# Damien's BMS Harness catches fire



## kennybobby (Aug 10, 2012)

He has posted a video showing some details. This is serious enough to warrant it's own thread.


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## kennybobby (Aug 10, 2012)

It appears that the battery and bms harness were not covered or enclosed, not sure if this was a contributory factor or not










He said he wasn't interested in the root cause and wasn't going to investigate; he's somewhat on the front leading edge of diy builds and not sure that attitude helps peel back the foreskin of technology for others to follow.



















Kinda scary how there was still quite some energy in the cells when he stomped on it with the bare copper wires showing; no fuses on the wires from the cells to the BMS


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## Functional Artist (Aug 8, 2016)

I'm impressed how even with a "raging" fire going right on "on its "lid" the module didn't "light up" too
...but, yes, very concerning
...& I agree, warrants further investigation 

Hopefully to help further the discussion, here is some "stock" Chevy BMS info (I threw together real quick)


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## remy_martian (Feb 4, 2019)

The "fire" appears to have been on the ABS lid, , which has flame retardant in it, and the questionable materials (plumbing insulation?) used on the insulated coolant hoses at the firewall (doesn't look factory) which may not be rated as self extinguishing.

Damien noted that the wires were glowing red after the fire (burning plastic) was extinguished with water, so that constant high temperature ignition source is likely what kept the flame-retarded plastic burning.

The construction of the Volt pack, which is a sandwich of metal plates, and having coolant in their loops, meant a lot more heat would be needed to raise the cell temperatures to criticality than was there.

Most of the fire seems to have been in the materials used for the hoses at the firewall, which was well removed from the cells in any case.


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## MattsAwesomeStuff (Aug 10, 2017)

kennybobby said:


> He said he wasn't interested in the root cause and wasn't going to investigate; he's somewhat on the front leading edge of diy builds and not sure that attitude helps peel back the foreskin of technology for others to follow.


_retch_

I too agree though. The most interesting part of this is the post-mortem. I don't get why "So a fire spontaneously started that could have started any time" isn't an interesting problem to solve. Damien has pretty thin skin and is constantly worn down by trolls and naysayers, so, maybe he just doesn't want to get into it because he's going to be wading into accusations of the blame game rather than the technical aspects.

He cites the late Jack Rickard back in the day, who was a bombastic proponent of never using BMS's, as all they did were ruin batteries. Though Damien's said in the past that he avoids religious discussions, of which whether or not to use a BMS is one of, and that his choice is to use one.

He puts blame on the BMS wires not being fused immediately after leaving the battery, and instead all the way over on the BMS side. So if two BMS wires ever overheat, or abrade, or get mouse bitten, or anything, you have that distance of wire where they will merrily short and there's nothing to stop them.

For what it's worth, I think the Gen2 Volt bms changed this and put the fuses at the battery, not at the BMS like on the Gen1, but I might be mistaken.



remy_martian said:


> Most of the fire seems to have been in the materials used for the hoses at the firewall, which was well removed from the cells in any case.


Wouldn't have helped if the car itself lit on fire. They've cooked eventually.


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## remy_martian (Feb 4, 2019)

If you look at the volume of burned plastic, it's not the fire retardant ABS battery cover - the cover was merely kindling for the flammable stuff above (including the polycarb see-thru cover that was not lit off).

Don't use flammable materials in the same compartment as people, high current/voltage electrics or batteries....including plywood.


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## Functional Artist (Aug 8, 2016)

MattsAwesomeStuff said:


> "So a fire spontaneously started that could have started any time"


Fires don't just start spontaneously (I think Columbo, said that)

It looks like he was using stock Chevy Volt BMS "pigtails" which are well built & very robust.
...so, unless damaged I can't see any way that its wires could "just short", "out of the blue"

Was he using some "custom" PCB in the BMS satellite?
...maybe "it" could have caused the short?
(there's plenty of places inside "there" that could potentially short the module)

Here is a stock BMS satellite








I would also question that (blue) coolant line & "floppy" junction (just above the area)

Could it have potentially leaked or sprayed the "area"
...& maybe even filled the BMS connector "well" (on the module) up with coolant?
(which, I believe, could have "spontaneously" caused multiple shorts)

Here is a pic of the BMS connector "well" 








Just "thinking out loud"


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## remy_martian (Feb 4, 2019)

No


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## Tomdb (Jan 28, 2013)

the batteries are not covered in the vehicle. They are just mounted on the metal bases and have not other cover on them.

