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BATTERY CARE

 

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ASSAULT ON BATTERIES

 

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The battery is the hardest-working component in your cellphone. They’re subjected  to continual abuse and lead short, miserable lives, but it doesn’t have to be like that...

 

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Did you wait for the low battery warning on your phone to flash, before you put it on charge? Probably not, we’re all guilty, but by continually re-charging a battery before it has properly discharged, its life will almost certainly be shortened. 

 

Nickel cadmium (nicad), and to a lesser extent, nickel metal-hydride battery packs do not respond well to repeated top-up charges, after a while they become accustomed to shallow charge-discharge cycles and eventually their capacity will be reduced. That’s only part of the problem, though. The fast-chargers supplied with most phones actually shorten the lives of the cells inside the battery by over-charging them slightly each time. The combined effects of this treatment typically result in a halving of life expectancy, from a potential of 1,000 or more cycles, to 500 or less, depending how often the phone is used. A battery that might otherwise have lasted a couple of years may need replacing after just a few months.

 

It doesn’t have to be like that, the first thing to do is to avoid top-up charging. Leave the phone switched on when you come home, and don’t put it on the charger until the battery warning comes on or the phone switches itself off, that will go some way to help prevent cell-imbalance, which gives rise to the so-called memory effect.

 

Cell imbalance or ‘memory’ occurs when the cells inside the battery reach varying states of charge. Most fast chargers work by sensing a small drop in voltage and a rise in temperature in the pack, but this can happen when only one cell has reached full charge, leaving the others with a partial charge, and hence a reduced capacity for the pack as a whole.

 

However, careful charging won’t help batteries that have already developed a memory, but there’s something you can do about that as well. Cell imbalance can be eliminated by discharging all of the cells in the pack, so that they’re on an equal footing the next time they’re charged. In practice it can take several complete charge/discharge cycles to completely restore the pack’s capacity, and even then it may never fully recover, due to the damaging effects of fast charging, but if the battery is still relatively new, regular discharging or ‘conditioning’ can significantly extend a battery’s useful life.  

 

Discharging is not simply a question of draining the battery, moreover the contacts should never be short-circuited. This will almost certain blow an internal fuse, or rupture the cells; in extreme cases this could result in an explosive release of super-hot gasses, and you would not like that! Nicad and NiMh cells must never be discharged to less than 1 volt per cell, doing so risks a condition known as deep-discharge or reverse polarity, which effectively destroys the cells.

 

That brings us to the subject of this months accessory review. We’ve been looking at a selection of chargers, that have built-in dischargers or conditioners. They have specially designed restive loads that give a controlled discharge, with a safety cut-out, that protects the cells from over-discharge. 

 

To assess how well they work we’ve tried them with a selection of batteries of known performance, both new and old, and checked their capacities before and after each charge/discharge cycle using the same procedures we developed for our standard battery tests. We also measured the charge and discharge currents, and cut-off voltages, to ensure they wouldn’t cause any damage to the batteries they’re used with. For the record all the units were satisfactory, though one or two of them were quite close to what we would consider to be the minimum safe cut-off voltage. 

 

In general it’s inadvisable to discharge NiMh batteries, they can develop cell imbalance but they have a higher self-discharge rate than nicads and the charge will eventually drain away. If you have a NiMh pack that has developed a memory put it to one side for two or three weeks, and try again, it might well recover on its own. All of the chargers we’ve tested say they can be used safely with both types of battery, though none of them mention that NiMh packs have different charge characteristics, and may not achieved full charge when the charging cycle is completed. We have found that in most cases full charge is reached by removing the battery for a couple of minutes, and replacing it on the charger.

 

For once we’ve managed to pin-down manufacturers and suppliers to recommended or suggested retail prices, though be warned they’re for guidance only and the street prices may be appreciably lower. By the way, cell phone accessory dealers always leave off the VAT, the prices we’ve shown are VAT inclusive.

 

ALLGON ALL-CHARGER

Unusual desk-top or wall-mount design with flip out stand on the back. All-Charger can accommodate both the phone and a spare battery, at the same time. The instructions are not very clear on this point but it only discharges the battery pack, and not the battery which is on the phone. The phone was a tight fit on our sample, we later discovered the contact plate had worked loose, but it was a simple matter to click it back into place. Charging starts automatically when the phone or battery is inserted, discharge mode has to be manually selected. The indicator for the solo battery back charger is a bit confusing, it changes to yellow whilst discharging, and green when fully charged, but there’s not a lot of difference between yellow and green. Discharge current is below 300mA, which gives a discharge time of around 3-hours on a 1AH pack. Charge performance is good, all batteries were restored to full capacity. Worth considering.

