Downhill battery full charge causes engine noise

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Downhill battery full charge causes engine noise

Post by niroinca » Sat Jun 23, 2018 10:46 pm

I drive the 2018 Niro hybrid. When coming downhill over a large distance where I'm only using the brakes, as soon as the battery goes to full charge either the ICE or the electric motor comes on full speed. I can tell from the very loud noise it makes. I don't understand why it does that. My first guess was that it is running the electric motor at full speed to burn off the excess charge. It is quite loud so it could be the ICE, but it makes zero sense to burn fuel in this scenario. My other guess is overcharging takes it over the acceptable voltage and trips some circuits. Why won't they simply disengage the charging circuits instead of letting it charge to 100%? Has anyone else experienced this?
2018 Kia Niro LX + tech package

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Re: Downhill battery full charge causes engine noise

Post by smileymiley » Sun Jun 24, 2018 8:36 am

Don't think the battery should be charging that much. Consesus on here is for the battery to peak around 75%. I'd get it checked out by Kia.
Vini, Vidi, Velcro

I came, I saw, I stuck around

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Re: Downhill battery full charge causes engine noise

Post by djbobbins » Mon Jun 25, 2018 9:18 pm

I took my Niro to the Alps last summer and experienced the same thing - the drive from the mountain resort down into the valley was about 15km of downhill, mainly switchback roads.

The battery gets to fully changed and then the internal combustion engine kicks in; my assumption is that this is to provide engine braking of some sort. I did the same trip on multiple occasions and didn't notice any ill effects.

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Re: Downhill battery full charge causes engine noise

Post by Topicalcat » Tue Jun 26, 2018 7:03 pm

That comment about engine breaking makes sense. If the battery will accept charge then the action of using the motor to charge the battery will act to retard the car. However once the battery is charged you no longer have that braking effect and for safety sake need the engine.

I would guess that with the throttle closed the engine when it comes on is using little or no fuel, one of the advantages of fuel injection and a closed throttle. I would be interested to hear further comments on this. When I get my Niro and go to France I will have a 30 mile downhill section coming down from the plateau on the Massiff Central on the A75 autoroute after the Milleau bridge down to the coastal plain. I used to come down in a lower gear in my diesel with no throttle and used to record 99.9 mpg which was as much as the display could cope with. In reality it must have been much better than that.
Last car a Hyundai IX35 diesel. Next car eas going to be be a Niro PHEV until this latest hiccup with deliveries.

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Re: Downhill battery full charge causes engine noise

Post by h2onorth » Tue Jul 31, 2018 9:47 am

Hi all interesting topic which has been raised before by a few. Some contributors also mentioned a "hot smell" from battery area which is not mentioned by current topic. During this downhill scenario has anyone tried sport mode and manually put car in 2nd or 3rd (speed permitting).
If so what data from car was obtained and was engine speed raised or lowered?.
I read recently that the PHEw car displays the revs in certain modes of driving, in which case this would be useful in this scenario.

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Re: Downhill battery full charge causes engine noise

Post by JOL54 » Tue Jul 31, 2018 6:38 pm

Nowhere is there a rev counter on my PHEV.

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