Solar dump.

[DShK]

38 minutes ago, rusty69 said:

I got. a victron mppt this week and a raspberry pi (actually, I got 11,don't ask). God my head hurts. 

Ha, if you want any help setting up venusOS let me know. I think I've got a good grip on it now. I have my LFP charge regime pretty nicely programmed in NodeRed. One nice thing to know is, if you have a victron shunt - you can turn on something called "DVCC" and it will allow your MPPT to compensate for any volt drop to the battery!

[rusty69]

1 minute ago, DShK said:

Ha, if you want any help setting up venusOS let me know. I think I've got a good grip on it now. I have my LFP charge regime pretty nicely programmed in NodeRed. One nice thing to know is, if you have a victron shunt - you can turn on something called "DVCC" and it will allow your MPPT to compensate for any volt drop to the battery!

If only you'd said that 2 days ago, I might have more hair left.

 

Node what now? 

[DShK]

21 minutes ago, rusty69 said:

If only you'd said that 2 days ago, I might have more hair left.

 

Node what now? 

Haha oh no!

 

If you install the version of VenusOS called "VenusOS Large" you can use a flow graph programming interface called nodered. This is endlessly augmentable (like you have "libraries" in normally programming. I've done some rudimentary programming to control my LFP charging, and created an interface to adjust this. It really adds a lot of functionality to the whole setup. For example - I can control if my B2B charger (and thus alternator charging) comes on from the helm (using my phone), and have it switch off automatically based on SoC or voltage. If it's a super sunny day - just keep it off to save fuel!

Edited July 17, 2023 by DShK

[rusty69]

3 minutes ago, DShK said:

Haha oh no!

 

If you install the version of VenusOS called "VenusOS Large" you can use a flow graph programming interface called nodered. This is endlessly augmentable (like you have "libraries" in normally programming. I've done some rudimentary programming to control my LFP charging, and created an interface to adjust this. It really adds a lot of functionality to the whole setup. For example - I can control if my B2B charger (and thus alternator charging) comes on from the helm (using my phone), and have it switch off automatically based on SoC or voltage. If it's a super sunny day - just keep it off to save fuel!

Hmm. OK. I might have a bit more learning to do. Will get back to you when my brain stops throbbing. 

[David Mack]

7 hours ago, DShK said:

concluded that there are too many variables to allow a system to potentially drain your batteries without input. I decided to just do it manually

So if you forget to turn off the solar dump when the sun goes down, you can drain your batteries manually?

A bit like the 1-2-both-off switches which seem designed to let you unintentionally flatten your start battery as well as the domestics.

[MtB]

4 hours ago, rusty69 said:

I got. a victron mppt this week and a raspberry pi (actually, I got 11,don't ask). God my head hurts. 

 

 

It'll have to come off, then.

 

 

[Tony Brooks]

7 hours ago, David Mack said:

So if you forget to turn off the solar dump when the sun goes down, you can drain your batteries manually?

A bit like the 1-2-both-off switches which seem designed to let you unintentionally flatten your start battery as well as the domestics.

 

Don't count on this, but with proper Solar connections my understanding is no, but it seems some Victron controllers do not have such connections and this ignores the current rating on the Solar terminals on other brands that have them. I suspect a VSR feeding the heater from the batteries would do the trick. 140 amps should be enough.

[Tony1]

 

Apologies if this method has already been mentioned (I think it has but I dont understand electrical jargon, so not sure):

In my case the immersion heater element is powered as a normal 240v load, so its power comes from the batteries via the inverter, rather than directly from the MPPTs. 

It's a simpler thing to set up, but if I understand it correctly (which is by no means certain), this method has the disadvantage that because all of the water heating energy is being taken from the batteries, I am cycling maybe 50% more energy through my (lithium) batteries than would otherwise be the case. And that will probably reduce their longevity correspondingly, from say 15 years down to maybe 10 years.

You also have to manually switch on the immersion heater, but tbh that's no hassle really. If for example I want to wash some clothes, I would rather do that in the morning, to give them more daylight hours to dry- so with my setup I can heat up the immersion early doors, knowing that the charge I've used will be replaced as the day goes on.

