don't think it is, but for sure some existing installations (especially DIY) won't meet some of the requirements... 😞

 

I totally agree that these regs are going to cause some major trauma for DIY lithium installers. 

For one thing, buyers of used batteries like myself dont have a fully detailed manufacturer documentation and guidance on installation and operation. 

I do have a data sheet, which I guess is better than nothing:

https://www.lithionbattery.com/wp-content/uploads/2019/12/Valence-U27-12XP-Data-Sheet-210623.pdf

 

I also dont have any invoices, specs or other proof of the install work that was done by boat electricians, and in any case 60% of it was done by me.

 

My BMS is effectively a pair of BMV712s, which will disconnect the batteries and sound an alarm in the event of extreme high or low voltage, but I'm not sure the alarm is audible to a steerer. In fact, if the engine is running I would very much doubt it. 

 

It could be a nightmare for me trying to meet those regs, but my hope is that if I get the BSS completed  by November, the new rules wont be in place, and I'll have 5 years to put something in place that will meet the coming regs.

 

 

 

 

 

3 minutes ago, IanD said:

 

AFAIK there's no evidence that LFP suffer from memory effect in this way, even if chemistries like NMC (which also have shorter lifetime) do. Like fire risk, I suspect that people are failing to distinguish between the two... 😞

 

I've gotten an impression that there is some degree of memory effect with my batteries, but it doesnt seem to be extreme. 

I spent most of the summer of 2021 with the batteries between 60% and 85% because there was so much solar they never got discharged much, then in the winter when I started cycling at lower values, I did notice some slightly unusual behaviours on the first discharge that took the SoC below 30%, in that the resting voltage didnt seem to correspond very well to the SoC. 

But that said, it didnt last very long. 

But I recall Nick saying that it was better for the longevity of lithiums if you periodically give them a stretch, i.e. a full cycle between 100% and 5%.

I dont think I've ever gone down to 5%, but I do try to give them a full(ish) cycle every few weeks at least.

 

[IanD]

2 minutes ago, Tony1 said:

 

I totally agree that these regs are going to cause some major trauma for DIY lithium installers. 

For one thing, buyers of used batteries like myself dont have a fully detailed manufacturer documentation and guidance on installation and operation. 

I do have a data sheet, which I guess is better than nothing:

https://www.lithionbattery.com/wp-content/uploads/2019/12/Valence-U27-12XP-Data-Sheet-210623.pdf

 

I also dont have any invoices, specs or other proof of the install work that was done by boat electricians, and in any case 60% of it was done by me.

 

My BMS is effectively a pair of BMV712s, which will disconnect the batteries and sound an alarm in the event of extreme high or low voltage, but I'm not sure the alarm is audible to a steerer. In fact, if the engine is running I would very much doubt it. 

 

It could be a nightmare for me trying to meet those regs, but my hope is that if I get the BSS completed  by November, the new rules wont be in place, and I'll have 5 years to put something in place that will meet the coming regs.

 

 

The devil will be in the details, and I don't know if anybody has seen the ISO regs yet -- but the comment that some parts are more stringent than the ABYC ones is worrying... 😞

 

It's possible that the rules for LFP will be significantly relaxed compared to NMC, as they really ought to be -- when things go wrong with NMC there's a risk that they catch fire and destroy your boat (insurer panic warning!), with LFP the risk is that at worst you end up killing some expensive batteries -- which are probably not insured anyway, so you have to cough up to replace them.

 

To repeat, LFP are safer than LA which insurers have been happy with for years -- no risk of leaking acid or explosive gas generation when overcharged.

 

Let's hope insurers (and BSS regulators) realise this... 😉

[Tony1]

1 minute ago, IanD said:

 

The devil will be in the details, and I don't know if anybody has seen the ISO regs yet -- but the comment that some parts are more stringent than the ABYC ones is worrying... 😞

 

It's possible that the rules for LFP will be significantly relaxed compared to NMC, as they really ought to be -- when things go wrong with NMC there's a risk that they catch fire and destroy your boat (insurer panic warning!), with LFP the risk is that at worst you end up killing some expensive batteries -- which are probably not insured anyway, so you have to cough up to replace them.

 

To repeat, LFP are safer than LA which insurers have been happy with for years -- no risk of leaking acid or explosive gas generation when overcharged.

 

Let's hope insurers (and BSS regulators) realise this... 😉

 

It sounds like once the initial ignorance and suspicion have subsided, the regs might be relaxed to suit the lower risks of lithiums. 

 

It seems to me that it might be wise for DIY lithium installers to get their BSS done before those new regs come into force, rather than have to meet a whole new raft of requirements. 

