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Dashboard Symbols

Lead acid batteries v/s Lithium ion batteries

Lithium ion batteries used in electric vehicles

Are there Battery level indicators on the dashboard of four wheeler vehicles?

Can Lithium ion batteries in electric vehicles assist the driver in observing the battery level indicator?

If Not, is it technically feasible for implementation?

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    There is a battery symbol on 4 wheel vehicle yes, and it should turn on when giving power to the vehicle (2nd position of the key). If it goes on while riding, it means your battery isn't charging anymore.
    – LeRouteur
    Jul 20, 2022 at 12:11

2 Answers 2

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Estimating the state of charge of a battery is generally a non-trivial engineering task.

In this regard, Li-Ion batteries in the smartphones are (somewhat) easier than the lead-acid batteries used in cars. Using only the battery voltage, one can estimate a Li-Ion battery state of charge to within 20%, the voltage of a Lead-acid battery (while connected to unknown sources and consumers of electricity) can only show if the battery is dead flat or not.

In order to adequately know (to within 2-5%) what is inside the battery, you need:

  • A means to measure the current going in/out
  • A means to measure the voltage of the battery
  • A means to integrate over time the current going in/out without piling up much of an integration error
  • A means of periodic calibration of 0% and/or 100% level in order to account for the battery aging and the inevitable accumulation of integration error
  • The integrator has to be always on in order to maintain the knowledge of the present state of the battery
  • An adequate model of the battery self-discharge (easy for Li-Ion - they almost don't have any self-discharge).

Modern smartphones have everything this and still fail sometimes (e.g. when the phone is left unused for a few months or when the battery is aged)

In a car, you have to measure adequately a wider range of currents (e.g. the crank amps vs. the car alarm consumption) in a wider temperature range and other rough conditions (vibrations, etc). This is why it is usually not done.

SOME modern cars (e.g. equipped with start/stop system) maintain internally some knowledge of their battery state, but they generally don't show something like this on the dashboard (otherwise, the user will try to fiddle with it).

In marine/offroad/RV communities, some OEM battery monitors employing the above method of current integration are popular. What they have in common is that they are rather expensive, rather complex to install and they still do have some caveats.

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  • Thanks. Can replacing the Lead acid batteries by Li-Ion bateries in the four wheeler vehicles will solve the problem? Jul 21, 2022 at 17:56
  • Thanks. Can Lithium ion batteries in electric vehicles assist the driver in observing the battery level indicator? Jul 22, 2022 at 14:20
  • Thanks. This feature will be visible on the dashboard of electric vehicles 2022? Jul 22, 2022 at 14:52
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    @PrashantAkerkar Sorry, I cannot understand either of your questions. As I said, Li-Ion batteries are easier to estimate, but not much easier. If you don't use the described method, all you can have is "100% full" and "Low battery" and nothing in between.
    – fraxinus
    Jul 22, 2022 at 14:52
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    p.s. Every electric vehicle I have seen so far (fat bikes, cars, etc...) has a battery indicator with 1-5% resolution.
    – fraxinus
    Jul 22, 2022 at 14:54
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There will be a battery indicator in the instrument cluster, but it will not indicate how well charged the battery is; the light is not a "battery level indicator" as in the title to your question.

Instead, the indicator light will show if the battery is being charged (by the alternator), or is not being charged. Thus, as correctly indicated by LeRouteur in comments, if the light is illuminated the battery is not being charged; this is expected when the ignition is "on" but the motor is not yet running. When the motor is started, and the alternator begins to charge the battery, the indicator light should turn off.

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  • Thanks. Why technically is a limitation of showing the % battery level indicator in a four wheeler vehicle as we are able to see in a Smartphone device? Jul 20, 2022 at 20:08
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    @PrashantAkerkar I have no idea if there's a technical limitation or not, I'm not an EE. However, I'm confident these sorts of decisions (choosing information and manner of display) are more driven by economics (how much will it cost to do that?) and design style (what does the driver expect to see in the instrument cluster?). An indicator of the state of battery charge is very uncommon in internal-combustion powered cars and trucks. However, such gauges are expected (and do appear) in electrically-powered (or partially electrically-powered) vehicles. Jul 20, 2022 at 20:14

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