I didn't think it was but wasn't sure hence asking.wheeler wrote: 06 Oct 2024, 12:13 Thats not really the same thing as a volt drop test but yes there is an acceptable limit for this.
Firstly i wouldn’t use a voltage display on a diag tool, there is too much of a delay, use a proper voltmeter connected directly to the battery.
A good battery should not go below 9v on cranking.
An old way of testing a battery would be to disable the engine from starting (removing the fuel pump fuse for example) then crank the engine for 10 seconds. A good quality meter will have a max/min record function, set it to record minimum & it should not go below 9v with 10 seconds of cranking.
Fully agreed about resolution on diag tools (unless picoscope
)So that is interesting because it drops to 9.5 or 9.7V but is REALLY sluggish turning over.
If I did disconnect fuel and crank, it wouldn't be anywhere near that voltage after 10 seconds. It would probably just grind to a halt!!!
Thanks for the advice. Have a great Sunday.
