# Voltmeter in car acting up

**URL:** <https://community.cartalk.com/t/voltmeter-in-car-acting-up/178104>\
**Category:** General Discussion\
**Tags:** acadia, gmc\
**Created:** [July 17, 2021, 10:44pm UTC](https://community.cartalk.com/t/voltmeter-in-car-acting-up/178104 "2021-07-17T22:44:14Z")\
**Posts on this page:** 1\
**Showing post:** 9

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**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\
**Post date:** [July 18, 2021, 12:32pm UTC](https://community.cartalk.com/t/voltmeter-in-car-acting-up/178104/9 "2021-07-18T12:32:00Z")

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Is this new behavior?  
It might be a “smart” charging system that reduces voltage to save gas.  
That’s what my 2017 Tucson does.  
Sometimes voltage drops to 12.6V.  
More about it here:

> [@Overriding a "smart" battery management system](https://community.cartalk.com/t/overriding-a-smart-battery-management-system/171538):
>
> Like many modern cars the Tucson reduces battery voltage when it decides the battery is charged “well enough”. It does this to mainly save a little fuel and also avoid over charging the battery. I have a voltmeter plugged into a 12V port so I can monitor system voltage while driving. When the battery is full (or nearly full) system voltage drops to 12.6V, with 4 exceptions. When steady cruising it raises the voltage to 13.x or 14.x (varies with temperature) volts for a few minutes every ho…

You can get one of these for comparison:

[https://www.amazon.com/gp/product/B01M9IKYVH](https://www.amazon.com/gp/product/B01M9IKYVH)

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