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[Burnsy]

Another dumb question from me......just took battery out of my daily driver vehicle reading 13.04 volts.......in the morning, with battery still out of truck, it should still be at 13.04 correct? Or should it diminish some? I took the 13.04 reading two minutes after turning off truck after driving a while, then i removed the battery from the truck and i plan on checking it in the morning, and a couple times thru the night etc

 

[sgtsandman]

If I remember correctly, a good battery that has sat holds something like a 12.8 volt charge. As they age that drops. RonD is better at those numbers than I am but I'm inclined to believe a drop from 13.04 to high 12 volts is fine. I have heard that whatever you set the battery on while it sits can make a difference. Something non conductive is good like a piece of wood to keep it off the pavement. A rubber mat is better.

 

[Burnsy]

If I remember correctly, a good battery that has sat holds something like a 12.8 volt charge. As they age that drops. RonD is better at those numbers than I am but I'm inclined to believe a drop from 13.04 to high 12 volts is fine. I have heard that whatever you set the battery on while it sits can make a difference. Something non conductive is good like a piece of wood to keep it off the pavement. A rubber mat is better.

Thanks...I have the battery still in the truck just not connected

 

[Burnsy]

It's been disconnected about an hour its at 12.99 now, started at 13.04

 

[sgtsandman]

Thanks...I have the battery still in the truck just not connected

It's been disconnected about an hour its at 12.99 now, started at 13.04

That's fine and you sound like you are good. I do similar when I go on deployment. I park the truck, disconnect the negative terminal, and chock the wheels so I can release the parking brake. The truck has started right up months later when I return.

 

[Burnsy]

If its overcharging does that point to bad battery or does that mean bad alternator/voltage regulator? My alternator was tested a little over 14 with no load just engine running....13.92 with rpm's increased .......didnt test with headlights or radio on.......was told alternator has a ground fault and couldnt be tested OUT of the vehicle.....

 

[Curious Hound]

Brand new, good battery with nothing g attached should settle out around 12.6 - 12.8 volts and hold for a looooong time.

Your alternator has to develop a higher voltage in order to charge the battery. If it's equal to the battery voltage, current will not flow because there is no difference in "potential". If the alternator voltage is less than the battery, it can not charge the battery and will cause problems.

When you first start the car, the alternator will might make upwards of 14.5 volts for a short period, maybe a few minutes, in order to make up for the energy used by the starter (one of the most power hungry loads in most normal vehicles). Then the voltage should drop to maybe around 13.5 volts +/- a few tenths. This makes sure the battery is being lightly charged. If the voltage remains high, battery damage will eventually occur. @RonD has a more intricate writeup of all this.

The purpose of the battery is to start the engine and occasionally supplement the charging system during brief periods of high current draw.

 

[Burnsy]

I had a weak battery this morning, horn barely worked...here's what happened....i noticed just a very little bit of crud on the neg connector last night, but by connector i mean at the end of the cable i have a crimp with eye, it's solid looks factory....THAT screws into the main connector via 8mm bolt.......to clean the crud i undid the 8mm bolt separating the cable/crimpeye from the main connector.....the main connector stayed on the neg terminal......i left the positive cable connected.......i cleaned the crud on neg crimp/eye then screwed that cable back into the main neg connector..........it was late so i didn't do anything after that, didn't try to start it......came out this morning ready to go, tried to start it and just got clicks.....was able to jump it.....drove five minutes to work, turned off truck, tried restarting it, it started,....tried it three hours later, clicks again.......maybe i didn't drive far enough to work to charge it good but residual charge started it immediately? Could i have a drain? That's why i disconnected it from the truck tonight, to see if it holds.......im stumped, all i did was disconnect and clean the crimp eye and reconnect.....should i have removed the MAIN connector at battery rather than removing the CABLE from the main connector? Seems like its the same principle basically.....only outside variable is maybe i left a door not totally shut but i probably would have noticed that......my ignition will also allow the key to come out of the barrel in any position so i have to make sure ignition is in the true off position when i remove key but im used to it, it's habit to check... i don't think i did that but i guess its a possibility.....i DO have a very little battery juice coming out of the top caps, just enough to notice, i wipe it away, it's hardly anything, battery is from aug 2021 rural king battery......theres no jimmy rigs, pretty clean,normal truck for the most part 01 3.0.

