Jump to content

Over active ammeter


Recommended Posts

who designed ammeters and oil pressure gauges!

Have had trouble with both,but over the last year ammeter has driven me crazy it always registers plus 15

Amps with engine running,but when I switch main beam it goes up to 25 amps , but with engine off it registers minus with an electric load , is this something to do with alternator diodes or rectifiers acting up,

Faulty earthing or light switch,any help would be most appreciated.

Michael.

Link to post
Share on other sites

That's normal if your ammeter has been wired to measure the total output of the alternator, like my 1969 TR6 is . For normal running it uses about 15 amps to run the Bosch fuel pump plus miscellaneous electrics. Switch on the lights and it generated extra current for the lights, in your case 10 amps=120 watts for the main beams.

 

I can't see any problem with your alternator system.

 

Note I modified my alternator to 45 amps output and fitted a 60 amp ammeter-that's about as far as I'm prepared to push the existing wiring with the total alternator output going through the dash mounted ammeter. Later TR's with a voltmeter avoid this problem. If originality is not important and you're not happy with the ammeter set up you could change to a voltmeter to monitor alternator performance.

Link to post
Share on other sites

Thanks Roger- I agree , it's one of the jobs on my list for next winter but in the meantime I keep a wary eye on how long the charging rate stays above 30 amps after start up and a wary nose sniffing for any burnt wiring smells.

Seems OK in the short term.

Link to post
Share on other sites

Michael- that is happening because the feed for the fuel pump has been taken direct from the battery -shown as red on this sketch. (presumably via a relay so it only comes on with the ignition). If you don't want the standing 15A shown you need to move the pump feed to the other side of the ammeter so it is fed direct from the alternator - shown as green

If you do that the ammeter will register the pump current as a discharge until the motor is started but after that will only show the current into/out of the battery.

post-7865-0-79114800-1517261593_thumb.jpg

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.