alternator output

[dazleeds]

hi all
been getting a lot of dead batterys in the morning recently always bumps off and holds charge for the day but next morning its dead again
how do i check if alternators runnin rite?? if not any other ideas of what is draining it?? have tried a few batterys so dnt think its the batt please help getting sick of bumping off now Daz leeds

[Andy_magic]

To check the alternators output get a multimeter and check the voltage with the engine running. It should be around 14-14.4 volts. A little less wont matter but if your getting less than 13.5 volts the alternators done for.

Another cause of flat batteries is something like a boot light staying on, check for the obvious lights etc.

Alternators can also discharge a battery overnight if the diode pack dies.

Take the negative lead off the battery, set you multimemter to AMPS and see how much current is flowing with everything off, there should be next to nothing. If your seeing high readings, try disconnecting the alternator and checking again.

I fudged diode pack in an alternator will allow the battery to charge up fine, but then lets the battery's power to flow back into the alternator.

[dazleeds]

can you change the diode in the alternator?? and where is it exactly??
gonna try borrow a meter tomoro after ive bumped her off AGAIN
cheers all Daz leeds

[Andy_magic]

According to the ETK the diode pack is inside the alternator itself. Looks like it could be tricky to change without the right tools. I was looking at the Bosch 65 amp, but the 80 and 90 look very similar.