[remy_martian]

In the case of a boat, I'd cut a square hole in the bottom of the boat then seal a stainless steel battery box with a plastic bottom to that hole - in the event of a fire, the flaming batteries get delivered to Davey Jones locker.

 

[Ohno]

In the case of a boat, I'd cut a square hole in the bottom of the boat then seal a stainless steel battery box with a plastic bottom to that hole - in the event of a fire, the flaming batteries get delivered to Davey Jones locker.

Ha ha! I've seriously considered that. As usual the devil is in the details. For one thing there's a hydrofoil directly beneath the batteries. The batteries are in two boxes on deck. Floating them off with a helium balloon might be easier. 300lbs each though? Maybe not.

 

[Ohno]

Thanks, yes, in this blogpost https://www.oudevolvo.nl/en/blog/2018/09/27/stainless-steel-battery-boxes-for-tesla-modules/

And when I stopped blogging updates can be found on Instagram @oudevolvo eg around

http://instagr.am/p/CNErkAKH7hG/
And on Facebook OldVolvo

Your build is very impressive. What beautiful work.

Can you think of any way that you would change your battery box design to better contain a fire?

 

[brian_]

Cool boat build

Nice project:
Professional Boatbuilder: Electric Foiling Catamaran from Recycled Parts

 

[remy_martian]

The wands for height control are brilliant...I'm now wondering if there's a mechanical wave height averager that could be introduced using adjustable-valving shock absorbers (or even corn starch dampers, lol).

 

[Ohno]

The wands for height control are brilliant...I'm now wondering if there's a mechanical wave height averager that could be introduced using adjustable-valving shock absorbers (or even corn starch dampers, lol).

Smarter people than me have figured out how to control ride height, roll and pitch electronically. I'm thinking all the sensors that control a quadracopter would do the job. Somehow tie those things to servos and hydraulics.

My new boat skirts the whole control issue by keeping the hulls slightly in the water.

 

[Ohno]

In a catamaran with packs in each hull, should the connecting wires be de-energized when the vehicle is Off, or will they be Hot all the time?

If using used modules from a wrecked car, then just assume that you will have a fire--are you wanting to save the vehicle or just save your life? Is it just a run-about type of boat or a live-aboard?

An EV has safety aspects to protect first responders in the event of a crash that a Boat doesn't necessarily need, just depends upon your level of risk tolerance.

Cool boat build

I don't know. Do car guys de-energize cables that run between battery packs?

 

[kennybobby]

Yes, best practice is there should be no HV outside of the pack when the vehicle is Off.

 

[remy_martian]

Safety requirement, not merely best practice. It used to be "best practice", which is nowadays unacceptable for occupant and first responder safety in roadgoing and competition vehicles. There are too many conversions being done these days to where someone will wreck and electrocute a responder....then we are done as hobbyists as we either get regulated to death or outright banned. There's no nicespeak on this - if there's more than 60V on ANY wire, it needs to be able to reliably get shut off in the closed box that put the voltage out.

"Wetted area" increase...yuck. But you're the boating genius here.

Meanwhile, yes, you could use a flight controller's pitch, yaw, and roll sensor to move the surfaces. Instead of your wands, use the four motors and props from a quadcopter, each placed in each of four corners of your boat that are actually flying in air (a couple of feet above water so they don't dunk) to servo the position in the air, then run those down with a control rod/wire to a trim tab on the foil control surfaces. The trim tab acts as a force multiplier and is usually how autopilot servos move control surfaces on aircraft. This should only pay attention to the gyro on the flight controller and will not care about wave heights and should not require a single line of code to be written.

 

[oudevolvo]

Can you think of any way that you would change your battery box design to better contain a fire?

Thanks!
In the first place my fire mitigating action will be not to use Tesla batteries anymore.
Nowadays there are safer batteries that will give me the right volume, weight and kWh at 96s.
There are two things that could have been better on the box I made:
1) Smarter vent valve positions (so the exits would be where even less damage would occur).
2) A hose connection (not sure how to seal/close that when not in use) onto the box that the firemen could have used to put water inside the box to even better cool at the exact right place

 

[remy_martian]

What did you use for vent valves?

 

[oudevolvo]

What did you use for vent valves?

I used vent valves taken from a Tesla Model S battery pack.
Visible on the left and right front sides here

http://instagr.am/p/COKFu1en8Wt/
And a separate breather valve also taken from a Model S pack.

Nowadays I use these Vent valve for battery box - EVcreate

 

[Ohno]

Thanks!
In the first place my fire mitigating action will be not to use Tesla batteries anymore.
Nowadays there are safer batteries that will give me the right volume, weight and kWh at 96s.
There are two things that could have been better on the box I made:
1) Smarter vent valve positions (so the exits would be where even less damage would occur).
2) A hose connection (not sure how to seal/close that when not in use) onto the box that the firemen could have used to put water inside the box to even better cool at the exact right place

What an interesting idea to provide a fire hose connection. It might be asking a lot that a firefighter would have the presence of mind and courage to connect to it but I can picture a fill pipe that exits at the car side with a valve that can withstand maybe 800c? It could not be a liquid tight valve probably. I wonder if such a thing exists?

Do you think in your case the vents directed heat at combustable parts near the battery box? Or could the heat radiating from the box have ignited nearby combustibles?

Thanks so much for taking the time to respond. I am in awe of what you produced. Such a heartbreaker to see it damaged.

