My DIY iPhone Battery Packs

Posted by Jonathan on September 9, 2009 in iPhone, Projects |

DIY 6000 mAh iPhone Battery Pack


Years ago I had a 12 volt battery pack I made out of (8) 1.5v AAs, giving me 3000 mAh for my old iPod Classic. I used the Lithium AAs from Energizer. Since the iPhone wont charge on the firewire 12 volt pins I used the charge converter offered by CableJive to convert the 12volts to 5 volts USB. When I had a case on my phone I had to use a extension cable I made for the dock connector with the charge converter to let it work with my case. I decided a month ago that I needed a new one that could  work out of the box with the iPhone. A couple weeks ago I was able to start work on it.

High Capacity 6000 mAh Version:

I used the same type of case with my new one, it’s a point and shoot camera case. I’m still using (8) AA batteries, BUT I got (2) sets of (4) AAs in parallel. That gives me 6000 mAh at 6 volts using the 3000 1.5 volt lithium AA batteries from Energizer. Here is the spec sheet for those batteries. From what I  found on the internet the iPhone 3Gs has a 1250 mAh battery so this pack has 5 times the capacity.

I am using AA batteries because I don’t need to use this case everyday. I just need it for emergencies, like when the power was off for a week in my area due to a huge ice storm. Using the AA batteries I was able to watch movies on my iphone all week when I had nothing to do, which was most of the time. Since i am just using a 9 Volt Snap connector I could get special rechargeable batteries that would hook into it. I could even hook a 9 Volt battery into it. The regulator should convert anywhere from 5.5 volts to 35 volts down to 5 volts. Though the bigger the drop in voltage the more heat the regulator produces.

Since I have improved my modding skills since I made that first battery pack years ago I wanted to make this one better in every aspect. Instead of just having a cable come out of the pack with a dock connector on the end I wanted to make it where the cable was able to be removed. This allows to make the battery pack to look nicer and more compact.

Making the pack work with the iPhone requires some work. You can’t just use a regular regulator to drop the 6 volts to 5 volts. You need to use a LDO(Low Drop Out)  regulator. This is because the 6 volts to 5 volts is a drop of 1 volt and most regulators need at least a drop of around 2 volts to work. The LDO regulator is made to work with Low drop voltages like 1 volt.

You need to provide a voltage of around 2.8 volts to the Data – and around 2 volts to the Data +. That means you need some resistors in the design of the circuit board. I like using a circuit board because I can remove parts quickly and easily if I need to. I also left extra spots on the board that will allow me to add more connectors easily.

I went with a Type A USB connector for all my Misc USB devices that I need to charge or even the iPhone. I also added a 2 pin Molex plug that provides a 5 volt and ground that I can use with my really short spiral iPhone cable that I made. Now you might be asking yourself how I am able to only use a 2 pin cable when the iPhone needs those voltages on the Data pins. Well I was able to use 1/8 watt resistors and fit them into a dock connector to make the voltages I needed. I did this in a dock connector that is one of the medium sized ones, not the large one. SEE PHOTO BELOW.  I bought some small dock connectors(same size that comes on the dock cable you get with the iPhone) to try and do this. When I got them I looked at the size of the connector and just laughed because I’m good, but not that good. There was no way I was fitting four resistors in about 3-4 mm of space.

I did try and add a USB Mini B and a USB Micro AB connectors, but the pins are so small I will either need to make a special circuit board or buy some smaller hookup wire. Both of those options will take longer than I want to spend and I don’t have a use for them yet. I can add them quickly when I do decide to implement them since I left spaces open on the circuit board for more connector wire hookups.

I added a switch to cut off the voltage being supplied to the regulator because it was pulling a small amount of current even with no device attached. it  It was still regulating the voltage even with no current draw. I did not add a LED to this version like I did in my first, because I thought it was unnecessary and a waste of good power.

I also added a tripod connector onto the case so I could attached it to the iPhone using my tripod case mods. I will eventually add another tripod connector to the other side of the case so I can hook the iPhone to the battery pack and then hook the battery pack to the tripod.

I will not be providing a How-To Tutorial on this Battery pack, but I will provide a parts list and Schematic on the resistor layout if anyone requests it. If you want to make your own battery pack email me and I will try and get detailed information up as quick as possible.


3000 mAh version:

I made a smaller 3000 mAh version to see how small I could make the circuit board, make one that fits in  your pocket easier, and because I has the extra parts laying around. I made a very short dock cable to go along with this version and I have parts coming to make another short cable with the USB end being a right angle connector.

I will not be providing a How-To Tutorial on this Battery pack, but I will provide a parts list and Schematic on the resistor layout if anyone requests it. If you want to make your own battery pack email me and I will try and get detailed information up as quick as possible.


My Old One:

I just thought I would show you a picture of the one I made years ago for my iPod Classic. This one was 3000 mAh at 12 volts.

Credits goes to Pinouts.ru for the voltages I needed on the Data Pins.

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