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How To Make a Light and Portable Battery for Night Photography

This post is part of a series called Night Photography.
Everything but the Camera: More Essential Night Photography Gear
Observation, Visualisation and Composition for Night Photography

In the previous article I outlined a basic setup for most night photography situations and investigated the variety of equipment readily available to photographers "off the shelf."

But night photography isn't just about developing a specific skill set and having the right equipment, as an element of luck is also required. Subjects like fireworks, lightning and astrophotography can be tricky to capture due to their unpredictable nature and fleeting presence.

To increase your chances of photographing these subjects, you need to use a combination of specialised equipment and specific shooting techniques. By following these guidelines you can increase your chances of "getting lucky."

Getting Lucky

Photo of a meteor as it enters the earths atmosphere
Capturing a meteor as it enters the earth's atmosphere is difficult and requires some luck. To get this shot of a meteor strike I took 300 individual frames over a period of ten hours.

The best way to photograph difficult subjects, like a meteor shower, is to have the shutter open for as long as possible. You can do this by using a single long duration exposure, or by shooting a series of shorter duration shutter speeds with multiple frames—my preferred technique.

For longer duration shutter speeds at high ISOs, you will also need to use some form of noise reduction. If you choose to do this in camera, you effectively double your power requirements.

This means you will need to power the camera for very long periods of time, and it's unlikely your cameras standard battery system will make the grade, so an alternative solution is needed.

Absolute Power

Digital cameras use direct current (DC) electricity to provide the power they need to run. They use internal DC battery systems with voltages generally rated between 5 and 12 volts, or convert 240 volt alternating current (AC) power to the DC power that the camera needs.

Image of lightning over electric power lines
Electrical power....for some night photography subjects you need plenty of it! The ability to power a multitude of electronic devices as well as your camera in the field is crucial—especially when filming in remote areas.

You can power your camera for extended periods in a number of ways: using an AC power supply unit (PSU) with AC power, using an AC power supply with DC batteries and an inverter, or using a custom DC power solution. All have advantages and disadvantages.

Using an AC power supply with AC power allows you to run the camera indefinitely from either a mains power source or a generator, but this does limit the locations available to you for positioning the camera.

Generators are heavy, noisy machines that require fuel, and transporting one around with you on location is impractical if you need to move camera position frequently. Mains power has even more limited accessibility.

Using an AC power supply with 12 volt DC batteries and an inverter is a better option and offers far more flexibility in terms of where you can position your camera, as it is a more portable solution.

Unfortunately you lose up to 25% of the DC batteries' available power due to the three-step process of converting 12 volt DC to 240 volt AC and then back to the DC voltage required to power the camera.

Nikon D7000 camera connected to a 150 Watt inverter that is running a Nikon EH-5a AC Power Supply Unit
This D7000 is being powered by a 12 volt battery. It is connected to a 150 Watt inverter that is running a Nikon EH-5a AC Power Supply Unit.

The best solution on offer is a custom-made DC power system, and this is what I use for powering my cameras for extended periods. Batteries last longer using this method, as you bypass the DC-AC-DC conversion process. It's also very portable—the best of both worlds.

I have built my own all-weather power packs that use 12 volt batteries and a step-down voltage regulator to convert the 12 volts coming from the battery to the 9 volts my Nikon cameras require.

This system can supply the camera with all the power it needs to run continuously for not just hours but days, depending on what battery I connect.

Until recently I have been using Lead-Acid deep-cycle AGM gel cells rated at 10-15 amp-hours to power my cameras. They are cheap, safe to transport, and supply plenty of power, but they do have some issues you need to be aware of.

Continuously discharging them at close to 100% will make their performance degrade rapidly. Even the deep cycle versions which are designed to circumvent this problem will eventually fail if you always fully empty them of their charge.

They are also very slow to charge—you can only supply about 10% of the rated amp-hour current during charging. A 15 amp-hour battery being fed 1.5 amps will take approximately 10 hours to return to full charge after it has been fully discharged. This means you would have to leave it on charge all day to use it again the next night.

The other disadvantage is that because they contain lead, they are quite heavy and aren't terribly good for the environment. The higher the amp-hour rating, the longer the battery will last, but the heavier it will be. This limits their portability, and I am sure you don't want to carry around a 20kg battery with you wherever you go.

Recently I have been experimenting with deep-cycle Lithium Iron Phosphate (LiFePO4) alternatives, and so far they are working really well and deliver close to full power until completely discharged.

They also tolerate being fully discharged much better, and can be charged far more quickly than Lead-Acid batteries. They are also much lighter, environmentally friendly, and very safe to use, unlike some lithium battery varieties, which are a fire hazard or can explode.

