Voltmeter for vehicle battery to monitor inside of cab

[electroniclearner820327]

I just had the idea to get one of these due to not trusting the intermittent battery light so then I can monitor the actual voltage when driving without having to pop the hood at a layby and check manually when that light is coming on and off.

I have been monitoring it more regularly now after driving and so far have not seen any decline in voltage when I park up so doesn't seem to be an indicator of battery drainage.

Having something like this I feel would give peace of mind as regardless, of the light not having correlated with actual battery malfunction yet, it does make me twitchy each time it decides to come on while driving.

With a dedicated voltmeter for it I could feel more confident.

How would I wire it? As I already have a connection running from the vehicle battery into the back to the dc-dc charger anyway, could I piggyback on those wires somewhere to save me having to run another long length out to the motor? I am guess yes? If so where and how should it be put on? Of course in the right place on the run, but how in terms of wiring technicalities? I could put the positive for the device into the positive on the terminal of the battery isolator switch between the starter positive to dc-dc charger positive input then negative can go to the negative busbar for the everything else, including the circuit for the starter and leisure as the instructions for the dc-dc charger stipulated they should share a common negative so I ran that cable into the back as well?

Btw could the light coming on be an indication of the voltage being too high rather than too low? I did read in the manual and it did not indicate that as a reason it would come on from what I recall.

[SteveThackery]

The voltmeter draws only a small amount of current, so you can basically connect it anywhere that you can find 12V, provided that the 12V disappears when the ignition is switched off. That means you shouldn't connect it directly to the battery. However, your vehicle probably has a 12V socket (used to be for the cigarette lighter), and provided that goes dead when the ignition is switched off, that could be an ideal solution.

In your fifth paragraph you discuss various places you could connect the voltmeter, but without knowing a lot more detail about the exact wiring it's hard to advise you on this. Because of the low current drawn by the voltmeter, you can safely connect it to any negative busbar or other negative feed. It's the 12V feed that must go on and off with the ignition switch.

In the old days the battery light was connected directly to the alternator and showed whether the alternator was energised and producing current (it went off when the alternator was producing enough voltage to keep itself energised). Nowadays I don't know if that is still true. It could be that the battery light is switched on and off by an ECU (electronic control unit), in which case it could be ised to indicate an excessively high voltage as well as a failure to charge. It is certainly possible, but I'm afraid I don't know whether it is actually done.

But your voltmeter will let you see what is happening. You should expect to see a voltage of at least 14.0V when the battery is charging.

[ledtester]

You might try connecting it to the cigarette lighter socket -- the socket is usually turned off when the car isn't running.

There may be some regulation between the battery and the socket -- that's something to test.

There are a lot of such voltmeters available online at the usual places -- Amazon, ebay, Aliexpress.

https://search.brave.com/images?q=cigarette%20lighter%20volt%20meter

[BILLPOD]

Good Morning Electroniclearner820327,   I've got one of these that works by Bluetooth to your cellphone:
https://www.amazon.com/QUICKLYNKS-Battery-Monitor-Bluetooth-Device/dp/B01MT4583U/ref=sr_1_7?adgrpid=1334807686682980&dib=eyJ2IjoiMSJ9.QdLsGesFXqoRom3VDNiZvsUrnYdHFcFlKeRwZYOFudQ7tl9P8yDSMmhfZ_zn3dczRB8qnZxn7bH8QPxlHIiM8xYfPes62eQZo23T9eq7iiuBhJ_cY_VNan3phgkrQpS0xg-uT19sUNADUs5fQs3uNTlImZBf2UvKJ2SlU_PVlVj-n9EYhU3xq8ofywbQNb9Ni8JlHlPmJQYX4TrUAYLPjgi4MowchXUaNuZiNSmnwJN8nehAwlZIA3xM6G4h2Ei_BYzZQgdU1T_jLDbudapawpHboO1TjxlTZ-wQ8s5QFR0.DhK6BQHtS_-z8Htg_rS0_3bhSTM3uoRBwBCXATPsO4k&dib_tag=se&hvadid=83425629455349&hvbmt=be&hvdev=c&hvlocphy=59456&hvnetw=o&hvqmt=e&hvtargid=kwd-83425837482286%3Aloc-190&hydadcr=24629_13493443&keywords=bluetooth%2Bbattery%2Bmonitor&mcid=4f80857b083939acb3732e45655aa81d&msclkid=995e1c7c41781f010073740fe8f7d906&qid=1752410521&sr=8-7&th=1

[Ian.M]

For accuracy, ideally a battery voltmeter should be wired direct to the battery terminals, so you are measuring the actual battery voltage, not the battery voltage minus whatever voltage drops exist in the vehicle wiring harness.   The positive wire to the voltmeter should be fused with a 1A inline fuse as close as reasonably possible to the battery terminal.

