Car battery dead just about every morning

1. 2019-05-21 at 4:49 PM UTC

   #1
   

   A College Professor victim of incest [your moreover breastless limestone]
   After jump-starting and going for a good drive, shut the motor off and let it sit a few minutes.. battery measures 12.5V , sounds healthy to me. It will probably crank and start fine for the rest of the day now, but after it sits all night it's going to need another jump.
   
   With the motor running, measuring 13.9V across the battery.. suggests the charging system is good.
   
   Read a good blog post about diagnosing this issue which led me to measure this
   
   If it's not clear - the black lead from the meter is clamped onto the negative terminal of the battery, and the red probe is lightly touching against the plastic case of the battery.
   
   Folks, do you see a problem here? I had never heard of this phenomenon before not that I know what that word means.
2. 2019-05-21 at 5:05 PM UTC

   #2
   

   Star Trek VI: The Undiscovered Country Dark Matter [my scoffingly uncritical tinning]
   Its the dirt on the outside of the battery making a negative galvanic potential. Dissimilar metals and all. Switch to measuring amps - you will have nothing at all as far as current goes
3. 2019-05-21 at 5:09 PM UTC

   #3
   

   stl1 Cum Lickin' Fagit
   A Fluke meter? I'm impressed! Those will set you back around $200 or more. Got a couple myself. You may just be reading nonsense that means absolutely nothing or you may be reading stray voltage through the goop on your battery.
   
   Try disconnecting the battery terminals and give them and the battery posts a good cleaning with a battery cleaning tool (under $5). Then, mix up a solution of water and baking soda and apply it to the battery using a paper towel. Also use the towel to wipe down and clean any goop from the top of the battery. Hose of any residue and wipe dry. Reattach cables and retest. If reading zero, you've solved the mystery as well as a drain on the battery. If still reading voltage, it's just meter magic.
4. 2019-05-23 at 10:26 PM UTC

   #4
   

   A College Professor victim of incest [your moreover breastless limestone]

   Originally posted by Star Trek VI: The Undiscovered Country Its the dirt on the outside of the battery making a negative galvanic potential. Dissimilar metals and all. Switch to measuring amps - you will have nothing at all as far as current goes

   
   Can't, it only measures current thru the clamp, I don't have a meter that can be placed in the circuit and measure current through the leads.
   
   It really does seem like it was shorting across the grime, I had checked the connections for tightness and they were good. Cleaned the battery up and reinstalled and it's not dead in the morning now.
   
   

   Originally posted by stl1 A Fluke meter? I'm impressed! Those will set you back around $200 or more. Got a couple myself. You may just be reading nonsense that means absolutely nothing or you may be reading stray voltage through the goop on your battery.
   
   Try disconnecting the battery terminals and give them and the battery posts a good cleaning with a battery cleaning tool (under $5). Then, mix up a solution of water and baking soda and apply it to the battery using a paper towel. Also use the towel to wipe down and clean any goop from the top of the battery. Hose of any residue and wipe dry. Reattach cables and retest. If reading zero, you've solved the mystery as well as a drain on the battery. If still reading voltage, it's just meter magic.

   Which models do you have? I think I'd like to get something like the 87V for measuring small currents, I'll probably also get one of their oscilloscopes used on ebay once I learn more about the specs on scopes.
5. 2019-05-23 at 10:59 PM UTC

   #5
   

   snab_snib African Astronaut

   Originally posted by A College Professor Folks, do you see a problem here? I had never heard of this phenomenon before not that I know what that word means.

   
   i've never heard of grime being so bad that it shorts... you know if you cross the battery terminals you can melt rebar, right?
   but if cleaning it doesn't work, there's a parasitic draw or the battery is fucked. post make model year and engine size and i might look up TSB/ETMs for it. depending on things, it could also be some system failing to shut off, so in the mean time, i suggest you just disconnect the terminals when you're not using the car, and see if the problem goes away in that case. that would narrow it down between the car or the battery. just to let you know if it's a parasitic draw/ short to ground problem, it could be expensive to diagnose and fix. unless you find evidence of rodents and can inspect wires for rodent damage. next step in 'throwing shit at the wall and seeing if it sticks' would be going through the ETM's (electrical troubleshooting manuals - simplified circuit diagrams for various systems and communications networks) and finding EVERY ground point on the vehicle and making sure it is both clean and tight. some points will be easy, many will be difficult and require you to remove trim or components.
6. 2019-05-23 at 11:02 PM UTC

   #6
   Erekshun Naturally Camouflaged
   Sell it to a nigger or cholo and get something else. Unless you stole it.
7. 2019-05-23 at 11:52 PM UTC

   #7
   

   AngryOnion Big Wig [the nightly self-effacing broadsheet]
   Do a draw test with a brake lamp bulb if your meter can't do a regular amp draw test.
   Also check and make sure the trunk light and glove box lights are turning off.
8. 2019-05-24 at 12:12 AM UTC

   #8
   

   A College Professor victim of incest [your moreover breastless limestone]
   Can you explain this brake lamp draw test? Yeah there weren't any lamps on, previous owner unhooked them because they were staying on lol.
   
   PS the cleaned battery has been installed and sittin for 24hrs and it's at 12.4V, down from 12.5 when installed. sounds like it's gud now.
   
   edit:also i'm parking it inside now, so possibly Lt. Col. Aquino was sneaking into my car at night and smoking big doinks listening to my radio running shit down
9. 2019-05-24 at 12:29 AM UTC

   #9
   

   OG_GREENPLASTIC_JOHNSON_III African Astronaut
   its interference from magnetic fields mike pences agents have been paying off the gangstalkers to emit from their handheld EMF rainbow devices
   The following users say it would be alright if the author of this post didn't die in a fire!

   • Star Trek VI: The Undiscovered Country
10. 2019-05-24 at 12:35 AM UTC

    #10
    

    A College Professor victim of incest [your moreover breastless limestone]

    Originally posted by OG_GREENPLASTIC_JOHNSON_III its interference from magnetic fields mike pences agents have been paying off the gangstalkers to emit from their handheld EMF rainbow devices

    
    okay THIS pisses me off.
11. 2019-05-24 at 1:05 AM UTC

    #11
    

    OG_GREENPLASTIC_JOHNSON_III African Astronaut

    Originally posted by A College Professor okay THIS pisses me off.

    
    it simply would NOT HAVE BEEN AN ISSUE if the **logs** would have been kept more securely
12. 2019-05-24 at 7:24 PM UTC

    #12
    

    Star Trek VI: The Undiscovered Country Dark Matter [my scoffingly uncritical tinning]

    Originally posted by snab_snib i've never heard of grime being so bad that it shorts… you know if you cross the battery terminals you can melt rebar, right?

    
    Leakage current is something that will happen no matter what you do. Even an normal insulator will leaks some current. The path of the leak can have a very high resistance (like dirt), or current can be transmitted ionically (like in solutions/fluids)- if you don't have a very low resistance short (as provided by an iron bar) then only a small current will flow, and heating won't be noticeable.