My 2 cents is, corrosion/moisture gets in there and causes a short which then propagates.

If you use OEM batteries always bear in mind how the OEM intended them to be used, if they are not waterproof/resistant. That is why putting batteries a sealed box is minimum requirement.


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## Bratitude (Jan 23, 2020)

the gen 1 volt battery dose not have cell level fusing, the gen2 dose, right on the ribbon cable to the cell tap connector



this plus the fact the battery was not sealed off from the elements, as tom said, leading to moisture exposure(Ireland is a wet place)

cell level fusing, a properly enclosed battery, and use of fire retardant materials (as remy stated)

Damien moves fast and break things. good for development, but dont follow as he dose, but as he says.


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## Functional Artist (Aug 8, 2016)

Tomdb said:


> corrosion/moisture gets in there and causes a short which then propagates.


In where?
...on the battery module, in the "well" where the orange connector "plugs in"?

On these modules, in that "well", each pin is well segregated from the others
...& even more so, when the orange connector is "plugged in"










IMO
It seems like it would take a lot of moisture & corrosion to be able to cause a short "in there"
...& (for comparison) look at all of the other modules & connectors
(they look pretty "clean" to me, in the pics & video anyways)


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## Functional Artist (Aug 8, 2016)

Doing more research, into this, according to this video (posted 6/25/2019) he was using a SimpBMS 





He doesn't really say in the video 
...but, it looks like he's using the SimpBMS with the "stock" Chevy Volt BMS satellites, that are on the modules.

He also states, that he made "an absolute mess of the wiring" 
...& had to go back & "rewire the modules"
...& then his voice kinda "shudders" a bit when he says "we got that...done today" (~3:10 in the video)

Also,
The SimpBMS "master" PCB doesn't seem to be in its own little box
...it looks to be just mounted inside the "big" control box


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## Tomdb (Jan 28, 2013)

Notice the location and proximity of the firewall to where the connector was and where the fires started.

Any form of debris and moisture has a path straight down onto. Who knows what caused the fault it can be a debris or something causing.

You see how the cell tap connector is not fully divided and nor are these sealed connectors. I bett you they retain water as they do not look like they have any drainage. Plus they point upward.


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## electro wrks (Mar 5, 2012)

Bratitude said:


> the gen 1 volt battery dose not have cell level fusing, the gen2 dose, right on the ribbon cable to the cell tap connector


Some later model Tesla S and X modules have a ribbon type BMS cell taps. These ribbons have obvious short sections of narrowed conductors as fusible links. I've seen these fusible link sections blown on modules that had been through accidents or other rough treatment that must have caused shorts in the taps.

For limited, test and experimental use, it's probably alright to use un-fused BMS taps, if you can do it carefully and safely. For final assemblies in EVs, some kind of fuse system in the BMS taps, like Tesla and others have, should be used.


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## Functional Artist (Aug 8, 2016)

Tomdb said:


> You see how the cell tap connector is not fully divided and nor are these sealed connectors. I bett you they retain water as they do not look like they have any drainage. Plus they point upward.


Well, let's see "if" &/or "how much" water, the BMS connector socket on a Chevy Volt (Gen 1) module, will hold.


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## remy_martian (Feb 4, 2019)

The battery is in a steel box in a Volt, so I'm having a hard time following why you're playing Betty Crocker with the connector receptacle.

Water cannot short adjacent pins. He's not running a submarine in ocean water - there is no conduction path.

If there was corrosion from water, which is highly unlikely with gold contacts, contact resistance would go up, but no heating since the BMS channels are high impedance.

