Since the battery used in Polaroid Land Camera was discontinued decades ago, new owner should modify the battery compartment for using market available battery to power it up.
Before we decide what battery should be used, we should know the battery voltage requirement of individual Polaroid Land Camera.
There are categories:
1) One 4.5V DC Power -- Model 100, 101, 102, 220, 225, 230, 240, 250, 340
2) One 3.0V DC Power -- Model 103, 104, 125, 135, 210, 215, 315, 320, 330, 420, 430, 440
3) Two 3.0V DC Power -- Model 335, 350, 35, 360, 450, 455
The cameras use two 3.0V DC power have an electronic timer on the back. The second 3.0V is for powering up the electronic timer. Personally I love the electronic timer which will start timing when I pull the exposed film out from the camera, and beep me when the set time is reached. Many people on the web are saying they can use their iPhone, and etc. to count the time, but those cannot beat the convenience from a built in timer. Mechanical Timer may fail to work but the electronic timer is accurate.
The battery
There are four main source of battery that you can use in your Polaroid Land Camera:
1) Alkaline battery - AAA (LR03), LR44 bottom cell
2) Lithium battery - CR123A, CR2
3) Zinc Air battery - PR44 (1.4 volt)
Among all these battery, Zinc Air battery provides the highest energy density. Lithium the second and Alkaline is the worst.
1) AAA (LR03) Alkaline battery can be found in your local grocery stores. They are widely available and the price is cheap. the only drawback to use Alkaline battery is the possible leaking of fluid after period of time. The leaked liquid will damage the electronic circuit and make your machine useless. Each AAA battery is 1.5 volt and has ~800mAh capacity.
2) Many people said Lithium battery (CR123A, CR2) is difficult to obtain. However, if you are a Polaroid Land Camera guy, you can easily get them from the camera shops where you will buy your Fujifilm Instant Pack film (FP-100C or FP-3000B). CR123A is more common than CR2 as they are also being used in other applications like powering up a flashlight. In my opinion, CR2 is going to be obsolete, therefore you should keep in mind when select which battery model you are going to use in your revitalized Land Camera. CR123A (~1,500mAh) has higher capacity than CR2 (~800mAh), but 800mAh is far enough than is needed. Both CR123A and CR2 are 3.0 volt battery.
3) Zinc Air Battery is used for mini devices like hearing aids. They have higher capacity but they have 1.4 volt output. It might be OK for putting two Zinc Air battery in serial to obtain 2.8 volt for a 3.0 volt system. However, the voltage will be lower than "normal" if you put 3 pieces in serial to get a 4.2 volt. Considering the voltage will be dropped further to 1.3 volt after a few hours of usage. The lowered voltage will affects the accuracy of the shutter timing. It can be compensated by adding some light compensation. A Zinc Air battery PR44 type has a capacity of 600mAh in general.
4) If you love the size of PR44 but have doubt on the 1.4 volt, then your only choice is the Alkaline LR44 battery. They have ~100mAh capacity but can output 1.5 volt. They can power up your Land Camera for a few pack of films (maybe 8 to 10 pack) and will used up completely. Both LR44 and PR44 battery are not easy to obtain.
My recommendation
Using AAA (LR03) battery is always the best option in your project. They are easy to obtain and the battery rack you needed to fit into your land camera battery compartment is easy to be found too. However, please take out the battery after use. Otherwise, you will end up with a messy battery compartment and a lot of cleaning job.
Lithium battery is also a good source for powering up the 3.0 volt camera. Their high energy density and compact in size makes you worry free on dead battery. If you can get a battery holder for these Lithium battery, just go for it. If you cannot get a battery holder....... just use a electrical tape to fix the battery terminals in your land camera to the battery ( the positive battery terminal attach to the White contact, and the negative battery terminal attach to the Black contact ).
I don't recommend using LR44 or PR44 in your land camera if you can work out the modification with AAA or Lithium Photo battery.
Further reading
If you want to know how to do the battery conversion of your Land Camera, please visit
Instant Option for instructions.