Two USB batteries in series?

[Linker]

I need at least 10 volts for a project, and need a (cheap) rechargeable power source. I like the cheapness and convenience of usb battery banks.

Would I be able to put two different usb batteries in series without any issues?

Thanks

[CodeNova]

1 minute ago, Linker said:

I need at least 10 volts for a project, and need a (cheap) rechargeable power source. I like the

Would I be able to put two different usb batteries in series without destroying the battery?

Thanks

I would advise against it, unless the batteries specifically say something about load sharing.

[W-L]

2 minutes ago, Linker said:

I need at least 10 volts for a project, and need a (cheap) rechargeable power source. I like the cheapness and convenience of usb battery banks.

Would I be able to put two different usb batteries in series without any issues?

Thanks

You would be far better to get a power bank that has a DC jack output which can provide a variable voltage. This one here can go from 12-24V. 

https://www.amazon.com/XTPower-MP-10000-External-Battery-10000mAh/dp/B075FP1VF7?th=1

[CodeNova]

25 minutes ago, Linker said:

I need at least 10 volts for a project, and need a (cheap) rechargeable power source. I like the cheapness and convenience of usb battery banks.

Would I be able to put two different usb batteries in series without any issues?

Thanks

something like this is an option also, this one is for 12v, they also have one for 9v, nothing for 10v unfortunately.

[mariushm]

Get a boost (step-up) regulator or build one yourself from parts. 

 

eBay is full of 1-2$ step-up boards which allow you to configure the output voltage and work from around 3v and up.

 

Here's an example: https://www.ebay.com/itm/2A-DC-DC-Boost-Step-Up-Voltage-Converter-Micro-USB-2-24V-To-5-28V-Adj-Regulator/112931387130?hash=item1a4b3c36fa:g:h2kAAOSwHgday3gf

 

Here's another design : https://www.ebay.com/itm/Boost-Buck-DC-adjustable-step-up-down-Converter-XL6009-Module-Voltage-NEW/191673952440?epid=592613290&hash=item2ca0a868b8:g:0CAAAOSwLVZVs4ch

 

You connect the input voltage to the board, and measure the output voltage with a multimeter. You can adjust the output voltage with that potentiometer on the circuit board.

 

If you want to make your own, *33063 or *34064 chips are super cheap and easy to build even on a prototyping board, but also really inefficient.. from 5v to 10v you're probably looking at 65% efficiency compared to the boards above which are probably above 85% efficient (they use chips running at higher frequencies)

Saying * because they're so old chip designs that they're made by lots of companies. For your needs 33063 or 34063 is same thing, I think 33063 lacks inverting option, but you only care about step-up mode.

 

33063 : https://www.digikey.com/products/en/integrated-circuits-ics/pmic-voltage-regulators-dc-dc-switching-regulators/739?FV=ffe002e3&quantity=10&ColumnSort=1000011&page=1&k=33063&pageSize=25&pkeyword=33063

34063 : https://www.digikey.com/products/en/integrated-circuits-ics/pmic-voltage-regulators-dc-dc-switching-regulators/739?FV=ffe002e3&quantity=10&ColumnSort=1000011&page=1&k=34063&pageSize=25&pkeyword=34063

 

For these parts there's free calculator which tells you the values of other parts you need: https://sourceforge.net/projects/mc34063uc/

Here's an example, for 4.75v .. 5.25v in, 10v +/- 0.2v at 0.25A output :

 

 

So you'd need a 33uH or higher , 1.5A+ inductor , a 1n5817 diode and a bunch of ceramic capacitors and resistors besides the chip and an electrolytic capacitor (at least 100uF, 120uF in the picture, but I would use 330uF or 470uF or something like that, rated for at least 16v)

[Unimportant]

12 minutes ago, mariushm said:

If you want to make your own, *33063 or *34064 chips are super cheap and easy to build even on a prototyping board

I'd advice against building any switching converters from scratch if you do not have the experience in board design, and especially not on prototype board - The thing will ring like a bell. Controlling parasitics and careful design of the current loops is key in switching converters.

[Linker]

2 hours ago, Unimportant said:

I'd advice against building any switching converters from scratch if you do not have the experience in board design, and especially not on prototype board - The thing will ring like a bell. Controlling parasitics and careful design of the current loops is key in switching converters.

I'm actually not against this- I am in an electrical engineering class, and have the tools and materials to do this.

I could actually probably get a project grade out of this, hah. (Need the power for another project)

[Linker]

2 hours ago, mariushm said:

Get a boost (step-up) regulator or build one yourself from parts. 

 

eBay is full of 1-2$ step-up boards which allow you to configure the output voltage and work from around 3v and up.

 

Here's an example: https://www.ebay.com/itm/2A-DC-DC-Boost-Step-Up-Voltage-Converter-Micro-USB-2-24V-To-5-28V-Adj-Regulator/112931387130?hash=item1a4b3c36fa:g:h2kAAOSwHgday3gf

 

Here's another design : https://www.ebay.com/itm/Boost-Buck-DC-adjustable-step-up-down-Converter-XL6009-Module-Voltage-NEW/191673952440?epid=592613290&hash=item2ca0a868b8:g:0CAAAOSwLVZVs4ch

 

You connect the input voltage to the board, and measure the output voltage with a multimeter. You can adjust the output voltage with that potentiometer on the circuit board.

Thanks, probably will go with this. Depending on how things go, I might need up to 18 volts.

[mariushm]

Note that a step-up regulator like these 3x063 chips can't produce any voltage at any current ... for example with 5v input you may be able to produce 10v at up to 0.3A but at 18v you may only get 0.1A max, with around 60% efficiency.

There are much better regulator chips, these two are simply cheap and easy to put on a prototyping pcb (with 0.1" spaced drilled holes) due to the lower operating frequency (typically less than 80kHz). Better chips run at much higher frequencies (like 250kHz and higher) and that's where it's quite difficult, practically impossible, to get such circuits working on breadboards and even on 0.1" proto pcbs it's difficult (you need to get inductors and capacitors as close as possible to IC pins and having drilled holes spaced 0.1" apart makes it hard)

 

If you wish to elaborate on what you need 10v or 18v for, maybe we could give you some tips about how to accomplish some things. There may be other ways to design what you want to make.

 

[Unimportant]

59 minutes ago, Linker said:

I'm actually not against this- I am in an electrical engineering class, and have the tools and materials to do this.

I could actually probably get a project grade out of this, hah. (Need the power for another project)

If having the tools and materials means you can etch custom circuit boards and you stick to the recommended layout from the manufacturer in the datasheet without getting creative then yes, go for it.

 

Otherwise simply buy one.