The voltmeter itself may have separate connections for instrument power and measured voltage, (very common with LED display digital types that have relatively high power consumption), and in that case the measured voltage connection should come from the battery and the instrument power from a (fused) switched accessory positive from the ignition switch.  Its also common for cheap LED voltmeters to either have a single negative connection or to have two, that pretend to be separate but actually have direct connection on the PCB between them.  In that case, do *NOT* connect the power negative to chassis or a ground from the wiring loom, it needs to go direct back to the battery, again to avoid measuring wiring loom voltage drops.

[SteveThackery]

For accuracy, ideally a battery voltmeter should be wired direct to the battery terminals, so you are measuring the actual battery voltage, not the battery voltage minus whatever voltage drops exist in the vehicle wiring harness.

I knew someone would bring this up, but I think it only complicates things. He just needs some idea of if and when the battery is being charged. That's why I suggested the cigarette lighter socket. It will be more than sufficient to do the job.

[Ian.M]

Well if your accuracy requirements are low enough, you can get complete voltmeters that plug in the lighter socket, e.g. this one: https://www.amazon.co.uk/Multibao-Cigarette-Voltmeter-Voltage-Detector/dp/B09NPMP8CB

[BeBuLamar]

I just get a cheap battery powered DMM and the lghier plug. No mod and after a while if there is no problem you don't need it. With a 10 Megahohms input impdedance whatever resistance in the wiring harness is insignificant.

[radiolistener]

While connecting a voltmeter to a convenient 12V source like the cigarette lighter might give a general indication of charging, Ian.M is absolutely right - if your goal is to monitor the actual battery voltage accurately, especially under load or fault conditions, the meter must be wired directly to the battery terminals.

This is because voltage drops across vehicle wiring - caused by current draw from other components, wire resistance, poor connections, or corrosion can significantly distort the reading. For example, if there's a heavy load on the same wire, you'll see an artificially low voltage, if there's current flowing into the wire (e.g. from a charger, solar panel, etc), the reading might be falsely high. These effects depend on unpredictable random factors like wire condition and contact quality.

For reliable results, especially when diagnosing intermittent issues like warning lights, only direct battery terminal measurements with proper inline fuse protection can ensure you're seeing what the battery itself "sees."

[Stringwinder]

A 50 µA panel instrument, a TL431 as adjustable zener and a new scale. Draws less than the self discharge current of a 50-100 Ah car battery. (Separate 100 Ah battery used with solar panels on roof rack for photo safaris in my case.)

[Sorama]

While connecting a voltmeter to a convenient 12V source like the cigarette lighter might give a general indication of charging, Ian.M is absolutely right - if your goal is to monitor the actual battery voltage accurately, especially under load or fault conditions, the meter must be wired directly to the battery terminals.

This is because voltage drops across vehicle wiring - caused by current draw from other components, wire resistance, poor connections, or corrosion can significantly distort the reading. For example, if there's a heavy load on the same wire, you'll see an artificially low voltage, if there's current flowing into the wire (e.g. from a charger, solar panel, etc), the reading might be falsely high. These effects depend on unpredictable random factors like wire condition and contact quality.

For reliable results, especially when diagnosing intermittent issues like warning lights, only direct battery terminal measurements with proper inline fuse protection can ensure you're seeing what the battery itself "sees."

Huh?
If there would be a voltage drop it would mean there is an issue.

The idea is to know  whether the battery is being charged or not.

You do t need a 6.5 digit meter for that nor any exact battery voltage as any 12V power line will tell you if there is a problem or not.

But even a voltmeter will not tell you if there is enough charge in the battery.

[UnijunctionTransistor]

Selected one of the many digital voltmeters available online, trimmed the lead wire to proper length, attached a cigarette-lighter plug, double sticky tape, and in less than 15 minutes you are good to go.

This particular model will display two decimals below 10.0 volts, but even a single decimal is enough for general purpose battery monitoring.

[radiolistener]

The idea is to know  whether the battery is being charged or not.

