After a +100km run Sat I did a engine compression test. The test obviously involves cranking over the engine many times for all 8 cylinders and takes a toll on the battery.

The car hasn't been run since then and tonight I go out to he garage to start another project and there's a intermittent 'pinging' from the LH front fender. I open the hood and as best I can tell it came from around the ABS system. The car wouldn' turn over but the lights would come on very low so there was some juice so the batts on the charger.

Any clues as to what gives off the noise?

Batt is in its 2nd season with no previous issues and the system indicated good charging when tested ~1mth ago.

 

Just charge it up - possibly the alarm/chime... doesn't really matter - if the voltage is below 7v odd stuff can happen...

Alan

 

Did that..........full charge, car starts and operates per normal.

Checked engine running voltage again............+14v.

Car wont start 3 days later.

Batt must be going terminal dead or I've a electrical discharge so given the potential latter issue can I diagnose with a simple DVM?

 

yes if you have a DVM that can check a 10 amp load.

 

It can................so in series with which post?

 

Put it in series with the battery ground - common to battery -Ve 10A positive to rear ground point - start on 10A range - get the interior lights off (pull connection on bottom of the hatch receiver to disable the hatch light switch... see what you get?

If its below 200mA switch to that range and see what you get.. you are looking for 50mA or less - ideally about 15mA...

If its that low you are good...

Alan

 

I guess I would come to the same conclusion if the lights were dim, but Numbers are surely helpful w/electrical stuff. you don't say what the volts are w/ign off???? It sat 5 days. I've never done comp test, but you did it with ign on?? If not, how does that use juice?

 

Steve...........I just recharged the batt., installed it and checked voltages. 14.1v engine running, 13.2v engine off. I'm assuming the non running voltage shall drop as the car cools..........below zero air temps tonight.

To do a compression test you need to remove all spark plugs and turn the engine over with the starter while a guage is inserted in each spark plug hole for each 8 cylinders. When I did my test I did remove the fuel pump fuse but not the ign fuse...........perhaps there lies my error.

Alan............thanks for the amperage numbers.............thats the next test.

 

Using the starter to do compression checks was the high amp draw that sucked your battery down to its knees ... as the starter is by far the most hungry of electrical accessories ( check the gauge of the supply cable): pulling fuses & relays during this process is for safety reasons - and has an insignificant effect on battery draw down.
Perhaps hooking the charger up before starting the compression test could be added to the procedure ... ( BTW, that is done by the dealership when running an active series of OBD II scans on '96+ models due to heavy current demands - as opposed to simple code scans)

 

Thanks Garth............never would have thought to install the charger prior to the test.

If my batt. fails again in the next few days then she's toast.............I'll buy new in the spring.