My lithium build

[Trident]

I am a flexible panel sceptic. Had two sets of flexi panels and both bit the dust very quickly. They both had poor output compared to cheap framed panels. If anybody knows a good reasonable cost flexible panel of about 100w or so I could add a couple to the sprayhood.

Take a look at Renogy - I've fitted hundreds of these now and the oldest are just coming up 5 years and look and work like new. Very good prices too. For tight spaces we've been fitting them to spray hoods using neodymium magnets on the panel with its mate under the canvas so they can be demounted easily - tested up to about 45 knots so far without anything coming awry. This also means you can move them to get better angle of incidence in a pinch which as you say with tillable panels - is worth a lot (we did some experiments last summer and reckon about 30-40% a day can be gained.

I have two flexi panels (175w each) in storage with magnets and long leads to a pre-wired plug for MC4 solar connectors as my emergency back up - not needed yet in real life , but if we have a really bad few days of solar bringing these out to face the sun directly all day will put in a very good boost.

 

[geem]

This is the internet - without photos it never happened?

...

No boat caught on camera ..... yet.

Not a single Lifepo4 prismatic fire in that video. You have the wrong tech

Take a look at Renogy - I've fitted hundreds of these now and the oldest are just coming up 5 years and look and work like new. Very good prices too. For tight spaces we've been fitting them to spray hoods using neodymium magnets on the panel with its mate under the canvas so they can be demounted easily - tested up to about 45 knots so far without anything coming awry. This also means you can move them to get better angle of incidence in a pinch which as you say with tillable panels - is worth a lot (we did some experiments last summer and reckon about 30-40% a day can be gained.

I have two flexi panels (175w each) in storage with magnets and long leads to a pre-wired plug for MC4 solar connectors as my emergency back up - not needed yet in real life , but if we have a really bad few days of solar bringing these out to face the sun directly all day will put in a very good boost.

Sounds good. I think a couple of Ronogy panels mounted on an acrylic canvas sheet that we can fold the size of a single panel would work for us. We have plenty of deck space.
I found the tilting aspect of panels a real surprise. 30/40% is huge. It makes solar arches seem very inefficient if they are fixed horizontally

 

[Trident]

I found the tilting aspect of panels a real surprise. 30/40% is huge. It makes solar arches seem very inefficient if they are fixed horizontally

Flat is easy I guess - on cats its a no brainer as there is so much flat real estate that the mechanisms to tilt make no sense - last summer I fitted out a hull of one 42 cat as a recording studio for the owner (1200 AH LifePo4, 5 kw inverter etc ) and we put 1600w on an arch to add to the 900w of flexi that fitted happily on the roof.

( The 1600w of the latest most efficient panels (Maxeon 4) took exactly the same space as my 1040w of panels that were the best available 4 years previously so the technology is moving at a pace. )

Anyway, we did all the tilt tests for this guy over a week or two but in the end he decided it was simpler to just load another few hundred watts of panels on more roof space and not have to worry about active input.

 

[geem]

Flat is easy I guess - on cats its a no brainer as there is so much flat real estate that the mechanisms to tilt make no sense - last summer I fitted out a hull of one 42 cat as a recording studio for the owner (1200 AH LifePo4, 5 kw inverter etc ) and we put 1600w on an arch to add to the 900w of flexi that fitted happily on the roof.

( The 1600w of the latest most efficient panels (Maxeon 4) took exactly the same space as my 1040w of panels that were the best available 4 years previously so the technology is moving at a pace. )

Anyway, we did all the tilt tests for this guy over a week or two but in the end he decided it was simpler to just load another few hundred watts of panels on more roof space and not have to worry about active input.

Cats have a huge advantage over monohulls with regard to mounting solar. We are limited in space so the guardrails are a good choice for our miserly 720w. I am pleasantly surprised how much they harvest due to the ability to optimise the angle of dangle. It wasn't something I thought about when we put them there. A couple of 100w Ronogy or even 4x50w size panels would be a good option for us as they would stow below nicely when on passage or try your fixing method with magnets on the sprayhood. Where do you get such high powered magnets?

 

[Poey50]

This is the internet - without photos it never happened?

