Risk of poisoning with 12V Battery not vented properly

[HeyBales]

Basic wiring 101 applies here.
High voltage system stays like it is, simple and to the drive motors only.
All 12 volt needs stay 12 volt in the rest of the vehicle. It’s called a voltage regulator I think,
That will meet the needed current levels of the entire Maverick.
That regulator should cost no more than $15
bucks.

The high amp, CCA that the ICE starter needs should be a cake walk for the drive battery.
No more low battery conserve bullshit.

Drive battery gets below a 50% state of charge. Ice starts, charges.
I will admit it might freak out a Maverick owner to hear his truck start up at 3 AM. PMSL

You hit the nail for the why.

Not just owners freaking out - mechanics - off needs to be off for the 220V system to not kill someone not totally prepared.

Orange cabling might not be enough, voltage adapter could fail, regulator sure can.
Even motherboards being fed 3.3V +-5% from a power supply regulator, with it's own regulator to supply the RAM power with even tighter tolerances - will fail and fry the RAM.

So just like the 5 cent fusing protecting itself by allowing the $100 component to blow.
Except now the $5 regulator blows, the fuse doesn't, and all your modules are fried.

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[zen_]

Title corrected.

This was not meant to kick dirt on the hybrids. I love my Mav. I just wanted to make others aware of the risk.

Fair enough, probably a decent reminder for those of us that did an AGM swap to maybe double check the vent hose got hooked up correctly.

I am going to assume that the 12v battery is inside the cabin on the hybrid Maverick, and other hybrids like the Prius for packaging reasons with the wiring to the accessories and high voltage battery relays. Would be interesting to know if the putting the battery in the cabin also helps a bit with lifespan and terminal corrosion. The little regular lead acid battery in my Prius C lasted 7 years, and I think the huge AGM battery in my A6 lasted 7 or 8 as well.

 

[HeyBales]

H2S inhalation from a car battery is certainly a 'thing', albeit super rare.
Hydrogen sulfide inhalation from car battery killed mother, daughter, medical examiner says - WFTV
A Rare Case of Hydrogen Sulfide Toxicity From a Malfunctioning Car Battery

Is there more to that Alabama story? Oh yeah. Some of the so-called news stories I've read on that Alabama one make it sound like there was no vent tube present (doubtful), others note it wasn't connected to the battery (more likely). Assuming the vent tube wasn't connected, is that a FoMoCo issues (i.e. came from the factory that way) or dealership issue (wasn't "checked" during whatever servicing was done)? Only the lawyers/juries will sort that out, may have nothing to do with what I consider common sense.

Lemme ask you hybrid owners - any mention in your OM about periodically checking the in-cabin 12v to see if the vent tube's connected? Anything in FoMoCo's recommended maintenance on that? If not, one possibility I see from this lawsuit is - you might see that in print in the future.

Do I want additional sensors/safety measures as OEM equipment for this (i.e. H2S detectors integrated into the OBD system)? No way.

I do own a hybrid ('26 Prius) with a dinky (45 Amp hr) 12v Yuasa 345LN1-MF battery (non-sealed FLA) in the rear hatch area inside the cabin. It has a vent tube (they call it an 'exhaust hose'). It's mentioned in the OM - but I've found nothing in Toyota's recommended maintenance literature about periodically checking it.

Does "properly connected" include the vent tube?
(I recall a thread with replacement battery where the vent tube holes needed to be punched out 1st - otherwise vent tube was hooked in to a blocked hole)


Owner Checks and Services
Make sure you perform the following basic maintenance checks and inspections every month or at six-month intervals.

Check Every Month
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Function of all interior and exterior lights.
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Windshield washer fluid level.

Check Every Six Months
Battery connections. Clean if necessary.
Body and door drain holes for obstructions. Clean if necessary.
Cooling system fluid level and coolant strength.
Door weatherstrips for wear. Lubricate if necessary.
Hinges, latches and outside locks for proper operation. Lubricate if necessary.
Parking brake for proper operation.
Seatbelts and seat latches for wear and function.
Safety warning lamps (brake, ABS, airbag and seatbelt) for operation.
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Changing the 12V Battery - Hybrid Electric Vehicle (HEV)