There had to be a short between wires. The only way that could happen is a wire breaking off, then arcing as it flapped in the literal breeze. 

Damien doesn't want to play, but looking at BMS logs, if his system does logging, should reveal a flakey channel reading that eventually goes open. He may be aware of one that he could have procrastinated in fixing. 

Like Shuttle Orbiter Columbia, the readings go haywire, are blown off by the operators, then the melting happens.


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> The battery is in a steel box in a Volt, so I'm having a hard time following why you're playing Betty Crocker with the connector receptacle.
> 
> Water cannot short adjacent pins. He's not running a submarine in ocean water - there is no conduction path.
> 
> ...


1.) No, the traction battery pack in a Chevy Volt, is NOT housed in a steel box. (& it certainly wasn't in this car)

In a Chevy Volt the traction battery pack is just "clamped" down to a steel "tray"
...& then, has a plastic/fiberglass "cover" bolted down over it. 
...but, when installed in the car, the "steel" floor "is" a secondary "safety barrier" between the battery pack & the occupants.

2.) When investigating a fire, the first & main place to look is at the "point of ignition"
...& that "point of ignition" is easily identifiable, in this situation
...& the "fire" seemed to be concentrated "in" or "at" the BMS connector receptacle 

3.) That BMS "pigtail" looked to be "stock" (as all of the others)
...& they are usually "pinned down", to the module, with a proximity clip (& not literally "flapping" in the breeze) 
...& looking at the pics & the video, "it" looks to be in its "stock position" & mostly still intact (just burned up)

4.) I agree, Damien "should be" the one "spear heading" this investigation (he has info "we" don't)
...& because he knows what & how he did things
...& he's right there "at the scene"


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## piotrsko (Dec 9, 2007)

@Functional Artist should verify, but the bms wiring on a gen 1 is about 26 ga stranded going to the top tabs of the battery. That is big enough to not immediately fuse open when shorted between cells. The external cabling is in a (abs?) plastic braided wear sleeve and burns pretty well with lots of black smoke as does the wiring Insulation, connectors and cell cap. So one short between cells and the whole thing is going to end up cascading as you progress through the harness. I don't suspect water intrusion and judging by Damiens lack of response, suspect wiring error or piss poor installation/error. Don't know if the wiring is euro approved but there have been issues with VW peanut based harnesses and rodent intrusion in Germany and France.


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## Functional Artist (Aug 8, 2016)

piotrsko said:


> Functional Artist should verify, but the bms wiring on a gen 1 is about 26 ga stranded going to the top tabs of the battery.


The wires in a Chevy Volt BMS "pigtail" seem to be ~20g.










piotrsko said:


> one short between cells and the whole thing is going to end up cascading as you progress through the harness.


Where do you think this "short" could have been?
I didn't see any of the other BMS harnesses affected, except that one, that caught on fire

More thoughts & info (to further the discussion)


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## remy_martian (Feb 4, 2019)

The wire would break off at the crimp, not in the middle where you made your snip. Was the "proximity clamp" in place?


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> The wire would break off at the crimp, not in the middle where you made your snip.


It doesn't look like it would make a difference (see video)



remy_martian said:


> Was the "proximity clamp" in place?


The "base" of the proximity clip looks to be still on the module
...but, we may never know "if" it was actually attached 
...& looking at the other modules, in his pack, it looks like some are connected & some aren't

Is anti-freeze or coolant more "conductive" than plain water?


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## remy_martian (Feb 4, 2019)

No.


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## Functional Artist (Aug 8, 2016)

Well, Ummm...according to the official report released by the NHTSA:
*Chevrolet Volt fire investigation*
"The first fire erupted three weeks after NHTSA conducted a side-into-pole crash test on the Volt, a more severe crash test than any standard tests other cars must pass (though simulating a not-uncommon type of crash in the real world). During the test, the structure of the collapsed car broke through to the liquid-cooled battery pack. The batteries were not discharged after the test, as General Motors protocol specified. The car was then rotated 360 degrees, slowly, to simulate a rollover. *This allowed coolant from a burst coolant line to drain onto a printed circuit board on top of the battery pack, according to General Motors. Later, after the car was left out in the cold, the coolant crystallized, creating a short in the circuit that provided a path for the battery's energy to run away.* This overheated the battery pack by allowing it to drain too quickly and caused the fire."

