asavage
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Re: Anatomy of The DC/DC Converter

It's hard for me to make an informed guess about your situation. I don't service these; I own one, and do a lot of reading about them, and I have experience both in the automotive industry and other disciplines to draw on, but I'm nothing like a expert, more of a well-informed generalist.

The "during hard acceleration" immediately brings to mind the prevalence of internal coolant leakage in the Drive Unit ("DU") and how coolant can move (slosh?) in the DU during driving. There's a lot of exposed circuitry on the inverter boards on that side of the DU, and one of them is down low. Coolant droplets (or more) moving around in the DU's inverter? Definitely sounds like an area where "intermittent" may come into play.

But, when the DU is drawing a lot of juice, the input voltage to the DC-DC drops, sure. How does that interact with how the DU triggers a shutdown ("neutral")? I've no good guesses, but I'd want to make certain that the battery voltage -- which is essentially the output of the DC-DC -- remains in the 11.5-14.5v range at all times.

If it was my vehicle sitting in my driveway, I'd buy a low voltage datalogger and monitor the battery voltage. If the DC-DC's output varies more than a couple tenths during any driving mode, I'd consider that suspect, but I'd also like comparative data from a well-functioning rig. Voltage dataloggers aren't all that expensive, esp. when facing a multi-thousand dollar repair bill. If the DC-DC output doesn't move much while driving, and a DU shutdown is triggered, I would not be looking hard at replacing a DC-DC. AFAIK, all the DC-DC Converter does by itself is provide the 12Vdc (nominal), besides the HV passthrough to the A/C and heater. And a datalogger would do an excellent job of determining if it's doing that job well. I can't think of other testing that would be needed to condemn or confirm its operation. Note that merely watching a voltmeter would likely not be a good way of doing this, because very short transient voltage changes are difficult to see visually, even with old-school mechanical movement analog voltmeters, and nearly impossible (for me) via modern digital VMs.

Once these cars are out of warranty, I suspect a lot of them are going to end up being sold for parts, as the available resources to troubleshoot and repair them are minimal. Unless you're an enthusiast, the path of least resistance is to move to another vehicle and leave the problems behind.

If the tech is certain that the DC-DC is at fault, it may be worth a roll of the dice, but dealers won't let you discuss directly with the techs so you can't get a feel of their certainty. Sometimes you'll get a clue via the tech's notes in your "file", but that's not much to base an expensive decision on.

My experience with auto repair facilities in general is that if they mis-diagnose an expensive problem, mostly they do not offer any compensation on the original repair; sometimes, you'll get a discount on subsequent parts replacement costs, but they are diagnosing via parts replacement at your expense. That's my experience from both sides of the transaction.
Regards,
Al Savage
2014 Rav4 EV, Shoreline Blue Pearl, #2609, first use 04Jun2014, 49k miles (Aug2017), OpenEV-SE 40A. First DU replacement May2018 59k.
2018 Model 3 LR AWD, blue. 9.6kw solar
http://nissandiesel.dyndns.org
alflash
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Re: Anatomy of The DC/DC Converter

under construction
Last edited by alflash on Fri Mar 11, 2022 5:19 pm, edited 1 time in total.
Russian fascists are killing the civilian population of Ukraine.
asavage
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Re: Anatomy of The DC/DC Converter

While the 12v can be monitored in the car, without a datalogger short transients would go unnoticed.
Regards,
Al Savage
2014 Rav4 EV, Shoreline Blue Pearl, #2609, first use 04Jun2014, 49k miles (Aug2017), OpenEV-SE 40A. First DU replacement May2018 59k.
2018 Model 3 LR AWD, blue. 9.6kw solar
http://nissandiesel.dyndns.org
alflash
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Re: Anatomy of The DC/DC Converter

under construction
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Shaf
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Re: Anatomy of The DC/DC Converter

asavage wrote:My experience with auto repair facilities in general is that if they mis-diagnose an expensive problem, mostly they do not offer any compensation on the original repair; sometimes, you'll get a discount on subsequent parts replacement costs, but they are diagnosing via parts replacement at your expense. That's my experience from both sides of the transaction.
My fear as the Tech has already replaced the 12V Toyota Battery and is now assuming that the DC-DC Converter is the cause of the weak battery. A new DC-DC Converter has been ordered and is in transit. I'll post the final results next week after it is installed.
Rich
Shaf
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Re: Anatomy of The DC/DC Converter

[/quote]Did they check the converter fuses (without removing it)?[/quote]
I have not talked to the Technician
alflash
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Re: Anatomy of The DC/DC Converter

under construction
Last edited by alflash on Fri Mar 11, 2022 5:20 pm, edited 1 time in total.
miimura
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Re: Anatomy of The DC/DC Converter

alflash wrote:
Shaf wrote:
Did they check the converter fuses (without removing it)?
I have not talked to the Technician
It's a pity. Checking 3 converter fuses is possible without removing DC/DC converter...
Even if they found that one or more fuses were blown, the dealer would still replace the whole converter. Only independent shops will open the DC-DC and replace a fuse.
2012 Shoreline Blue #1462 w/JdeMO | 2018 Tesla Model 3 LR | 4.32kW Motech/Enphase PV Solar + 2x Powerwall 2 AC| Leviton EVB40 40A & Jesla Home Charging | 2015 e-Golf LE (returned)
alflash
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Re: Anatomy of The DC/DC Converter

under construction
asavage
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Re: Anatomy of The DC/DC Converter

Shaf wrote: Thu Oct 07, 2021 12:07 am
Did they check the converter fuses (without removing it)?
I have not talked to the Technician
Rich, what was the outcome? Were they able to get this permanently repaired?

As Vlad implied, there is a definitive external fuse check (at least, for the heater fuse) the doesn't require any disassembly. That check is in the TSB I referenced earlier. But, a failed fuse wouldn't have had the symptoms you describe.

You mentioned:
Shaf wrote: Wed Oct 06, 2021 4:15 am UPDATE 6 WEEKS LATER: the Technician at Crown Toyota replaced the DC to DC Converter which did not remedy the fault. They told me that this resulted in a "new" Trouble Code which indicated the Traction Battery needs replacement. I have filed a claim with Toyota's Platinum Warranty services as the RAV is now beyond the Battery's 8 year warranty.
The HV Traction Battery has a high failure rate of the two DC contactors. Same problem as on the early Tesla Model S vehicles.
Regards,
Al Savage
2014 Rav4 EV, Shoreline Blue Pearl, #2609, first use 04Jun2014, 49k miles (Aug2017), OpenEV-SE 40A. First DU replacement May2018 59k.
2018 Model 3 LR AWD, blue. 9.6kw solar
http://nissandiesel.dyndns.org

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