You do t need a 6.5 digit meter for that nor any exact battery voltage as any 12V power line will tell you if there is a problem or not.

You're right that any significant voltage drop typically indicates a problem - but only if you're measuring at the correct point. That’s exactly why connecting a voltmeter anywhere other than directly at the battery terminals can be misleading.

In a vehicle, wires and connections are exposed to vibration, moisture, corrosion, and mechanical wear. A wire might be partially damaged, corroded, or have a poor contact, which can create resistance. As a result, the voltage at some 12V line inside the vehicle might appear low - making it seem like the battery is undercharged - even if the battery is actually in perfect condition. Or worse, it might appear normal while the battery is failing, simply because you're measuring after a faulty connection.

If your goal is to know whether the battery itself is being charged, and what its voltage is under various conditions, then the only reliable method is to measure voltage at the battery terminals. This eliminates the influence of unknown or degrading vehicle wiring and ensures you're seeing the true battery status - not what’s happening downstream at, say, the cigarette lighter or a fuse panel.

In short: if you want to monitor the battery, measure at the battery. Anything else may tell you more about the wiring than the battery itself.

But even a voltmeter will not tell you if there is enough charge in the battery.

a voltmeter alone won’t give you the full picture of battery health unless it's connected directly to the battery terminals and used properly.

When voltage is measured at the battery terminals, you can absolutely assess both the state of charge and get a good indication of the battery’s condition. Measurements taken elsewhere in the vehicle’s wiring, such as at a cigarette lighter or accessory circuit - are affected by wire resistance, voltage drops, and potential faults. These measurements not only fail to represent the actual battery voltage but can’t reliably indicate battery condition at all.

To evaluate state of charge, just let the battery rest for 30-40 hours at ~25°C without any load or charging. Then measure the open-circuit voltage directly at the battery terminals. This gives you the battery’s EMF. Then you can estimate the charge level in percents with this simple approximation:

State of charge (%) = (Voltage - 11.7) * 100

To assess internal resistance, again connect the voltmeter directly to the terminals. Measure the voltage with no load, then under a significant load (e.g., headlights + heater).

Even without measuring current, a large voltage drop under load indicates high internal resistance - a sign of battery aging or failure.

But notice very important thing - in all cases, reliable conclusions require voltage measurement directly at the battery terminals. Anything else may mislead you due to unknown wiring losses or faults.

[radiolistener]

This particular model will display two decimals below 10.0 volts, but even a single decimal is enough for general purpose battery monitoring.

Your photo shows 12.0 V, which is quite low and potentially concerning. If the engine is off and there's no charging, this voltage indicates a low state of charge - roughly around 30%. A healthy, fully charged battery should read about 12.7 V at rest (no load, no charging).

After charging, the battery may retain higher voltage for some time (due to internal chemical processes), which gradually stabilizes to its true open-circuit voltage 12.7 V over the course of approximately 30-40 hours.

If the engine is running and charging is active, you should typically see 13.0 to 14.4 V, depending on the vehicle and temperature.

So while a single decimal reading is sufficient for general monitoring, a consistent reading of 12.0 V should be investigated further. in most cases, this discrepancy is due to the fact that you're measuring voltage somewhere within the vehicle’s wiring rather than directly at the battery terminals. Your example with a plug-in voltmeter in the cigarette lighter illustrates this well - it highlights the practical limitations and potential inaccuracy of such measurements.

For meaningful and reliable battery voltage readings, the voltmeter should be connected directly to the battery terminals. Only then you can accurately assess the battery’s actual condition and charging state.

[Sorama]

The idea is to know  whether the battery is being charged or not.

You do t need a 6.5 digit meter for that nor any exact battery voltage as any 12V power line will tell you if there is a problem or not.

You're right that any significant voltage drop typically indicates a problem - but only if you're measuring at the correct point. That’s exactly why connecting a voltmeter anywhere other than directly at the battery terminals can be misleading.

In a vehicle, wires and connections are exposed to vibration, moisture, corrosion, and mechanical wear. A wire might be partially damaged, corroded, or have a poor contact, which can create resistance. As a result, the voltage at some 12V line inside the vehicle might appear low - making it seem like the battery is undercharged - even if the battery is actually in perfect condition. Or worse, it might appear normal while the battery is failing, simply because you're measuring after a faulty connection.

If your goal is to know whether the battery itself is being charged, and what its voltage is under various conditions, then the only reliable method is to measure voltage at the battery terminals. This eliminates the influence of unknown or degrading vehicle wiring and ensures you're seeing the true battery status - not what’s happening downstream at, say, the cigarette lighter or a fuse panel.

