Each and every engine start, can be a 'LOAD TEST' if one has a fast responding voltmeter.

So with such a voltmeter attached directly to battery terminals, crank the overnight cold engine. What was the minimum voltage seen, If it was over 7.6, the engine started.

If it remained in the mid 11's or higher the battery is healthy.

When Voltage falls during cranking to the low 8's, on an overnight cold engine, or worse, a warm one, start shopping for a battery deal.

An actual load test requires loading the battery to 1/2 The cca rating of the battery, and it must maintain 7.5 volts for 30 seconds.

But in reality that is a rather insanely abusive test, when fuel injected engines start in 5 seconds or less.


In your PM you stated you measured a parasitic draw anywhere from 0.5 to 2 amps

YOu cannot measure self discharge of a battery itself via an ammeter.

If you want to test if your battery has a soft short/ excessive self discharge, fully charge it, disconnect it from any potential parasitic draw, then measure the resting voltage. Measure it again in an hour, 12 hours, and 24 hours. If at one hour it stayed above 12.8v, and 24 hours stayed above 12.6v, then it is likely good to go for a while longer.

If it drops to 12.5 instantly when removed from charger, it is either no where near full charged, or is not so healthy but might be OK for 6 or 8 more months. If it drops to 10.7v or less, it has a shorted cell or is just disgustingly sulfated and would struggle to start an engine ever.

If fully disconnected resting voltage remains above 12.7v 24 hours after removing from a charging source then it does not have excessive self discharge, and 90% of the time is still a realtively healthy or better battery.

But it is also possible to have a battery remain above 12.7v 24 hours off the charger, and be incapable of starting an engine.

Voltage is ONLY indicative of state of charge on a battery that is not under a load, and has not been charged or discharged for a period of time. 'Surface charge' a voltage reading shortly after shutdown, almost always misleads one into thinking the battery is more charged/ more healthy than it is, but watching voltage maintained during engine starting removes ALL the mystery, and no need to deal with some halfwit in an Autoparts store.

One can take their tool, and adjust the tension and the surface area the of thr clamps on the battery terminals, and force an OK battery to read weak. 'Good thing we have one right here for sale.....'

Excessive self diacharge can certainly be happening in concert with a large parasitic load, but you say you have measured 0.5 to 2 amps with all fuses disconnected.

And for other readers.

a 2 amp 'trickle charger' for 12 hours, on its best day, can only ever return 24 amp hours into a battery. Most batteries in Vans are no less than 55 amp hours, and a group 27 can be 100 amp hoursm abnd a group 31 uptro 130 amp hours.

This 24 amp hours assumes that the charger is able to bring the battery to, and HOLD the battery in the mid 14v range the entire 12 hours. This is so excrucitaing unlikely to occur, that any statement of truly fully charged, is uttered only by the unexperienced. It takes a ridiculously time to achieve truly fully charged status, and the older and more abused the battery is, the Longer it takes and the more important the 14.5v sought anfd more importantly HELD, for the entire time, is.

putting a 'trickle charger' on a battery is absolutely NO guarantee the battery is indeed fully charged, Not even if the charger's marketing material leads one to believe the CHarger will restore any battery to maximum potential function, then finish off the owner with the best fellatio they ever received.

The most competent of mechanics, seem to be among the most oblivious in terms of the proper care and feeding, and judging the health of, a lead acid battery.

replacing a battery while there is still a significant parasitic draw, is just a guarantee that the new battery's dies prematurely as well.

There is NO need to take a battery to an Autoparts store foir it to be tested. Most just use a tester which puts a small load on teh battery, watches how much the voltage falls, and comes up with a Ohm/ resitance reading, which then correlates to a CCA figure, along with some math to attempt to correct the fact that the battery is likely not being tested at 0F(CCA), or 32F(CA) or 76f(MCA).

As Said one can get vastly different CCA readings from such testers, just by the pressure and surface area the testers clamps are exerting on the battery terminals.

Also a lot of the carbon pile load testers, can only do 100 to 150 amps of load. whereas a true CCA test is 1/2 the CCA rating of the battery, and it must maintain 7.5 volts or higher after providing that load for 30 seconds.

Since fuel injection causes engines to start so quickly, performing this 'tru CCA test' is abusive and can actually push a weak battery over the edge. Which can be a good thing, if one is headed into the wild blue yonder hundreds of miles from the nearest battery vendor.

Put the DMM's leads right on the 'well charged' battery terminals and start the engine.

A truly healthy fully charged battery will remain 11.7v or higher during the 150 to 180 amp load. The load can briefly spike to as high as 240 amps on a gas engine before settling to the 150 to 180 amp range, just to get the engine moving. Diesels can be much higher spike in amperage due to the extra compression.

I have a digital voltmeter on my dashboard, and watch it every engine start.
It only samples voltage 2x per second, but when I ran my last battery to the ground, it was hitting low 8's and high 7's, even on the warm/hot engine, and when it dipped to mid 7's, it cranked so slow it was overwhelmingly obvious that it was no longer to be trusted and should be replaced.

Nobody needs to goto an AP store for a load test.
It's a waste of time and effort, for anybody who can watch a voltmeter on the battery terminals while the engine is cranking.