LiFePO4 batteries are a lot more expensive to purchase initially, but over time they should work out cheaper, as they can be charged and discharged far more often than the lead acid alternatives.

Lead-Acid gel cell Lithium Ion and LiFePO4 batteries
A variety of 12 volt battery options exist....Lead-Acid gel cell, Lithium Ion and LiFePO4 are just some of the different types of batteries available that can power all manner of electronic devices.

Disclaimer: This next part will involve some electronic skills like soldering. If you aren't confident of doing this yourself, you may need to have a technician do it for you, as there is a risk of damaging your camera. If you reverse the polarity of the power going into your camera or supply it with too much power, you may damage it beyond repair. You have been warned.

After deciding on a battery system, you then need to convert the 12 volts coming from the battery to match the voltage required to power your camera, and there are several ways to do this.

One way is to take apart an old camera battery that is no longer working, or use a cheap after-market battery available for your particular camera model. You then solder a couple of wires from the output of a DC voltage regulator onto the positive and negative terminals of the battery.

Essentially you are using the old battery as a shell and connecting the new battery to its terminals to supply power. You will need to do some research to find the battery voltage required by your camera and which pins on the battery are the positive and negative terminals that supply DC power.

You may also need to remove the old battery cells and bypass any electronics inside the battery, as there is often a printed circuit board present. This PCB is used to monitor charging and other battery functions, but is no longer needed.

Also, some camera manufacturers and third parties supply adapters, which allow you to do the same thing without having to fuss with an old battery. If you can find an adapter for your camera from a reputable source, this is the way to go.

When you insert this dummy battery into the camera, the wires running from it may prevent the battery door on the camera from being closed, and this makes it more prone to water damage.

It also means that if your external 12 volt battery fully discharges during shooting, the camera may not shut down correctly, and you could lose some data present on the recording media.

Making a DC Power System

A better alternative involves cutting the cable from an AC power supply unit and wiring a DC voltage regulator to this cable to provide the required power from a 12 volt DC battery to the camera.

Output cable cut from the power supply unit
I purchased a cheap aftermarket power supply unit from a Chinese manufacturer rather than the more expensive Nikon made EH-5a Power Supply Unit. The only part you will be using is the output cable, which needs to be cut from the PSU. You then connect this to the output from a DC voltage regulator.
DC voltage regulator in a plastic casing
DC voltage regulators (inset) such as the one shown above can be purchased very cheaply via eBay or electronic sales websites. I have mine housed in a plastic casing to protect it from water and dust and cable tied to prevent the wires from being accidentally pulled loose.

Once you have cut the AC adapter cable from the PSU, it has to be connected to the output terminals of the voltage regulator. I have soldered the AC adapter cable onto wires that are then connected using screws on the voltage regulator.

You then connect the input terminals of the voltage regulator to an external 12 volt battery, making sure you have correct polarity. I have added a 10 Amp fused male cigarette lighter plug connection to this cable so I can easily exchange batteries.

All of my batteries use a female cigarette lighter connector to power my devices. This means I can power my cameras using a variety of different battery types.

Voltage regulator diagram
By turning the voltage adjustment screw on the voltage regulator and monitoring the output, you can match the voltage required by your camera.

After you have connected a 12 volt battery, the power coming from the step-down voltage regulator needs to be adjusted to match the voltage required by your camera. In the case of my Nikon cameras, it must be the same as the output from an AC PSU, which is 9 volts.

base of the Nikon AC PSU and pinout assignment diagram for the AC output cable
The base of the Nikon AC PSU has all the information you need...the output voltage is listed as 9 volts at 4.5 Amps. The pinout assignment diagram for the AC output cable is also displayed, with the alignment notch shown at the bottom.

You adjust the output voltage coming from the DC voltage regulator by turning the voltage adjustment screw and monitoring this voltage with a multimeter until it matches the required output.

You must connect the multimeter's probes to the AC output cable's pins with the correct polarity, as shown on the PSU's pinout assignment diagram.

Insert the probes from a multimeter into the pins from the output cable and measure the voltage coming from the DC voltage regulator
Insert the probes from a multimeter into the pins from the output cable and measure the voltage coming from the DC voltage regulator. It should match the polarity and normal output voltage from the AC power supply. In this case the multimeter reads 9.22 volts with correct polarity... close enough to the 9 volts needed by my cameras.

Once you have set the correct voltage and checked polarity, this cable is ready to connect to your camera to supply power.

If you don't own a Nikon camera, you will need to modify the design of this DC power system to suit your own needs according to the camera you have.