In short: if you want to monitor the battery, measure at the battery. Anything else may tell you more about the wiring than the battery itself.

But even a voltmeter will not tell you if there is enough charge in the battery.

a voltmeter alone won’t give you the full picture of battery health unless it's connected directly to the battery terminals and used properly.

When voltage is measured at the battery terminals, you can absolutely assess both the state of charge and get a good indication of the battery’s condition. Measurements taken elsewhere in the vehicle’s wiring, such as at a cigarette lighter or accessory circuit - are affected by wire resistance, voltage drops, and potential faults. These measurements not only fail to represent the actual battery voltage but can’t reliably indicate battery condition at all.

To evaluate state of charge, just let the battery rest for 30-40 hours at ~25°C without any load or charging. Then measure the open-circuit voltage directly at the battery terminals. This gives you the battery’s EMF. Then you can estimate the charge level in percents with this simple approximation:

State of charge (%) = (Voltage - 11.7) * 100

To assess internal resistance, again connect the voltmeter directly to the terminals. Measure the voltage with no load, then under a significant load (e.g., headlights + heater).

Even without measuring current, a large voltage drop under load indicates high internal resistance - a sign of battery aging or failure.

But notice very important thing - in all cases, reliable conclusions require voltage measurement directly at the battery terminals. Anything else may mislead you due to unknown wiring losses or faults.

Sorry but this is a kind of nonsense.
I have been analyzing car electronics and car battery issues for more than 20 years.
You can reliably measure the battery voltage at any point in the car.

Again (as I said before), if there would be an issue with the location of measurement because of what ever reason ( bad contact) then that is exactly what you would want to know, so definitely not measure straight at the battery itself.

[floobydust]

electroniclearner820327, intermittent battery light is on the vehicle's instrument cluster, but not sure what a "cab" means in the UK. What vehicle is this? Here a cab=taxicab. Some semi trucks (24V) have a cab though.

The alternator lamp can caused by many things, usually it's the brushes worn out, a belts, bad connection- that causes the alternator to intermittently cutout. Check the wiring - including the battery terminals. Very important.
A modern vehicle has ECU-control and there are many extra reasons for the light to come on. Overheating alternator (plugged vents), voltage too high or low, no output, battery voltage low, overcurrent etc.

For a few decades I have used a voltmeter in vehicles. Some at the cig lighter, others wired direct.
Not a huge difference, there is (at cig lighter) extra voltage drop due to the wiring and electrical loads but still good enough to check the charging voltage. You might see 0.2V of slop.

You can buy cheap voltmeters for a couple pounds from Aliexpress or eBay etc.

[radiolistener]

Sorry but this is a kind of nonsense.
I have been analyzing car electronics and car battery issues for more than 20 years.
You can reliably measure the battery voltage at any point in the car.

Again (as I said before), if there would be an issue with the location of measurement because of what ever reason ( bad contact) then that is exactly what you would want to know, so definitely not measure straight at the battery itself.

I’m genuinely unsure whether you're being trolling or serious. Are you truly suggesting "after 20 years of experience" that one can reliably assess battery condition by measuring voltage at any random point in the vehicle’s wiring? This is complete nonsense.

Sorry, but even a junior technician with basic electrical knowledge understands that according to Ohm’s law, any resistance in the wiring - due to length, connectors, corrosion, or poor contacts will cause voltage drops under load or charging. These drops make such measurements inherently unreliable for evaluating the true state of the battery.

I don't believe that a person "with 20 years of experience" with car wiring can not know Ohm's law.

If your goal is to assess the battery itself, not the condition of downstream wiring, the only correct method is to measure voltage directly at the battery terminals. Anything else reflects conditions in the wiring, not the battery.


Personally, I would never trust voltage readings taken from a cigarette lighter socket  even if using a high-precision, calibrated instrument  simply because I understand the inherent limitations of such a measurement point and why the results cannot be considered reliable.

That’s precisely why, whenever I need to verify the battery voltage, I open the hood, take a digital multimeter, and measure it directly at the battery terminals. While my car alarm system does provide onboard voltage monitoring - even with remote access - I don't rely on those readings, as I’ve repeatedly observed discrepancies compared to the actual voltage measured at the terminals.

