Amp meter on my 40 - what is it actually showing?

[Mechman]

im after some clarification of what my amp meter is actually showing.
i am asuming that the 40's amp meter is actually showing the current flow from the battery? when i have lights on, or brake lights.. indicators.. what ever.. the neadle drops towards the -30. it get significantly closer when using all 3 of the above items. i am asuming also that this is not taking into account the charge from teh altenator going back into the battery... and i should not be worried????????


Rob

[the_smoo]

it should be showing the sum of all current flow..

ie if you had the engine off, with all your shite switched on, then you will see it move away from the middle position (0 amps) and move toward
-30.

When running with nothing on, the meter should be above 0 indicating that current is being supplied by the alternator to the electrical system/ battery..

SO it should be showing you the charge from the alternator as well..

be worried if you are always below 0

[stuee]

I rekon all is good. If the ameter is on one on one side of the battery it will only show the current leaving or entering the battery. In you case, because it goes to -30 amps when the various lights are on it is most likely measuring the current leaving the battery. If you want it to display a positive value you should be able to simply reverse the connections on the gauge. Unless you are getting flat batteries constantly you've got nothing to worry about

If you're still unsure get an auto-electrician to look at it.

[the_smoo]

I rekon all is good. If the ameter is on one on one side of the battery it will only show the current leaving or entering the battery. In you case, because it goes to -30 amps when the various lights are on it is most likely measuring the current leaving the battery. If you want it to display a positive value you should be able to simply reverse the connections on the gauge. Unless you are getting flat batteries constantly you've got nothing to worry about

ummm.. if you have to disconnect the meter and put it in backwards .. why bother having a guage that shows +30 and -30...


With my engine running, and nothing electrical switched on, my meter sits above 0 about half way to the +30.. As i switch stuff on, the needle dips back toward 0.

it therefore MUST be taking the charge current into account..

[Mechman]

hmmm... its not really clear.. even tho i wired the damn thing up. the amp meter is in serries from teh batery to all the other shite... so it would make sense to me that its only showing flow... but having said that, im a mechanical engineer not this voodoo electric stuff. the alternator seems to be charging ok.. it starts great, had done since getting back on the road a few months back.

i will use my multimeter to check the charge going into the battery when the motor is running.....