NA Car 12v lead acid testing NA

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
91310D64-485F-4AD3-A189-DEAD2C6940E2.jpeg I have an 18 mo old NAPA battery in a spare car. I run the car / take it for a spin weekly. Recently it stopped holding the charge for that week (it’s not completely dead but doesn’t always crank - we gave not had below 0C in my garage this winter). I take it to NAPA and he puts it on charge, tests the voltage & says its good.
I say, it was just charged, good chance the voltage is going to test ok. I asked about a discharge test to see if it will produce x amps over time under load thinking they probably have a graph to make plots on - nope.
I guess it’s possible the car has suddenly developed an electrical leak in the past month but I am dubious.
 
Is it clean? That could cause it to discharge over time, scrub it with water and baking soda. Then make sure all your lights and stuff are shutting off. You don't say what year, but newer cars have a fuse you can pull to shed most of the unnecessary load during shipping, find and try pulling that.
 
You need to confirm starter and alternator are good as well.

And wiring/grounds of all 3.
 
Looks like a loose ground ,may have developed.
 
I ran into some loose ground last weekend hiking up a hill. Damn near caused me to fall.
 
frfly172 said:
Looks like a loose ground ,may have developed.
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455 Bravo Uniform said:
You need to confirm starter and alternator are good as well.

And wiring/grounds of all 3.
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weirdjim said:
It's probably a bad ground ... or a loose connection ... or something else. :cheerswine:
Jim
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I agree with the above. Check the connections. It happened to me. If the battery is testing good and is getting a charge, look at the wiring.
Another thing that happened to me was the starter relay shorted to the hood. Tricky to find since it always started fine when the hood was opened.
 
If it's not charging well in the car, dirty terminals are often a Cause. Clean them and put some white grease on them before you put the battery cables back on.
 
While your car sits idle, it slowly consumes battery charge. Your weekly spin in the car may not be enough to fully charge the battery, so its state of charge is gradually degrading.
 
The terminals are shiny and clean enough to eat off, and I did nothing to them. They were tight as well.
I am running it now; voltage across the battery terminals not the connectors is 14.1v. I think the charging system is fine. Not sure why I'd want to check the starter. If I grease the terminals they will become caked in dirt because it is so dusty out here - have learned that the hard way when I moved here.

So a 20 minute idle or a 10min idle combined with a 10mi run down the highway is not enough to charge the battery. In January. When all the previous 17 months with this technique were fine. And all the previous years with other batteries.

I wouldn't be so torqued about it if the battery were easy to get to but some dough-head put it in front of the LF tire; difficult to get at.

Thinking some type of better long-term, low-use battery with a trickle charger maybe.
 
Let'sgoflying! said:
suddenly developed an electrical leak
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It's possible, but they really call it parasitic drain. With a fully charged battery, everything off to include courtesy lights, remove negative cable off battery, connect a meter selected to DC AMPS on a 5-10 amp scale between negative cable and negative battery terminal. Anything less than .05 amp should be good. If higher than .05 amp start pulling fuses till load goes down. If all the fuses out and still over .05 amp, key switch could be worn internally, starter bendix could be bridged, a shorted wire somewhere.....

A 1 amp drain will kill most car batteries in 2-4 days.

EDIT: was informed my figures were a bit dated for vehicles since most now have one or more computers in various sleep modes. So a reading of less than .1 amp should be good and anything above that should be suspect.
 
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Verify no oarasitic drain as noted above, then when replacing battery, get an AGM.
 
You can buy a cheap battery tender for $20 and a cable end adapter with ring terminals that's permanently installed on your battery for $5.

I have about a half dozen of these installed on various vehicles and equipment. Never a dead battery.
 
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