[Sorama]

Sorry but this is a kind of nonsense.
I have been analyzing car electronics and car battery issues for more than 20 years.
You can reliably measure the battery voltage at any point in the car.

Again (as I said before), if there would be an issue with the location of measurement because of what ever reason ( bad contact) then that is exactly what you would want to know, so definitely not measure straight at the battery itself.

I’m genuinely unsure whether you're being trolling or serious. Are you truly suggesting "after 20 years of experience" that one can reliably assess battery condition by measuring voltage at any random point in the vehicle’s wiring? This is complete nonsense.

Sorry, but even a junior technician with basic electrical knowledge understands that according to Ohm’s law, any resistance in the wiring - due to length, connectors, corrosion, or poor contacts will cause voltage drops under load or charging. These drops make such measurements inherently unreliable for evaluating the true state of the battery.

I don't believe that a person "with 20 years of experience" with car wiring can not know Ohm's law.

If your goal is to assess the battery itself, not the condition of downstream wiring, the only correct method is to measure voltage directly at the battery terminals. Anything else reflects conditions in the wiring, not the battery.

Really?
Are you going to explain an engineer what Ohms law is?
It seems you don’t understand what TS is looking for.
Read between the lines.

And try to understand why I’m telling its better to measure somewhere down the road instead of next to the battery.
It seems I have to explain some basics too.

Anyway, other members here have explained well what TS could or should even should do.

[floobydust]

Old cars, power went through the ignition switch first and the loop de loop back to the alternator and under hood loads. There is a sizeable voltage drop due to this.

Modern cars, for power loads they use relays located under the hood. It's close to the alternator and battery.
You don't see big voltage drops at the cig lighter, other than close by local stuff like the cabin blower fan.
Headlights, cooling fan, air con, some ABS - the bigger loads takeoff points are under the hood.
My Toyota uses #20AWG wire for the cigarette lighter "accessory outlet" with 3A fuse, it's pretty cheap- minimum copper is the goal nowadays.

[Sorama]

Old cars, power went through the ignition switch first and the loop de loop back to the alternator and under hood loads. There is a sizeable voltage drop due to this.

Modern cars, for power loads they use relays located under the hood. It's close to the alternator and battery.
You don't see big voltage drops at the cig lighter, other than close by local stuff like the cabin blower fan.
Headlights, cooling fan, air con, some ABS - the bigger loads takeoff points are under the hood.
My Toyota uses #20AWG wire for the cigarette lighter "accessory outlet" with 3A fuse, it's pretty cheap- minimum copper is the goal nowadays.

It depends on what you consider an old car: even in the 80’s cars had a permanent 12V power supply ( so not going through the ignition switch) for the radio to keep its memory and other things.

[radiolistener]

Modern cars, for power loads they use relays located under the hood. It's close to the alternator and battery.
You don't see big voltage drops at the cig lighter, other than close by local stuff like the cabin blower fan.

If other devices are connected to the cigarette lighter circuit  such as a dashcam, phone charger, or similar accessories - voltage drops can and often do occur, especially under load or if the wire is partially shorting to ground - with high enough resistance to avoid triggering a fuse or being noticed as a full short circuit, but still low enough to significantly affect the voltmeter readings.

But the larger issue is that unless you personally installed and thoroughly verified the entire wiring path, you can’t be certain of its condition, what additional loads might be present, or exactly where in the power distribution the cigarette lighter is connected. That uncertainty makes any voltage readings taken from it unreliable for assessing actual battery voltage.

Even if you did wire everything yourself and are confident in the quality, automotive wiring is constantly exposed to vibration, temperature changes, and corrosion. Over time, this can degrade contacts and increase resistance - which again makes voltmeter readings from the cigarette lighter an unreliable diagnostic source.



PS: I once witnessed a situation involving a so-called "engineer" at an authorized Toyota service center who had modified the vehicle’s wiring. From his perspective, everything appeared to be done correctly. However, he failed to realize that the wire in question was carrying digital data, not just a simple control signal. As a result, the modification led to intermittent malfunctions of the power window control system.

He spent a long time troubleshooting the issue without understanding its cause. When I tried to get clarity on what was going on, he was defensive, insisting that he was a certified engineer and knew what he was doing, citing service procedures and internal regulations. Eventually, I managed to get enough information from him to understand the root of the problem - and it became clear almost immediately.

Needless to say, my opinion of his professionalism changed significantly, and I never went back to that service again. This is the real case that happens with me in the past. Since then, I have made it a point to thoroughly verify and oversee any work performed by so-called "engineers" at authorized service centers.

