SuddenStop License Plate Frame
An extra margin of safety against being
The SuddenStop license
plate frame can be seen in this image - the vertical strips
of red lights on either side of the license plate.
It is a subtle rather than in-your-face obvious extra
indicator, but the flashing (of course not apparent in the image) helps
make it stand out some more.
Have you ever been rear-ended?
Or, even worse, have you rear-ended someone yourself? Even
if the answer to both questions is no, you probably already know
how easy it is for a slight bit of inattention to result in an
expensive and potentially dangerous crash.
Here's a device that claims to
help draw attention to your vehicle when you're suddenly braking
heavily, making it easier for the driver behind you to notice
your sudden braking and encouraging him to respond sooner, too.
Will it save you, for sure,
from ever being rear-ended again in the future? We can't
answer that question with certainty, but even if it slightly shifts the odds
in your favor, perhaps it is a worthwhile investment ($30) for
you to consider.
What the SuddenStop Does
The unit detects when you're
braking heavily and rapidly flashes two vertical strips, each of
four bright red LEDS, for two seconds when this occurs.
It is hoped that this
flashing will alert drivers behind you more than the regular
brake lights, causing them to react and start slowing down
What you get
The SuddenStop License
Plate Frame comes in an easily openable plastic display case.
Inside is the unit itself and a sheet of light card that doubles
as both a promotional piece and instruction/mounting guide.
The frame is made out of
black plastic, with two vertical rows, each of four red LEDs, on
either side. The frame is slightly wider than a typical
frame, due to the width of the LED panels on either side.
It measures 13.7" x 6.25", and I
had no problem fitting it on several test vehicles (although
there was no spare room remaining on the sides when mounting it
on one of the cars).
The unit comes complete with
four CR2032 button type batteries already installed. It
doesn't refer to any warranty, but the manufacturer advises they
have a one year warranty offered on the product.
The unit lists for $29.95
and can be purchased on the
website or through various other outlets (listed on the
manufacturer's website) for as little as $22.
Installation and Operation
Installing the unit is very
simple, and most importantly, doesn't require any wiring.
All you do is to unscrew the current license plate, then place
the SuddenStop frame next to the car and your license plate on
top of the SuddenStop, and then screw the combined plate and
frame back onto the vehicle.
The unit has batteries
already installed and doesn't need wiring in to the
vehicle's braking or other electrical systems. All you do
is mount it to the vehicle - what could be simpler than that?
There is one potential issue
when installing the frame. They assume you'll be able to
simply reuse the screws you are already using to mount your
license plate, but the SuddenStop adds about an extra ¼" of
thickness, and it is possible your existing screws might not be
long enough to handle this extra thickness.
If they're too short,
SuddenStop offers to supply you with a set of longer screws for
free, but this is a hassle. Considering that four screws
probably cost less than 20¢ maximum, it is a shame they don't
simply include screws with the frame to start with.
The unit is self-contained
and battery powered, with the manufacturer estimating a 2 - 3
year life for the batteries. The battery life of course
depends on how often it is triggered by strong braking on your
A weakness of the unit is
not knowing when the batteries are failing. The
manufacturer suggests either doing some test brakings to see if
the unit activates (which requires someone to be behind you to
watch for the lights coming on or not) or hitting the 'test'
switch to confirm the unit still has live batteries.
Unfortunately, hitting the test switch requires you to unscrew the
unit because the switch is on the back not front of the unit.
Unscrewing the unit is an inconvenient and dirty task that few
of us would wish to be doing every month.
A related weakness is that
you can't replace the batteries. When the batteries die,
you need to buy a new unit. While the cost of the
SuddenStop isn't very high ($30 or less), it is still a measurable
cost, compared to a dollar or two for new batteries if the unit came with regular
How it Works
There is a very simple
pendulum lever switch inside the unit. When braking force
is applied to the unit, the lever swings over, closing an
electrical circuit and activating the
light flashing sequence. The lever is only activated by
braking, not by acceleration, and doesn't seem to be affected by
simple bumpy rough road movement either - I'm guessing because
the unit requires the lever to make contact for more than a
brief fraction of a second before activating.
This is a simple way to
detect strong braking in your car. But, because it is so
simple, it has some limitations. The unit can be made more
sensitive if it is on an angle facing one way, and it can be
made less sensitive if it is on an angle the other way.
This angle can occur either if your license plate doesn't mount
exactly vertically on the rear of your vehicle, or if you're
going up/down a hill.
If the frame is sloped so
that the license plate is looking upwards to the sky, or if the
vehicle is going downhill, it becomes more sensitive to braking.
If the frame is sloped so the license plate is looking down to
the road, or if the vehicle is going uphill, it becomes less
sensitive to braking.
Some vehicles have slopes on
their license mounts, usually in the 'up to the sky' direction,
making the unit more sensitive and more likely to activate even
with gentler amounts of braking, an effect compounded if you're
going down a hill, too. This isn't necessarily a problem -
better the unit activates more regularly than the unit
be insensitive and not activate when needed, but more
activations will also mean the batteries get used up more
Using the SuddenStop
The SuddenStop is very
simple to use. Once you've mounted it on your vehicle, the
rest happens automatically. When you brake harder than
normal, you trigger the SuddenStop and it fires a two second
burst of blinking red LEDs to hopefully warn the driver behind
you of your braking.
The exact amount of braking
needed to activate the SuddenStop varies depending on the angle
the SuddenStop is mounted, and if you're driving on the flat,
uphill or downhill.
One could obsessively debate
whether the SuddenStop activates at too weak or too strong a
degree of braking, but this is a matter of personal
opinion and is really missing the point. The key thing is
that sometimes it comes on to supplement your other brake lights
and to provide an extra level of warning to the driver behind.
It isn't intended as a primary warning system, but rather as a
supplementary system, and if you view your glass as half full,
you'll accept that when/if it comes on, it might help reduce the
chances of a rear-end collision, and if it doesn't come on, it
in no way increases your chances. In other words, heads
you win, tails you don't lose.
How much extra warning does
the SuddenStop provide? This is hard to answer accurately.
The LEDs aren't particularly bright, and in strong sunlight they
seem even less apparent than at night. Their rapid
flashing helps compensate for their lack of brightness, and
again we view this as a glass half full thing. Some
drivers might overlook seeing them immediately, others might
immediately notice them. Worst case scenario is that
you're no worse off than without the unit, and best case
scenario might save you from a nasty rear end collision.
The manufacturer points out
that as little as a quarter second of extra warning at 60 mph
represents 20' of extra distance traveled (to be exact, it is
22') and this might make all the difference between a rear-ender
or not. This sounds like a very strong reason to consider
adding a SuddenStop to your vehicle.
A Possible Embarrassment?
While the underlying purpose
of the SuddenStop frame is definitely benevolent and well
meaning, you don't want to give a policeman another reason to
stop you and another reason to cite you.
There's an unfortunate resemblance
between this plate frame and laser jammer type frames - a policeman
might see your SuddenStop frame and misidentify it as a laser
jammer frame (they also use LEDs) and so decide, without telling
you why, to go hard on you rather than to go easy on you.
We'd recommend that SuddenStop add some clear branding to their
frame so as to make it obvious to police that you're not trying
to cheat their laser guns, but rather are safety conscious and
trying to cut down on accidents.
This is potentially a very
helpful and interesting
gadget at an affordable price. If it works, you're
definitely better off, and if it doesn't work, you're only down
something less than $30. Available from the
manufacturer's website and elsewere.
A good gift for gadget and
car lovers, and for the safety conscious.
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2 Nov 2007, last update
21 Jul 2020
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.