WARNING: Batteries normally produce explosive gases which can cause personal injury. Therefore, do not allow flames, sparks or lighted substances to come near the battery. When working near the battery, always shield your face and protect your eyes. Always provide correct ventilation. WARNING: When lifting a plastic-cased battery, excessive pressure on the end walls could cause acid to flow through the vent caps, resulting in personal injury and damage to the vehicle or battery. Lift the battery with a battery carrier or with your hands on opposite corners. WARNING: Keep batteries out of reach of children. Batteries contain sulfuric acid. Avoid contact with skin, eyes or clothing. Shield your eyes when working near the battery to protect against possible splashing of acid solution. In case of acid contact with skin or eyes, flush immediately with water for a minimum of 15 minutes and get prompt medical attention. If acid is swallowed, call a physician immediately. WARNING: Battery posts, terminals and related accessories contain lead and lead compounds, chemicals known to the State of California to cause cancer and reproductive harm. Wash your hands after handling. WARNING: This vehicle may have more than one battery. Removing the battery cables from only one battery does not disconnect your vehicle electrical system. Make sure you disconnect the battery cables from all batteries when disconnecting power. Failure to do so may cause serious personal injury or property damage. WARNING: For vehicles with Auto-Start-Stop the battery requirement is different. You must replace the battery with one of exactly the same specification. WARNING: For vehicles equipped with a 12V battery vent tube, always properly reconnect the vent tube to the battery after disconnecting. Failure to follow this instruction could allow harmful gasses to enter the vehicle cabin, which could cause personal injury or death.

 

[Darryl]

Again, now a direct question.
Why Oh why does the Mavbrid, or any hybrid need a 12 volt battery ?

To start the ICE ? Our little back up Noco battery boosters are Lipo with enough grunt to start a 6.0 L diesel right ! Or so they/them say.
:’P

See my comment earlier. (I think it posted)

 

[Darryl]

Fair enough, probably a decent reminder for those of us that did an AGM swap to maybe double check the vent hose got hooked up correctly.

I am going to assume that the 12v battery is inside the cabin on the hybrid Maverick, and other hybrids like the Prius for packaging reasons with the wiring to the accessories and high voltage battery relays. Would be interesting to know if the putting the battery in the cabin also helps a bit with lifespan and terminal corrosion. The little regular lead acid battery in my Prius C lasted 7 years, and I think the huge AGM battery in my A6 lasted 7 or 8 as well.

It's in the cabin because that's where the space is. But I believe it helps prevent corrosion as well . Batteries installed remotely tend to have less terminal corrosion. Also, if everything else is working correctly, a remotely installed battery can often last longer because HEAT kills a battery. Cold whether simply let's you know it's bad.

 

[Propane Burning Man]

Mavster Mechanic and I are on the same page, there is something fishy. This sounds like foul play to me. But maybe I have watched too many episodes of "Accident, Suicide, or Murder?" on Peacock. Great series BTW. Check to see what kind of Life Insurance the victim has. Is wife in line to get a big check? If yes indeed, investigators need to get a search warrant and go get her PC or laptop or smart phone see what she has been searching. "How to kill someone with hydrogen sulfide" maybe? Did she contact the life insurance company 2 hours after he was found dead? Watch the series, that kind of thing really happens. My good friend 40 years ago had a hit on him for a $10,000 life insurance policy by his first wife! Had a near death experience but survived. Has lead shot in his chest around his heart and lungs to this day! No joke. So no, I don't believe this is an accident. Way too unlikely in my mind.

 

[Probity]

Changing the 12V Battery - Hybrid Electric Vehicle (HEV)

WARNING: For vehicles equipped with a 12V battery vent tube, always properly reconnect the vent tube to the battery after disconnecting. Failure to follow this instruction could allow harmful gasses to enter the vehicle cabin, which could cause personal injury or death.

There you go - and because curiosity got the best of me, looked in the '25 Mav OM, searched for 'vent hose' got similar info:

 

[zen_]

It's in the cabin because that's where the space is. But I believe it helps prevent corrosion as well . Batteries installed remotely tend to have less terminal corrosion. Also, if everything else is working correctly, a remotely installed battery can often last longer because HEAT kills a battery. Cold whether simply let's you know it's bad.

Yep. In my help desk days I replaced hundreds of laptop batteries, most of them that were killed or degraded by just a few improper shutdown -> backpack hot pocket trips. It's a miracle of sorts that Microsoft's inability to make an operation system that sleeps in sleep, or for laptop manufactures to put basic battery management in place has not caused way, way more fires...on the topic of battery safety.

 

[First Sergeant]

I've also heard of Aviation and Automotive Carbon monoxide poisoning caused by a leaking exhaust on an air-cooled engine, that uses a heat exchanger on the exhaust for cabin Heat.
In the early seventies when I was getting my pilot's license. We had carbon monoxide discs in the school planes. I have no idea if they were replaced every year.

