12V inverter vs. 12V battery charger?

[Dan O'Connor]

Hi, I'm trying to turn a car headlight into a lamp that you can plug into a
normal wall outlet, and I tried two things:

First, I took a 1 amp/ 12V lawnmower battery charger and hooked it up to the
light, and this produced light, yet it was fairly dim.

Second, I took simply a 12.6 V/ 3 amp inverter alone, and hooked that up to
the light and the wall outlet. This blew the circuit breaker.

My question is, what do I need to do to make this scenario work, and power
the headlight so it is fairly bright, with the inverter? Because using the
battery charger it is too dim.
Thanks.

 

[Clarence]

Hi, I'm trying to turn a car headlight into a lamp that you can plug into a
normal wall outlet, and I tried two things:

First, I took a 1 amp/ 12V lawnmower battery charger and hooked it up to the
light, and this produced light, yet it was fairly dim.

Second, I took simply a 12.6 V/ 3 amp inverter alone, and hooked that up to
the light and the wall outlet. This blew the circuit breaker.

My question is, what do I need to do to make this scenario work, and power
the headlight so it is fairly bright, with the inverter? Because using the
battery charger it is too dim.
Thanks.

A 120 to 12.6 volt 6 Amp transformer will operate most headlights. (50 to 70
VA)

 

[Ken Taylor]

Hi, I'm trying to turn a car headlight into a lamp that you can plug into a
normal wall outlet, and I tried two things:

First, I took a 1 amp/ 12V lawnmower battery charger and hooked it up to the
light, and this produced light, yet it was fairly dim.

Second, I took simply a 12.6 V/ 3 amp inverter alone, and hooked that up to
the light and the wall outlet. This blew the circuit breaker.

My question is, what do I need to do to make this scenario work, and power
the headlight so it is fairly bright, with the inverter? Because using the
battery charger it is too dim.
Thanks.

Was it actually an inverter, or a power supply? If it was an inverter,
chances are you've blown it, as it is supposed to produce mains voltage out
from 12V in (and supposedly you connected the output to your mains, which is
why the breaker blew). As Clarence says elsewhere, use a properly rated
power suuply.

Ken

 

[andy]

Hi, I'm trying to turn a car headlight into a lamp that you can plug into a
normal wall outlet, and I tried two things:

First, I took a 1 amp/ 12V lawnmower battery charger and hooked it up to the
light, and this produced light, yet it was fairly dim.

That's not so good because a battery charger has circuitry in it to take
it through several stages of charging, protect against overcharge etc.

Second, I took simply a 12.6 V/ 3 amp inverter alone, and hooked that up to
the light and the wall outlet. This blew the circuit breaker.

Do you really mean an inverter? they are for converting from DC (usually
lead acid battery) back to AC, so not what you want.

I think you need a transformer.

 

[Roger Hamlett]

Hi, I'm trying to turn a car headlight into a lamp that you can plug into a
normal wall outlet, and I tried two things:

First, I took a 1 amp/ 12V lawnmower battery charger and hooked it up to the
light, and this produced light, yet it was fairly dim.

Second, I took simply a 12.6 V/ 3 amp inverter alone, and hooked that up to
the light and the wall outlet. This blew the circuit breaker.

My question is, what do I need to do to make this scenario work, and power
the headlight so it is fairly bright, with the inverter? Because using the
battery charger it is too dim.
Thanks.

A lot more current....
Typical modern car headlamp, will draw 8.5A, when running, and over 20A,
when
cold. The first supply didn't have circuit protection internally, so the
transformer voltage just 'drooped', and the lamp ran, but the battery
charger would have overheated in a short time. The second circuit had a
lower impedance transformer, and a fuse to protect it from the overload.
A 'tail' light, will draw about 2A, and the second supply would probably
drive this.
I'm assuming that the second unit, was really a transformer, not an
'inverter'...

Best Wishes

 

[Dan O'Connor]

Yeah, my mistake, I meant a 12V transformer. I had a 3 amp one of those
wired up to the light and the wall outlet, and I blew a circuit breaker in
my house. Is there a certain electric component I need to add into the
circuit in series that will make the light work (not necessarily at full
power) with this transformer without blowing a circuit breaker?

Thanks

 

[Peter Bennett]

Yeah, my mistake, I meant a 12V transformer. I had a 3 amp one of those
wired up to the light and the wall outlet, and I blew a circuit breaker in
my house. Is there a certain electric component I need to add into the
circuit in series that will make the light work (not necessarily at full
power) with this transformer without blowing a circuit breaker?

Thanks

The 3 amp transformer should not have blown the house breaker, unless
the circuit was already very close to overloaded.

Are you sure the transformer was connected the right way around - if
you connected the secondary (12 volt) side to the 120 volt outlet,
that may be the reason the breaker blew.

What you really need is a 12 volt transformer rated at 10 amps or more
(if one of the other poster's numbers are correct).

Anything simple that you add in series with the light will dissipate
power and get hot. If the lamp really wants 9 amps, and you try to
reduce the current to 3 amps, the lamp will be very dim.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[Dan O'Connor]

I think I wired it correctly, I wired the two yellow wires to the outlet,
and the two black wires on the other side to the light. However,, I was
only using a two pronged plug, and I didn't connect the third wire on the
yellow wire side (which had 2 yellow wires and one black wire) to anything.
Could that be my problem?

 

[Ken Moffett]

I think I wired it correctly, I wired the two yellow wires to the outlet,
and the two black wires on the other side to the light. However,, I was
only using a two pronged plug, and I didn't connect the third wire on the
yellow wire side (which had 2 yellow wires and one black wire) to anything.
Could that be my problem?

If my years of experience serve me correctly, you got it backwards. I
can see why the circuit breaker tripped. "Normally" the black wires are
the primary (115v) and the yellow wires are the secondary (12v). The
yellow/black wire is a center-tap on the secondary. If you have an
ohmmeter, measure the resistance of the two windings to verify this. The
higher resistance winding will be the primary and should be connected to
the house power. The low resistance winding is the secondary and should
be wired to the lamp. If you connect the lamp across the two yellows,
you will get about 12v and overload the transformer. The transformer can
only supply 3A but your load is trying to draw 9A. If you connect your
lamp between one yellow and the yellow/black, you will get about 6v to
the lamp. The lamp will be pretty dim, and you're still overloading the
transformer. Now the load only tries to draw 4.5A, but the transformer
is still only able to supply 3A safety.

Per another poster...Get different (bigger) transformer.

With that...I have successfully used lamp dimmers (available at hardware
stores) in series with transformer primaries to control the
secondaries' output voltages for low-voltage lamps, heaters, and
hot-wire foam cutters.

Hot---dimmer---primary---neutral

 

[Fred Bloggs]

I think I wired it correctly, I wired the two yellow wires to the outlet,
and the two black wires on the other side to the light. However,, I was
only using a two pronged plug, and I didn't connect the third wire on the
yellow wire side (which had 2 yellow wires and one black wire) to anything.
Could that be my problem?

Sounds like you connected a center tapped step-down secondary to the
line - and this IS a problem. Your thread belongs on
sci.electronics.basics and not here, and I don't know what degree of
mental vacancy plays around with electrical equipment at line voltages
when you clearly lack even the slightest clue as to what you're doing.