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STAYING IN CHARGE

 

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If you use a mobile phone in your car then it makes sense to power it from the  vehicleís electrical system. Rick Maybury looks at a variety of battery charge and saver cords in this monthís accessory roundup

 

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A carís electrical system is a source of almost unlimited power for a cellular phone, however, itís not just a matter of running a couple of wires to the phone, try it and youíll almost certainly wreck both the phone and its battery.

 

Hereís why. Car and van electrical systems operate over a surprisingly wide voltage range, from under 11 volts or less on a cold day, up to 15 volts on a fast run. Most mobile phones require a steady 6 volt DC supply. Virtually all mobile phones have some form of internal over-voltage protection, but they can only tolerate a few extra volts for a short while, after that itís goodbye phone.

 

It is therefore vitally important to control the amount of current the phone is allowed to draw from the supply; current consumption increases slightly when the phone is in use but it soars if the phone battery is flat. If unchecked it the battery will draw excess current and overheat, resulting in irreparable damage. In addition to the wide voltage variations, car electrical systems can be exceptionally noisy, with all sorts of high and low frequency interference, caused by the ignition and other electrical components switching on and off, which also generate high voltage spikes, that can easily destroy delicate electronic microcircuits

 

A properly designed car power cord can overcome all of these problems. You may also come across car adaptors,  talk-and-charge adaptors and saver-chargers. Most of them are based around a small electronic module, housed inside a bulbous cigar lighter plug, connected by a curly lead to a phone supply or accessory plug.

 

Car adaptors or battery-savers are the most basic, all they do is power the phone. The regulator circuit is usually built inside a dummy battery, which clips on the back of the phone.  Quite frankly we canít see a lot of point to them, if youíre going to use the phone in a car you might as well charge the battery at the same time. Thatís precisely exactly what a talk-and-charge or saver-charger does. Most of them are relatively simple controlled-current trickle-chargers, that supply enough power to keep the battery topped up, and power the phone. The next step up is a car cord with a rapid or fast charger circuit. These also have a controlled output, but operate at higher current levels, that charges the battery in a quarter to a third of the time of a simple trickle charger.  Various charging techniques are used, including negative Delta V -- the system used on most standard and accessory fast chargers -- we have also come across devices that use timed stepped current, and pulse charging systems.

 

 

Just to complicate matters there are a number of other considerations. The most obvious one is the differing charge characteristics of nicad and nickel metal-hydride batteries, which in some cases can mean a NiMh battery never achieves a full charge, no matter how long itís left connected to a power cord. Quite a few phones have their own built-in charging systems, that vary in complexity from simple current and voltage regulators, to intelligent systems that are designed to communicate with the mains power adaptor, needless to say very few accessory car cords have that kind of sophistication. Then thereís the problem of non-standard car cigarette lighter sockets. Bet you thought they were all the same? Well theyíre not, the design varies slightly from make to make of car and in extreme cases the plugs can be a very tight fit, or flop about, making intermittent contact.

 

Okay, so now youíve got a car cord, but  where are you going to put your phone? You should also be thinking about some sort of holder or cradle. By sheer coincidence that just happens to be the subject of next monthís accessory roundup, but if you canít wait hereís some good reasons why you need one. If you leave the phone on a seat or worse still, on the top of the dashboard, it will slide around and probably bump into something, or end up on the floor. Youíll probably get away with it a few times, but eventually it will damage the phone. If the phone is lying flat, and below the carís waistline then reception will be severely impaired and you may miss incoming calls. Then thereís the safety aspect, you shouldnít attempt to make or take calls whilst driving, but this is the real world, and if the phone rings whilst youíre on the move most people will be tempted to try and answer it, without necessarily pulling over to stop. If the phone is not in the driverís field of vision they will have to take their eyes off the road. All it takes is a split second loss of concentration to make it into the accident statistics...

 

Hopefully we havenít put you off, car cords are an extremely useful accessory, and not that expensive, though as usual we have refrained from including any prices in our survey. Manufacturers and distributors are reluctant to give us recommended or suggested prices, and by the time they reach the dealers shelves,  prices end up all over the place.  The majority of the cords weíve looked at are designed to fit the Motorola Micro TAC family of mobile phones, including the Classic and Elite, though in general the regulation and control circuitry will be the same for a lot of other types of phone. However, be aware that some phones have very specific power requirements, or you may invalidate your guarantee if you use a power cord, other than that supplied by the phone manufacturer. If in doubt check.