From my 1400 watts of panels I can get a tank of water that is hot enough to wash in for maybe 5 or 6 months of the year. With fewer panels, that window of solar hot water will shrink-  to a point where, if you have say 600 watts of panels, you might only get hot water for maybe 2 months, and even that on the sunnier of the summer days.

 

 

Edited July 18, 2023 by Tony1

[magnetman]

13 hours ago, Swanky pirate said:

Lol 11 but about the lfp battery it's a big problem all the electric cars use them and the new narrow boats dont know the answer. 

I meant the solar panels but yes the batteries are going to landfill as well I suspect. A lot of hype marketing around using old batteries as 'ore' and large scale recycling but this conveniently ignores the established fact that new technology replaces old technology. Having said that Lead Acid batteries are very widely recycled so its possible. Very high demand would need to be guaranteed for quite a while which seems a bit awkward. 

 

 

[blackrose]

15 hours ago, ditchcrawler said:

In that case you will probably fall at the first hurdle. First problem finding an electrician who understands boats, secondly one who understands what you are trying to do. This is the sort of thing normally done DIY by geeks using PMW controllers to control the amount of power going to the heater, looking at battery states of charge and switching accordingly. If I was going to do it I would use a 1Kw 230 volt immersion heaater and switch the AC output from my invertor, much easier that switching 50 to 100 amps DC smaller cables etc.

 

Mmmm but that's just using your inverter/batteries to power the immersion heater which is fine on a sunny day for a short time if you have enough panels and don't forget to switch it off. I have done what you're suggesting a few times myself on a sunny day for an hour and a half but it's not a solar dump load and not what the the OP was asking about. 

 

10 hours ago, David Mack said:

So if you forget to turn off the solar dump when the sun goes down, you can drain your batteries manually?

 

 

No, the whole point of a SOLAR dump load system is that it doesn't use the batteries.

Edited July 18, 2023 by blackrose

[Psychalist]

Manually controlled use of excess capacity can work but automatic use of spare solar needs, as Brian suggested, some kind of control. My belief is it can be done with the 'load' circuit of an MPPT but will depend on the logic of the MPPT and require some control logic and programming. As I understand it, most MPPT load functions are simple timer based controls of a circuit, typically derived from switching something like street lights on and off and switch on the load whether there is solar available or not but are limited to the rating of the controller.

 

The load circuit on my Epever uses both solar and battery, so still has the possibility to drain the batteries. If the load exceeds the MPPT rating the load circuit control trips. This can happen, for instance, when the start-up current of an inverter is switched on (lots of smoothing capacitors to charge?).

 

The key to controlling the output requires a way to determine when current is coming from the battery. On the Epever, the metric available is battery current, which shows negative when the load drain current exceeds the MPPT solar battery charge current available. Logic would be needed to monitor this and control the load to a level above where the battery drains, probably also taking into consideration battery SOC. Whether to use AC or DC or not is an interesting issue as there should be less involved with a DC solution - this has been discussed in another thread. I haven't implemented either as I realise the amount of hot warm water generated will be limited with our modest installation. That said, when the sun is shining and batteries are charged by 9am, I'd like to use that excess.

 

 

[rusty69]

15 hours ago, DShK said:

Haha oh no!

 

If you install the version of VenusOS called "VenusOS Large" you can use a flow graph programming interface called nodered. This is endlessly augmentable (like you have "libraries" in normally programming. I've done some rudimentary programming to control my LFP charging, and created an interface to adjust this. It really adds a lot of functionality to the whole setup. For example - I can control if my B2B charger (and thus alternator charging) comes on from the helm (using my phone), and have it switch off automatically based on SoC or voltage. If it's a super sunny day - just keep it off to save fuel!

I have a question 🙋‍♀️

 

The top line says "turn off solar if in float". How are you achieving that? I only ask because my victron mppt has a toggle switch on the menu setting that turns off the charge source, but it suggests its for maintenance purposes only. Are you using a relay to switch the panels off? 

[IanD]

1 minute ago, Psychalist said:

Manually controlled use of excess capacity can work but automatic use of spare solar needs, as Brian suggested, some kind of control. My belief is it can be done with the 'load' circuit of an MPPT but will depend on the logic of the MPPT and require some control logic and programming. As I understand it, most MPPT load functions are simple timer based controls of a circuit, typically derived from switching something like street lights on and off and switch on the load whether there is solar available or not but are limited to the rating of the controller.

