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Discussion Starter · #1 ·
I have a cigg lighter with voltage reading. When I start the car it is 14v. After a while it goes gradually goes down to 12.6. This is while driving. I have no clue if this is normal behavior for a 2020 honda insight EX? Cause it has no alternator just the converter. Has anyone else put a meter on there's?

Btw this is without any accessories.

Thanks
 

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2019 Honda Insight EX
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I think @pasei's the only one here that ever reported using a voltage reader. Maybe he can chime in? It seems reasonable to me for it to be at 14v initially cause the heaviest drain is when you start the vehicle.
 

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This is normal with this car, and actually every one of them. I have one of those outlet plugs that displays voltage. You can watch it jump between 14 and 12 throughout the drive.

The basic theory is that you cannot charge a 12 volt battery with 12 volts, it will take years to get up to full charge because as you approach the 12 volts the current will start to go to nearly nothing. So they set the charge to normally around 14.5 volts. Conventional cars have a voltage regulator built into the alternator, these car do not have alternators, so it is controlled by logic, I assume in the DC to DC converter or the Body Control Module.
 

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The Insight has its own 12 volt battery charging logic. The charge current is up to 14.5, but at various times the charge disappears and the charge voltage is not applied and you can see 12.2-12.7 volts. The logic is not clear to me, but it depends on the battery level at the moment and the mode of operation of the car. So I noticed that if the EV mode is on, then the battery at this moment (most often) is not charging. But if the low beam headlights are on, then the battery (most often) is charged with 14.2-14,5 V.
 

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Discussion Starter · #5 ·
Yes I've been monitoring it since the weekend. It's repeatable behavior so I figured it was normal. I just couldn't really find any information besides one post. Coming from extensive knowledge of cars with alternators this just was new to me.

Thanks for the replies. Might help someone not to freak out.
 

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The Insight has its own 12 volt battery charging logic. The charge current is up to 14.5, but at various times the charge disappears and the charge voltage is not applied and you can see 12.2-12.7 volts. The logic is not clear to me, but it depends on the battery level at the moment and the mode of operation of the car. So I noticed that if the EV mode is on, then the battery at this moment (most often) is not charging. But if the low beam headlights are on, then the battery (most often) is charged with 14.2-14,5 V.
The logic is pretty simple. With this car, and most others, the current flowing into the battery is monitored. However the sensor is not on the battery so it will pick up whatever is going through that wire. If it gets above a certain amount, I have no idea what that is, it raises the voltage because it thinks the battery is not fully charged. Even though with the vehicle running the DC to DC converter will provide the power to run the starter instead of the 12 volt battery, everything still flows through those same battery wires and the same current sensor. If you know anything about off grid solar system it works the same way. And honestly, current is just the flow of electricity, so you can just think of it as water instead.
 

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I took this after a 15 minute drive. My voltage did not waiver. I do have all accessories on. AC, Radio, Auto everything...

View attachment 7500
precisely because there is a significant current consumption in the 12 volt network, there is a constant charge of 14.5 volts. If you turn off the electrical consumers (radio, air conditioner, etc.), you will soon see a value of 12.2-12.7 (this will be the battery voltage, taking into account the minimum consumption). But periodically the system (even if consumers are not turned on), after a certain discharge, it will start charging again and you will see 14.5 volts.
 

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The logic is pretty simple. With this car, and most others, the current flowing into the battery is monitored. However the sensor is not on the battery so it will pick up whatever is going through that wire. If it gets above a certain amount, I have no idea what that is, it raises the voltage because it thinks the battery is not fully charged. Even though with the vehicle running the DC to DC converter will provide the power to run the starter instead of the 12 volt battery, everything still flows through those same battery wires and the same current sensor. If you know anything about off grid solar system it works the same way. And honestly, current is just the flow of electricity, so you can just think of it as water instead.
On the Insignt there is a sensor on the positive terminal of the 12 volt battery.
38920-TXM-A01
Sensor Assy., Battery (LARGE) (12 VOLT)
 
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