...

No boat caught on camera ..... yet.

PS: Rod Collins is only offering $50 for a very specific scenario and has this to say about himself.



DIY LiFePO4 Batteries On Boats - Marine How To

Two points. You continue to conflate LFP with the wider lithium ion family. We all know some members of that family are volatile which is why marine installations use the most stable member. Second, Rod Collins is being modest.

 

[Baggywrinkle]

Not a single Lifepo4 prismatic fire in that video. You have the wrong tech

Two points. You continue to conflate LFP with the wider lithium ion family. We all know some members of that family are volatile which is why marine installations use the most stable member. Second, Rod Collins is being modest.

No, a good LiFePO4 prismatic battery will better mitigate the effects of thermal runaway, it will not stop or prevent it if it is triggered by a breakdown of the separator in the battery due to a manufacturing fault or external heating from another source. The mitigation includes safe venting, insulation from surrounding cells in an attempt to prevent heat transfer or explosion of the cell - all easier with LFP as it is the safest of the technologies available, it has the highest onset temp, the lowest temperature increase and releases the least CO during a runaway event - but it still burns.

A prismatic battery can swell which can cause deformation of bus-bars or connections leading to further problems - hence why they are clamped together to help mitigate against deformation ... there have been multiple experiments at work into battery failure and thermal runaway is normally triggered for testing by nail puncturing or external heating to induce a controlled failure.

As with everything it is the manufacturing process and the design of components which will set the failure rate of a component in service. To believe it is impossible and will never happen is naïve IMO - the probability is very low given trusted component suppliers with state of the art manufacturing facilities and quality control.

 

[geem]

No, a good prismatic battery will better mitigate the effects of thermal runaway, it will not stop or prevent it if it is triggered by a breakdown of the separator in the battery due to a manufacturing fault or external heating from another source. The mitigation includes safe venting, insulation from surrounding batteries in an attempt to prevent heat transfer to the surrounding cells or explosion on the cell. A prismatic battery will swell which can cause deformation of bus-bars or connections leading to further short-circuits - hence why they are often clamped together to help mitigate against deformation ... there have been multiple experiments at my work into this and thermal runaway is normally triggered for testing by nail puncturing to induce a controlled failure.

As with everything it is the manufacturing process and the design and components which will set the failure rate of a component in service. To believe it is impossible and will never happen is naïve IMO - the probability is very low given trusted suppliers with state of the art manufacturing facilities and quality control.

So you have to fire a nail through to create thermal runaway? Fortunately we don't carry nails on our boat.
The cells are robustly compressed. Robustly restrained in their dedicated battery box. Fitted with a class T fuse next to the battery. The charging is controlled by a Victron smart shunt. The BMS will also cut the charge if excessive. The install is fully compliant with ABYC standard for lifePO4 installation in a marine environment. What am I doing wrong?

 

[Baggywrinkle]

So you have to fire a nail through to create thermal runaway? Fortunately we don't carry nails on our boat.
The cells are robustly compressed. Robustly restrained in their dedicated battery box. Fitted with a class T fuse next to the battery. The charging is controlled by a Victron smart shunt. The BMS will also cut the charge if excessive. The install is fully compliant with ABYC standard for lifePO4 installation in a marine environment. What am I doing wrong?

Absolutely nothing wrong, and I am not trying to criticize your build at all - I will be installing LFPs on my next boat too. The only element you can't control is the behaviour of the components in service - that's where all the variables come into play that the manufacturer hasn't necessarily mitigated for, along with latent manufacturing faults. Here you need a statistically significant volume of product in service to say what the failure rate really is.

Thermal runaway of LiFePO4 is around 270°C so as long as there is nothing in close proximity with a melting or ignition point around this temperature (e.g. polycarbonates, epoxy resin, and polyester webbing straps will melt) then all should be fine. Ventilation should dissipate the gasses and fiberglass should withstand 270°C

 

[geem]

Absolutely nothing wrong, and I am not trying to criticize your build at all - I will be installing LFPs on my next boat too. The only element you can't control is the behaviour of the components in service - that's where all the variables come into play that the manufacturer hasn't necessarily mitigated for, along with latent manufacturing faults. Here you need a statistically significant volume of product in service to say what the failure rate really is.

