VIDEO CAMERA 1995

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SHOP WINDOW -- BATTERIES 95

 

INTRO

Yes, it’s that time again, the annual, the exclusive, the one and only Video Camera camcorder battery test, warts and all....

 

COPY

Ask any camcorder owner what aspect of video movie-making they’re most dissatisfied with and it’s a fair bet most of them will come up with the same reply -- batteries. They’re definitely the weak link in the chain. They never last long enough, always running out at the worst moment, and have comparatively short lives, at least that’s the way it looks. The truth is it doesn’t have to be that way. A typical nickel-cadmium battery can endure over 1,000 charge/discharge cycles before there’s any significant reduction in capacity, that equates to a five or six year life. In practice most camcorder owners will be lucky to get more than a couple of hundred cycles from their battery packs before they need replacing, but why?

 

The problem is simple, nicad batteries work best when they’re charged slowly and gently, at the so-called overnight or ‘C/10’ rate, which takes around 14 hours. They should also be fully discharged before being re-charged, and ironically, last longer when they’re used regularly. Compare that with what happens in real life. Camcorders are used intermittently, in short bursts with weeks, sometimes months of inactivity; battery packs are fast-charged in an hour or so, which accellerates wear and causes them to go into an overcharge condition, which further reduces efficiency. Camcorders never full discharge the battery, they have safety cut outs which may leave the battery with a 25% charge (so the tape can be unlaced and ejected). Moreover, most owners give their batteries repeated ‘top-up’ charges, which encourages what has become known as the memory effect, and after just a few months of this treatment the battery’s capacity falls off sharply.

 

It’s unlikely any manufacturer will every supply a slow-charger as standard, but there’s nothing to stop them designing dual-mode chargers, giving owners the option to treat their batteries more kindly. Quite a few of them now fit dischargers or refresh circuits to their mains chargers nowadays, these certainly help to reduce the possibility of cell-imbalance, one of the main precursors of the memory effect. Accessory dischargers are widely available for about twenty pounds, and with regular use there’s no reason why a nicad pack shouldn’t last for at least 500 cycles, that’s between two and three years for most users, which isn’t too bad.

 

TESTING TIME

That brings us neatly to this year’s mega battery test. We’ve made some changes, nothing too drastic; this year, for the first time we’re looking at the growing number of 4.8 volt packs, designed specifically to fit Panasonic machines (and clones). We were thinking about starting a separate section for nickel metal-hydride batteries but a couple of manufacturers declined to supply us with samples and in the end we didn’t have enough of them to make any meaningful comparisons. Maybe next year? We have dropped the charge-time figure, this has little or no bearing on actual performance, but rest of the tests remain exactly the same, so we can continue to compare the results from previous surveys.

 

Each battery is taken through a series of three charge/discharge cycles, to eliminate any cell imbalance, and to put them all on an equal footing. We then use each battery to power a Sony CCD-V6000 camcorder, in the manual record mode, and note how long it runs. This is repeated three times and we work out an average time. We use the V6000 for three reasons, firstly it’s a big, power-hungry machine that really tests each battery to the limit; second, it speeds things up, as it is the survey takes the best part of a month to carry out. Lastly, we can accurately compare the results with those from previous years. Incidentally, the recording times we achieve on the V6000 are about half what you might expect to get on a typical palmcorder or compact machine.  Consistency is important, so we use the same mains chargers and dischargers that we use every year.

 

We only test higher capacity packs, typically 1.8 Ah to 2.4Ah, and we ask each manufacturer if they would like to submit their highest rated clip-on battery as well. We specify Sony-fit packs, though increasingly manufacturers are moving over to multi-fit batteries. Whilst this has little or no impact on price, and no effect whatsoever on efficiency, we have noticed one or two packs have trouble fitting on some chargers. This is normally caused by the mounting lugs not activating a hidden safety switch on the charger’s face plate. Where this is the case we alert the manufacturer; so far they’ve all acknowledged the problem and assured us that there are will be no problems with future stocks. We’ll take their word for it, though if you come across any fitting problems please write in and let us know about it.

