I blew up the inverter????

Hi Patrick,

Proably right regarding the motor drive portion of the inverter. Although it would be a variable rate depending on the motor speeds, and pulse width chopping might be that slow.

The power supply for the 12 V probably runs higher. Do you have any technical info on this? The higher the frequency of a switching power supply, the smaller/cheaper it can be made, within the limits of the frequency range of the magnetic parts. I cannot see them throwing away that much money by running at 1970's switching power supply frequencies. When transistors and diodes are so much better these days.

 

Hi Ginny,

A battery with one or two bad cells might draw sufficient current to pop one of the large fuses or fuse links. However that should not have damaged the inverter, as I suggested to you in my post #20. I suggest we wait to see exactly what fuses or fusible links were found to be bad, before we continue to guess.

When you next have a chance to speak to the service writer, you might want to ask:

• how did the tech determine that the inverter had failed?
• is it possible that replacing the bad fuse(s) (and perhaps the 12V battery) will resolve the problem?

 

Referring to p. 05-487 of the 2005 repair manual, regarding DTC P0A09 and P0A10, which both relate to the DC/DC Converter Status Circuit, this is how the DC to DC converter is described:

"CIRCUIT DESCRIPTION
The DC/DC converter converts the DC 201.6 V of the HV battery into DC 12 V in order to supply power to the vehicle’s lighting, audio and ECU systems. In addition, it charges the auxiliary battery.
A transistor bridge circuit initially converts DC 201.6 V into alternating current, and a transformer lowers its voltage. Then, it is rectified and smoothed (into DC) and converted into DC 12 V.
The DC/DC converter controls the output voltage in order to keep a constant voltage at the terminals of the auxiliary battery."​

The repair manual is silent about operating frequency of the DC/DC converter, which I suppose makes sense since the repair philosophy is just to identify that the inverter is bad, then replace it.

A simplified circuit of the DC/DC converter is provided on the cited page. This circuit makes it quite clear that if the 12V battery polarity is reversed, then current will flow into the two diodes that compose a full-wave rectifier, which would cause the DC/DC fuse (the one that resides in the 5" grey and clear plastic box) to pop. By the way, the output of the full-wave rectifier is filtered with an inductor and a capacitor, according to the simple circuit diagram.

Galaxee previously noted that in some but not all cases of jumpstart polarity reversal that her DH knew of, the DC/DC converter failed. We have a current example where a PriusChat member installed a battery with incorrect polarity, which should be the worst-case scenario; nevertheless the DC/DC converter survived.

Perhaps the DC/DC converter diodes have a current rating just above 100A, so depending upon the circumstances and how quickly the DC/DC fuse pops, some diodes survive while others fail.

 

If its a full wave bridge then the reverse current and voltage rating would double.. you'd have 2 series diodes in parallel.

Seems the bridge rectifier should be more robust than that. Why doesn't any of the fragile components like computer and electronics fry?

$4800 is BS.. maybe $10 for 50 amp bridge.

 

Hi Scruge,

The simplified circuit diagram does not show a bridge rectifier with 4 diodes. It is a full-wave with 2 diodes. The DC/DC fuse is 100A; hence the diodes should be rated at least at that current-carrying capacity.

The MSRP of the Classic inverter is $3,477; 2G is probably similar. Champion ToyotaWorld

The dealer techs do not have the facilities or training to replace individual inverter components in the field. Hence the fact that the cost of two 100A diodes might be $10 or $20 is irrelevant unless you can find someone to successfully take apart, repair, and reassemble the inverter.

Hobbit took apart an inverter several months ago and documented his findings on his website. It does not appear particularly easy to put back together, keeping in mind that coolant is flowing through the assembly so you have to restore the watertight integrity of the completed product, portions of which are exposed to 500VAC.

I assume that most of the ECUs have series diodes to prevent the flow of incorrect polarity current. A couple of the ECUs may have crowbar diodes to force popping of the associated fuses in that event. This may be intentional, so that Toyota has a way to prove owner misuse.

 

Hey Patrick Wong, so what do you do for your day job? Your knowledge of the Prius is impressive.

 

Cool. Time for someone to start an inverter rebuild service.

 

Just to satisfy my morbid curiosity, what is the cycle rate on the AC Voltage in a Prius?:tea:

 

Thanks for the interest. My day job as a pricing manager for a computer technology company is largely irrelevant to Prius! (BTW I am actively looking for a new situation and am open to nationwide relocation; any leads via PM to that effect would be greatly appreciated!)

