Originally Posted by disappoint
I must have missed the part where you checked the voltage with and without load after charging/desulfinating.
Jesus freakin' christ THIS^
FBB, you're still acting as if the battery operates on invisible voodoo magic.
You may have a bad battery or alternator cable for all we know.
You said the battery tested bad with a conductance tester
. I do not recall you sharing the actual results.
You said the battery measured 11.86v. That is almost completely discharged.
Neither of these things are terribly conclusive, unless the tester gave a very obviously bad result (e.g. measured 100cca). We also don't know how much your battery actually charged, and you did not bother checking voltage after (assumably) charging.
Point being, 100 replies are you are still at square one
because you are ignoring simple questions/advice, apparently in favor of doing everything you can do cling to your possibly-bad-but-we-still-have-no-idea battery.
Please get a voltmeter. You can get one that will measure voltage accurately enough for the cost of a Happy Meal
Then, put the battery in your car and tighten the connections. Flip the headlights on for a few second to get rid of any surface charge, if it has recently come off a charger (I would just do it anyway to make sure the voltage stabilizes).
Turn everything off, including the ignition switch (pull the key out), close the door, and measure the voltage with the probes directly on the battery posts (the round bit coming out of the battery, not what clamps onto them.
Record this voltage. If it is not ~12.4v volts or more, it's not even close to fully charged. But if it's at least about 12.1v, we will continue testing.
Get a helper. Have them try to start the car while you keep your probes on the battery posts. It doesn't matter if it cranks or how fast- just tell them to keep turning the key forward while you observe the voltage.
Most likely, you will see it drop. A lot. <10v.
What have we determined from that? That the battery is likely shit...but we want to do one more thing.
Repeat the cranking (load) test, but with one probe on the negative post and one on a good ground (stab a shiny part of the engine). If you read more than a quarter of a volt, you have a ground issue.
Repeat that test once more, but go from the positive post to the big terminal on the starter. Again, any significant voltage reading is bad.
A Honda Fit (literally pretty much any of them...that's a fairly new model) should not have cabling issues. If it's never had a starter and no one's fucked with the battery terminals, the cables are likely fine. However, you can also simply test between the battery post and the terminal. Even though the terminal may LOOK tight and corosion-free, it's not impossible to be losing voltage between the post and the terminal. Also, when cables go 'bad', it's usually just that the end of the cable has oxidized; I've probed into cables a mere inch or so down the line, and found almost all the battery voltage being dropped across that area. You don't HAVE to do these vdrop tests, and I doubt they will expose a problem, but it's a good idea
Again, a low voltage reading between the battery posts during cranking will strongly indicate a bad battery. That is the single most important thing you can you do. But I'm trying to get across how invaluable a voltmeter is. You can troubleshoot every single aspect of a starting/charging problem with very few exceptions.