 

The load circuit on my Epever uses both solar and battery, so still has the possibility to drain the batteries. If the load exceeds the MPPT rating the load circuit control trips. This can happen, for instance, when the start-up current of an inverter is switched on (lots of smoothing capacitors to charge?).

 

The key to controlling the output requires a way to determine when current is coming from the battery. On the Epever, the metric available is battery current, which shows negative when the load drain current exceeds the MPPT solar battery charge current available. Logic would be needed to monitor this and control the load to a level above where the battery drains, probably also taking into consideration battery SOC. Whether to use AC or DC or not is an interesting issue as there should be less involved with a DC solution - this has been discussed in another thread. I haven't implemented either as I realise the amount of hot warm water generated will be limited with our modest installation. That said, when the sun is shining and batteries are charged by 9am, I'd like to use that excess.

 

 

To make this work you need something that monitors SoC, solar panel output, and water temperature, and decides what to do. If there's "spare" power from solar and the batteries are full and the water isn't hot, turn the immersion heater on. If it takes more power than the panels are putting out, turn if off when SoC has dropped a bit, and wait for the batteries to fill up again.

 

A Raspberry Pi plus some switching/sensing hardware can do all this, but as well as having the knowledge to build/program it you need to know what SoC is and how much power the MPPT controllers are putting out -- I think @nicknorman did this.

 

An off-the-shelf commercial solution could use Victron gear like their MPPT controllers (and inverter/charger) controlled by a Cerbo GX, but this probably costs a lot more than you want to spend.

[blackrose]

From what others are saying this doesn't seem as simple as I was led to believe. 

 

Bimble make it sound very simple in their description but I guess not. 

 

https://www.bimblesolar.com/12v-300w-screw-in-water-heater

 

They must end up with a lot of unsatisfied customers which makes me wonder why there are no caveats about equipment capabilities and installation requirements?

[DShK]

14 hours ago, David Mack said:

So if you forget to turn off the solar dump when the sun goes down, you can drain your batteries manually?

A bit like the 1-2-both-off switches which seem designed to let you unintentionally flatten your start battery as well as the domestics.

Yep, it's possible. I have the victron VRM open while I work so I do keep an eye on it. But that's just my specific situation - definitely an easy thing to forget.

 

5 hours ago, Tony1 said:

 

Apologies if this method has already been mentioned (I think it has but I dont understand electrical jargon, so not sure):

In my case the immersion heater element is powered as a normal 240v load, so its power comes from the batteries via the inverter, rather than directly from the MPPTs. 

It's a simpler thing to set up, but if I understand it correctly (which is by no means certain), this method has the disadvantage that because all of the water heating energy is being taken from the batteries, I am cycling maybe 50% more energy through my (lithium) batteries than would otherwise be the case. And that will probably reduce their longevity correspondingly, from say 15 years down to maybe 10 years.

You also have to manually switch on the immersion heater, but tbh that's no hassle really. If for example I want to wash some clothes, I would rather do that in the morning, to give them more daylight hours to dry- so with my setup I can heat up the immersion early doors, knowing that the charge I've used will be replaced as the day goes on.

From my 1400 watts of panels I can get a tank of water that is hot enough to wash in for maybe 5 or 6 months of the year. With fewer panels, that window of solar hot water will shrink-  to a point where, if you have say 600 watts of panels, you might only get hot water for maybe 2 months, and even that on the sunnier of the summer days.

 

 

Combined with the above concern, I guess you could, rather than program the dump load to automatically come on (as I think this could lead to flattened batteries). You could use your own sense to turn on the heater, but then program the load to be switched OFF if SoC/voltage etc get too low. Also could put it on a timer. That way you know your batteries are never going to get too drained.

 

 

4 hours ago, magnetman said:

I meant the solar panels but yes the batteries are going to landfill as well I suspect. A lot of hype marketing around using old batteries as 'ore' and large scale recycling but this conveniently ignores the established fact that new technology replaces old technology. Having said that Lead Acid batteries are very widely recycled so its possible. Very high demand would need to be guaranteed for quite a while which seems a bit awkward. 

