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JonnyAlpha
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Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 2:36 pm

Hi;

We are updating our Pi Jam equipment and have decided to get 10 x Pi 4s. Along with these we are getting a couple of CamJam Robotics kits, however I need some advice on what power packs to buy to enable the Pi and the Robotics kit to be mobile.

I have used the CamJam kits before with a Pi 3 and used a these 5000mAh USB packs
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1

But I have heard the Pi 4 is more power hungry so hence the advice request.

The robots will only be used for the duration of the Pi Jam (1 hour or so) so don't need to last too long before needing a re-charge?

Thanks
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DougieLawson
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Re: Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 3:18 pm

Buy the official power supply. That's guaranteed to work with a RPi4B (any flavour).
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rpdom
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Re: Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 3:41 pm

DougieLawson wrote:
Fri Sep 13, 2019 3:18 pm
Buy the official power supply. That's guaranteed to work with a RPi4B (any flavour).
Oh yes, and run extension leads to each of the robots. :lol:

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DougieLawson
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Re: Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 3:44 pm

rpdom wrote:
Fri Sep 13, 2019 3:41 pm
DougieLawson wrote:
Fri Sep 13, 2019 3:18 pm
Buy the official power supply. That's guaranteed to work with a RPi4B (any flavour).
Oh yes, and run extension leads to each of the robots. :lol:
Sorry, I read "mobile" as meaning "phone".
Note: Having anything humorous in your signature is completely banned on this forum. Wear a tin-foil hat and you'll get a ban.

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W. H. Heydt
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Re: Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 4:19 pm

Step 1. Determine the actual power requirement for your setup. The max power for a Pi4B is 3A @ 5v, but that includes 1.2A for USB devices. Your actual requirements may be less.
Step 2. Determine the power output (W) and energy capacity (Wh) of your proposed supply.
Step 3. Make sure that the output in Step 2 meets or exceeds the requirements in Step 1.
Step 4. Make sure that the total available energy capacity meets or exceeds the power from Step 1 times the desired duration.

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JonnyAlpha
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Re: Raspberry Pi 4 Recommended Mobile Power

Fri Sep 13, 2019 4:51 pm

Thanks all :-)
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diogen151
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Re: Raspberry Pi 4 Recommended Mobile Power

Sat Sep 14, 2019 6:37 am

Most power banks have overestimated capacity.
It's more convenient to use two Panasonic NCR 18650 batteries with real 3400mAh capacity; in parallel this configuration give more than 6 Ah.
This mean to buy apropriate power bank electronic; this one I've testes in several projects with succes.
https://www.aliexpress.com/item/3296822 ... 4c4d9w4RqS
You can use USB 5V output as well as separate 5 V pins for soldering output wires.
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Re: Raspberry Pi 4 Recommended Mobile Power

Sat Sep 14, 2019 6:55 pm

diogen151 wrote:
Sat Sep 14, 2019 6:37 am
Most power banks have overestimated capacity.
It's more convenient to use two Panasonic NCR 18650 batteries with real 3400mAh capacity; in parallel this configuration give more than 6 Ah.
This mean to buy apropriate power bank electronic; this one I've testes in several projects with succes.
https://www.aliexpress.com/item/3296822 ... 4c4d9w4RqS
You can use USB 5V output as well as separate 5 V pins for soldering output wires.
I think the bigger issue is that Li Ion/LiPo rating are given in Ah without stating that that is at 3.7v (nominal). That's why I spend so much time recommending that people convert everything to Watts (W) and Watt-hours (Wh) when figuring battery capacities and run times. Thus a 4Ah "powerbank" has 14.8Wh. A Pi that is going to require 2A needs 10W. So that battery has an expected run time of just under 1.5h, then adjusting for losses, it would probably be more like 1.2h. (Ignoring the fact that a 4Ah "powerbank" won't actually deliver 2A.)

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