03/12/2025 10:13 am
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Hi,
Thanks for making this product.
Still new at this, trying to power a R Pi 5 with display and NVME, presume I will need close to the 5A.
What battery do you recommend? Not a powerbank, but a battery I can solder in.
The 2S / 4S batteries with 25W+ are RC / hobby batteries, is this what people are using?
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05/12/2025 8:59 pm
Thank you for being here.
The requirement when choosing batteries are mostly dependent on the BMS. Would prefer that you use a 4S battery pack. This is because, as your required power output is 25W (or near), the USB converter will take in a little more power than that from the input batteries.
The lithium ion battery packs usually have a protection voltage of 3V/cell. So, at 4S, the voltage input to the USB-PD converter will be at least 12V (when battery pack is near complete discharge), and it will draw about 2.5A at this voltage. So, you can have a BMS of 3A for 4S battery pack and it should work well in most cases. Or could use anything above 3A.
But when you opt for 2S cells, the cell pack can discharge to 6V (3V/cell) and the required BMS current draw will be around 5A. So, you will need battery packs that have BMS of 5A or higher when you use 2S cell pack.
Another major consideration is the cell quality and discharge rate. If you are using 1S2P and trying to draw this 5A from it, each cell should be able to supply 5A current. So if you are choosing a 2500mAh single cell, you will need at least 2C or higher rated cells. Higher C rate cells are usually costly. But if you opt for 4S, each cell has to supply almost half of this current (when in 1S4P configuration) and you will be able to choose from more cell options in this case. Also since the discharge rates are less in 4P, the cells usually are subject to less strain and life might improve (as they are discharged at almost half of the C rate compared to that of 2S)
Please let us know if you need any clarifications on this. Might have went a little technical. But we could break it down for you and help you with understanding if needed. Just comment and let us know and we will be happy to help.
