Car shuts off with no power or power brakes on EV mode

2648 Views 6 Replies 6 Participants Last post by EV Nerd, Sep 17, 2021

Intensevlarity888

Discussion Starter · Sep 17, 2021

Hi everyone,

I had an issue few times this year, where the car turned off with no power while driving downhill. Today, I took the car to the dealer this morning, and was told (1) Honda's Diagnostic tools could not find indications that an error or an issue occurred, (2) could not replicate the problem, and (3) without a diagnostic capture of the incident the dealership could do nothing about it.

Here is what happened below:

(1) State of the car:
Car was in HV mode with 80% of battery, and not going uphill. Going downhill.

While driving downhill few times the car turned off with no power to the car and no power break functions to use. I had a difficult time maneuvering the car to come to a complete stop. Tried starting the car but no power was available and had to boost. I also had to boost the car with Honda road side assistance many times as the car would not start.

This power failure only happens in EV mode and I always have to drive in HV mode I fear of driving the car and having no power if it turns off while driving.

This has also occurred ona straight road as well few times in EV mode.

Honda simy replaced my battery and said there's no issue. Prior to bringing it to Honda CAA told me the batter is in good health and good state. Honda said the battery cells were dead and needed a better replacement.

I'm confused and concerned for the safety while being on road and wondering if anyone else had a similar issue or if they know how I can tell Honda to duplicate the issue so Honda can acknowledge it.

I would greatly appreciate it if anyone can advise or tell what they have done in this situation.

Thank you.

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Clarity_newbie

· #2 · Sep 17, 2021

@Intensevlarity888

That sounds incredibly dangerous. I find it incredulous Honda CAA and their authorized dealer network have no better response than sorry...come back when you can prove it.

I personally have never heard this particular issue before. I would think it's in the ECU/computer program or a electrical short somewhere based on your description. In EV mode...downhill = Regen back to battery typically. To shut off and lose proper control is crazy.

In a regular car, I would think the driver would get the same sensation if the fuel pump all of a sudden quit.

I'm not sure I'd drive it...I'd try to force Honda to send one of their regional folks to diagnose. In the US, we can also report such dangerous behavior to an arm of the government responsible for vehicle safety. Sometimes they are effective in getting the attention of the car manufacturer and force corrective action.

Good luck.

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tommyboy

· #3 · Sep 17, 2021

I had that happen many years ago (not a hybrid or electric). The black box is not capturing the past incident and the event must be in real time at the dealer. We would lose everything because a sensor that measured engine speed at the flywheel would intermittently fail and tell the car it was off, so it would shut down. It finally happened at the dealership and they fixed it. 6 months later the manufacturer (GM) put out a TSB for it and I was given a credit toward the purchase of a new GM vehicle (never used).

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fotomoto

· #4 · Sep 17, 2021

Intensevlarity888 said:
Honda said the battery cells were dead and needed a better replacement.

I’ve had a Nissan OEM 12v battery crap out @ 14 months due to one bad cell. Good one day, bad the next, car completely dead; not even a click when turning the key (remember those days?).

If the issue is still happening with the new OEM battery, I’d suspect poor grounding next.

GOOD LUCK!

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EV Nerd

· #5 · Sep 17, 2021

In my 20 years of driving EVs, the number one cause of "weird behaviors" is a weak and/or failing 12V auxiliary battery. I'd focus in that area.

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2002

· #6 · Sep 17, 2021

Intensevlarity888 said:
Honda simy replaced my battery and said there's no issue. Prior to bringing it to Honda CAA told me the batter is in good health and good state. Honda said the battery cells were dead and needed a better replacement.

How does the battery replacement fit into the problem timeline? I'm taking a guess that you started experiencing the problem X months ago, when you took it in the first time they said your 12V battery was fine. You continued to experience the problem, then Y months ago you took it in a second time and this time they said the 12V had dead cells so they replaced it. I assume the problem continues to occur even with the replacement battery, but have there been any changes after that? Does the problem happen less frequently with the replacement battery? You mentioned that when the problem occurred you had to get a jump start to get the car started again. Do you still have to do that with the new battery?

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EV Nerd

· #7 · Sep 17, 2021

2002 said:
How does the battery replacement fit into the problem timeline? I'm taking a guess that you started experiencing the problem X months ago, when you took it in the first time they said your 12V battery was fine. You continued to experience the problem, then Y months ago you took it in a second time and this time they said the 12V had dead cells so they replaced it. I assume the problem continues to occur even with the replacement battery, but have there been any changes after that? Does the problem happen less frequently with the replacement battery? You mentioned that when the problem occurred you had to get a jump start to get the car started again. Do you still have to do that with the new battery?

Could be a component within the 12V Auxiliary battery system, like the DC-DC, that isn't doing its job of keeping the Aux battery healthy.

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