[floobydust]

I find it's about the wiring voltage drops, and at the take-off point too. It's not about what is supplied battery power. In the 1960's it was the clock that got battery power, 80's the radio, 90's the power door lock remote RX etc.

Radio BATT+ connects to where? The fusebox bus, along with a dozen other devices. If the fusebox is located under the hood, or in the cabin kickpanel it's a couple metres extra wire.
Point is, that node you will see the sag in voltage if many loads are running. Not due to the one radio BATT+ wire though.
Again it's not enough voltage to be really far off the state of the electrical system. As well, you have the ground voltage drops to look at and include.
Cigarette lighter usually grounded to the body/firewall which is a ways away from the battery and a lot of steel.
I will play with it, experiment - rear window defog, brake lights are popular (not under the hood, rear of vehicle) loads.

I just bought a car voltmeter 52mm Stepmaster (stepper motor analog pointer) and it works gross. Drove me nuts needle bobbing up and down, despite the 5-1/2 digital LED display one being pretty stable - at the cig lighter. Had to take the scope out to the car and look at the noise spikes. The ignition system and fuel pump are most of it.
edit: added pic, these are a chinese clone of the Japanese Defi gauge

[radiolistener]

You're absolutely right - when measuring voltage at an arbitrary point in the vehicle wiring, such as the cigarette lighter, you're observing not just the battery voltage but the combined effects of voltage drops along the wiring path. Current may be flowing through shared sections of wire due to other active loads, and those wires may be long, undersized, or using the vehicle chassis as part of the return path.

Each of these elements - wire length, connections, shared circuits, grounding through body panels - introduces potential sources of voltage drop, or instability. If the voltmeter itself is powered from the same circuit it’s measuring (as many plug-in meters are), the readings can be further distorted under load.

This is precisely why accurate battery voltage measurements must be taken directly at the battery terminals. The difference becomes especially evident when testing battery internal resistance under load - for example, by switching on high-current consumers like headlights and heating elements. In such cases, the voltage drop at remote points (the cigarette lighter) can be significantly greater than at the terminals due to high current, misleading your assessment of battery condition.

Also, as you’ve already noticed, the quality of the voltmeter matters. Many low-cost plug-in car voltmeters lack proper filtering, temperature compensation or accuracy, and are easily affected by electrical noise from the ignition system, fuel pump, or other switching loads. For serious measurements, even an inexpensive but proper handheld DMM will generally offer better reliability and stability.

For that reason, whenever I need to accurately assess the battery’s state of charge or condition, I always use a multimeter connected directly to the battery terminals.


As I mentioned earlier, in my vehicle the battery voltage is monitored both by the onboard electronics and the security system, allowing me to remotely check the voltage via the security remote control unit. The displayed value is shown with one decimal place and often matches the actual battery voltage - but not consistently. Sometimes I see no difference with DMM on battery terminals, but sometimes I see 0.1..0.3V difference. It's difficult to say whether the discrepancies are due to voltage drops within the wiring or the limited accuracy of the security system's ADC, I just don’t spend much time analyzing it, as I recognize that this method of measurement is inherently unreliable.

[floobydust]

Even if you go through all the hoops - ECU-controlled alternator can confuse you. They don't keep a lead-acid battery at 100%, they'll do regen and charge if you are decelerating. To achieve a higher fuel economy number. It's terrible I have to manually top up the battery (charge to 14.4v) every month or two. Many cars also have a current-sensor at the battery terminal so the ECU knows what the load is.

I'll see 13.2V-13.4V which is normal for Toyota in summer. They use a lower voltage for some reason, I think it's less water loss. After starting it will go up to 14.0V for a while.

[radiolistener]

yeah, charging voltage control in modern vehicles can be quite unpredictable. It's difficult to determine the exact logic behind the ECU choice of charging voltage. In my own experience, I typically observe values in the range of 13 to 14 volts, though occasionally it drops below 13 V or rises above 14 V, probably depending on driving conditions, temperature, and system behavior.

One thing I’ve noticed is that charging behavior also seems to depend on the type of battery installed. For example, with a conventional lead-acid battery, the system would regularly charge up to around 14.4 V. In contrast, with my current hybrid battery, the charging voltage tends to stay lower - typically around 13.5 to 14 V. It's difficult to say what exactly causes this difference, as I haven’t changed any settings - the system configuration remains the same.