Electrical safety when working on the hybrid battery

In the battery itself, when you pull the service plug, you don't have a ~ 202-volt stack anymore. The service plug splits it, not right in the middle, but into roughly a 130-volt and a 72-volt stack. You would still want to take care around those.

If you next removed a bus bar from the middle of the 130-volt stack, you would have two 65-volt stacks (and a 72-volt stack), and you could likewise strategically choose the next few bus bars you remove, to get quickly down to less-dangerous voltages. Insulated tools and gloves are common sense for such work; you should also be familiar with how to test electrical gloves for any pinholes.

At voltages below what might give you a dangerous shock, the battery modules might still have adequate current capacity to do other unfriendly things, like spit molten steel from your screwdriver tip into your face.

Do people often jump in with fewer precautions and live to tell the tale? Sure ... I've also done various things in my life that I got away with, but those still aren't what I would teach anybody to try.

One more thing to remember: isolation faults (the P0AA6 code) can be a frequent reason for working on the battery. Such a fault, by definition, means the current paths you know about aren't the only ones there are, and they don't all have to be interrupted by pulling the service plug. Working on a battery because of a P0AA6 code calls for all the precautions you can muster, until it's disassembled and cleaned up.

 

Watch videos of Green tech green bean guys changing n working on battery in Prius. Lots videos from the pros and owners of these businesses.make a mental note of safety equipment gloves etc . And nite wet businesses are located mini strip malls etc . Remember these aren't lithium-ion batteries they're lowly NIMH old cell phone tech . Not much blowing up etc going on . Swelling leaking yes .

 

Hi @indel, in the past 5 years selling hybrid batteries, I honestly haven’t had a single customer (no matter how naive they were) get seriously hurt or kill. That said, the risk is always there, so it’s worth respecting.

From personal experience, the most you can get is a pretty solid zap and you’ll definitely remember it… but you can usually shake it off assuming you don’t have any heart issues.

Hybrid packs are roughly 220V DC. DC generally doesn’t penetrate skin as easy as household 240V AC (60Hz) can, but it can still bite you hard.

Also, those super thick high-voltage gloves can make the job almost impossible. The main rule is simple: don’t complete the circuit. Example: you can touch the most positive terminal stud with one hand, but the other hand better be smart and don't touch the most negative terminal stud even with the service plug off.

Pretty sure I made a video on this years ago — I even got zapped on camera for the love of science. Painful, but manageable

 

Discussions of what it takes, AC or DC, to ruin a person's day occasionally happen here, and every now and then it is worth reposting some information that's often kept on display around physics labs. I'll put the link here again, 'cause it doesn't hurt to have it in multiple places.

Electrical Safety: The Fatal Current

I've put that link in other threads (like here, with other interesting links and discussion).

The web site I was linking to seems to have had a reorg around 2024 and the links I posted earlier don't work. The one above is to the Wayback Machine, so should continue to work.

 

Right shoe soles . And what not . I was carrying a rack of modules and had something touching . I could feel the juice biting on me said 175V . Set rack down it stopped . Duh. Put it on slow charge went to parts store .

 

I understand that working inside the battery itself is dangerous for a layman, but to simply remove and replace a hybrid battery are the same precautions required? As long as you have removed the orange plug are there serious risks if you don't plan on opening up the batteries?

I watched this 8 year old video by a presumably pro hybrid tech, and he has not taken any special precautions. He pretty clearly states as long as the plug is removed you are good to go. Is this guy giving bad advice?

 

I found the Chrisfix video after I posted here. Yes, it's a much better how-to, yet as you mention he never really mentions safety factors.

Someone even asks him about this in the comments section and he just reiterates pulling the orange plug.

Could you link the gloves you are going to use? Will they allow enough dexterity to do the job?

 

He's kinda not wrong, as long as there is no P0AA6 isolation fault code being reported for the battery. (A person following best practice would still wear PPE all the same.)

If there is a P0AA6, do ya feel lucky? Well, do ya?

I've never been in the same room with a pair of 8000V-rated gloves, but I bet they're uncomfortable and limit dexterity. 1000V (class 0) should be plenty for a gen 3. (You should even be able to get away with class 00 as long as you're not inside the inverter or MGs during operation.)

 

P0A7F - Hybrid/EV Battery Pack Deterioration


It's taking more than 24 hours for each of my posts to be approved by a moderator, so this will probably be my last post here....thanks for the help

 

except for this one:

Thank you very much!

 

You might be close to five by now, which (IIRC) is the magic number where they don't need mod approval anymore. Chin up!

 

Ha! That would have been nice to know.

Anyway, it's now been a week since learning about the death of the Prius.....taking in all factors it appears that selling it off to Copart is really the best course of action. This car is the single worst used auto purchase of my life. Nobody's fault but my own. I didn't do the research, so I had no clue about the piston ring failure/oil burning. How Toyota got out of recalling these 2010s......smh.

Everything beyond that was just pure bad luck. My wife wrecked it two weeks after we dropped full coverage (her fault) and we paid $2500 just to make it road worthy (it was never really the same), EGR failure in 2020 where I actually had to buy the part from Saudi Arabia and somehow replaced it on my own (miserable experience), against my better judgement I let my son take it to Tulsa where he blew out a fuel injector and barely limped it home before a full engine failure (should have junked her then, another $1500), and then the coup de grace was putting a new set of tires on it and then 48 hours later it throws this battery failure code at me. All the while having to pour copious amounts of oil in it as it burned it up at a record pace. Time to walk run away.

 

That sounds like a nightmare.

What does a person have to do to blow out a fuel injector?

 

Just toodlin' down the highway between Wichita and Tulsa......at least it failed on his way back, but his mother and I were on tenterhooks. It was late at night in a rainstorm with three other kids (he'd just turned 18). *sigh*