Every professional cameraman will, at some point, confront the battery issue, occasionally with foresight, usually with hindsight. Batteries are the least exciting part of your high tech, precision engineered, and expensive kit. Yet battery power, or the lack of it, is the most likely cause of irritation, unforeseen costs and delay or indeed ultimate failure […]
Every professional cameraman will, at some point, confront the battery issue, occasionally with foresight, usually with hindsight. Batteries are the least exciting part of your high tech, precision engineered, and expensive kit. Yet battery power, or the lack of it, is the most likely cause of irritation, unforeseen costs and delay or indeed ultimate failure missing that shot that professional cameramen will face. Sometimes there are no second chances!
There is a bewildering array of cell technologies on the market. NiCad is hardly used; NiMH is, and indeed sales are increasing due to the high power demands of Digital Cinema cameras and 3D rigs, but its not popular for shoulder-mounted cameras, due to the weight of the large cell types and the shorter cycle life of the small cell types. NiMH requires sophisticated charging, using temperature algorithms, too complex for most modern chargers. NiMH benefits include no safety or environmental issues, thus no transport or air travel restrictions and, higher weight balances a front-heavy camera. So for frequent flyers, needing a high capacity battery to run a big camera with a large HD lens, NiMH is still the way to go.
Nonetheless, the market has moved to Lithium ion. In the past, this was mainly based on a single size, 18650 commercial 3.6V cell. A 4S3P (in series and parallel) pack makes up a 14.4V battery. The advantage is lightweight; the limitations are low tolerance for high loads (above 5-6A,) such as lighting, and the relatively shorter life expectancy, higher costs and more recently transport restrictions. Why? The Li-ion electrolyte has a low flashpoint, low tolerance to overcharge, and increased volatility if over-discharged.
Sophisticated safety electronics are required poorly designed and manufactured cells can be hazardous, and one cell will then ignite the entire pack, the last thing one wants on a passenger aircraft. US authorities recorded over 100 incidents in 2007, which led to a total ban on transporting Li-ion batteries in the hold of a passenger aircraft and limitations on hand luggage, with a complete ban on 160+Wh batteries and a hand carry limit of two batteries over 100Wh. US authorities can fine a maximum of $250,000; other countries tend to confiscate, delay ( Beijing Olympics) or do nothing, some of the time. The result is confusion.
Massive technical progress in cell chemistry driven by the laptop and the automotive industries has changed things. Quick charging, while technically feasible, yet commercially still too expensive, is probably just around the corner. A new generation of cells has overcome the high load issues, and doubled life expectancy. These new lightweight, high current, cell packs capable of handling 10A so in demand with ENG crews and Steadicam operators are now available.
More than 12 different variants of Li-ion, chemical mixes on anode and cathode material (Manganese, Iron Phosphate, etc.) and more in the pipeline are flooding the market. New cell manufacturers have appeared with varying levels of quality. The result: more choice, but also more uncertainty, more safety incidents and more pressure to restrict.
Millions of cell packs have been recalled in the past years, due to safety concerns, resulting in huge costs. One well known corporation lost US $500 million in one recall. This year, incidents of low-cost video batteries exploding included a serious fire at a Japanese broadcasters facility. Other batteries have smoked and flamed in the kit room.
HOW DOES A PROFESSIONAL CHOOSE THE RIGHT BATTERY?
Feedback from potential customers unhappy with the reliability of their batteries, show that most field issues are related to two recurring themes:
The customer has selected, or, more accurately, has been sold, the wrong battery for their application, normally, because the camera features and total price dominated the sales discussion.
The battery was fine, but has deteriorated and suddenly fails, and the customer had no way of anticipating this. Bit like jumping blindfold off the skyscraper, not the fall that killed, but the impact.
To achieve reliability, the best advice is to focus on application needs first, considering the points below, then consider the price!
Power requirements are on the rise, thanks to HD, 3D and solid state memory. If your camera draws 45W and your light 35W, your average load is c. 57W (Fill lights are typically used 1/3 of the time). If you use on-board monitors, wireless transmitters, etc, you need to factor them in.
Remember, most camera specs are not overestimates! Lights feed off power taps, that can be regulated at 12V (Sony Camera) or unregulated, in which case, add 25% so 35W is actually 43W.For both ENG and production, the battery should run the application for at least two hours. This avoids multiple unplanned battery changes; a four battery system should give one change in the morning and afternoon and one at lunch.
Note: A new 100Wh battery might have 80Wh or 50Wh after six months.
Ignore this at your peril! If you run a 45W camcorder, a 35W light and 10W accessories, your continuous load is 90W. The startup spike is much higher. So if your battery specs state: maximum continuous 73W, problems are pending. So plan your load and get a suitable battery. If there are no maximum load specs, its probably not a suitable battery!
Batteries are almost human, everyone will die at some point, but long before that, theyre ripe for retirement. You need the tools to manage that decline; ideally a smart battery, with digital display giving both percentage and remaining runtime and access to a test charger that can cycle a battery and document results. If your battery has an LED, that only shows full or empty, regardless of whether full means two hours run-time or two minutes, youre the man with the blindfold! Replace batteries below 60% of initial rated capacity and manage and mix your inventory, so that no cameraman has all batteries below 80%.
Most professionals will factor safety into their purchase decision or so we think. The fact is that most batteries on the market are not considered safe by leading cell manufacturers, and many customers do not understand the risk or consider liability. With regards to travel, the international IATA regulations are clear, but is there any enforcement in the Middle East?
This will probably only change after a major airline incident.
Customers often ask why the price differentials are so significant. Manufacturers can purchase standard cells cheaply in batches from wholesalers; or premium cells direct from a leading cell manufacturer, pre-tested with cells matched for balance for longer life. Precision tooling, clean room manufacturing, all add to costs, but also to safety, reliability and better life. Your supplier will have made this choice for you. Housings can be cheap and simple or designed to spread impact. Internal wiring can be channeled or not. On-board electronics can vary dramatically in component quality and software sophistication. Electrical contacts vary enormously.
The best are self cleaning; have high surface area contact; are gold plated and high current capable; and ideally mechanically fixed to avoid wear. Many batteries are attached to the camera at one central point, better is at least a wide base 3 or 5 point connection with locking mechanism. This is all simple logic, widely ignored. The old adage you get what you pay for, applies here.
Although we were asked to talk batteries, in the industry, we know that the charger, if smart, is the key to a good battery system. If your battery manufacturer proudly claims: use any charger, it just underlines the lack of sophistication required. Ideally, your charger will have two way communications with the battery, an ability to test and calibrate, and it will have temperature channels and be upgradeable for implementation of future algorithms as technology develops. A good charger is a long-term investment, often used for 10-20 years.
A range of sizes, capacities, cell chemistries, a selection of chargers, from small travel, to multi-position, to test chargers and nowadays even car and solar chargers, and a wide range of accessories make a complete battery system.
Heat is a battery killer. Li-ion electrolyte crystallizes with permanent damage above 55°C, but, also the higher the ambient temperature the quicker the irreversible decline in capacity. Store batteries cool and do not let them become deep discharged, i.e. empty. Avoid loads above the recommendations and remember it is an electronic product; physical abuse will cost.
Price Warranty Service. Reliable battery systems are an investment. Warranty, service, the reputation and financial stability of the manufacturer, are key factors, next to price, determining the longer term cost of ownership. And just like with you, your value cannot be expressed in an hourly rate; it is about the quality of your kit, your experience, creativity, knowhow and track record.