multimeter help for hid

[s13tsilvia]

hey guys, ive never used a multimeter before and want to test how much power at the bulb im getting, where do i need to hook up my multimeter to and what settings??

 

[Morelite]

You can't measure at the HID lamp with a standard multimeter, you can however measure current or voltage on the primary side of the ballast.

 

[s13tsilvia]

yup that is fine, where will i need to place the probes?

cheers josh

 

[Morelite]

What is it you wish to measure, voltage or current? What lamp and ballast setup are you working with?

 

[s13tsilvia]

im working with a supposed 55w hid ballast and lamp assembly, i want to find the true power it is making at the bulb, i saw a post in the tweaking of the ballast by one of the guys who was measuring his bulb power by working out the ac readings im pretty sure, that is what i want to do.

 

[65535]

I think what he did is carefully inserted his DMM into the circuit on the lamp side to measure voltage and current AFTER the lamp started. That's just a guess though.

 

[BVH]

As 65535 said, You can easily measure total power, Watts at the bulb after it has started (the volt meter limitations are the reason for after starting. Your meter can see 25,000 Volts for a brief time). (you can hook your DC Ammeter into the circuit before you start as long as it measures 20 amps - DC) Many ammeters I found (at least the induction pick-up loop type, will not register DC circuit Amps, only AC circuit Amps.

It's easiest if you have two separate meters, one for Volts and one for Amps so you can read the data all at one time. If not, you will probably want to make the measurement during two different running cycles, once to measure Volts and once to measure Amps. (both times after full warm up)

The Ammeter goes "in-line" with the + or - wire, just one. Unhook the positive wire at the bulb or pigtail. Hook one end of your meter leads to the bulb (or pigtail from the bulb) and the other on the + wire you unplugged from the bulb/pigtail. BE SURE you have your meter set to measure Amps by having the test leads in the correct holes for Amps, not Volts and you have the selector dial in the correct position to read Amps DC. In this case, the current is going thru your meter to complete the circuit. Of course, if you have an induction Ammeter, simply clip the pickup around one of the bulb wires to read Amps.

With your other meter, or the same meter on a second run, make sure your meter is set for Volts, probably on the 300 Volt DC scale and touch one test lead to the positive wire and one to the negative wire.

As always, BE CAREFUL at all times when playing with high voltage. Even the best people make mistakes - as my Snap-On 7/16" combo wrench will attest to with the hunk of metal burned out of it.

I'll bet you find a total of 41 Watts or so going to the bulb.

 

[s13tsilvia]

thanks bvh, im pretty sure the one i have is an ac ammeter as i have no setting for dc amps by the looks of it. I shall have a crack tonight when i get home

 

[BVH]

I really think the AC / DC Amp think is unique to the induction pick-up loop type Ammeters.

 

[s13tsilvia]

when you say for the volts reading, attach a clip to the +ve and -ve wire do you mean attach the clip each to the bulb wires??

 

[s13tsilvia]

Heres a pic of my meter.