Case closed: NHTSA ends Chevrolet Volt fire investigation

They blame "coolant" that "drained" into a circuit board, for creating "a short" that "caused the fire".

IMO the same thing could have happened, in the BMS socket, on Damiens car.


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## piotrsko (Dec 9, 2007)

Ummm nope on the NHTSA report. My sources said it sat for a couple weeks inverted in a storage yard and only then caught fire. You indicated that storage in your second sentence. Aaaand, that only occurs if the batteries are leaking while inverted which is presumably not the case here. I have not noticed any moisture in the top covers in, what, 8 years?

Gonna have to stick with my initial premise that something was different from factory in the harness and that shorted to something else.
I could accept a mosfet failing to the on state.

Btw, thanks for verification of the wire gauge.


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## Functional Artist (Aug 8, 2016)

Whether coolant got in the "wrong place" thru inversion or a leaky coolant line (just above the area), my point was that "coolant" was blamed for causing the short, that caused the fire.

From my experience with shorts, a "shorted" unfused wire glows red hot & burns the wire insulation (& anything else along the way) all the way from the "point of the short", to the power source.

In this situation, "the short" didn't seem to "burn" any wires from a "distant short", all of the way back to the power source
...it seemed to be concentrated in just the one area (the BMS connector, on the module)

No problem, glad I could help


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## remy_martian (Feb 4, 2019)

Coolant was not blamed. An evaporate, due to a temporary inversion of the vehicle that subjected the area to being _temporarily_ flooded, in combination with cold temperatures was blamed for the formation of a conductive crystalline evaporate (which is not coolant).

If there was a coolant leak here, there would be no opportunity for it to fail to be replenished by more liquid coolant.

Coolant also burns, so the fire would have been much more extensive if there was a coolant leak.

We don't have enough data on what was going on with the BMS prior to the fire. I suspect he had flakey and then a dead channel on at least one sense wire before the fire - without that info, which only Damien knows, everything is mere guessing. The mere fact he won't dig further says he knows the cause in my mind and his failure to fix it led to near tragedy.

Meanwhile, his fail fast, fail often, super short cuts, make him very productive with solutions usable in the conversion movement, so not looking to him changing anything about how he does stuff.


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## Electric Land Cruiser (Dec 30, 2020)

Laughing out loud at the first 30 seconds of this video. He blames the BMS for doing it's best to burn down his car...a car covered in leaves and water that looks like an utter rust bucket. The battery box itself has huge gaps and looks pretty shoddily built and has rusty edges. Yes, it was the BMS 

It's raining in the video and the batteries are just sitting on the ground in the rain.


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## kennybobby (Aug 10, 2012)

remy_martian said:


> We don't have enough data on what was going on with the BMS prior to the fire. I suspect he had flakey and then a dead channel on at least one sense wire before the fire - without that info, which only Damien knows, everything is mere guessing. The mere fact he won't dig further says he knows the cause in my mind and his failure to fix it led to near tragedy.


Early in the video he mentioned that he checked the battery voltage was reading perfectly, then he started it up and backed it away from the barn. If the BMS wires were shorted then it seems that the voltage would be less than perfect, so not sure what he was measuring.

He was really really lucky to be there in the area to notice the smoke and take action.


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## D&VsEVJeep (Dec 9, 2021)

Wait...he has those batteries in there without a case around them??? I figured when I saw the video for the first time he had removed the case or something... Holy moly...


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## piotrsko (Dec 9, 2007)

There it is: "working perfectly" then doing something not related to BMS health, and probably not rechecking with a touch of jostling added on something done just "good enough for now" & never upgraded after 3 am gotta get it done assembly.