 

Make/model            Allgon All Charger

Typical price             £50

Suitable for            most makes, inc. Maxon 450, Ericsson 237/337, Motorola 5200, 7200, 8200, Flare, International, Elite, Nokia 2010, 2110, Orange 2140

Indicators            green LED for power on, dual colour (red & yellow) LEDs for charge and discharge

Features            simultaneous charge for battery and phone, discharge on pack only

Power source            plug-in mains module

 

Performance            ****

Ease of use            ***

Build quality            ***

 

VERDICT            80%

Contact            ALLGON ANTENNAS, Unit 11, The Courtyard Whitwick Business Park, Stenson Road, Coalville, Leicester LE67 3JP. Telephone (01530) 510013

 

 

HAMA IC HANDY CHARGER

Neat desktop charger/discharger unit for a single battery pack. Various types and styles of battery can be accommodated using an interchangeable adaptor plate. The device automatically senses battery voltage (4.8, 6 or 7.2 volts), which is displayed by one of three red LEDS. Battery capacity is shown graphically by a small LCD panel. Charging starts immediately, the discharge mode has to be manually selected by pressing a small button. Discharge time is around 2.5 hours on a 1AH pack with a current of 350mA.  A buzzer sounds and LED flashes when charging is complete and unit reverts to a trickle charge condition. It gets quite warm, so avoid leaving it on highly polished or delicate surfaces. A little pricey though performance is good and the discharge cut-off point on our sample was spot on the 1.0 volt safety limit.

 

Make/model            Hama 41060

Typical price             £70

Suitable for            Ericsson GH337, Motorola Micro TAC, Nokia 1011/2110, Seimens S1

Indicators            LCD capacity indicator, LEDs for power, charge, discharge and battery voltage

Features            single, multi-voltage battery charger with audible alarm

Power source            plug-in mains adaptor and car battery cord (supplied)

 

Performance            ****

Ease of use            ****

Build quality            ****

 

VERDICT            75%

Contact HAMA Unit 4 Cherrywood, Chineham Business Park, Basingstoke, Hants RG24 OWF. Telephone (01256) 708110

 

 

ORA FAST CHARGER PLUS

Simple desktop charger for single battery packs. Slot in the battery and the charging cycle begins, accompanied by a slightly irritating high-pitched whine. When charging is complete the red LED indicator flashes green. Discharge is manual, by pressing a small button on the top panel. There’s no power indicator, so unless a battery has been inserted there’s no way of knowing if the unit has been switched on or not. Charge current is a little below average, so it’s fairly relaxed in operation, but that’s no bad thing, a 1Ah pack takes just over 3-hours to charge from flat. Discharge current is 300mA, giving a discharge time of around 3-hours. Good performance with all packs fully charged. Good value, reccomended.

 

Make/model            Ora Fast Charger Plus

Typical price £40

Suitable for            most popular makes

Indicators            dual-colour LED for charge cycle and single colour LED for discharge

Features            single battery charger/discharger

Power source            plug in mains module

 

Performance            ****

Ease of use            *****

Build quality            ****

 

VERDICT            85%

Contact ORA  28/29 Faraday Road, Aylesbury, Bucks HP19 3RY

Telephone (01296) 415445

 

 

ORA QUICK CHARGER CONDITIONER

Smart-looking desk-top charger for a single battery pack. Easy to use, charging starts as soon as the pack is connected, with the option to run through a discharge cycle. Built-in sensor automatically checks if battery suitable for fast charging (i.e. no internal thermal cut-out) and alerts user with warning buzzer. Plenty of good advice and warning messages in the instructions, though they incorrectly state that it is powered from a 120 volt AC source. Charge state shown by a row of LED. Higher than average charge current will charge a 1Ah pack in around an hour. No power-on indication when unit is connected to the mains (but not operating). Discharge current of just below 400mA, a little on the high side but satisfactory. Cut-off voltage very close to 1.0 volt. Good performance, all packs fully charged. Worth considering.

 

Make/model            Ora Quick Charger Conditioner

Typical price             £50

Suitable for            most popular makes

Indicators            LEDs for charge level and discharge mode

Features            single battery charger/discharger

Power source            plug-in mains adaptor, car power cord (supplied)

 

Performance            *****

Ease of use            ****

Build quality            ****

 

VERDICT            80%

Contact ORA  28/29 Faraday Road, Aylesbury, Bucks HP19 3RY

Telephone (01296) 415445

 

 

UNIROSS UNIVERSAL FAST CHARGER/DISCHARGER

Very similar to the Hama unit (some might say identical...), though on paper at least it’s a tad cheaper and the discharge cut-off voltage on this particular sample was very slightly higher. Similar general comments apply though, it runs quite warm, and even though the guide price is a little lower it is still quite pricey.

 

Make/model            Uniross UCC1

Typical price            £64      

Suitable for            most makes (with suitable adaptor plate)

Features            single, multi-voltage battery charger with audible alarm

Power source            plug-in mains adaptor and car battery cord (supplied)

 

Performance            ****

Ease of use            ****

Build quality            ****

 

VERDICT            78%

Contact            UNIROSS Unit 4, Blackfriars Road, West End Trading Estate, Nailsea,  Avon BS19 2DJ. Telephone (01275) 858101

 

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Ó R. Maybury 1995 1110

 


 

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