wiring a jaycar amp meter

Submitted: Tuesday, Jan 18, 2011 at 23:41

ThreadID: 83739 Views:5551 Replies:1 FollowUps:3

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greg8049

Hi all, i have a little experience in 12v wiring but just want to be sure how to wire these items in.
I have a 20amp, amp meter from jaycar, on the back it has a + and a - symbol and i was told it has a internal shunt.
Would i be correct and say the + symbol is on the battery side and the load is on the - side?
So if i was putting it in a solar panel set up the positive wire from the mpps to the - side and then the + to the battery that is being charged, this would then tell me what amperage is travelling thought to the battery?
And another 20 amp meter for for other accessories,( cig lighter socket, fridge, internal lighting) once again all come off the - side and the + side to the battery to determine what amperage is being used from the battery?
It would be nice to know if i am correct, but please dont use any big confusing words, and thanks in advance
cheers Greg

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Reply By: Allan B (Sunshine Coast) - Tuesday, Jan 18, 2011 at 23:56

Tuesday, Jan 18, 2011 at 23:56

Hi Greg, no, the +ve goes to the source (the solar panel) and -ve to the load (battery)

In the second case you are correct. Again, the +ve goes to the source (battery) and the -ve to the load (accessories)

Cheers
Allan

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Follow Up By: greg8049 - Friday, Jan 21, 2011 at 23:03

Friday, Jan 21, 2011 at 23:03

thanks for the reply Allan, i will follow your suggestions as there has not been any other posts
You must be correct or there would have been someone else with other suggustions
cheers Greg

FollowupID: 714648

Follow Up By: Allan B (Sunshine Coast) - Friday, Jan 21, 2011 at 23:59

Friday, Jan 21, 2011 at 23:59

No worries Greg.

(Hey guys........ someone back me up....... if just to reassure Greg?? )

Cheers
Allan

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Follow Up By: KenInPerth - Saturday, Jan 22, 2011 at 10:22

Saturday, Jan 22, 2011 at 10:22

Late reply but yes - Alan is correct where in your case there should only ever be one direction of current.

The worst that will happen if you put it the wrong way round is that the needle will go the wrong way and hit the left hand stop probably without any damage to the needle.

This is assuming it is not an LCD / LED type meter which is a different discussion - if they have a negative indicator then they would just display a negative vaue if it was the "wrong" way round - same as a digital multimeter.

Just a note that if you had any application where the current can reverse direction (eg. if you put an analog Ammeter right on the positive terminal of the battery where you would see both discharge and charge current flow) you would need to use a "centre zero" meter - one where the needle stands staight up in the middle of the dial and can move both left and right of centre - in which case the -ve would normally go to the battery so discharge shows on the left half of the scale and charge on the right hand side.

Ken

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