DIY battery pack for phone, tablet

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pengyou
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DIY battery pack for phone, tablet

Post by pengyou » Wed Nov 08, 2017 8:41 pm

Please feel free to bump this to another location, or delete it if is inappropriate. I am looking for diy instructions to make a small battery pack for charging cell phones, tablets, etc. I have purchased 10,000 mamp and 20,000 mamp batteries before that are easily available but find that they are not adequate for my needs. They also usually only last 30-40 charges before I have to recycle them. I like to travel by train, most of which don't have electrical outlets in China, and would like to have the ability to go for a week with a cell phone, my watch an 7" tablet and a digital camera. What I am hoping to find is diy instructions that include a schematic and parts list. I have done some soldering and basic electronic stuff in the past, so would be able to take it from there. I am also willing to tackle a bms, or buy one if there is one commercially available.

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spinningmagnets
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Re: DIY battery pack for phone, tablet

Post by spinningmagnets » Wed Nov 08, 2017 9:03 pm

The battery is not the issue. You need to source a DC/DC converter that takes an auxiliary battery pack and provides 5V for a mini-USB plug for smart phones and tablet devices. Of course, laptop computers use a variety of input voltages so a solution for those is not as simple.

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There are several DIY battery pack kits out now, and more are on the way. Google Vruzend and NESE as an example.

https://endless-sphere.com/forums/viewt ... 31&t=88051
https://endless-sphere.com/forums/viewt ... 31&t=87434

These can all be configured as 1S packs of various sizes. That means that they will be 4.2V when fully charged, and 3.3V when low. A DC/DC converter for them will be a "step up" transformer to a voltage higher than 5V (for example, 2S / 8.4V might be useful for this), and as the voltage in the auxiliary pack slowly depletes down to 6.6V, there will be circuitry that adjusts the output to maintain a steady 5V output to the mini-USB plug.

There is no single way to accomplish this, for instance...you can configure the lithium auxiliary pack to be near 12V, because the 12V-to-5V mini-USB chargers are already common. For that method, you might consider using 4S LiFePO4 cells. The problem there is sourcing an affordable charger for the 4S LiFePO4 pack.

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wineboyrider
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Re: DIY battery pack for phone, tablet

Post by wineboyrider » Wed Nov 08, 2017 10:49 pm

Why not just buy one like this https://www.bestbuy.com/site/tzumi-pock ... Id=5638803 or 2 more?
ES IS SAVED! THANK YOU JUSTIN.

dustNbone
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Re: DIY battery pack for phone, tablet

Post by dustNbone » Thu Nov 09, 2017 7:20 am

Something like this for the charging side

http://www.ebay.ca/itm/Mini-4-2V-2A-Mic ... SwyWNZ5IWw

and maybe something like this for the output side (you could connect several of them if you want multiple USB outputs)

https://www.ebay.ca/itm/DC-DC-3V-3-7V-t ... SwHNxZ7GPW

and a cell or parallel set of cells of your choosing.

How you make it pretty and portable is beyond me. There's a ton of boards like those on eBay, etc. Maybe even one that integrates both functions.

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agniusm
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Re: DIY battery pack for phone, tablet

Post by agniusm » Thu Nov 09, 2017 12:35 pm

Hi. My NESE modules are ported so you could build your powerbank with quality cells which will last 100s of cycles. At the moment i have 2 to 6p which translates of up to 21000mah. The electronics i use are cheap powerbank mudules whoch give out 2.1A and 1A on 2 ports. I will have 8P tabs which will allow of upto 28000mah powerbank but it will be a huge brick :)
Take a look on my website http://18650.lt/index.php/resources/n-e-s-e-powerbank/

Image

The powerbank modules cost few bucks: https://www.ebay.com/itm/Dual-USB-5V-1A ... SwlQ9Zl9uw

pengyou
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Re: DIY battery pack for phone, tablet

Post by pengyou » Sat Nov 11, 2017 4:49 am

Thanks for the input. I have done the bestbuy power banks...my phone must ve an energy hog because the 20,000 mamp only charges it 4 times. That would get me by but then i have a camera battery to charge and a tablet. A second purpose if all of this is to get my feet wet in a simple electronics project. Its been a while...

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agniusm
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Re: DIY battery pack for phone, tablet

Post by agniusm » Sat Nov 11, 2017 10:20 am

There are few phones with 6000mah battery. Quick math would reviel if you get what you paid for. Look up your phones capacity, devide it from powerbank capacity and if the numbes match, you phone must be power monster. If it doesnt, probably powerbank holds some trashy cells.

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Ianhill
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Re: DIY battery pack for phone, tablet

Post by Ianhill » Sat Nov 11, 2017 11:58 am

I hate the 20000mah rating on powerbanks it's not a true reading of the energy contained.
We know they operate at 3.7v nominal so there should be 74wh available then the buck boost circuit wastes heat then the phone itself gets hot while charging so you can see where the missing energy goes even if the cells have stated capacity which I highly doubt I've never characterized one but I bet there no where near 20000mah even on a non cycled unit just horseshit figures.
Myself I would buy a lipo largest capacity then make a hardcase for it with two chambers one for the lipo the other for charge circuit, a dcdc convertor and a high power usb hub then you can charge all your items at once on the go.

How you maintain the battery and charge is another thought the USB charge on powerbanks is slow and pants myself I would go with a bms and a suitable laptop charger you should be able to cobble all this together fairly cheap and charge the power bank at 50w-125w with a decent laptop brick depending on the deal you can grab and discharge upto 100w the usb hubs they have a type c as well as 2.0 and 3.0 so your fast charging is covered for any device even the latest fanny craddock's.

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