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We have been building the 4WD Freenove car with a Raspberry Pi 4. We purchased two Samsung 18650 batteries.

When we try boot up from battery power the red LED turns on the Pi. However the green ACT LED doesn’t or barely lights up and we get no action!

If we plug the Pi in (while mounted and connected to the Freenove car) it boots up no problem.

What could cause this? The SD card works (evidenced by booting when plugged in), and we have red LED power light when powered via battery but it won’t boot!

Thoughts? Are my batteries dead? They are brand new!!

Photo of underside of Freenove car

Greenonline
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Saul
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3 Answers3

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Based on the information in your question, the likely suspect is the input voltage to the RPi is below 4.63V. Yeah - 4.63V is an odd number, but it's based on the value of the PMIC's internal reference - explained here.

For battery-powered projects, the RPi4 would ordinarily be a questionable choice - because it consumes the most power. See this table in the "official" documentation that lists the Typical Power Requirements for all RPi models.

But if you need the RPi4 performance, you need more stored energy. If you've not developed an energy budget, you should; here's a start. If you have other questions, we'll try to help, but suggest you provide more details in your question.

Seamus
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Answer

Your pink batteries might be fake.

I googled the FreeNove 4WD datasheet which says the following about their LiPo batteries requiring discharging current > 10A:

1. 4WD Smart Car Kit for Raspberry Pi

... Both flat and button top 3.7V 18650 batteries with discharge current >10A.


... For 18650 capacity, it should be 2000~3500 mAh. A bigger capacity may be fake.

References

(1) Freenove 4WD Car Kit for Raspberry Pi [Overview] 27,622 viewsOct 18, 2019

(2) Freenove 4WD Tutorial for 4WD Car Kit FNK0041 4,957 viewsMar 9, 2021

(3) Freenove 4WD Chapter2 Assembly & Chapter3 Test Freenove 4WD Pi Car 6,545 viewsAug 20, 2021

(4) Freenove 4WD Smart Car Kit for Raspberry Pi 4 B 3 B+ B A+, Face Tracking, Line Tracking, Light Tracing, Obstacle Avoidance, Colorful Light, Ultrasonic Camera Servo Wireless RC - Amazon us$70

(5) Freenove 4WD fnk0043 Tutorial pdf - FreeNove

.END

tlfong01
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Samsung 18650 35E batteries are 8A. You need Samsung 18650 25R with 20A.

8A is not enough for both the raspberry pie and the car.

user1620139
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