I decided to learn about Prius in the summer of 2006 after my 2001 had DTC P3191 and needed a new engine ECU. Later in the fall it needed a new traction battery, which increased my motivation to learn about the car, what are its common failure points, and to what extent a DIYer could reasonably implement quality repairs.

I've owned ~25 cars of a variety of Japanese/European/US makes and have been very interested in automobiles since I was a teenager applying too much force and snapping bolts on my family's vehicles. (My dad was a loyal Ford owner back then and the quality of hardware on the engines back in the 60s was pretty low. Fortunately he was and still is a very patient man and taught me how to drill out and remove the remnant of the bolts!) I do all maintenance and most repair of my vehicles.

I was interested in electronics from an early age and obtained the top FCC amateur and commercial radiotelephone licenses when in high school, so this provided exposure to analog electronics. I more recently have studied digital circuits. Finally, having worked in the computer industry (in finance, marketing and operations management) most of my career, I have remained reasonably familiar with the underlying technology.

Since Prius is basically a bunch of computers, electric motors, and a gasoline engine, I find my prior experiences in autos, electronics, and computers are relevant to understanding its operation.

This already exists although the price of up to $895 is high compared to the price of a salvage part:
DISCOUNTED INSURANCE SALVAGE

I assume that you are referring to the voltage used to power the AC synchronous MGs. The frequency is variable since the required MG speed is variable.

 

I wonder if the dealer thinks the fusible link is inside the inverter, thus replacing it requires an inverter replacement. Someone correct me if I'm wrong, but there are two high-amperage fuses -- a fusible link near the 12v battery, and a fuse in the big block in the fuse box under the hood. Replacing either of these does not require replacing the inverter, and in fact the inverter can't be diagnosed until they're replaced if they're blown.

 

I might have missed something - but I see multiple areas where Toyota has a responsibility.

First - The battery died for no apparent reason. It appears that the car is designed by Toyota to minimize use of the battery when shut off (unless it is not run for weeks at a time). So there was an unknown event which occurred.
Second - First the Toyota Salesman and then the mechanic instructed her to jump the car and how to jump it. If there was any question, they should have instructed her to have it towed in. After all the typical driver is not an expert. It appears that the owner excersiced due diligence in trying to start her car.
Third - Toyota has an obligation to design the car so inadvertent acts do not result in significant damage or bodily harm. This is why everything one buys today has more cautions than instructions on how to operate. Mfgs. are very sensitive to potential legal issuse when theri product is in use.

I am not a lawyer - just deal with them frequently - my suggestion is to find a lawyer who has had succes in defective product issues. Then provide your information and see if they are interested. Although it may be tempting, I would try to avoid an hourly fee arrangement.

 

Hi Ron,

Regarding your first point: In her first message, Ginny said that her car has 5K miles. Since it is a 2007, this is pretty low usage. Its not surprising that the 12V auxiliary battery will run low under conditions where the car is lightly driven.

Regarding your second point: In a subsequent message, she said that the car started after she jumpstarted and she let it run for 10-15 minutes. She says that she did not make a mistake jumpstarting, and I believe her since the car started.

However her first mistake was to only run the car for 10-15 minutes, as a 12V battery is not going to recharge after that short period of time, especially in Prius which is maintaining a voltage of only ~13.8V on the 12V bus. She should have left it READY for a couple of hours.

Then she said that she tried to charge the battery but the charger would not provide current. This may be a strong clue that the battery had failed; if she had a digital voltmeter she would have been able to assess the battery's condition. However I realize that this is going beyond what an average owner should be expected to do.

She subsequently called for tow truck assistance and the tow truck driver also tried to jump the Prius. Who knows what happened; perhaps the tow truck driver screwed up or else his boost device put too much voltage or the wrong polarity voltage on the Prius system.

Regarding your third point: With any car, if you reverse the polarity of the jump cables, you will cause damage. However with Prius and its unusually high electronics content, you have the potential to cause extraordinary damage. Since Toyota is selling the base Prius at the low $20K price point, I'm not sure it is realistic to expect that the car will be totally proofed against all possible user error.

Another error on Ginny's part was to accept the diagnosis of a failed inverter without probing into the thinking and evidence behind the diagnosis, or obtaining a second opinion. To her credit, she is now trying to correct that.