I heard one comment that inspectors might require evidence that lithiums were professionally installed, for example. If that is even close to being true, its going to effectively rule out any DIY installations at all. 

 

 

[IanD]

19 minutes ago, Tony1 said:

 

It sounds like once the initial ignorance and suspicion have subsided, the regs might be relaxed to suit the lower risks of lithiums. LFP

 

It seems to me that it might be wise for DIY lithium LFP installers to get their BSS done before those new regs come into force, rather than have to meet a whole new raft of requirements. 

I heard one comment that inspectors might require evidence that lithiums were professionally installed, for example. If that is even close to being true, its going to effectively rule out any DIY installations at all. 

 

 

Sorry to correct you, but everyone *really* needs to make clear whether they're talking about lithium batteries in general (including NMC etc) and LFP in particular -- which I sincerely hope is what all boaters mean... 😉

 

This is partly the reason for the mess that insurance companies have got themselves in, because there *have* been quite a few disastrous yacht fires (and house fires) where NMC batteries have been to blame -- but AFAIK there is no record of *any* fire caused by LFP batteries.

 

So some insurers (e.g. in the US) are lumping all "lithium" batteries together and requiring either professional installation, or at least batteries certified as meeting standards including disconnection and BMS which talk to the outside world -- and without this will either refuse cover, or limit/reduce payout of a claim.

 

None of this should be needed with LFP, but the penny doesn't seem to have dropped yet that not all "lithium batteries" are alike. Let's hope it does before the regs hit the UK canals... 🙂

Edited July 18, 2023 by IanD

[Tony1]

1 minute ago, IanD said:

 

Sorry to correct you, but everyone *really* needs to make clear whether they're talking about lithium batteries in general 

 

Oh no- I'm not going to get extra homework am I? 😀

 

[IanD]

8 minutes ago, Tony1 said:

 

Oh no- I'm not going to get extra homework am I? 😀

 

Yes. Write out 100 times: "I must distinguish between lithium batteries and LFP batteries when posting about them" 🙂

[rusty69]

21 hours ago, TheBiscuits said:

 

That normally hurts your ears ... 11 is louder than 10!

I got this notice from my insurance company about lithium - ion batteries the other day. Never had one before. 

[IanD]

6 minutes ago, rusty69 said:

I got this notice from my insurance company about lithium - ion batteries the other day. Never had one before. 

 

*Aaand* there's a perfect example of an insurer who doesn't know that "lithium-ion batteries (e.g. NMC)" and "LFP batteries" are completely different as far as fire risks are concerned... 😞

 

"Across the UK they have injured over 190 people and killed eight since 2020" -- all NMC...

"MUST have a dedicated Lithium fire extinguisher aboard" -- good luck with that, an NMC battery fire is almost impossible to put out because the battery provides both fuel and oxygen...

Edited July 18, 2023 by IanD

[DShK]

 

 

 

49 minutes ago, IanD said:

 

AFAIK there's no evidence that LFP suffer from memory effect in this way, even if chemistries like NMC (which also have shorter lifetime) do. Like fire risk, I suspect that people are failing to distinguish between the two... 😞

I was just going off what nordkyn design says (and I half take it as gospel, but perhaps that's wrong), although rechecking it it does say undercharging and then left to a period of rest. So more important if undercharging and left there on a shoreline.

Quote

Lastly, partial charging of a lithium battery should not be followed by a period of rest, especially if this is going to happen repeatedly at the same point on the charge curve, because this constitutes a memory writing cycle. Incomplete charging cycles are very common in marine house bank applications simply due to energy running out before the bank is full; these are of no concern because discharge normally occurs right away and charging ends randomly. On the other hand, systematic weak charging followed by a holding period, as it easily occurs when charging systems are misconfigured, gradually leads to near-complete loss of usable capacity from cumulative memory effect. Conversely, the battery must be charged properly from time to time to reset the state of the chemistry and erase any traces left by memory writing cycles.

7 minutes ago, rusty69 said:

I got this notice from my insurance company about lithium - ion batteries the other day. Never had one before. 

 

I think this is aimed at L-ion devices. Because they do cause fires. Think a boat caught fire recently due to someone charging their e-bike.

I've been toying with the idea of getting an e-bike. If I do, it's going to be one with a removable battery which is going to be charged either on the towpath or on the deck in an ammo box...

 

I reckon any new regs won't be that harsh. I mean, cmon, we can wire up our boats ourselves without needing an electrician (also a potential fire hazard if done poorly) so why would they impose strict regulation on one aspect of that?

