Keyring Phone Charger





Introduction: Keyring Phone Charger

In this Instructable, I made a simple keyring charger.

It can charge your phone's battery with a standard 9v battery.

If you ever travel and find that your battery is dying, just get a 9v battery and use your keyring to charge your phone.

For this project you'll need:

  • Car's USB charger
  • Micro USB to USB adapter
  • 2x 9v batteries or battery connectors
  • Sugru

Step 1:

I removed the connector from a 9 v battery.

Then, I soldered cables to it.

Alternatively you can buy a battery connector.

Step 2:

I took apart car's USB charger and soldered battery connectors to it.

Step 3:

I could have used USB adapter without opening it, but I wanted to make it smaller, so I did open it.

Step 4:

I removed the LED from the charger.

Then, I covered everything with Sugru.

I also made a pattern with a screwdriver.

Once I was happy with the result, I half-plugged the charger in the phone and let it dry.

Step 5:

I also made a protective cap for the connector.

Finally, I attached another connector from a 9V battery to my keys.

Now the charger can be easily attached to the keys.

If you need to give your phone a boost, take off the keyring and use a 9V battery to charger your phone.

Charging speed and efficiency will depend on your phone, cars USB charger and the battery you will use.

Smaller phones with a high capacity 9V battery will charge better than big phones.

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Most smart phone batteries are 1500-3300mah.

A 9V battery has 50-400mah and at 500mw load has less than 300mah capacity.

You're also losing 20% of that 300mah thru the circuit as heat.

Just exactly HOW much does this remaining 240mah charge your phone ???

Ref :

What is Sugru?

Is it Plaster Of Paris or Plastician or Poly Filler or Playdoh or somthing else?

It's usually available in several different colors at Lowe's, Home Depot, etc! At my Lowe's it's hanging next to the masking tape and paint supplies by the paint counter! If you wanna save some money search for the Oogoo (DIY Sugru) 'able!

It's silicone rubber paste. It's sets like RTV silicone.

It's a self setting rubber.

I don't know with what to compare it. Feels like a Playdoh.

Whenever I see a "Power" application of a 9V Block battery I cringe and think: The Moderator shall give them an "environmental unfriendly"(to say it nicely) label.

10 to 15 years ago it had been acceptable to use a 9v Battery for an 5 V microprocessor board using some 30mA.

But today in the age of cheap Chinese boost switch boards it is no longer acceptable to use a construct of 6 tiny 1,5 V cells(the 9V Block) for such an purpose. It is symply a waste of resources. Even here on "Instructables" symply type "18650" in the search bar and you will find a lot of Ideas to use scavenged liion cells from thrown away laptop batteries. Go to alibaba or other chinese markets and you will even find 0.8 - 5V boosters to 5 V USB, or buy a ready made one for an AA cell(like some one else here already suggested).

The 9V Battery Block should be reserved for some sub-milliamp applications where you need a free floating power supply with no noise, like pre amplifiars for the stage, E-guitars, microphones and such things.

I cannot see where you tied the two wires (step 2) onto the USB car charger.