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Car Battery Detector 24V 12V BM420 7 LED Display Digital Test Tool

Brand: YAWOA
3-7 Busines Days

BM420 battery tester with cigarette lighter.In-car cigarette lighter test,you can understand the car battery situation without fear of the outside weather conditions.

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  Delivery Policy

Handling time with 24 hours.

  Return Policy

30 days free return, 3 months exchange, 3 years warranty.


1. Plug the BM420 battery tester into your car cigarette lighter socket, easy operation.

2. In order to ensure accurate test results,please do not open other car devices,such as Refrigerator,navigator,stereo,air conditioner and so on.

Have you encountered these problems?

It's probably battery issue:

●Cann't ignition

●Headlight dimmed when slowing down

●Battery fault light is on

●Creaking when starting the car

BM420 Car Battery Tester 12V 24V will help you

BM420 battery tester with cigarette lighter.In-car cigarette lighter test,you can understand the car battery situation without fear of the outside weather conditions

BM420 is a portable car battery tester for daily use, perform fast and effective.

BM420 Car Battery Tester will automatic identification of 12V/24V batteries

The status current battery is indicated by the corresponding LED light,12V display green LED and 24V display red LED.

Swich to the left is Battery Load Test Mode:

* 12V Green LED: Current test battery is 12V.

* Full Green LED: Indicates that the battery is in good condition and has a good load capacity.

* Middle Yellow LED: Indicating that the battery is in very moderate condition,the carrying capacity is average.

* Low Red LED: Indicates poor battery condition and low load capacity.

Swich to the right is Battery Charging Test Mode:

* 24V Red LED: Current test battery is 24V

* Fault Red LED: Abnormal battery condition,high voltage

* Good Green LED: Normal working voltage

* Full Green LED: Good battery condition

* Middle Yellow LED: Medium battery

* Low Red LED: Low power, need to be charged

* OK Green LED: Check before charging

BM420 Car Battery Tester 12V 24V

For checking and testing the battery capacity,battery load capacity and the dynamo.

1) Connection:

Insert the cigarette lighter.

2) Checking The Dybamo:

Connect the testing device.Start the engine and switch off the headlights,radio etc.Star the engine again and switch on the headlights,radio etc.In both cases,then green signal LED "GOOD" should shine.The red signal LED " Defective" will start to shine if the dynamo in bad condition.If the situation happen,please go to local car workshop in your earliest time.

3) Checking The Charging Level:

Switch on the headlights for 1-2 minutes,then switch off.Remove the cable clips from the battery,wait approx.10 mins then switch the testing device on again.A signal LED will shine according to the charging status of the battery indicating " Full" " Half-full" or "Very low charge".

4) Battery Start Capability:

The battery needs to be charged up to the maximum.Remove the connection of the ignition coil then connect the testing device.Try to start the vehicle using the key in the ignition switch.The engine cannot start (interrupted ignition).When the green signal LED "Battery OK" starts to shine,the charging status of the battery is ok.

5) Start The Battery Capability Load:

Switch to the loading test mode,then start the engine.

cFull: six-five LED will be shine;

Middle: four-three LED will be shine;

Low: two-one LED will be shine,if no LED shine it means the battery capacity is very low,please charging the battery or change the battery.


If the battery is not in good condition,the signal lamp "Battery OK" will start to go off and charging status of the battery LED will not loght up.


Please use the battery tester in safe area,and follow the instruction.

Parking The car in safe area before performing the testing.

Voltage Thresholds Details:

Please check the below table for reference.

The threshold might be a little different due to the different battery type,please go to professional car battery workshop for further testing if in emergency.

Packing List:

1pc * BM420 Car Battery Tester

1pc * English User Manual

500 Items

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