 

Just a few general comments before we move on to look at the actual chargers. Only a couple of the models weíve looked at came with any instructions, and the oneís that did were very brief.  Most of them were fused, the oneís that were not relied on electronic cut-outs. We subjected them all to direct short-circuits lasting several minutes, in all cases they survived intact, without overheating or making funny smells.

 

A final word of warning. Although all of these car power cords have surge and over-voltage circuits they may not be able to protect the phone against the sometimes considerable voltage spikes that occur when starting a car or van, and in particular if the vehicle is being given a jump-start from another car. Itís a good idea to always disconnect the phone, the cord, or both before starting the car.  

 

 

Aico In-Car Saver-Charger

A relatively straightforward saver-charger though it is unusual in not having a replaceable fuse. The cigar lighter plug was a good fit in all test sockets. A green LED shows power on but not charge status. The polarity identifier on the Micro TAC phone plug not especially easy to see in poor light.

 

Make/model                  Aico AIP SCM0T2

Type                             trickle charger

Features                       single-colour (green) LED power-on indicator, fuseless cut-out

 

Instructions                   none

Build quality                  ****

WC Rating                    80%

 

Contact AICO INTERNATIONAL, Aico House, Faraday Rd, London Road Ind Est, Newbury, Berks RG13 2AD. Telephone  (01635) 49797

                       

 

Algon Charger Cable

Chunky rapid charger, protected by a 2A fuse. Sophisticated (for a car cord) negative Delta V charging system  with two colour (red/green) LED indicator, that shows when charging has finished, whereupon it automatically switches to trickle-charge mode. Micro TAC phone plug polarity identifier not easy to see in poor light. Fast and effective.

 

Make/model                  Algon 10.915

Type                             rapid charger with -Delta V/timer operation

Features                       controlled fast/trickle charging, 2-colour (red/green) charge indicator, replaceable 2A fuse

 

Instructions                   none

Build quality                  *****

WC Rating                    90%

 

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

                       

 

Andrew Rapid Charger

Very unusual rapid charger with slide-action cigarette-lighter module, that firmly grips any size or type of socket. It has a clip instead of an accessory plug, that attaches to the back of the battery pack. No replaceable fuse, but it does have an automatic electronic cut-out. It has a two colour (orange/green) LED to show charge status, and a microscopic switch on the back for standard or high-capacity batteries. The cigar lighter plug is easy to remove, once you learn the trick, the battery clip is more difficult. Generally well designed and very effective.

 

Make/model                  Andrew Rapid Charger

Type                             rapid charger

Features                     controlled fast/trickle charging, 2-colour (orange/green) charge indicator, custom-fit lighter plug, battery clip

 

Instructions                   ****

Build quality                  *****

WC Rating                    90%

 

Contact            ANDREW Ltd, Ilex Building, Mulberry Business Park,

Fishponds Road, Wokingham RG11 2GY. Telephone (01734) 776886

 

Andrew Saver Charger

Simple saver-charger with green LED power-on indicator. The plug-in cigarette lighter module is the same push-fit design as the rapid charger, though this time it has a standard phone accessory plug, instead of a battery clip. Unfortunately the one on our sample made an intermittent contact when pressed lightly. Raised bump on Micro TAC plug helps to identify which way round it goes. A good design, and it would have rated much higher but for the wonky plug.

 

Make/model                  Andrew Saver Charger

Type                             controlled current charger

Features                       push-fit cigar lighter plug, fuseless electronic cut-out

 

Instructions                   ****

Build quality                  **

WC Rating                    75%

 

Contact            ANDREW Ltd., Ilex Building, Mulberry Business Park,

Fishponds Road, Wokingham RG11 2GY. Telephone (01734) 776886

 

 

Hama Power Supply and Charger Module

Big ugly-looking saver-charger, electrically quite basic with simple chipless regulator circuit. It has a large red LED power-on indicator and is protected by a 1.5 amp fuse. No polarity identifier on Micro TAC plug, a real nuisance in the dark.