 

As far as nickel-metal hydride packs are concerned we use the same basic tests, though we have discovered that there can be problems with some chargers. This can result in the chargers switching off too early, so the battery never receives a full charge. The solution is to remove the battery, wait a few minutes and replace it on the charger again, in most cases the battery continues to charge to full capcity. However, one manufacturer told us that their NiMh batteries only charge properly on their own, purpose-designed charger, unfortunately it is not available in the UK, so we’ve left them out of the test. The test routine is also the same for 4.8 volt packs, though this time we use a Panasonic charger and an S90 palmcorder to check the running times. 

 

The data from the tests are used to calculate basic performance and value for money figures. We also compare the results with previous battery tests, which helps us to identify any trends. The results are condensed into a simple to understand star-rating which appears on the table on page XX.

 

In case you were wondering why we haven’t also tested lithium-ion accessory batteries as well, there aren’t any, apart from the Sony made ones supplied with their camcorders, and a handful of top-end machines from Hitachi and Canon.

 

SIDEBAR 1 -- HISTORY LESSON

Say happy birthday to your camcorder battery, the technology is ninety six years old this month. Way back in 1899 a Swiss scientist called Carl Jungner established the chemistry of the re-chargable nickle cadmium cell. In fact nicad batteries, as we know them today have only been around since the second World War, when the first sealed cells were developed. It was another twenty-five years before they were were sufficiently cheap, efficient and long-lived to be any use in domestic equipment. It didn’t happen overnight though, prices remained high for a long time; by the end of the sixties they were being used in torches and radio-controlled model aircraft. During the 1970s they progressed to electric razors and toothbrushes, then in the 1980s the microchip revolution gathered momentum and suddenly we were surrounded by dozens of power-hungry battery-powered electronic gadgets. Although nicads remained expensive they were still cheaper than disposable batteries in the long run. Some devices wouldn’t have existed without them, the cordless telephone for instance, and other developments which we now take for granted owe their existence to nicads. Electronic push-button tuners on televisions are another example. Before the development of non-volatile memories the only way to ensure station settings were not lost when the TV was turned off was to keep the tuner’s memory chip permanently energised by -- you guessed it -- a nicad battery. Today they do a thousand and different jobs, from keeping the clock running in a personal computer, to acting as standby power sources in telephone exchanges and hospitals.

 

You would have thought by now someone would have come up with an alternative to the nicad, after all, its getting on a bit now. They have comparatively short lives and there’s some concern about the impact the noxious brew of chemicals inside a nickel cadmium battery can have on the environment, if they’re not disposed of properly, (video, photographic and electrical accessory dealers know what to do with them). However, it looks as though they’re going to be around for a good long time to come. The most promising newcomers are nickel metal-hydride and lithium-ion, but neither of them can compete with nickel-cadmium on all counts. Both types of battery have higher power-densities -- ie they pack more energy into a smaller space -- and they don’t suffer from the dreaded memory effect, but they are still more expensive, and because of their higher internal resistance, neither can deliver continuous high currents for any length of time, they’re unsuitable for power tools, for example. Nevertheless we can expect to see more of both in specialised low-current applications, like camcorders and computers, and over time they should become a lot cheaper.

 

SIDEBAR 2 -- INSIDE STORIES

Camcorder battery packs are not, as many people suspect, miniature car batteries, they’re simply containers for banks of individual cells, similar in shape and design to disposable AA cells. Each cell has a 1.2 volt output, so to get the required 6 volts five of them are wired together in series. Higher capacity packs contain two or more banks of cells, wired together in parallel. Most battery packs contain a number of safety devices, including a thermal fuse, thermistor (changes electrical resistance whit it gets hot), and a polyswitch or fuse, which blows if the contacts are short-circuited.

