Engineering question

[BlkGS]

Bad information is worse than no information, you really should do your home work before posting such “inflammatory“ statements.

https://ecopowerit.com/blogs/news/safety-of-using-lithium-iron-phosphate-lfp-as-an-energy-storage-cell

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There is a huge difference between Lithium iron disulfide, which is what is in the energizer battery and Lithium iron phosphate, chemistry is the key.

Bad information implies what I posted is false, which it is not. Inflammatory... I see what you did there, lol.

The guys who sell you LiFePo say they don't explode, people selling teslas say they don't catch fire.... yet sheets of Lithium. Clearly do and shipping Lithium batteries requires extra precautions. I'm no chemist, as I've said, so I'm in no position to say who is right. But I'm sure as he'll not gonna believe a couple of sentences exclaiming how great something is from the sellers to make that decision. If they want to cut one open and prove it doesn't catch fire, I'd love to watch that video. Especially if they make sure at least something catches fire, lol.

 

[BlkGS]

Does this apply to all the automotive style lithium batteries? If so, that’s very comforting.

Most automotive Lithium batteries are Lithium ion. The burny burny explodey kind.

 

[84rzv500r]

Im not a chemist either... I did work across the the parking lot from Mendeleyev's office at St Petersburg Polytech. I did get the tour LOL
anywho I'll make a simple example... so lithium and sodium are alkali metals and they make strong base when combined with water yielding a impressive exothermic reaction... incidentally they are also some of the most common elements we have... however when these elements are combined in a molecule the properties can change dramatically... elemental sodium explodes violently when exposed to water, sodium chloride dissolves in water forming ions...

LiFePO4 is as safe as lead acid given the inherent danger of the associated power densities and likely environmentally a bit safer (ill leave that to the true propeller heads to figure out) its also overall better battery technology in most cases than Lead acid.

I went from 4 LA grp 29's to 1 LiFePO4 60Ah start battery and 2 x 100Ah house batteries and saved like 260lbs... 110% happy after 6 months of daily usage...

I used AYBC standards as a guideline and added automatic/manual FM200 fire suppression in the engine bay... Im not too worried about battery fires...

BTW I almost forgot do you know what an FRB lead acid battery is... I'll give you a hint there were commonly used in older large UPS systems so think about that for a bit... and of course you know charging a Lead Acid battery gives off what Mr Hindenburg? ? i know it was only named after the Barron but hey its a parable...

 

[dgfreeze]

Incidentally, years and years ago, when I was still a bit more “wet behind the ears”, I was doing some steel work (grinding and welding) on an old skid steer just above the battery. Incidentally, the battery was in need of a charge also, so I figured it would be a good idea to charge it while I worked. It wasn’t. After the ensuing explosion (blew half the top of the battery off), I realized just how stupid that was. Thankfully, most of my learning in life hasn’t been lessons that threaten my health. (**most**)

 

[Bluewater272]

Bad information implies what I posted is false, which it is not. Inflammatory... I see what you did there, lol.

The guys who sell you LiFePo say they don't explode, people selling teslas say they don't catch fire.... yet sheets of Lithium. Clearly do and shipping Lithium batteries requires extra precautions. I'm no chemist, as I've said, so I'm in no position to say who is right. But I'm sure as he'll not gonna believe a couple of sentences exclaiming how great something is from the sellers to make that decision. If they want to cut one open and prove it doesn't catch fire, I'd love to watch that video. Especially if they make sure at least something catches fire, lol.

But what you said/implied IS false. Lithium batteries have their own unique risks of course (as does any form of stored energy), but exploding if exposed to water is not one of them. If you've got a chunk of pure lithium metal in an oil jar on your boat, yeah, that might be a problem if you drop it.

 

[AZMark]

This went down a different path but I really wouldn’t worry about the weight of one more battery damaging the floor. I doubt they put a super thin floor in there just because it’s a compartment. Yamaha would expect people to dump quite a bit of stuff in there (including ballast on some boats). It’s also still structural and helping hold up the floor and seats which hold a lot more weight than 3 batteries.

 

[dgfreeze]

This went down a different path but I really wouldn’t worry about the weight of one more battery damaging the floor. I doubt they put a super thin floor in there just because it’s a compartment. Yamaha would expect people to dump quite a bit of stuff in there (including ballast on some boats). It’s also still structural and helping hold up the floor and seats which hold a lot more weight than 3 batteries.

I definitely agree that the floor in general will hold the weight of three batteries, I just get a little concerned about the weight of the third battery within the footprint of two. Plus the weight of the frame, which would essentially become at least close to the weight of four batteries in the footprint of two. That’s approximately doubling the pounds per square inch, which is the only thing that's making me nervous. I feel like it would be fine, but can't quite justify the risk. All this just because I've got a spare battery laying around...lol Now, if I ever do go lithium, I'd probably think again about stacking them, since they're so much lighter than lead. But short of someone coming up with a pretty definitive approval, it's just not worth the risk of damage, despite my feelings that it would likely be ok.