 

 

You can recover lithium from old batteries but it is much less dense than harvesting it from ore, so may well be uneconomical.

 

2 hours ago, rusty69 said:

I have a question 🙋‍♀️

 

The top line says "turn off solar if in float". How are you achieving that? I only ask because my victron mppt has a toggle switch on the menu setting that turns off the charge source, but it suggests its for maintenance purposes only. Are you using a relay to switch the panels off? 

It is the same functionality as that toggle, yes. I have no idea why it says it's only for maintenance. I have had no problem using it. I know that it is supposed to be bad for a controller to be disconnected from the battery, but I've seen it suggested that this isn't actually a problem. I don't know if this is doing the equivalent. I've had this setup for a couple months and the solar routinely gets turn off this way (it gets toggled when the batteries  are full - the float thing is merely there just in case - they never go into float). It's not been a problem.

 

2 hours ago, IanD said:

To make this work you need something that monitors SoC, solar panel output, and water temperature, and decides what to do. If there's "spare" power from solar and the batteries are full and the water isn't hot, turn the immersion heater on. If it takes more power than the panels are putting out, turn if off when SoC has dropped a bit, and wait for the batteries to fill up again.

 

A Raspberry Pi plus some switching/sensing hardware can do all this, but as well as having the knowledge to build/program it you need to know what SoC is and how much power the MPPT controllers are putting out -- I think @nicknorman did this.

 

An off-the-shelf commercial solution could use Victron gear like their MPPT controllers (and inverter/charger) controlled by a Cerbo GX, but this probably costs a lot more than you want to spend.

How can you know if there is "spare" output from the panels? I guess in theory you could write something which "probes" the output, by turning the load on and off periodically and seeing if the output increases. But it's not just going to output whatever is left over from what is being used.

 

I considered writing something which takes into account SoC, the forecasted solar (victron units can do this), the time of day. But there are just too many variables imo - perhaps the weather doesn't match what is predicted, or you're in shadow after midday. Perhaps you want to use the washing machine. It just seemed more sensible to just think "I've got full batteries, it's 10am, the sky is blue - I'll turn on the water heater".

Edited July 18, 2023 by DShK

[Tony1]

20 minutes ago, DShK said:

 

Combined with the above concern, I guess you could, rather than program the dump load to automatically come on (as I think this could lead to flattened batteries). You could use your own sense to turn on the heater, but then program the load to be switched OFF if SoC/voltage etc get too low. Also could put it on a timer. That way you know your batteries are never going to get too drained.

 

 

I normally set a 50 minute timer on my phone when I switch on the immersion, but of course I did forget that once.

But the batteries didnt flatten- the thermostat cut the immersion heating when the water got up to temp, so it sort of self regulated in a very rough way.

 

Over a full day the thermostat would cut back in and out, of course, and run the batteries down, so if I switched it on and left the boat for a day, the batteries probably would get depleted, especially if the solar charging was poor. 

 

It really does need a timer as you suggest, and I have my eye on a one hour timer in to replace the ON/OFF switch.

 

https://www.amazon.co.uk/gp/product/B0BCY2XBJW/ref=ox_sc_saved_image_6?smid=AKY3EFCGM0MJ6&psc=1

 

But I'm a bit reluctant to fit that, or anything else, until after my BSS is done in November.

I've heard a couple of vague rumours about a couple of BSS inspectors 'not liking' lithium batteries kept indoors (without a metal cage or similar)- so I'm not adding any further tweaks for the time being that might give rise to them 'not liking' some aspect of the electrical systems. 

 

Edited July 18, 2023 by Tony1

[DShK]

4 minutes ago, Tony1 said:

 

I normally set a 50 minute timer on my phone when I switch on the immersion, but of course I did forget that once.

But the batteries didnt flatten- the thermostat cut the immersion heating when the water got up to temp, so it sort of self regulated in a very rough way.

 

Over a full day the thermostat would cut back in and out, of course, and run the batteries down, so if I switched it on and left the boat for a day, the batteries probably would get depleted, especially if the solar charging was poor. 

