[zook37]

Re-installed the alternator after havigng it rebuilt the other night as it was belting over 16 volts back into the battery.


After refitment it all seems to be working ok. It is currently putting 14.1volts back in without any accessories such as a/c radio and lights etc on, and with everything at full tilt it is putting in around 13 volts. I am assuming this is within the normal range?




But can anybody tell me how to test for Current draw off the battery? I only have a cheapie kincrome digital multimeter and I have limited to zero knowledge on how to use a multimeter for checking current draw. I will post up a piccie of the multimeter so somebody can hopefully guide me in the right dirction!!

[zook37]

a pic of the unit:

[Rusho]

Ideally you need to break the circuit you want to test for load and insert the multi in series onto that circuit. As far as settings I think you need to move the dial around to '10A' and move the red lead up a hole, I think......! Could be wrong. If it works I'm right if it don't I'm wrong

[royce]

10 amps wont get you far measuring current on a car, you need a clamp meter

or a bit of ohms law and measuring the voltage across the earth lead will do it too, but youll need to find a smart person to work tell you how to work it out

[Rusho]

True 10A is sweet f all. Ohms law is volts(V) = current(I) x resistance(R)so...... Current = volts \ resistance(ohms) Not sure how you will get a proper resistance reading from a mutli though. Other helpful formula also include power P (watts) = V x I

[shep]

Rusho81 wrote:

True 10A is sweet f all. Ohms law is volts(V) = current(I) x resistance(R)so...... Current = volts \ resistance(ohms) Not sure how you will get a proper resistance reading from a mutli though. Other helpful formula also include power P (watts) = V x I

eh

[Rusho]

shep wrote:

Rusho81 wrote:

True 10A is sweet f all. Ohms law is volts(V) = current(I) x resistance(R)so...... Current = volts \ resistance(ohms) Not sure how you will get a proper resistance reading from a mutli though. Other helpful formula also include power P (watts) = V x I

eh

I read it in a book once shep. It had heaps of pictures though which made it easier to understand, which was good because I'm a dumb ass linesman

[shep]

i thought dumb linesman got turned into smoke.

[Rusho]

I must be dumb and lucky then

[foonji]

Remember the Triangles! PIR and VIR..

P over I & R

/P\
/I|R\

V over I & R

/V\
/I|R\

[paulv]

Short answer; don't worry about trying to measure amps.

If you can turn on all accessories the vehicle has lights, spotties, stereo, a/c, fan, etc, with the engine running and you are reading 13+ volts, both at the back of the alternator and at the battery, all is good.

[89_tintop]

you can measure any battery drain that may be occuring when the car is sitting then not runnin using you mulitimetre.

you want to move the black lead to the top hole, then turn the knob to the 10A spot.

disconnect the battery negative and put the red lead from the multi metre onto the negative post of the battery and the black lead from the multi metre onto the disconnected negative lead.

there should be a very low reading.. well under 1 amp. it should be 0.00 something.

they are right 10 amp draw isnt alot when it comes to a running vehicle. you will either need a really good ampmetre or a clamp style ampmetre.