Canister light burn tester

[TeamZissou]

Does anyone have experience and recommendations for resistor selection for a canister light burn tester. I have a 12 volt battery, 18 watt lamp that pulls 2 amps. I'd like to get a resistor that mimics the lamp to save the bulb, but achieve a similar burn time for periodic testing.

Thanks in advance for the input. Parts sources and photos welcome!

 

[KeithG]

Just use the bulb? An extra hour or 2 of burn time every 6 months should notmake a significant difference. You may find the bulb is cheaper than an alternative?

 

[miketsp]

..snip..
I have a 12 volt battery, 18 watt lamp that pulls 2 amps. I'd like to get a resistor that mimics the lamp to save the bulb, but achieve a similar burn time for periodic testing.

Something wrong there.
12V x 2Amps = 24W. Not 18W

18W should pull 1.5Amps @ 12V

8ohms @ 12V will pull 1.5A and dissipate 18W

If you're going to use a resistor remember that it will run very hot and you should buy one rated for more than 18W. I'd go for a series or parallel combination to spread the heat dissipation. Example put 8 resistors each 1ohm x 5W in series. These should easily be available at any electronic components shop.
Personally I'd just go to a car parts store and get some automobile lamps and sockets that add to 18W. For example a common tail light bulb will be 5W so 3 or 4 in parallel will be fine. Some shops sell 6W bulbs so 3 of those would be spot on.

 

[TeamZissou]

Mike, K, Thanks for the fast replies. I thought the power calculations looked wrong, too - But I spoke with a manufacturer's technician, who assured me that the 18W bulb (and light head) together draw about 2 amps; he mentioned the 21 Watt bulb drew about 2.5 amps. I'm not an electronics guy, but I imagine that it's lost in the light head ballast and efficiency.

So far I like the cheap option of the auto tail light bulbs that together will pull 2 amps.

K, If I had just one 12v canister, I'd probably just burn the lamp - but I have multiple and I'd like to put them on a standard burn tester with a watts-up (to collect the data) and a low voltage cut off (to keep from damaging the battery).

 

[lucca brassi]

You probably have HID bulb , old 18W from Welsh Alynn or 21W new bulb which is from Brightstar.

It pulls 2 Amp but just from micro seconds at ignition. In ignition process voltage charges big capacitor and instantly discharges over ignition coil which causes current flux.

some solutions

Dipl.-Ing. Peter Niehues, Kapazitätsmessung von 12V Akkus

Google Prevajalnik

 

[TeamZissou]

Lucca - thanks - That's what I was searching for - and I happen to read German, so Dipl. Ing Niehues' website was perfect. And you are correct - I have an older HID bulb.

 

[lucca brassi]

these are very good simple and relative cheap (that is not ) but first version was around 14$

Watt Meter & Power Analyzer /Watts up (Ver. 2)

or check others Tools>Watt Meter