 

It really does need a timer as you suggest, and I have my eye on a one hour timer in to replace the ON/OFF switch.

 

https://www.amazon.co.uk/gp/product/B0BCY2XBJW/ref=ox_sc_saved_image_6?smid=AKY3EFCGM0MJ6&psc=1

 

But I'm a bit reluctant to fit that, or anything else, until after my BSS is done in November.

I've heard a couple of vague rumours about a couple of BSS inspectors 'not liking' lithium batteries kept indoors (without a metal cage or similar)- so I'm not adding any further tweaks for the time being that might give rise to them 'not liking' some aspect of the electrical systems. 

 

Not sure it's a BSS inspector's place to "not like" something which AFAIK isn't on their checklist? A lockie told me there was going to be a new ISO standard (which I guess will probably make it to the BSS). But this is just about not connecting LA and LFP directly together.

[IanD]

10 minutes ago, DShK said:

Not sure it's a BSS inspector's place to "not like" something which AFAIK isn't on their checklist? A lockie told me there was going to be a new ISO standard (which I guess will probably make it to the BSS). But this is just about not connecting LA and LFP directly together.

I believe it's also about lithium-ion batteries with chemistries like NMC (same as EVs, phones, e-scooters etc) which occasionally catch fire when faulty or mistreated and are *very* difficult to put out.

 

Most boats -- especially on the canals -- use LFP batteries which are *much* safer, probably more so than lead-acid.

Edited July 18, 2023 by IanD

[Tony1]

3 minutes ago, DShK said:

Not sure it's a BSS inspector's place to "not like" something which AFAIK isn't on their checklist? A lockie told me there was going to be a new ISO standard (which I guess will probably make it to the BSS). But this is just about not connecting LA and LFP directly together.

 

I absolutely agree with you, but I think the key thing is not to get into a dispute like that in the first place, by very careful selection of your BSS inspector. 

Someone kindly gave me a name in the Northwest but I cant remember where it is, so I'm still on the lookout for a BSS inspector who isnt hostile to the idea of lithiums, and who wont try to look for an obscure regulation to deliberately find fault.  

 

I had a chap in recently to fit a new dripless stern gland seal, and when he saw my batteries in the bedroom he said "that would be a failure if it was inspected by xxxx", on the basis that the batteries werent held in a metal box of some sort. 

I don't know the regs at all, but it sounded a bit random. 

 

 

 

[DShK]

14 minutes ago, Tony1 said:

 

I absolutely agree with you, but I think the key thing is not to get into a dispute like that in the first place, by very careful selection of your BSS inspector. 

Someone kindly gave me a name in the Northwest but I cant remember where it is, so I'm still on the lookout for a BSS inspector who isnt hostile to the idea of lithiums, and who wont try to look for an obscure regulation to deliberately find fault.  

 

I had a chap in recently to fit a new dripless stern gland seal, and when he saw my batteries in the bedroom he said "that would be a failure if it was inspected by xxxx", on the basis that the batteries werent held in a metal box of some sort. 

I don't know the regs at all, but it sounded a bit random. 

 

 

 

True.

 

The regulation, afaik, only says that batteries need to be secured from moving in any direction. They do not need a lid if they wouldn't move if the boat was at 45 degrees. They do need to be insulated from shorts. For batteries that gas, there needs to be ventilation. There is no mention of metal boxes and/or lithium batteries as far as I know. If you're worried, I'd just be familiar with the checklist they use. If someone tries to point out a regulation that isn't on the BSS checklist - challenge them on it! I think they can use their discretion on wiring etc being in good order and safe, but "LFP bad" shouldn't be part of this.

 

As you say, best avoided if possible.

 

Or, do the petrol generator solution. Dump the lithium for the inspection and install a single LA battery for it 😄

Edited July 18, 2023 by DShK

[IanD]

2 minutes ago, DShK said:

True.

 

The regulation, afaik, only says that batteries need to be secured from moving in any direction. They do not need a lid if they wouldn't move if the boat was at 45 degrees. They do need to be insulated from shorts. For batteries that gas, there needs to be ventilation. There is no mention of metal boxes and/or lithium batteries as far as I know. If you're worried, I'd just be familiar with the checklist they use. If someone tries to point out a regulation that isn't on the BSS checklist - challenge them on it! I think they can use their discretion on wiring etc being in good order and safe, but "LFP bad" shouldn't be part of this.

