Car Chargers Keep Blowing Out

I got SIRIUS satellite car kit which plugs into the electrical outlets
in my Honda Accord (2004) and the first one died after less than a
week, then I exchanged it for a new charger and that one died in 5
minutes. I was then thrilled to find that a charger I have for another
device matches the specifications of the Sirius charger, so was using
that and now this morning that charger is dead. I'm starting to wonder
if maybe a power surge is causing this? Should I always unplug these
chargers when I turn off the car, and not plug them in again until the
car has been started? I took the one charger apart...can I repair it
by just replacing the little cylinder fuse inside? Are they easy to
find? Any help would be appreciated.

 

If you are referring to a glass cylinder with metal caps and a thin (but
broken) wire between them, yes. Go to any auto parts store, and they will
have a fuse of the proper length and amperage. Don't be tempted to replace
it with a higher amperage fuse though, it's a good way to have other, more
serious problems, including a fire.

If you are burning out chargers at that rate, you should entertain the
possibility that your radio is drawing more than it's designed amperage,
which could indicate an internal short, or possibly a bad ground, which is
less likely . I would go back to the dealer where I bought the radio and
have them check it for abnormally high amperage draw. I'd bet on this being
a radio problem rather than a charger or car power outlet problem.

Good luck

 

Thanks very much for the reply. It's a portable Sirius radio unit.
If it helps to narrow down the problem, this is the second radio too.
When I went to exchange the car charger, I had to also exchange the
radio itself (for inventory/returns purposes). So if it's the radio
causing the problem if it's happened with two different units, does
that change your opinion in any way? Thanks much.

 

If the fuses are burning out, it is due to more current flowing
through the fuse than it was designed to handle. There are at least
four reasons why this could happen:

1. Your alternator is operating at too high a voltage. If your car
regularly burns out other fuses in other circuits, this would be the
most likely culprit. But, have it checked anyway if you think this
might be the problem.

2. The radio is drawing excessive current due to some internal flaw.
This is less likely, since you have gone through two radios with the
same problem. But maybe it is a bad design.

3. The charger design is faulty. The fact that a different charger
also blew a fuse is not compelling evidence to me, because I do not
know that the specifications on the other chjarger really exceeded the
specifications on the charger that came with the unit.

4. There is a fault (intermittent open) in the power outlet or its
circuit. If the radio has its own internal rechargeable batteries, it
might run off of internal power when the external power was off, so
you might not notice it. The intermittent open causes excessive
thermal shock to the fusible wire, causing it to fail.

There are probably other possibilities that I have not thought of.
Somebody else will.

Hope this helps





Elliot Richmond
Freelance Science Writer and Editor

 

Thanks very much. THis does help. How do i determine if it even is a
blown fuse? Is it visible to the naked eye?

 

Yes. You say you have taken one of the chargers apart and you saw
something that looked like a fuse (small glass cylinder with metal cap
on each end). You should be able to see a small wire running through
the cylinder between the metal caps.



Elliot Richmond
Freelance Science Writer and Editor

 

I would be less inclined to blame the radio knowing that it had been changed
as well, and would look at the wiring more closely for a short or a poor
ground. The first thing I would want to do is to find out how much current
(amperage) draw the unit has while running. For instance, if it was
protected by a 14 amp fuse and drawing 10 amps regularly, (just as an
example) this might be enough to blow the fuse after a few days but not
right as soon as it is plugged in.

Maybe Tegger or some of the other guys here might give you a more current
(ouch!) answer. I'm 35 years away from twisting wrenches for a living.

 

Thanks much. Went to Radio Shack to get a replacement fuse (which were
naturally out of stock) and the manager guy there told me in general
it's not a good idea to have any charger plugged in until the car has
been started because it may not handle the power surge. Seems like a
lame answer to me.

 

I'm not exactly sure which 'replacement fuse' you are replacing?
Fuse inside the charger or one inside car? If a car fuse is blowing,
then the charger plug (into Honda power outlet) may be shorting. This
because a charger's plug is not properly designed to not shift.

Fuses blow typically because hardware has failed. Fuses do not
protect hardware. Fuses are for human safety; so that failed hardware
does not kill humans.