I'm guilty of that, really should do all sorts of upgrades to the ranger, but WTF, it runs to design specs now.

Have a bunch of those connectors unused, should use one to see how much effort it takes to set them alight. But not in the pack.


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## Functional Artist (Aug 8, 2016)

D&VsEVJeep said:


> Wait...he has those batteries in there without a case around them??? I figured when I saw the video for the first time he had removed the case or something... Holy moly...


Your surprised?

I'd say, at least 3/4 of the battery packs, in the builds on this forum, do not have a "case around them"
...or even a "main" or "central" batt pack (like most OEM EV's do)

Many of the older builds have battery modules "stuffed" just about everywhere
...in the glove box
...in the "former" fuel tank area
...under the hood
...in the trunk
...under the seats
...& some all of the above 

* I was hoping your (guys') build would/could be an example of a "more proper" DIY build 
...but, details have very "sparce" (so far)


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## piotrsko (Dec 9, 2007)

Define case. My volt pack has a kinda case, otherwise the coolant water wouldn't stay in. Then it's still on the metal pan sitting in a hard tonneau covered bed. THAT is a case, in a vague sort of way. It also has the plastic/glass thingey to keep assorted fingers out of the HV bits


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## remy_martian (Feb 4, 2019)

The pics that MotorTrend.com had of @D&VsEVJeep's Jeep were showing an extremely professional looking build.

Motor Trend....

"sparse"


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## remy_martian (Feb 4, 2019)

piotrsko said:


> Define case. My volt pack has a kinda case, otherwise the coolant water wouldn't stay in. Then it's still on the metal pan sitting in a hard tonneau covered bed. THAT is a case, in a vague sort of way. It also has the plastic/glass thingey to keep assorted fingers out of the HV bits


Case: a g-load-secured and sealed containment for batteries exceeding 60V that protects occupants and responders against a shock hazard for the entire EV (this includes cables that can get cut, so running them in conduit doesn't count) and provides time for occupant egress, including that needed to be extracted from wreckage, in the event of a battery fire. Bonus - the components in the case are protected against environmental damage because of the buckets of money poured into the case.


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> The pics that MotorTrend.com had of @D&VsEVJeep's Jeep were showing an extremely professional looking build.
> 
> Motor Trend....
> 
> "sparse"


Were getting off topic here
...but, to address your comment, their last post in the build thread (with anything meaningful about the build) was almost a month ago 
...& (in the pics) the Jeep was still mostly in pieces

I haven't seen the MotorTrend article 
...maybe because they didn't post it (it would have been a good addition to their thread)

It should be a "professional looking" build
...Daren "is" a "professional" Jeep builder


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## remy_martian (Feb 4, 2019)

It was posted in their thread...


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## D&VsEVJeep (Dec 9, 2021)

remy_martian said:


> It was posted in their thread...


I'll post a reply there to get this thread back on topic...


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## tmgrs2000 (Feb 8, 2021)

you were lucky that all you hard work didnt burn out . well done on getting the fire out. regardless what caused it. fire is a real thing and it just takes a few min to lost all your hard work ,money .workshop or even house.
keep the good work going all the best


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## remy_martian (Feb 4, 2019)

Out goes the baby with the bathwater....

Damien is getting a 12kWh BMW pack that someone donated, so that apparently is going to replace the Volt pack that he tossed into the weeds because of his BMS wiring fire, with the wee Beemer pack:






It is possible he has other plans for the singed Volt pack, but he's been pretty quiet about the whole thing.

Maybe he should send it to @Functional Artist for Youtube-learned "testing" and forensics? 😛


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## floydr (Jun 21, 2021)

A bench battery pack perhaps is what he said in the video.
Later floyd


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## MattsAwesomeStuff (Aug 10, 2017)

remy_martian said:


> It is possible he has other plans for the singed Volt pack, but he's been pretty quiet about the whole thing.


He was quite clear in the first video.

He's not going to do a post mortem.

The pack is not going back inside a vehicle. He considers it compromised. It will, at most, be a test pack in the shop.