You are correct Glen. Two of my boys had VW Beetles at one point and I made sure to keep a check on those heat exchangers. I also restored a 71 Porsche 911S Targa. Fun car, but strangely, had two heating systems. The heat exchanger type and a gasoline fueled heater, that had levers to adjust on the dash like most cars of the era, but the scary part was the gasoline tank mounted on the firewall in front trunk! Rusty thing. Man I made sure to remove gas line to it and cap it off real good. I had read a lot of stories on Porsche sites about "the BOOM box" No thanks!

 

[dochawk]

Thx, the last thing I saw with a battery with a vent tube was my 26 year old Yamaha dualsport dirtbike.

When I replaced the battery on my 2006 Miata, they gave me the wrong battery--for 2005, and presumably earlier ('06 was the year they got bigger, letting me fit).

I put it in the trunk, drove home . . . and there were black areas on the carpet of the trunk.

Turns out that it had vents, and when it fell over, it happily leaked.

I however, was less than happy . . .

The Northstar Devilles of the '90s had the battery under the rear seat (but the Eldorados had a much longer hood, and had it there). My 2002 had vents on the battery. I think that the 1999 inch have now does, too, but it's outside and it's dark.

Quick story ....I took my driver's test in a Beetle when I turned 16 .
mid-January , in Nebraska .
The tester was not happy in the cold , and I was scraping the frost off the inside of the windshield .

my first car was a '74 super beetle. It had the "dual preheat" muffler, one of three they used that year, that cost three times as much as the other two, or those for previous years

Anyway, having no radiator, it pulled outside air through the muffler to heat it.

I'd turn it on, and by the end of the school year (11 houses from mine, iirc), it was pumping air hot enough that the cables for the heat control would contract and pull the lever down1

 

[Glen Baker LLC]

.

You are correct Glen. Two of my boys had VW Beetles at one point and I made sure to keep a check on those heat exchangers. I also restored a 71 Porsche 911S Targa. Fun car, but strangely, had two heating systems. The heat exchanger type and a gasoline fueled heater, that had levers to adjust on the dash like most cars of the era, but the scary part was the gasoline tank mounted on the firewall in front trunk! Rusty thing. Man I made sure to remove gas line to it and cap it off real good. I had read a lot of stories on Porsche sites about "the BOOM box" No thanks!

I remember the gas heaters.
My dad installed them in his VW's. The circular vent, was on the passenger side. Boy, did it get hot.
We used to joke you could bake bread in that car. You also had to make sure that you ran it after turning the fuel off to cool it down.

 

[BillHanna]

My '75 Corvette has the battery behind the driver, no venting. I've been more concerned with an explosion than breathing vapor. Years ago, as my son started our Craftsman mower, the battery exploded, blowing the hood open and scattering the vent caps almost 15 feet away.

 

[Phimosis]

I didn't know there was a risk. I'm sharing just in case.

https://www.12onyourside.com/2025/1.../?utm_source=taboola&utm_medium=organicclicks

This is just a confluence of bad luck.
1) a properly functioning battery and charging system should never make H2S. When charging, normally, batteries off gas H2 and O2, which is highly flammable, but not toxic to humans. Releasing H2S is a symptom of overcharging and damaging the battery.
2) most cars don’t have the battery in the cabin.
3) batteries in cabin required to have vent tubes to the exterior.
4) H2S smells strongly of rotten eggs. 99.999% of people would roll down their windows before pulling over to try to find what was in their car and causing the horrid stench.

Overall, this is a one in a billion occurrence that required willful and deliberate decision making to keep one’s self in harm’s way, ie a Darwin Award contestant.

Mentioned earlier in the thread, you can’t smell H2S at high concentrations. Correct, but the level is so high that your brain is being poisoned and all of your senses are starting to fail.

0.1 PPM: rotten egg smell detectable
3 PPM: smell becomes offensive and sickening.
5PPM: nausea, headache, tearing
100 PPM: loss of smell. Altered mental status. Immediately dangerous to life.
500 PPM: permanent eye damage, Loss of consciousness, death.
1000 PPM: immediate death after one breath.

 

[Tiger Dude]

Something here isn't right. Either a defective battery or defective charging system that drove the battery to gassing. This just isn't a thing that happens.

 

[Mavster Mechanic]

Something here isn't right. Either a defective battery or defective charging system that drove the battery to gassing. This just isn't a thing that happens.

Could/would a short do this?

I'm skeptical too. This is very rare.

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