 

[84rzv500r]

I cut my 18 year old boat apart pretty seriously and added structural components to support new engine mount structure I dont think I would worry too much about the static loading in the horizontal plane (on the floor) i might worry a little about dynamic loading in the vertical plane as these parts are not as stout as the floor structure... there are tons of pics and measurements on my build thread (see Sig) one could imagine using 0.125 or 0.250 Coosa board bonded with structural epoxy to the existing tub structure to spread the load out a bit...

 

[Cobra Jet Steering LLC]

I think I'll be all but scrapping this double decker battery stacker idea. I still like the space saving aspect of it, but my concerns about the weight of a second battery stacked on top of the bottoms ones just doesn't make me feel good about it. If my two battery setup is lacking, I think all you guys preaching lithium are probably right. Thanks to all you guys who chimed in and talked me off my ledge.

one thing about a battery sitting up above the floor is the leverage it has in waves to rock the boat and a fulcrum effect on the hull stability in turns .

 

[BlkGS]

But what you said/implied IS false. Lithium batteries have their own unique risks of course (as does any form of stored energy), but exploding if exposed to water is not one of them. If you've got a chunk of pure lithium metal in an oil jar on your boat, yeah, that might be a problem if you drop it.

I implied nothing..I posted a video of the Lithium in a battery exploding when put in water. Maybe you know better than me and think it's a hoax. I don't know. All I know is I watched a guy cut a Lithium AA battery in half and it exploded in water. I don't know what formulations are used in a AA Lithium battery vs a Lithium for a car vs a Lithium for a boat vs a fancy LiFePo. I just know that I saw a video that the Lithium in a AA battery exploded when put in water.

 

[HangOutdoors]

Since we are discussing Lithium, here is an interesting article I read today.

There’s lithium in them thar hills – but fears grow over US ‘white gold’ boom (msn.com)

 

[Ericd]

I may have missed it in this thread, but isn’t there something you have to do to the boat’s charging setup when you mix lead-acid for starting and lithium for house?

 

[84rzv500r]

I may have missed it in this thread, but isn’t there something you have to do to the boat’s charging setup when you mix lead-acid for starting and lithium for house?

yes but I avoid that by having both strings using LiFePO4 batteries one that is from Dakota Lithium that has i think extra capacitance in the battery to deal with starting (remember MR-1's in jet skis start off of a 12-18Ah lawnmower battery just fine) and mostly the 2 x 7.5W solar panels keep the house string topped off all the time... Start and run on the 60Ah... Float on the pair of 100Ah... If i have to start on the house batteries the start current of the starters are way below the 200A max continuous draw they can support.

https://dakotalithium.com/product/d...r-starter-deep-cycle-lifepo4-battery-1000cca/

https://www.amperetime.com/products/ampere-time-12v-100ah-lithium-lifepo4-battery

 

[BlkGS]

Since we are discussing Lithium, here is an interesting article I read today.

There’s lithium in them thar hills – but fears grow over US ‘white gold’ boom (msn.com)

Here's a photo of what happens when a hill with Lithium in it gets wet.




Jokes aside, the mIning for all the materials to truly go large scale with Lithium batteries is an industry that Amerocans will both want to be in the US, but also not near their backyard, any sort of watershed, any sort of ancestral grounds, any sort of undeveloped wilderness, any sort of natural wonder, etc etc.

 

[FSH 210 Sport]

I may have missed it in this thread, but isn’t there something you have to do to the boat’s charging setup when you mix lead-acid for starting and lithium for house?

Yes Eric, you have to change how the dvsr operates otherwise the higher voltage of the LiFePO battery will keep the dvsr closed and the LiFePO battery will start transferring power to the lead acid start battery.

I set mine up on a manual switch, and you can set it up to an ignition hot as well.

When the engines are running they are putting out 14.4 volts which is above the nominal voltage of the LIFePO, 13.6, and the lead acid 12.5.

Make sense?

 

[dgfreeze]

Since this post took a little bit of a sideways turn, this incident kinda struck home with me, and made me chuckle a little. My work is in the landscape industry, and there’s a show in Kentucky called the Equip Expo (formerly the GIE Expo). Apparently DeWalt has a battery powered mower there that they had out in the demo area. It caught fire, and they shut down whole demo area. I have no idea what the cause of the fire was, or what kind of batteries it uses, nor is this me taking a side of any kind. I’ve also got a video of it, but not sure how to post videos. And no, I wasn’t there myself.

 

[Bruce]

Most automotive Lithium batteries are Lithium ion. The burny burny explodey kind.

LiPo (lithium polymer) are the burny burny explodey kind. There are typically used in toy RC devices and some hoverboards.

The lithium ion cells in most EVs are quite safe.

 

[Bruce]

I implied nothing..I posted a video of the Lithium in a battery exploding when put in water. Maybe you know better than me and think it's a hoax. I don't know. All I know is I watched a guy cut a Lithium AA battery in half and it exploded in water. I don't know what formulations are used in a AA Lithium battery vs a Lithium for a car vs a Lithium for a boat vs a fancy LiFePo. I just know that I saw a video that the Lithium in a AA battery exploded when put in water.

The non rechargeable lithium battery in the video is a different chemistry. Could be one of many. Interestingly those batteries are used for their long shelf lives and long lasting nature in devices. I have seen many of them but never heard of them causing fires. Most stories of lithium fires are LiPo.