 

Good points- Somewhere along the line, something might have happened. From my experience, most battery chargers will trip instantaneously if hooked up to reverse polarity. Certainly, the system should not be harmed by the battery charger (unless it was a supper heavy duty one used for boost starting a car).

Absent the issue of the battery charger, I would say that the tow operator may be suspect. But the point that I am making is that there have been multiple individuals on this site who have had issues with reverse polarity. I am new here so I don;t know how many but if we expand to all Toyota Prius owners, I would expect quite a number of batteries and other equipment over 1K has required replacement due to inadvertent error. Although my knowledge with electircity is not extensive - enough to be dangerous, I would think a simple 200VDC circuit with a quick acting fuse or CB and some capacitance could cheaply solve the problem. I still think that Toyota can;t plead that we made the car inexpensive so inadverent human actions can't be addressed. Part of vehicle design is to look at these issues and address the most significant. THe real issue is that until some lawyer takes on a reverse polarity case and wins, Toyota will certainly deny the claim. Will see what happens with her situation.

 

At least 2 different jump starts with different equipment, by different individuals. He said, she said. Owner misuse?
Why would Toyota admit fault in this situation?

 

The point that I was making is that Toyota certainly will not admit any fault. In this day of litigation, just look at Ford and the Pinto - It was shown that Ford chose to engineer the fuel tank in the manner they did and a cost basis - Ford lost many $ on that issue - but only have fighting it through the court system. WIth the Pinto - the only time there was an issue was if soneone rearended the car - certainly not a normal occurrence but it occurred frequently enough that lawyers were able to show there was a pattern. In the Pinto case it was related to personnal safety so the money damages were significant.

On a side note - I went to the NHTSA website to see what they had - there were a few complaints of cars dying on the road and the battery going dead but many related to the HID lights - I suspect that these complaints may be the reason that some have had Toyota replace them for free.

 

my scan gauge shows 13.7 volts
that sounds normal to me, not 14.8 volts.



each cell in a typical lead acid or gel type 12v battery has no-load voltage of 2.1 volt.
2.1v x 6 cells= 12.6 volts.
that is typically battery voltage without any load.

once engine powered generator/alternator is creating electricity it is necessary that voltage potential from generator be slightly higher than 12.6 volt, otherwise there will be no charge going from alt/gen to the battery and battery will become drained/depleted.

the voltage level that alternator produces varies based upon the internal temperature of voltage regulator, current, battery capacity and how car manufacturer has programmed the voltage regulator.
Current is often overlooked, but it is part of equation of voltage/amperage/load so it cannot be separated.

I remember the following, from my days when i worked on cars for living;

GM cars had typically charging voltage of 14.4 V or more when engine (alternator with built in voltage regulator) was cold, and as the car warmed up --charging voltage decreased to around 13.5 - 13.6 volts.
Japanese cars with tiny batteries (this was in 80's) and separate voltage regulators produced very high charging voltage in excess of 15 v when voltage regulator was cold, and then voltage would drop to around 14 to 14.4 volts depending on car make. If you would take a large capacity battery and connect to the same Japanese car, the voltage would drop to say 13,5 or 13,8 volts, but if you take huge battery -- voltage would be barely above 12.6 or 12.7 volts because of extra load (amps) that it would take to charge the huge battery with tiny alternator. Furthermore, if you would connect an amp meter -- it would become clear that voltage is not all that is important -- amperage is as important as the than voltage, because it is part of the formula.

therefore, voltage that you read on your electrical system is not all that you should take in consideration, but also amperage, size/capacity (resistance) of the battery and if engine is cold or hot.
and yes, 14.8 volt on a prius either indicate a charging malfunction (or even a weak battery) or a shitty measuring device.

 

You've got it nailed just about right. In the solar world we increase the voltage (both bulk and float) as the temp drops, lower it as it rises. 14.4 is considered the good average for a flooded lead acid battery. Testing a battery that has just had a load, OR, had just been charged will give a false reading due to surface charge. A battery should be measured at least one hour after being charged or discharged.

My scan gauge reads 14.0, with the occasional dip to 13.9 while "idling" with the lights and wipers on. It measures 12.7 first thing in the morning,,,ust right.

Icarus

 

Hi Ginny,

Thanks for the update. When you receive the quote, if you can scan the page(s) that show the specific part numbers and part descriptions, and post the page(s) as well as any DTC identified, that would be helpful.

However, since the fuse link has not yet been replaced, chances are there will be no DTC to retrieve. Regarding the 12V battery, I am glad that this is finally becoming part of the quote.