You will need to source an appropriate AC cable from a PSU that suits your make and model of camera, and solder it to the DC voltage regulator with the correct voltage and polarity.

One advantage of this system is that when using it with certain cameras, if the external battery becomes depleted it will automatically switch to the internal battery. This means the camera will shut down correctly, storing camera settings and leaving all recorded media intact.

Nikon D7000 camera with EP-5 battery cable and D700 with dedicated AC input terminal
Newer Nikon cameras like the D7000 (left) use an EP-5 battery adapter cable connected to the AC power supply. The D700 camera on the right has a dedicated AC input terminal, meaning you can also leave a standard Nikon EN-EL3e battery in the camera. 

Do You Have Protection?

Once you have completed your modified DC power system, you should buy a weatherproof housing to protect it from the elements. You need to buy one large enough to house the battery, DC voltage regulator, and all of the cables.

12 volt LiFePo4 battery and a cable with a female cigarette lighter connector added
By placing all of the various components into a dry box, you can leave it unattended overnight without worrying about rain or dust damaging the delicate electronics inside. The 12 volt LiFePo4 battery shown has a cable with a female cigarette lighter connector added. This allows the custom-made DC power cable to be plugged directly into it.

It is worth considering some form of protection for the camera as well. Having cables from an AC power supply or a DC dummy battery exposed makes it vulnerable to damage from the elements.

The easiest way of doing this is to use a shower cap—they are cheap, readily available, come in various sizes, and do a fantastic job of protecting your camera from dust and water.

You should also tether your tripod to the ground so that wind or a passing animal does not knock over your tripod. You can see my method for tethering tripods in the previous article I wrote.

Out in the Field

Many night photography subjects are found in remote locations, and getting to them can be a challenge. Having a reliable vehicle and the capability to power everything in the field is an important consideration when running digital cameras in these areas.

It's not just your cameras that require electricity, but also the peripheral equipment you need for a complete digital photography workflow. Batteries need to be regularly charged, digital data needs to be managed and archived, and communications and other electronic equipment all require power to function.

I have spent a great deal of time preparing my vehicle for filming in these locations. It has been fitted with a C-Tek D250s dual battery charging system that allows a deep cycle lead acid service battery to be charged by the alternator when the vehicle is running, or by a 120 Watt solar panel when the vehicle is stationary.

The service battery has a 600 Watt inverter connected to it, which converts the DC electricity from this battery to the AC power required by the electronics I need to run out in the field. I also have two 150 Watt inverters that run from the cigarette lighter connections in my vehicle, giving me a total of 900 watts of power to charge batteries and run electrical devices.

Inverter to convert the DC power from a battery to the AC power needed by electronic devices
Inverters convert the DC power from a battery to the AC power needed by electronic devices.

The service battery has a female cigarette lighter connection permanently attached to it, which can run DC-powered devices such as my laptop computers. I use a DC power supply for my laptops, as they are more energy efficient, and none of the inverters I have are the more expensive pure sine wave versions that many laptop AC power supplies require.

DC power supply powering a laptop computer
Using a DC power supply is a more energy efficient method of powering a laptop computer from 12 volt batteries, as it bypasses the three-step DC-AC-DC conversion process.

I have built two dedicated battery charging stations—one for my camera batteries and the other to charge my lead acid and lithium battery systems. This allows me to maintain charge in these batteries when I am driving or when I am camped at a location for several days, and helps to keep everything tidy and organised.

custom-made Charging Station  DC Power Box
This custom made Charging Station / DC Power Box has two 1.6 amp-hour (Ah) lead acid battery chargers and two 20Ah Lead Acid gel cells housed in an old Panasonic Video camera carrying case. These are two stage battery chargers and can be used on both my Lead Acid batteries and the Lithium Iron Phosphate batteries I use to power my cameras. 
Charging station using three Panasonic battery chargers
This charging station has three Panasonic battery chargers for the lithium ion batteries used to power my Lumix cameras, and I also have a similar setup for my Nikon battery chargers. By securing the chargers in place with cable ties, they can be easily removed if needed. These plastic cases are also stackable, so you can place them on top of one another.

Safety is another important consideration in remote locations. When traveling in these areas you should always take plenty of food and water with you, and consider hiring or purchasing a satellite phone or an EPIRB (Emergency Position Indicating Radio Beacon) in case of an emergency. Better to be safe than sorry.

The next article is my last on photographic equipment, where I will outline some recommended setups for night photography. After that I will move on to a series of articles on shooting techniques, the first of which is about observation, pre-visualisation and composition for night photography.

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