 

Make/model                  Hama 41160

Type                             saver charger

Features                       red LED power on indicator, 1.5A fuse

 

Instructions                   none

Build quality                  ***

WC Rating                    70%

 

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

 

 

Hama Power Supply and Charger cable

A marked contrast to the 41160, even some evidence of styling with its banana-shaped body. Altogether more sophisticated with microchip controlled charging circuit and green power-on indicator. Micro TAC 8200/Flare plug on our sample a poor fit.

 

Make/model                  Hama 41171

Type                             saver-charger

Features                       green LED power on indicator, 1.5 A fuse                 

 

Instructions                   none

Build quality                  ****

WC Rating                    80%

 

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

 

 

Ora Power Cord

Simple and to the point, controlled current saver-charger with red LED power-on indicator. Comes supplied with interchangeable cigar lighter plug tip, to suit different types of socket. Operates on 12 or 24 volt supplies. Micro TAC plug has moulded polarity identifier and highly visible white spot.

 

Make/model                  Ora MOTCP5

Type                             controlled current saver-charger

Features                       12-24 volt supply, red LED power-on indicator, 1.5A fuse, interchangeable plug tip

 

Instructions                   none

Build quality                  *****

WC Rating                    90%

 

Contact ORA  28/29 Faraday Road, Aylesbury, Bucks HP19 3RY. Telephone (01296) 415445

 

Power Wave Plug-In Charger

Fairly conventional design saver-charger with a controlled current output, red LED power-on indicator, and 12 or 24 volt operation, protected by a 2A fuse. Replacement of the latter needs care, the fuse is held in position by a small spring, if itís inserted before the fuse both it, and the fuse become firmly wedged inside; there are no instructions to make this point. The Micro TAC accessory plug has a moulded polarity identifier though it would still be quite difficult to tell which way round it is in the dark

 

Make/model                  Power Wave Plug In Charger (Nokia)

Type                             controlled current saver-charger

Features                       12-24 volt supply, red LED power-on indicator, 2A fuse

 

Instructions                   none

Build quality                  ****

WC Rating                    85%

 

Contact GRM Ltd., GRM Building, Copse Road, Fleetwood, Lancashire FY7 6RP. Telephone (01253) 773177

 

 

Power Wave Plug-In Charger

A more advanced stepped-current pulse charger that gives the battery a more thorough charge by cycling high and low currents. Our test sample was designed for Nokia phones. In common with all other Power Wave saver-chargers it will work on 12 and 24 volt supplies (used on commercial vehicles, trucks etc.), in fact they claim it is safe up to 60 volts. Fast and efficient.

 

Make/model                  Power Wave Plug In Charger (Motorola)

Type                             stepped current pulse charger

Features                       green LED power-on indicator, 2A fuse

 

Instructions                   none

Build quality                  ****

WC Rating                    90%

 

Contact GRM Ltd., GRM Building, Copse Road, Fleetwood, Lancashire FY7 6RP. Telephone (01253) 773177

 

Vivanco Car-Adapter

About as simple as it gets, this car adaptor is designed just to power the phone from the carís electrical system. The regulator circuit is housed inside a dummy battery pack, which fits on the phone in place of the normal battery. The cigar lighter plug has a green power-on indicator, and it contains a 2A fuse. It works, and thatís about all there is to say about it.

 

Make/model                  TAM-400

Type                             car adaptor

Features                       green power-on indicator

 

Instructions                   ***

Build quality                  ****

WC Rating                    70%

 

Contact            VIVANCO, Unit C, ATA House, Boundary  Way, Hemel Hempstead HP2 7SS. Telephone (01442) 231616

 

Vivanco Plug-In Car Adapter

Call us old-fashioned, but weíre slightly bemused by this saver-charger, which whistles. Thereís a distinct high-pitched Ďsissingí noise coming from this one, itís not very loud, and you wouldnít hear it above normal road noise, but it is very strange. The charger itself is an advanced controlled current design with 2-colour LED indicator, though due to the lack of instructions you have to work it out for yourself that orange indicates a fast charge rate, green shows charging has been completed

 

Make/model                  TSM 5/7

Type                             rapid charger

Features                       2-colour (orange/green) charge indicator, 2A fuse

 

Instructions                   none

Build quality                  ****

WC Rating                    85%

 

Contact            VIVANCO, Unit C, ATA House, Boundary  Way, Hemel Hempstead HP2 7SS. Telephone (01442) 231616

 

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R. Maybury 1995 3011

 


 

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