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2021 Niro PHEV EX
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Discussion Starter · #1 ·
Anyone have a clear understanding of what these two modes of the auto battery saver+ do? I believe it's only seen on PHEV and EV. This from p.H38 of the 2022 owner's manual, and as they appear in the menu for my car:

"Cycle Mode : When the vehicle is OFF with all doors, hood and liftgate closed, the Aux. Battery Saver+ periodically activates according to the auxiliary battery status.

Automatic Mode : When the engine start/stop button is in the ON position with the charging connector plugged in, this function activates according to the auxiliary battery status to prevent over-discharge of the auxiliary battery. "

Mine is set to automatic mode. Who keeps the engine start/stop ON while plugged in? I don't. Also, both "activate according to the auxiliary battery status" - which implies that's when the 12V battery voltage drops below a threshold. Seems to me if keeping the 12V battery up while the car is off is the goal, cycle mode would be preferable - even if it means the hybrid battery discharges. Or would it even discharge, if also plugged in? Count me confused. :confused:
 

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2021 Niro PHEV EX
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122 Posts
Discussion Starter · #3 ·
this may be helpful

Thank you Perk. That's a thorough thread explaining many nuances of the battery saver, including how for some people it may be best to disable altogether.
I'm looking for info as to why one might use the "cycle" vs. "auto" option - or even just the difference. Auto seems to be the default.
 

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2021 Niro PHEV EX
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122 Posts
Discussion Starter · #5 ·
you’re welcome. can’t help you with your options; my 2018 only has on and off……..
I was going to say, there've definitely been some software updates and I've seen for others the battery saver is just on or off. I refer to the 2022 owner's manual because it's more accurate; the 2021 manual is missing a few things my car has or does.
 

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2021 Niro PHEV EX
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122 Posts
Discussion Starter · #6 ·
Replying to myself - figured this out. There is no switchable mode. Aux battery saver+ is either on or off.

The auto vs. cycle refers to when the saver is enabled it has two similar modes of operation, depending on respectively whether the car is off and unplugged, or on - and strangely, the OM says if the charging connector is also plugged in. If the charging connector is plugged in, the car won't fully "start" anyway, but display something like "Unplug charger to start car." Absent another, better explanation, I suspect this is a typo in the owner's manual, as it doesn't make sense.

So far I've also empirically determined the 12V battery is substantially charged in just two car states: when the HV battery is actively taking a charge via the connector, and when the car is on. It charges more quickly in the second state. When the car is off and not charging - plugged in or not, the 12V slowly discharges unless it reaches some low threshold, then the aux battery saver(+) triggers. The above two states also correspond to when the Kia Connect/Hyundai Blue API sends the 12V "car battery" percentage in its vehicle info response. Under normal conditions it doesn't display at least in my Connect app. I do see it in a Home Assistant integration. When the car is neither actively charging nor turned on, the same API query's response is simply missing the 12V battery percentage.

My takeaway is: let the car do its thing. Make sure aux battery saver(+) is on - the default, the 12V battery is in good or excellent condition (don't wait until it's marginal because of age etc.), and most importantly, address any parasitic/"vampire" loads that may drain it, particularly when off. The charging the car is capable of seems to be relatively low current, so it's possible for a large-enough unintended load to eventually deplete it and easily ruin a battery not designed for deep cycle operation.
 
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