 

As you say, best avoided if possible.

https://panbo.com/abyc-ratifies-e-13-their-first-lithium-battery-standard/

 

E-13’s recommendations take effect for systems manufactured or installed after July 31, 2023. So, manufacturers, installers, and boat owners have a year to prepare for the requirements. Also, the standard’s scope lists that it applies to systems of 600-watt hours or greater. For a 12-volt system, that means systems with a capacity of 50 amp-hours or more.

 

Much of E-13 requires the batteries be installed, operated, and maintained according to manufacturers’ recommendations. In the case of the higher quality batteries that include thorough documentation and specifications, that seems like a fine recommendation. But, there are lots of lithium batteries available on Ali-Express, Amazon, eBay, and other sites that come with varying amounts of information. Additionally, the information they do include can be of dubious quality.

 

Edit 9/9/2022 – I’ve been in touch with a representative of the ABYC who clarified that E-13 is more restrictive than E-10’s 1 inch of movement requirement. His point being no visible movement is a higher standard than one inch of movement. For whatever reason, in my first reading, that wasn’t how I interpreted it. With his clarification, I now see how that’s a stricter requirement. But, it also seems more subjective than a specific measurement.

 

dave

August 12, 2022 at 12:19 pm

by the way ISO/TS 23625:2021 is also ratified and will be approved standard for RCD boats . in Europe the RCD has the force of law unlike ABYC

ISO/TS 23625:2021 is very similar to ABYC TE-13 except in places it offers more stringent specifications then TE-13, but both look like they used the same root documents !!

[Tony1]

1 minute ago, DShK said:

True.

 

The regulation, afaik, only says that batteries need to be secured from moving in any direction. They do not need a lid if they wouldn't move if the boat was at 45 degrees. They do need to be insulated from shorts. For batteries that gas, there needs to be ventilation. There is no mention of metal boxes and/or lithium batteries as far as I know. If you're worried, you can see the checklist they use online. If someone tries to point out a regulation that isn't on the BSS checklist - challenge them on it. I think they can use their discretion on wiring etc being in good order and safe, but "LFP bad" shouldn't be part of this.

 

As you say, best avoided if possible.

 

I must apologise as I've said this before somewhere, but maybe worth repeating: I was in a marina chandlery a few months ago and explained that I would be looking for a BSS inspector later in the year. The person behind the counter gave me a business card and said this person was someone they knew who had expanded his general boat repair/maintenance/gas work into providing BSS inspections. 

"So he's new. Is he likely to be very keen then, do you think?"

"Oh yes" they replied. "He'll be keen as mustard doing his inspections"

As always, I was polite.

"Great, I'll keep him in mind"

The business card went into the bin as soon as I got back to the boat. 

 

 

[DShK]

7 minutes ago, IanD said:

https://panbo.com/abyc-ratifies-e-13-their-first-lithium-battery-standard/

 

None of this looks difficult to comply with or unreasonable!

[IanD]

12 minutes ago, Tony1 said:

 

I must apologise as I've said this before somewhere, but maybe worth repeating: I was in a marina chandlery a few months ago and explained that I would be looking for a BSS inspector later in the year. The person behind the counter gave me a business card and said this person was someone they knew who had expanded his general boat repair/maintenance/gas work into providing BSS inspections. 

"So he's new. Is he likely to be very keen then, do you think?"

"Oh yes" they replied. "He'll be keen as mustard doing his inspections"

As always, I was polite.

"Great, I'll keep him in mind"

The business card went into the bin as soon as I got back to the boat. 

 

 

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... 😉

 

5 minutes ago, DShK said:

None of this looks difficult to comply with or unreasonable!

 

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

Edited July 18, 2023 by IanD

[David Mack]

4 hours ago, Psychalist said:

As I understand it, most MPPT load functions are simple timer based controls of a circuit, typically derived from switching something like street lights on and off and switch on the load whether there is solar available or not but are limited to the rating of the controller.

If 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!

(Unless someone puts solar panels under the street lights in an attempt at perpetual electrical motion).