Thermal runaway of LiFePO4 is around 270°C so as long as there is nothing in close proximity with a melting or ignition point around this temperature (e.g. polycarbonates, epoxy resin, and polyester webbing straps will melt) then all should be fine. Ventilation should dissipate the gasses and fiberglass should withstand 270°C

I think you are clutching at straws. There isn't a documented thermal runaway/ fire event of lifepo4. Rod Collins who wrote most of the ABYC standard on lifepo4 has had a standing bet for several years that nobody can produce one for a battery in service. He will pay money for the evidence.

 

[Poey50]

This thread started by Will Prowse is helpful.
Can LiFePO4 Batteries Combust in Thermal Runaway Event?

 

[lustyd]

I would not under any circumstances like to have that going off in my bilges thank you.

Again though, unless you're wanting trouble you wouldn't install those batteries on a boat. Those look like Lithium-ion 18650 cells which are a fire hazard and are the reason EV fires are dangerous and hard to deal with.

Boat batteries are LiFePo4 and are not a fire hazard.

 

[lustyd]

Sounds good. I think a couple of Ronogy panels mounted on an acrylic canvas sheet that we can fold the size of a single panel would work for us. We have plenty of deck space.
I found the tilting aspect of panels a real surprise. 30/40% is huge. It makes solar arches seem very inefficient if they are fixed horizontally

On my Renogy panels I fitted strips of UPVC cloaking profile using the middle hole on either side to give them a little stiffness. The end holes then have bungee through the hole in the panel and a matching hole in the UPVC and I can use this bungee to strap them to various places. Underway they sit over the hatch on the coachroof and bungee to the hand rails on the cabin top. At anchor we often move them to various other places including the guard wires and bungee them in place. The bungee has hooks on the end for convenience. I bought a reel of solar cable and made up various extension leads to allow different parallel or serial configurations around the boat.

While this might sound like a faff it's only a minute or two and they end up secure enough to leave in place. Generally we can get away with one position per day depending on what the tide is doing and how desperate we are for power. Usually the battery is full by lunchtime though, so we don't often move them again.

 

[Baggywrinkle]

I think you are clutching at straws. There isn't a documented thermal runaway/ fire event of lifepo4. Rod Collins who wrote most of the ABYC standard on lifepo4 has had a standing bet for several years that nobody can produce one for a battery in service. He will pay money for the evidence.

Reader Challenge:
I will continue to offer a challenge that I have been offering now for 12+ years on the Internet and that is; the first person to bring me an image of a lithium iron phosphate cell, properly installed, that erupted into flames or resulted in an explosion due to overcharging, I will pay them$50 cash for that image! In 12+ years not one person has been able to bring me such an image…This is because LiFePo4 is an extremely safe chemistry.

This challenge is a bit moot IMO

1. $50 Dollars ... a sum that can be wagered without any real conviction.
2. "properly installed" - any idea what that actually means? ABYC and Manufacturers instructions? What about proximity to other things? Materials used?
3. ... and it can only be down to overcharging? - that's a bit specific. No manufacturing faults in the batteries or BMS allowed?
4. Proving that it was the cell that ignited first is also going to be difficult after the fact if it wasn't filmed.

So you need a fire, then you need to have filmed this random event happening to prove it was the battery that ignited first, know the challenge exists, then prove it was due to overcharging, and get past whatever the definition of "properly installed" is - not surprised no one has collected.

The problem with the whole thing is that thermal runaway needs something to start it - if you want to study thermal runaway you need to induce it (inflict damage or heat the cell) because it's not viable to pick out a cell with a manufacturing fault in the separator that will enter thermal runaway on its own - doesn't mean it doesn't happen (it can be induced by heating) or that there aren't any faulty cells out there. The relative low temperature (270°C) during thermal runaway in LiFePO4 chemistry is also unlikely to ignite anything - it's unlikely, but not impossible - any fire is more likely to result from deformation of the batteries resulting in secondary problems.