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## remy_martian (Feb 4, 2019)

The pack is allegedly compromised, but risking burning down the barn is ok.

Makes sense.


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## MattsAwesomeStuff (Aug 10, 2017)

remy_martian said:


> The pack is allegedly compromised, but risking burning down the barn is ok.


It won't be subject to constant vibration and acceleration changes in the barn. 

It can't strand him out on the highway in the barn.

It can be disconnected from a BMS and manually kept an eye on in the barn.

Any time he's using it, he's paying attention to it in the barn, unlike driving.

Since the batteries are almost certainly just fine, I'd say him not putting it back in the car is a matter of superstition and abundance of caution. Using them on the bench, ehn, fine.


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## remy_martian (Feb 4, 2019)

None of the conditions you listed (he claims he only needs 5 miles of range...) would affect a properly installed and monitored pack. 

So, to paraphrase, which seems to be in vogue on this site these days, you're saying the barn is more tolerant of half-assery 😂


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## MattsAwesomeStuff (Aug 10, 2017)

remy_martian said:


> None of the conditions you listed [..] would affect a properly installed and monitored pack.


Balderdash. You can't reconcile the supernatural.

And, he said he only needs 5 miles of range most of the time. And that the new pack is temporary.


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## Electric Land Cruiser (Dec 30, 2020)

Hopefully he doesn't just put the new pack inside the box that's full of condensation.


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## D&VsEVJeep (Dec 9, 2021)

Electric Land Cruiser said:


> Hopefully he doesn't just put the new pack inside the box that's full of condensation.
> View attachment 133606


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## markg (Jan 4, 2019)

Is that screenshot from the video immediately after the fire, where he was spraying down that area with a garden hose? Or is that truly condensation, from some other time?

I don't disagree with your implied premise, the HVJB should have a good gasket and be well protected. I just don't know that that's representative of the box in its typical use.


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## kennybobby (Aug 10, 2012)

After the fire and garden hose.


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## remy_martian (Feb 4, 2019)

markg said:


> Is that screenshot from the video immediately after the fire, where he was spraying down that area with a garden hose? Or is that truly condensation, from some other time?
> 
> I don't disagree with your implied premise, the HVJB should have a good gasket and be well protected.


While a good gasket will prevent water ingress, it will not help with condensation.

To mitigate condensation, you need to vent the box, and be able to drain it. Metal stays colder during temperature rise and close dewpoints at high humidity.

Short cuts get the project done quickly, but could also mean the car (or yourself) gets done quickly if calamity ensues from the short cuts.


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## asymptonic (Oct 14, 2021)

This brings up an interesting question for me. How is condensation dealt with in sealed battery box design? I know those air permeable blowout vents exist but they presumably would allow humid air in?


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## Electric Land Cruiser (Dec 30, 2020)

asymptonic said:


> This brings up an interesting question for me. How is condensation dealt with in sealed battery box design? I know those air permeable blowout vents exist but they presumably would allow humid air in?


You can use little IP68 vents like this one, they let air pressure in and out but are water and dust proof. LEAF packs have these from the factory probably other packs too.



https://amzn.to/3Xt94iH


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## asymptonic (Oct 14, 2021)

Yeah, that's what I meant in my post. But do those block humid air from entering?


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## Electric Land Cruiser (Dec 30, 2020)

asymptonic said:


> Yeah, that's what I meant in my post. But do those block humid air from entering?


Yep, I don't know how or why but they do.


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## asymptonic (Oct 14, 2021)

Gas permeable only I guess. So you'd want to seal your box on a 0% humidity day and you're all set.


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## Electric Land Cruiser (Dec 30, 2020)

asymptonic said:


> Gas permeable only I guess. So you'd want to seal your box on a 0% humidity day and you're all set.


Easy to find a low humidity day in CO  or you could purge it with nitrogen or something before sealing.


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## remy_martian (Feb 4, 2019)

🤦‍♂️

The insert material in the Amazon one is "PTFE" - most likely Goretex. 