 

[Ohno]

Safety requirement, not merely best practice. It used to be "best practice", which is nowadays unacceptable for occupant and first responder safety in roadgoing and competition vehicles. There are too many conversions being done these days to where someone will wreck and electrocute a responder....then we are done as hobbyists as we either get regulated to death or outright banned. There's no nicespeak on this - if there's more than 60V on ANY wire, it needs to be able to reliably get shut off in the closed box that put the voltage out.

"Wetted area" increase...yuck. But you're the boating genius here.

Meanwhile, yes, you could use a flight controller's pitch, yaw, and roll sensor to move the surfaces. Instead of your wands, use the four motors and props from a quadcopter, each placed in each of four corners of your boat that are actually flying in air (a couple of feet above water so they don't dunk) to servo the position in the air, then run those down with a control rod/wire to a trim tab on the foil control surfaces. The trim tab acts as a force multiplier and is usually how autopilot servos move control surfaces on aircraft. This should only pay attention to the gyro on the flight controller and will not care about wave heights and should not require a single line of code to be written.

That would be a lot of fun to play with - on the next boat maybe. This one needs to be a more practical daily transporter from our non ferry serviced island. I'm even hoping it can push a small steel hay barge around a couple of times a year, but that might be asking too much.

 

[Ohno]

Thanks!
In the first place my fire mitigating action will be not to use Tesla batteries anymore.
Nowadays there are safer batteries that will give me the right volume, weight and kWh at 96s.
There are two things that could have been better on the box I made:
1) Smarter vent valve positions (so the exits would be where even less damage would occur).
2) A hose connection (not sure how to seal/close that when not in use) onto the box that the firemen could have used to put water inside the box to even better cool at the exact right place

On second thought it might be that introducing water into a sealed box where temperatures may be 800c might cause the water to flash to steam and explode. I will leave that for others to test.

 

[oudevolvo]

Do you think in your case the vents directed heat at combustable parts near the battery box? Or could the heat radiating from the box have ignited nearby combustibles?

Thanks for your kind words. I think the flames coming from the vents ignited surrounding stuff. Higher up there was mostly radiation and there the damage is not that bad although it has burned there and also underneath the dash.
See also http://instagr.am/p/CiVWyI8tkMz/ Regarding the hose connection, in my view it can add value in two stages:
1) At the very beginning of a fire where you might be able to cool it down to stop thermal runaway
2) At the end of a fire to ensure it does not light up again
Then just a metal (quick connect) cap can do the trick.
At the hottest point during the fire I'd not suggest to use/open it.
In my box, three Tesla modules burned until there was nothing to burn anymore.
When the heat was more or less gone, the firefighters tried to open it, but I suggested to cut off the MSD instead so that was the way to extra cool down instead of the hose connection. See photo 2 here http://instagr.am/p/CWxV47Yojzt/
But in your case (if you still want Tesla modules on a boat) I'd say try to ensure each module is contained so in worst case it can burn without igniting others.
Think the issue in a Tesla (and others) and the main reason for submersing cars is that you never know if the surrounding batteries got just too hot or not.
In my case I was quite sure the front would not re-ignite since there was simply nothing left to burn.

 

[electro wrks]

But in your case (if you still want Tesla modules on a boat) I'd say try to ensure each module is contained so in worst case it can burn without igniting others.

This is one of the key safety features in the early battery patent(s) for the Model S and X battery enclosure. Also included in the patent(s) are pressure pop-off valves and a plenum built into or near the enclosure to direct flames and hot gasses down and away from the vehicle.

oudevolvo, could a pop-off or burst valve and vent tube system, of sufficient cross sectional area, directed flames and hot gasses away from your car, and limited the damage from the fire? Do you think the 2mm stainless steel wall thickness box would have generally contained the fire with these features in place?

You mentioned radiant heat damage. Extra shielding or insulation would help prevent this.

 

[kennybobby]

In my case I was quite sure the front would not re-ignite since there was simply nothing left to burn.

Do you think that overcharging was a factor in your fire?

 

[oudevolvo]

Do you think that overcharging was a factor in your fire?

Not likely. The car was not plugged in and the cell with the highest voltage was at 4,05V the evening before the fire.
Will share further details in a blogpost later.

 

[Ohno]

Thanks for your kind words. I think the flames coming from the vents ignited surrounding stuff. Higher up there was mostly radiation and there the damage is not that bad although it has burned there and also underneath the dash.
See also http://instagr.am/p/CiVWyI8tkMz/ Regarding the hose connection, in my view it can add value in two stages:
1) At the very beginning of a fire where you might be able to cool it down to stop thermal runaway
2) At the end of a fire to ensure it does not light up again
Then just a metal (quick connect) cap can do the trick.
At the hottest point during the fire I'd not suggest to use/open it.
In my box, three Tesla modules burned until there was nothing to burn anymore.
When the heat was more or less gone, the firefighters tried to open it, but I suggested to cut off the MSD instead so that was the way to extra cool down instead of the hose connection. See photo 2 here http://instagr.am/p/CWxV47Yojzt/
But in your case (if you still want Tesla modules on a boat) I'd say try to ensure each module is contained so in worst case it can burn without igniting others.
Think the issue in a Tesla (and others) and the main reason for submersing cars is that you never know if the surrounding batteries got just too hot or not.
In my case I was quite sure the front would not re-ignite since there was simply nothing left to burn.

So it seems that your battery box worked well to contain the fire. Possibly if vents are directed away from combustibles and with the addition, perhaps, of some shielding and/or insulation a battery fire might not necessarily be a disaster.
I'm sorry that I can't simply build a battery box that could be jettisoned into the water. It seems like the most elegant option since we are surrounded by water. Maybe on the next boat!