 

[RonD]

5 min drive won't charge a battery enough to hold a charge any length of time, even a 10 or 15min drive
Once a battery is below 12 volts you will get the "click, click, click"
And battery has most likely been damaged, repeating this damages it more each time

Car batteries are made to start the engine and be immediately recharged, and not used again until the next startup
They are made with thin plates so they can release a lot of AMPs instantly, starter needs 60 to 75amps
These thin plates can warp and short out if battery is drained too low

RV/trailer Batteries are made with thick plates, so they release amps slowly and can be drained down below 12volts without too many issues


If you see liquid on top of a battery then its most likely bad by now, even a little fluid, unless it was from rain, lol
Battery is most likely self draining now

Rural King says they have a 24month free exchange, or 72month prorated
Take advantage of that, as soon as possible

Then get a Volt/ohm meter to test your charging system, $10-$15 and it will save you lots of money in the future

 

[Burnsy]

5 min drive won't charge a battery enough to hold a charge any length of time, even a 10 or 15min drive
Once a battery is below 12 volts you will get the "click, click, click"
And battery has most likely been damaged, repeating this damages it more each time

Car batteries are made to start the engine and be immediately recharged
They are made with thin plates so they can release a lot of AMPs instantly

RV/trailer Batteries are made with thick plates, so they release amps slowly and can be drained down below 12volts without too many issues


If you see liquid on top of a battery then its most likely bad by now, even a little fluid, unless it was from rain, lol
Battery is most likely self draining now

Rural King says they have a 24month free exchange, or 72month prorated
Take advantage of that, as soon as possible

Then get a Volt/ohm meter to test your charging system, $10-$15 and will save you lots of money in the future

Thanks. I took readings, see my first comment ....i probably need a battery, just wondering how it all went bad from a simple disconnect and reconnect......my battery is one year replacement im at almost two years, oh well....

 

[RonD]

All batteries will have a FALSE higher voltage after being charged, like when driving

To test battery wait about 2 hours, write down volts, then after sitting overnight test it again, should be exactly the same, if its lower, then could be a vehicle drain or bad battery, more on this down farther

New battery will be 12.8-13.0v, 100% capacity
3 year old battery 12.6v, 75% capacity
5/6 year old battery 12.3v, 50% capacity...............and time to shop for battery sales

Voltage, at battery, with engine running, 13.5v to 14.8v is OK, after startup it will be in the 14+ range
After a drive but BEFORE shutting off the engine retest batter voltage engine idling
13.5 to 13.8v is OK, up to 14.2v can be OK


Voltage dropping when vehicle sits
After driving unhook one battery cable, and wait, after 2 hours test voltage write it down
Then test voltage again after 6 to 8 hours or more, should be EXACTLY the same
If it has dropped more than .2v then battery has internal short self draining, replace it
If its the same you have an AMP draw in the vehicle higher than it should be, 0.03 to 0.07amps is expected, you can use an amp meter to test for this

 

[Burnsy]

All batteries will have a FALSE higher voltage after being charged, like when driving

To test battery wait about 2 hours, write down volts, then after sitting overnight test it again, should be exactly the same, if its lower, then could be a vehicle drain or bad battery, more on this down farther

New battery will be 12.8-13.0v, 100% capacity
3 year old battery 12.6v, 75% capacity
5/6 year old battery 12.3v, 50% capacity...............and time to shop for battery sales

Voltage, at battery, with engine running, 13.5v to 14.8v is OK, after startup it will be in the 14+ range
After a drive but BEFORE shutting off the engine retest batter voltage engine idling
13.5 to 13.8v is OK, up to 14.2v can be OK


Voltage dropping when vehicle sits
After driving unhook one battery cable, and wait, after 2 hours test voltage write it down
Then test voltage again after 6 to 8 hours or more, should be EXACTLY the same
If it has dropped more than .2v then battery has internal short self draining, replace it
If its the same you have an AMP draw in the vehicle higher than it should be, 0.03 to 0.07amps is expected, you can use an amp meter to test for this

Thanks Ron....im confused by one sentence you wrote in one of your paragraphs, I included the paragraph here below my comment....the third sentence you say voltage should be EXACTLY the same, in the last sentence you say if its the same I have an amp draw.....did you mean to say if its NOT the same I have an amp draw?? Sorry I'm not great with electric . Thank you
"Voltage dropping when vehicle sits
After driving unhook one battery cable, and wait, after 2 hours test voltage write it down
Then test voltage again after 6 to 8 hours or more, should be EXACTLY the same
If it has dropped more than .2v then battery has internal short self draining, replace it
If its the same you have an AMP draw in the vehicle higher than it should be, 0.03 to 0.07amps is expected, you can use an amp meter to test for this ..........."

 

[2011Supercab]

If the disconnected battery voltage is the same after sitting 6 to 8 hours the battery is OK, Then you must have an amp draw in the vehicle draining the battery while it's connected

 

[Burnsy]

If the disconnected battery voltage is the same after sitting 6 to 8 hours the battery is OK, Then you must have an amp draw in the vehicle draining the battery while it's connected

What are the common culprits?

 

[Burnsy]

It's the next morning, battery stayed at 12.90 overnight disconnected.........i hooked up both cables, pos first, and after 15 minutes its at 12.67....after another 15 minutes 12.72