If "the manager guy there told me in general it's not a good idea to
have any charger plugged in until the car has been started because it
may not handle the power surge", then that charger is defective by
design. SAE and ISO standards are explicit. Charger can experience up
to (if I remember) 230 volts on 12 volt supply. A charger should
withstand at least 60 volts due to a rare condition that all vehicle
electronics must withstand without damage: load dump.

IOW start a car every time and have no electronics damaged. How
often is the car computer destroyed by a startup surge? This was
standard probably longer than you have existed. The Radio Shack
manager would be hyping a myth.

But again, not entirely clear which fuse is blown. Therefore I am
not sure a charger failure occurred. Charger plug into Honda's power
outlet may be defective by design. Shifting the plug may cause a short
circuit that blows Honda's fuse. Honda's fuse blows to protect you
from a short circuit created by a defective (by design) charger power
plug.

 

Most modern high current electronic devices use switch-mode power supplies,
which are compact, inexpensive and efficient. One of the peculiarities of
switch-mode supplies is that they draw more current at lower voltages
(pretty much constant power), so if you are trying to power them while
cranking the current may be too high.

While you are looking at it, jeffy, if the fuse is in the part that plugs
into the socket unplug it and give it a feel after it has run a minute to
see if it is hot. It may be that the socket is bad (oxidized center contact)
and is simply overheating the fuse.

Mike

 

I really appreciate everyone's thoughts. It's all pretty interesting to
me , although frustrating too. TO answer W_Tom's question, it is the
fuse inside the car chargers that keep blowing...and it doesn't happen
on the car charger for my MP3 player or my cell phone...it's only
happening with the ones using the Sirius radios....last night I put a
new fuse in and made sure to have it unplugged from the socket before
starting the car and so far, so good...the other thing I should add is
that there are two sockets in my car, one in the between the seats
console and one under the dash....I haven't been able to pinpoint if
both are causing the fuse blowouts or not...maybe I should buy a bunch
of fuses and do a lot of testing with each socket to see if it's one or
both that are causing the blowouts.

 

A short ciricuit before the fuse will not blow a fuse. If the fuse
"is the fuse inside the car chargers", then short circuit that can blow
the fuse is insiide Sirrius equipment - not in a power outlet.

BTW, what numbers define that fuse? One kludge solution might
involve replacing that fuse with an automatically resetting type fuse
such as from Raychem/Tyco.

 

Also an Accord 2004, I had a problem with cell phone charger. The
charger worked fine in other cars, but blew the Honda fuse
immediately. Honda dealer said yeah, they've seen that a lot, that
Honda sockets are "funky". A new charger has worked for me, the few
times I've used it, though I expect it to blow at any time. Beats me
what the actual problem is.

J.

 

Appreciate the info. I've learned that you don't need to buy a new
charger, just change the fuse. You can get 4 for about a buck fifty.

 

Completely irrelevant to the problem is what JXStern has posted, as
demonstrated by facts in a previous post. He says:

But jeffy3 says fuses inside a Sirrius charger are being replaced.
That 'funky' Honda power outlet cannnot and will not blow fuses inside
a Sirrius charger - obviouslyt. Two events are completely different.
Also in that other post is a question : what is the size of that
Sirrius fuse? Responses will only be as good as information provided -
which is why replacement fuse numbers were important.

 

There are two ways it can blow the fuse in the charger. The first is if the
fuse is in the plug - a common location. In that case the poor connection
conducts heat straight into the fuse. The second is if the poor connection
reduces the voltage into the charger to the extent that the charger draws
too much current in order to supply the required power. Either of those is
not unusual.

Mike

 

The fuses are the 5x20 mm 2 amp 250v

 

This discussion somehow moved to another newsgroup -
sci.electronics.basics . Answers relavent to numbers on this fuse are
listed there. I am assuming this is a fast blow type fuse AND that the
replacement fuse is same as those provided originally. As noted in
that other disucssion, Radio Shack now considers the technically
informed as undesireable. Radio Shack no longer provide important and
relevant specs on their products. This being a symptom of a technical
product retailer now run by bean counter school management - and that
explains why so many responses can only be speculation.

 

To be clear, mine was blowing the Honda fuse immediately, dealer when
through a handfull just showing me what was going on.

J.