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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

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    How are your samsung batteries wired to the freenove car and Pi? Post a photo.
    – CoderMike
    Commented Jan 31, 2022 at 16:43
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    Ya, we would need to see how these are wired, and if you have a regulator in use, how that is wired. Nominal voltage for those are 3.6V so if you are using them in parallel, I doubt there is enough voltage to boot. If the batteries are in series with no regulator, you would have 7.2 Nominal which is a little high, and those cells can be as high as 4.2 each, so 8.4 which is too high for the Pi. So you really should be running these in series with a good 5v regulator to bring the voltage down to the right range.
    – Chad G
    Commented Jan 31, 2022 at 17:47
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    Ok I will it is built into the actual car so it is a full kit. Trying to figure out how to add a pic
    – Saul
    Commented Jan 31, 2022 at 18:16
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    I have added an image of the back of the car. The battery system is on the actual car. As mentioned the Pi shows a red led when we switch it on just won’t boot up! (Unless we plug it in!)
    – Saul
    Commented Jan 31, 2022 at 18:26
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    The car comes directly from the freenove 4wd smart car kit we didn’t do any of the battery wiring and the pi is getting some power because of the red light
    – Saul
    Commented Jan 31, 2022 at 18:38

3 Answers 3

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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.

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    thanks. The kit was purchased as a gift by my father to my son! I agree that the pi4 may be too power hungry ultimately for this application. However we purchased two 3.7v 18650 batteries so we should have sufficient voltage! I will review the other docs you link to to see what more I can learn and will share more later. Thanks again!!
    – Saul
    Commented Feb 1, 2022 at 20:01
  • @Saul: Good luck - there are lots of Q&A here on power-related issues, but let us know if we can help.
    – Seamus
    Commented Feb 2, 2022 at 21:46
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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

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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.

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1
  • it's not a pie
    – jsotola
    Commented Sep 6, 2023 at 22:41

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