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ACCESSORIES
HEAD
STAYING IN CHARGE
INTRO
If you use a mobile phone in your car then it
makes sense to power it from the vehicle’s
electrical system. Rick Maybury looks at a variety of battery charge and saver cords
in this month’s accessory roundup
COPY
A car’s electrical system is a source of
almost unlimited power for a cellular phone, however, it’s not just a matter of
running a couple of wires to the phone, try it and you’ll almost certainly
wreck both the phone and its battery.
Here’s 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 it’s 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 can’t see a lot of point to
them, if you’re going to use the phone in a car you might as well charge the
battery at the same time. That’s 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
it’s 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 there’s the problem of non-standard car cigarette
lighter sockets. Bet you thought they were all the same? Well they’re 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 you’ve 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 month’s accessory roundup, but if
you can’t wait here’s 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. You’ll
probably get away with it a few times, but eventually it will damage the phone.
If the phone is lying flat, and below the car’s waistline then reception will
be severely impaired and you may miss incoming calls. Then there’s the safety
aspect, you shouldn’t attempt to make or take calls whilst driving, but this is
the real world, and if the phone rings whilst you’re 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 driver’s 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 haven’t 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 we’ve 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 we’ve looked at
came with any instructions, and the one’s that did were very brief. Most of them were fused, the one’s 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. It’s 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 it’s 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 car’s 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 that’s 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 we’re slightly
bemused by this saver-charger, which whistles. There’s a distinct high-pitched ‘sissing’
noise coming from this one, it’s not very loud, and you wouldn’t 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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Ó R. Maybury 1995 3011
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