While Gortex will block water, it will *not* block humid air. That's the entire point of using Goretex in activewear clothing.

So, yes, in humid places, your metal box will lag in temperature rise and sweat during close dewpoint spreads 

There's also no such thing as a "sealed" box unless you go military/satellite spec. on all of your feedthroughs and weld/braze the box shut.

Your metal battery box WILL sweat water. It will pool at the bottom. 

You could heat the box to drive the dewpoint off, but Landcruiser doesn't use battery heaters 😛 So, it obviously needs a drain.


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## Electric Land Cruiser (Dec 30, 2020)

remy_martian said:


> 🤦‍♂️
> 
> The insert material in the Amazon one is "PTFE" - most likely Goretex.
> 
> ...


The battery is heated every time the vehicle is driven or charged. No heaters needed.


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## asymptonic (Oct 14, 2021)

Yeah, I had serious doubts of getting a complete seal anyway. Drain it is. Now to research that...


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## remy_martian (Feb 4, 2019)

Battery heaters are a couple of kW of heat. Driving your car at 8kW draw around town produces how much heat? You're saying the HV battery is 70% efficient? 😂

The battery heaters can be turned on to prevent condensation inside the battery box. Since EVs spend over 80% of their time parked, how exactly is your genius idea supposed to work on a cold Florida morning?

Again, caught bullshitting...also, go ahead and tell us how Goretex stops water vapor like you stated it did. It doesn't. You're freely advising people about things you don't actually know, but when you're among people that don't know, you can get away with it.

How much will a corroded battery pack cost (Tesla modules' cells get rusted really fast, but Tesla keeps the modules warm when the car is parked) the people following your sage advice?


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## Electric Land Cruiser (Dec 30, 2020)

remy_martian said:


> Battery heaters are a couple of kW of heat. Driving your car at 8kW draw around town produces how much heat? You're saying the HV battery is 70% efficient? 😂
> 
> The battery heaters can be turned on to prevent condensation inside the battery box. Since EVs spend over 80% of their time parked, how exactly is your genius idea supposed to work on a cold Florida morning?
> 
> ...


You obviously don't know how EVs behave in cold weather. Yes when the battery is 0F they are likely 70% efficient if not worse.

LEAF uses the same amphenol vents, probably assembled in a tightly climate controlled factory. I don't have one of those. I can only do my best to copy the OEMs.

A corroded battery can cost your house or your life if it leads to a fire. Park your homemade EV outside.

There is no such thing as a "cold" Florida morning. Built your vehicle for the place you live in. I live in the desert. Damien lives in Ireland. His should be better than mine but it looks way worse.


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## remy_martian (Feb 4, 2019)

More anecdotal nonsense. 

Where's that paper on EV batteries cycling in the cold being acceptable for longevity? 

Comparing an OEM EV battery SYSTEM (people who rely on peer reviewed research) as being overdone compared to an iphone outside? 😂

Why are you citing water ingress and penetration standards (IPxx) for water vapor, which is what the man asked about?


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## asymptonic (Oct 14, 2021)

Pretty sure resources not withstanding this is the right approach:



US20150171491A1 - Method of preventing condensation of battery pack - Google Patents



Translating through the lawyer jargon (I embarrassingly wound up with a patent that I wish I didn't): Method for measuring temperature and humidity inside and outside a battery enclosure to determine whether to blow air into the box or raise the temperature with heating. I like the idea of calculating dew point via ambient and box temperature and wasting a small amount of power to keep battery box temperature above where condensation could be possible.


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## Electric Land Cruiser (Dec 30, 2020)

remy_martian said:


> More anecdotal nonsense.
> 
> Where's that paper on EV batteries cycling in the cold being acceptable for longevity?
> 
> ...


What is anecdotal about Nissan using the same vents on their batteries? I told you I copied the OEM battery.

Here is a photo since you don't have any first hand experience.


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## remy_martian (Feb 4, 2019)

The vents are irrelevant to the question that was asked, which was not about water ingress and pressure equalization...


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