Newbie: I am not getting enough amperes

Hello there

A petrol burner I have uses 12V DC to heat a glow plug to ignite petrol.

I have connected my glow plug to laptop charger that has been set to 12V DC. On the back of the charger it says it allows for max 6A at 12V.

My multimeter says i am getting aprox 1AMp through my glow plug. Problem is that the glow plug doesnt get hot like ot should.

Earlier today, we connected the same glow plug to my friend's power supply. There, the glow plug worked just fine, but there, it got 5,5 amps.

So my question is: why isn't my power supply giving enough amps? It says it should give max 6A on the back.

Thanks for your time.

Kind regards,
Marius

hi,
Use an ohm meter to check the COLD resistance of the glow plug, it could be much lower than its HOT resistance.
If the COLD plug draws too much current it maybe your power supply is going into current limit at 1amp.

ericgibbs said:

hi,
Use an ohm meter to check the COLD resistance of the glow plug, it could be much lower than its HOT resistance.
If the COLD plug draws too much current it maybe your power supply is going into current limit at 1amp.

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Hello,

Thanks for quick reply.

My multimeter says cold resistance is 0.7Ω.

NOTE: When I measured amps, the amperes would jump between 0,6 and 1,5.

What are your views?

Thanks.

Kind regards,
Marius

0.7 Ω on a 12 V supply implies about 20 A. It might be a bit less if the resistance changes when hot.

You need a 20A supply.

The laptop power supply will not produce 6 A into such a low resistance. Even if it can produce 6 A into a 12 V load, with a 0.7 Ω load, it might well only produce 1 A.