Flaming Wires Between Graph & Battery (OUCH)

[Tennessee Boy]

Here’s my thoughts.  The battery the OP linked to is not a lithium battery.  If the link is correct then there was no BMS to provide short circuit protection.   There is no mention of a battery fire just burning alligator clips.  If the battery didn’t burn then I don’t see how it could be a battery problem.   I agree with what @guitarplaya39 said about a bad connection increasing resistance which causes heat when current runs through it.  The alligator clips are not ideal but I don’t think your small graph would draw enough current to cause them to get that hot that fast.   Was the graph even on when the fire started?  The fact that both clips started burning immediately when connected screams short circuit.  Water is a conductor so if there was some water in the bottom of the boat that would increase the chances of two wires being shorted out.  I see many potential short circuits in the pictures provided especially in a wet environment.
 

To me the obvious answer is a short.   You need better connections with fewer exposed wires and you need fuse protection.  
 

Glad you’re okay and that you caught some fish!

[AJ Hauser]

On 9/24/2023 at 12:20 PM, scaleface said:

I couldnt find terminals small enough to fit the wires and large enough to go over the post. So I did this. No problems.

 

 

I appreciate the tip - now let's talk about this sandals with socks situation... 

On 9/24/2023 at 12:35 PM, king fisher said:

Luckily the ten gallons of gasoline in jerry jugs, ended up being in the float on the other side of the plane. 

 

Yeah that could have been... bad... yikes!

23 hours ago, Tennessee Boy said:

Was the graph even on when the fire started?

 

Great question - no - I had just connected the clips but then moved the wires and they may have touched / sparked. That has happened many times accidentally before, but on this day, it was more... eventful... 

[flyfisher]

On 9/24/2023 at 10:15 AM, Catt said:

 

Everytime it floods cars catch on fire but that doesn't mean anything?

not really unless it is backed by something other than anecdotal data like you are presenting.  

[Tennessee Boy]

23 minutes ago, flyfisher said:

not really unless it is backed by something other than anecdotal data like you are presenting

https://www.usfa.fema.gov/blog/ig-102022.html

[flyfisher]

16 minutes ago, Tennessee Boy said:

https://www.usfa.fema.gov/blog/ig-102022.html

good stuff for the coastal inhabitants but most of the country isn't on the coast.

[Catt]

9 hours ago, flyfisher said:

not really unless it is backed by something other than anecdotal data like you are presenting.  

 

Eye witness accounts are not real evidence?

 

8 hours ago, flyfisher said:

good stuff for the coastal inhabitants but most of the country isn't on the coast.

 

Hurricanes mostly effect coastal inhabitants, guess thar means its less real?

[flyfisher]

8 hours ago, Catt said:

 

Eye witness accounts are not real evidence?

 

 

Hurricanes mostly effect coastal inhabitants, guess thar means its less real?

eye witness is real evidence of course but that also doesn't mean it is indicative of an overall stance.  This particular article mentions saltwater specifically and that saltwater causes fires on batteries.  I have yet to research it, because mainly I don't care, but I wouldn't be surprised at all if we see an increase in those types of fires due to the saltwater component, just happens that an electric vehicle has a lot of batteries to catch fire.

[Bankc]

Remember, there are a bunch of different types of "lithium" batteries.  And they're very, VERY different from one another.  

 

EV's are almost always lithium ion.  Same with cell phones.  These are the ones that are known to explode, catch fire, and be almost impossible to put out when they do.  They also have a very high energy density (lots of charge per gram), and a long lifespan, so that's why they're used.  Typically, so long as they have a good BMS (battery management system) that doesn't allow them to overheat, they're fairly safe.  Though, flood a battery with salt water so the internal cells short before the connection to the BMS, and there's not much you can do.  

 

Trolling motor and starter batteries are typically lithium iron phosphate or LiFePo4.  They're much safer and much less likely to overheat, explode, or catch fire.  They're also usually about the same size as lead acid or AGM, but weigh significantly less.  So they have a higher energy density than lead acid or AGM, but nowhere near the energy density of a lithium ion.  They also tend to last a long time.  So they're a good choice where safety is a top concern and you can live with the larger and heavier size.  I.e. not good for cell phones and EV's, but good for replacing older styles of batteries.  
 

Then there's lithium polymer batteries.  These have enormous energy densities!  They're also very, very dangerous and much more likely to catch fire and explode.  But they're much lighter than even lithium ion.  They also don't have very long lifespans.  You'll find these most often in things like drones, where weight is crucial and safety isn't (since no one is riding in the drone, it won't will anyone if it explodes).  They typically come in soft pouches to allow them to expand if they overheat so they don't explode.  But if they expand, they're useless and dangerous, so throw them away.  

 

And there's lithium iron disulfide batteries.  These are typically sold as replacements for normal alkaline batteries, like AA, AAA, 9v, etc.  They're not rechargeable, but they tend to last longer than alkaline batteries, especially in storage, and they almost never leak, unlike alkaline batteries.  So while they're more expensive, they're great for devices that you don't use that often, but don't remember to remove the batteries when you store them.  They're also better in high drain devices.  They're safer and less likely to explode and catch fire than even the alkaline batteries that we all grew up with and never feared.  

 

And there are even more types of "lithium" batteries out there, but those the main ones you'll run into.  And my point is, "lithium" isn't a category of battery, as one type of "lithium" battery has almost nothing to do with any other type.  It's just an element on the periodic table and one of the most common elements at that.  

[AJ Hauser]

28 minutes ago, Bankc said:

Remember, there are a bunch of different types of "lithium" batteries.  And they're very, VERY different from one another...

 

Dang. I had no idea. Thanks!