Edited July 18, 2023 by DShK

[rusty69]

2 minutes ago, DShK said:

 

 

I was just going off what nordkyn design says (and I half take it as gospel, but perhaps that's wrong), although rechecking it it does say undercharging and then left to a period of rest - 

 

I think this is aimed at L-ion devices. Because they do cause fires. Think a boat caught fire recently due to someone charging their e-bike.

I've been toying with the idea of getting an e-bike. If I do, it's going to be one with a removable battery which is going to be charged either on the towpath or on the deck in an ammo box...

 

I reckon any new regs won't be that harsh. I mean, cmon, we can wire up our boats ourselves without needing an electrician (also a potential fire hazard if done poorly) so why would they impose strict regulation on one aspect of that?

They did specifically mention e-bikes. When I asked if it applied to laptops, phones, drills etc, etc, they said no. 

 

So, I'm not sure what the definitive list is, or whether it applies to fixed installations. Looks like an insurance company knee jerk scatter gun approach to me. 

Edited July 18, 2023 by rusty69

[IanD]

2 minutes ago, DShK said:

I'm just going off Nordkyn design which I 

 

I was just going off what nordkyn design says (and I half take it as gospel, but perhaps that's wrong), although rechecking it it does say undercharging and then left to a period of rest - 

 

I think this is aimed at L-ion devices. Because they do cause fires. Think a boat caught fire recently due to someone charging their e-bike.

I've been toying with the idea of getting an e-bike. If I do, it's going to be one with a removable battery which is going to be charged either on the towpath or on the deck in an ammo box...

 

I reckon any new regs won't be that harsh. I mean, cmon, we can wire up our boats ourselves without needing an electrician (also a potential fire hazard if done poorly) so why would they impose strict regulation on one aspect of that?

 

The Nordkyn page is literally correct, but read carefully what it says -- charge zig-zagging up and down (like the immersion case) doesn't cause any problem without long rest periods at partial charge, and this only becomes a problem anyway if you never take the battery up to 100% SoC which makes it recover. Neither will be the case here, so no problem.

 

It probably is aimed at Li-ion (NMC) batteries in things like escooters, but it doesn't say that this *doesn't* apply to "lithium-ion" batteries in boat house battery banks, and more especially LFP ones.

 

I really hope your last point is correct (and there's no reason it shouldn't be given the actual safety record of LFP batteries), but this assumes insurers and BSS inspectors appreciate the difference between the battery types -- and right now they often seem to just lump everything under the "lithium" label and declare it as dangerous.

[David Mack]

4 hours ago, IanD said:

probably is aimed at Li-ion (NMC) batteries in things like escooters, but it doesn't say that this *doesn't* apply to "lithium-ion" batteries in boat house battery banks, and more especially LFP ones.

If it said just "lithium batteries" it would presumably apply to all lithium battery chemistries. But I would have thought any insured person would have a good basis of claim if they specifically had Lithium Iron Phosphate batteries, especially if that term is used throughout the manufacturer's literature.

[IanD]

14 minutes ago, David Mack said:

If it said just "lithium batteries" it would presumably apply to all lithium battery chemistries. But I would have thought any insured person would have a good basis of claim if they specifically had Lithium Iron Phosphate batteries, especially if that term is used throughout the manufacturer's literature.

The problem is that all lithium batteries including LFP are "lithium-ion", and that's the only term the insurer uses and applies restrictions to -- which includes boat battery banks according to what was posted...

[MtB]

4 minutes ago, IanD said:

The problem is that all lithium batteries including LFP are "lithium-ion", and that's the only term the insurer uses and applies restrictions to -- which includes boat battery banks according to what was posted...

 

AND includes batteries in phones, cordless power tools, car keys, laptops and a tonne of other stuff. 

 

(As pointed out by Tony1.) 

[IanD]

3 minutes ago, MtB said:

 

AND includes batteries in phones, cordless power tools, car keys, laptops and a tonne of other stuff. 

 

(As pointed out by Tony1.) 

Yes, it's idiotic, it's a panic CYA notice written by somebody who doesn't understand the problem... 😞

[ditchcrawler]

36 minutes ago, MtB said:

 

AND includes batteries in phones, cordless power tools, car keys, laptops and a tonne of other stuff. 

 

(As pointed out by Tony1.) 

Which are all a greater risk

[MtB]

4 minutes ago, ditchcrawler said:

Which are all a greater risk

 

And all commonly found in boats, which haven't burned down.

 

 

[magnetman]

You will be refused travel on GWR rail services if you attempt to bring an escooter onto the train. This does not apply to ebikes. 

 

Something going on here not related to the battery chemistry.