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High-current 5V & 3.3V battery power bank

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Acam

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Hello!

Just writing to ask if anyone has come across a high current (5-6A output) 5V and 3.3V battery powered powerbank. I would need two outputs, one 5V with a capability of about 4A and one 3.3V @ 2A. I was thinking of using parallel high capacity 18650 batteries together with a DC/DC converter and other logic.

It would be nice to find a ready solution to this, but all powerbanks that I've found are usually one or double-output USBs of about 1-2A each.
My 3.3V could be derived with my own step-down converter or linear regulator if I at least could find a high current 5V powerbank.

kind regards,
Jonas
 

SunnySkyguy

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d123

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Probably no use to you, I read something about using super capacitors along with batteries working together, can't remember where, probably Wikipedia.
I just remember that it said they are used for large loads to restore/recharge energy quickly on all manner of things, including train brakes. The (smaller than for a train) 22,000uF one I noticed later was about 5 dollars/pounds. If yours is a constant load then probably won't be of use to you.
 

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My 3.3V could be derived with my own step-down converter or linear regulator if I at least could find a high current 5V powerbank.

kind regards,
Jonas

Here is a simple linear regulator. The load gets 3.3-3.4 V at 2A.



Use a zener voltage 0.6-0.7V greater than your desired output voltage.

Four rechargeable cells will not necessarily total exactly 5V. Therefore you can add a fifth cell to obtain 6V or more, then build an additional regulator to output 5V. Make that zener voltage 5.6V.

A pack of C or D rechargeables gets expensive if they are truly full capacity (rather than a housing for a AA cell). Also consider using a lead-acid 6V battery, as might be found in a lawnmower or motorcycle shop.
 
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Acam

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Your load duration is not specified and battery watt-hour needs to satisfy this. But there are many sources of Buck regulators in all sizes. TO start your project conider higher voltage battery banks of LiPo and define your Vin range and multiple output ranges.

https://webench.ti.com/webench5/power/webench5.cgi?app=powerarchitect&lang_chosen=en_US

Consider solutions for each like LM3152-3.3 and LM3150

Thank you for pointing out the LiPo batteries, didn't know about them so I hadn't even considered them as an option. Also when googling LiPo I found a lot of UBEC, SBEC and battery low voltage indicators with both 3.3V and 5V outputs with several amperes for a reasonable price.
So now I just have to consider designing my own or buying these ready ones and integrate these inside our product.

Jonas
 

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