 

Nickel cadmium and nickel meta-hydride cells are similar in construction. The cell is made of two thin metallic plates, separated by a porous insulator. The plates are then rolled tightly into a cylindrical shape. In the case of a nicad cell the plates are treated with cadmium and nickel compounds, and the seperator is soaked in a potassium hydroxide electrolyte gel. When charging a constant current passes through the cell, cadmium hydroxide on the negative plate is transformed into cadmium metal, and nickel hydroxide on the positive plate changes to nickel oxyhydroxide. During discharge current flows in the opposite direction, through an external circuit, and the chemical processes are reversed.

 

Nickel metal hydride cells have a similar construction to bicads, but a different chemistry. Nickel hydroxide is produced from the positive electrode and metal hydride on the negative electrode during the charge phase, when the cell discharges they change back again.

 

6-VOLT PACKS

 

MAKE/MODEL

Ah

££s

RT

£/min

£/Ah

RATING

Bandridge VB466C

1.8

30

45

0.66

16.6

 

Bandridge VBL466E   

2.4

40

66

0.60

16.6

 

Batpack SB67H

 

19

 

 

 

 

Cullmann 8165            (d,e)

 

 

 

 

 

 

DSM Ultimate UH1      (c)

1.9

30

57

0.52

15.7

 

Duracell DR11           (a,e)

3.0

 

72

 

 

 

Hahnel Cam Pack 2000 (e)

2.0

24

44

0.54

12.00

 

Hahnel Cam Pack 2400 (e)

2.4

45

56

0.80

18.75

 

Hama CP408

2.4

50

48

1.04

20.83

 

Hama CP409

3.3

75

93

0.80

22.70

 

IQ NP88

3.3

50

68

0.73

15.15

 

Keene NP77-24

2.4

35

64

0.54

14.58

 

Keene NP77-33

3.3

50

81

0.61

15.15

 

Millennium 4060A      (c,e)

2.0

40

61

0.65

20.00

 

Optronix OP-3S            (d)

 

37

 

 

 

 

Sunpak RB-77E

 

37

 

 

 

 

Sunpak RB-800V

 

44

 

 

 

 

Sunpack RB800VL

 

50

 

 

 

 

Uniross VP66S

2.4

43

62

0.69

17.91

 

Uniross VP246  (e)

2.4

50

57

0.87

20.08

 

Uniross VP330  (e)

3.0

55

66

0.83

18.33

 

Varta V110 (e)

2.4

40

61

0.65

16.66

 

Varta V210 (a,e)

3.0

60

62

0.96

20.00

 

Vivanco BP2406

2.6

40

58

0.68

15.38

 

Vivanco BP3336 (e)*

3.3

40

71

0.56

12.12

 

 

* due to be discontinued, hence unusually low price

 

4.8 VOLT PACKS

 

MAKE/MODEL

Ah

££s

RT

£/min

£/Ah

RATING

Bandridge VB364D

2.0

30

46

0.65

15.00

***

Hahnel Campack 4.8

2.4

44

66

0.66

18.33

**

IQ BS10E

1.2

18

35

0.51

15.00

****

Keene NP10-26

2.6

35

62

0.56

13.46

*****

Panasonic VSB0190

1.3

35

40

0.87

26.92

*

Uniross VP260

2.6

40

62

0.64

15.38

***

Varta V201 (a)

1.6

43

44

0.97

26.87

*

Vivanco BP-2468

2.6

40

77

0.51

15.38

****

 

Key:

Ah - stated capacity in ampere-hours; RT - recording time in minutes; £/min -- price per minute of running time; price per ampere-hour;

Rating -- out of ten

 

Notes:

(a) nickel metal-hydride

(b) built-in accessory shoe

(c) 7.2 volt output

(d) power indicator

(e) multi fit, ie Sony, JVC & Panasonic

(f) supplied with carry case

---end---

© R.Maybury 1994 XXXX

 

 


 

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