Tow Truck Driver Reverse Polarity Jumpstart

Thanks, everyone, for your input so far. I heard back from the man investigating this matter for AAA, but I’d like to doublecheck with you all about the accuracy of what he wrote.

First, let me refresh your memory: the 12v battery had gone dead in October 2021 while I was away; a neighbor might not have been driving it frequently enough. Another neighbor had tried to jumpstart the 2002 Prius with his car and told me that it was completely dead. I was out of the area for two additional months after that, so I figure that the 12v battery was certainly going to be dead when I returned.

The AAA investigator today wrote me about the 12v battery (which he knew was severely depleted):

“if the battery had been cross-connected, there would have been sparks immediately at the point of contact with the terminal and a loud pop. The result would have left the terminals with severe burn marks on the terminals and post.”

a) Would that be an accurate statement if the 12v battery had been severely depleted?

b) The investigator also wrote that because the alarm was going off continuously, this meant that “the jump box was connected correctly or there would not have been power for the alarm to work.”

I *think* he shows a lack of knowledge there about how reverse polarity can force electricity to go the wrong way and that the “jump box” (the portable battery used to try to jumpstart the 12v battery) had itself been the source of power for the alarm to work.

There’s no explanation provided by anyone, including the Toyota service department, about what else could have caused 3 fuses plus the 100 amp fuse to blow.

I had heard from someone else outside of this forum that the tow truck driver should not have kept charging the 12v battery in a way that kept sounding the alarm system continuously (and when the car had not restarted). From what the last neighbor told me, the car had been completely dead during his attempts to jumpstart the 12v battery.

The AAA investigator is denying the claim, but to me, he might be doing so based on incorrect information being provided to him and not realizing that.

If I”m wrong in my reasoning, please let me know.

 

After knowing the 100 amp fuse had been blown but telling me the hybrid batteries had checked okay, the service department told me ten days later they got the car running for 30 minutes and then the hybrid batteries failed. But without the 100 amp fuse working, the hybrid batteries would have gotten depleted, wouldn't they?

 

Thanks for clarifying that the 100 amp fuse doesn’t affect the charging of the hybrid batteries.

Although you wrote above that the hybrid batteries didn’t fail, the service department had conveyed that although the hybrid batteries had initially checked out as okay, the hybrid batteries *did* fail after the car was run for 30 minutes and therefore that it would also cost another $3200 or so to fix the car by replacing the hybrid batteries. But I’m not sure I can really trust what they said because it took them more than ten days to explain why all of a sudden their service estimate included replacing the hybrid batteries——with no explanation why. (Apparently, according to the AAA investigator, the service department also recommend replacing them due to the age.)

I had wondered if one of my neighbors might have blown the 100 amp fuse by accidentally jumpstarting the car with reverse polarity (and personally, I would accept the cost of that damage because they were trying to help me out). However, there were two people who witnessed an effort to jumpstart the 12v battery in October, which was completely dead. The alarm system had not gone off at that point.

Afterwards, in December, then the tow truck operator had attempted to charge the 12v battery with the alarm system going off for at least five minutes, even though the car had not started, and that hadn’t happened before. That’s what had seemed unusual and problematic to me, and which had pointed out the possibility of jumpstarting the battery with reverse polarity. Another person said that the driver should have stopped right away to check the polarity.

Does it still seem the tow truck driver didn’t do anything wrong?

There’s still a mystery about how the 100 amp fuse got blown and why three other fuses blew, too. It was because the three fuses kept blowing but I had been told the hybrid batteries were okay that I had authorized a complete electrical diagnosis for $675 (which never got completed).

 

I’m afraid so, Tom, although I’m not an expert.

Quite a few years ago, I had trickle-charged my Prius in my garage, and had had a friend of mine start up the engine for 30 minutes every two months to keep the hybrid batteries charged. I don’t think I had had a problem when I came back to drive it.

 

Remember, the service advisor had said the hybrid battery had checked out okay, which was why I went ahead and authorized the electrical diagnosis. At some point, maybe without even finishing the first day of work on the car, he left on emergency leave and no one was able to find his notes for ten days (until he apparently came back). A completely different person’s name showed up on the service estimate the next morning after he was out on leave. For ten days, no one could answer any of my questions about why the service estimate included replacing the hybrid batteries, and I’m not sure what I was eventually told was actually true.

Despite their age, the hybrid batteries can apparently last up for 200,000 miles, so there’s a chance that I might have 30,000 more miles available from them.

I’ll look into having the car towed to another auto repair place that specializes in hybrid vehicles.

 

I belatedly realized that I had specifically asked the service department for input about what might have happened several times, which I’ll share a little later.

1) Thanks for bringing up the scan results, but no, the service department hadn’t provided them to me (and I doubt they would have been able to get them from the existing severely depleted 12v battery). There had been no indication of any actual reason to replace the hybrid batteries until after I had repeatedly asked why they recommended replacing them, and it took more than ten days for them to come up with any reason at all. Although I was finally texted after a very long delay that the car had been made to run for 30 minutes and then the hybrid batteries failed, this had NOT been documented in the notes.

It’s helpful to learn that the hybrid batteries should not be assumed to be dead at this point until proven otherwise.

2) The car hadn’t started in the first place (back in October) because the person I had left it with might not have driven it enough (despite my instructions). Another neighbor had later tried to jumpstart it (from his vehicle) in October, said it was completely dead at the time, and there was a witness to that. That was a bit unusual, but maybe the other vehicle hadn’t had enough power.

3) I had texted the service department: “The tow truck driver may have accidentally generated a reverse polarity charge of more than five minutes, continuously setting off the alarm system. Could anything else have been damaged by that?”

He had replied: “Possibly. But unfortunately, we can not tell. We only know what the vehicle is currently informed us. We need to replacer the 100amp fuse and auxiliary battery and continue from there.”

On the 24th, I’d written:

“I had written earlier that the tow truck driver had kept trying to jumpstart the battery for maybe 10 minutes even though the alarm system was going off. Does it sound like he unknowingly caused more damage to the electrical system, perhaps due to reversing the polarity? I also wrote: “I need to know from you if it appears the tow truck driver, when he kept charging the 12v battery despite the alarm system going off, probably caused more damage to the car, and what that would mean for being able to fix the Prius completely.”

The response from the service department was:

“Yes, my educated guess. There’s a possibility that the vehicle was jumped backward, causing the 100 amp fuse to be blown, but there’s not way for me to say that is the case.”

I had read elsewhere that charging with reverse polarity can set off other electrical systems, which is why I belatedly realized, long after the tow, that maybe the tow truck driver might have used reverse polarity by accident. Remember, the alarm system had not gone off in October when a jumpstart was attempted.

Note that the service department did NOT tell me that what I had written couldn’t have happened. They didn’t say, “setting off the alarm system when jumpstarting a severely depleted battery is normal and routine” or “it doesn’t mean anything that the alarm system was being set off continuously by charging the 12v battery.” They didn’t say that it’s not possible to set off the alarm system by charging the battery with reverse polarity.

What did seem obvious is that using reverse polarity by accident is a pretty common way of blowing the 100 amp fuse (and 3 other fuses).

Curiously, AAA is saying that there are no burn marks, which means to them that no one ever charged the battery with reverse polarity. So what blew all the fuses?

If the service department was charging a MUCH more reasonable fee to replace the 100 amp fuse, I might have just gone ahead with that. But charging $1548 to replace a $15 part was really over the top, plus the other contradictory stuff that was said threw everything into question.

At this point, I’m thinking of having the car towed to another auto repair place I’ve used before. I can’t trust the service department.