IMO anything that can deform and simultaneously deliver huge currents is a fire hazard that we need to think about when installing, even if the chemistry inside will only deliver pizza oven temperatures it is still enough to induce combustion given the right circumstances.

Rod Collins also knows that thermal incidents are down to more than just battery chemistry and the BMS ....

Solar Charge Controller Failures - Professional BoatBuilder Magazine

His parting comments ....

In a perfect world, every onboard component would be installed according to American Boat & Yacht Council (ABYC) or International Organization for Standardization (ISO) standards, or a manufacturer’s explicit instructions. Sadly, we all know that doesn’t always happen, and even when it does, perils still lurk. I’ve been involved in the extensive deliberations of ABYC’s lithium-ion/high-capacity battery subcommittee since 2013, but recently I encountered a solar charge controller failure scenario none of us on the committee, not even the components manufacturers, ever brought up or discussed. It’s an example of how a seemingly minor error can lead to a succession of failures and a potentially dangerous situation.

 

[lustyd]

This challenge is a bit moot IMO

If you can find any picture of any LiFePo4 that caught fire not deliberately it would be a good start. Until then you're on your own

 

[mattonthesea]

Slight thread drift here: in the midst of all the myths and apocryphal tales I've heard that it's not a good idea to use a LifePo4 for engine starting. I'm building a B2B with Lead Acid so not planning to do so; but if my LA flattens for some reason would it hurt to start with the LFP and switch back to LA straight away? I assume that the alternator will be ok as it will have something to charge (LA) all the time and the switch away from LFP can be done as the engine fires, so not much charge at that time anyway.

TBH I can't see why the LFP wouldn't be good as a starter; the power draw should be no more than for LA and it's not for that long. Am I missing something (internal resistance etc)? NOT PLANNING ON IT - JUST CURIOUS

 

[lustyd]

I think it's because the BMS may shut the battery down in various conditions, so it's useful to have a LA in there to protect the alternator for simplicity. Lithium start batteries have been around for a long time so they do work.

 

[Baggywrinkle]

If you can find any picture of any LiFePo4 that caught fire not deliberately it would be a good start. Until then you're on your own

https://www.fire.tc.faa.gov/pdf/TC-16-17.pdf

In general, of all of the lithium-ion cells that were tested, LiFePO4 would be considered the safest cathode material because of the relatively low temperature rise and the resulting low likelihood for thermal runaway to propagate.

Note the use of "low likelihood" ..... Unfortunately to measure thermal runaway, you need to deliberately start it. It can of course start in a faulty or internally damaged cell, but those are hard to find, so you have no YouTube videos ..... yet.

I believe they are perfectly safe statistically for marine use, but to deny thermal runaway exists, or to claim that fires can't happen because you personally haven't witnessed them or seen a photo is a bit naïve IMO.

.... but I guess the Titanic was unsinkable too .... so watch this space

 

[Trident]

Where do you get such high powered magnets?

I got them from Amazon - with a predrilled countersunk hole in the middle ideal for bolting them to the panels - there is no way on earth a man can pull them directly apart even though they are the size of a 50p piece. You have to slide them side to side to take them apart. Pack of 10 for £14.99 in the UK

https://www.amazon.co.uk/dp/B08NP4X...1_4&amp=&crid=22KWMZOL0WJS6&amp=&sprefix=neod

 

[lustyd]

I got them from Amazon - with a predrilled countersunk hole in the middle ideal for bolting them to the panels - there is no way on earth a man can pull them directly apart even though they are the size of a 50p piece. You have to slide them side to side to take them apart. Pack of 10 for £14.99 in the UK

https://www.amazon.co.uk/dp/B08NP4X...1_4&amp=&crid=22KWMZOL0WJS6&amp=&sprefix=neod

Magnets like that tend to be quite brittle and often shatter on impact if you let them snap together so may need something soft in the mix for longevity.

Edit - never mind - clicked the link, saw the steel cups, I'm wrong

 

[Trident]

Magnets like that tend to be quite brittle and often shatter on impact if you let them snap together so may need something soft in the mix for longevity.

They're for attaching to a spray hood normally so a nice soft bit of canvas in between - though in the last two years I've been using them I've had no problems reported but thanks for the warning