Multimeter?

So the picture with a DC output & the long explanation of how to replace the internal rectifier pack with an oversized external one doesn't imply they where internally rectified?

Alex Buell was thinking very hard :

Both readings are good and both will decrease - the first once the battery has been topped back up (expect 13.8v or slightly higher) and the second once the battery falls back to it's normal resting state (around 12.7).

Set the meter up to measure current on the 10amp range and wire it with a 21watt bulb in series with one of the leads, then wire that in series between a battery post and all of the leads which were connected to it. That will involve disconnecting one set of leads from the battery terminal and the safest to disconnect is the black or negative side. Then watch meter and let the cars electrics settle down, it may take upto an hour, before you can get a sensible (everything on standby) reading.

Series is like this-

Battery negative__________12v lamp_______meter______wires you took off terminal

Dave Plowman (News) presented the following explanation :

Which can be avoided by simply shorting the two terminals of the meter, until the surge has passed. As someone else mentioned - make sure all the doors and bonnet are closed, in my own case I would also need to close the bonnet or put a weight on the bonnet switch to fool it that it was closed.

Mark formulated on Thursday :

Agreed!

Your old AVO when it left the factory was only guaranteed to 1%. I have digital ones ranging in cost from two for a fiver to several hundreds of pounds and I find the cheap ones generally just as accurate as the expensive ones. The better ones just tend to be more rugged and with better misuse and fault protection.