Losing Battery Charge (1 Viewer)

[-VSG-]

Any tips on where to start?

I just bought a new battery.

When I turn the key to the on position, before starting the truck, the voltmeter drops to just above the orange level and the "charge" light stays on. It feels a bit sluggish to turn over too.

Once started the charge goes back to full and there's no problem. It doesn't seem to matter whether it sits for 15 minutes or 3 days. Either way it's the same thing.

I would think the battery might be bad, but once it's running the charge is full, unlike when the old battery was dying.

I guess I'll start by making sure the battery is good. But any ideas in case it is not the battery?

 

[roscoFJ73]

Check the ground wire on the engine block. They often corrode really bad there and go unnoticed.
If thats not it have the charge checked on the alternator.

 

[soggy60]

following on rosco's response, negative battery cable connects to motor mount stud 'under' a/c compressor. check there for corrosion of wire & connection.

 

[-VSG-]

Cool, thanks for the info. I'll look into that when I get home tonight.

Just so that I understand (keep in mind, electrical stuff to me is gibberish)... If it is a corroded grounding wire - the battery isn't necessarily losing charge. But the car just isn't getting as much voltage from the battery due to the poor connection right?

 

[Mountain Goat]

Sort of, yes. It really means that the starter or other electrical systems are not getting enough current.

Voltage is the force that pushes electricity through a conductor (wire). A common analogy is like water pressure in a pipe. Voltage is measured in VOLTS.

Current is the actuall amount of electricity flowing throught a conductor. A similar analogy applies here - volume of water flow in a pipe. Electrical current is measured in AMPS. An AMP actually equates to a finite number of electrical charges flowing past a given point in a conductor per second.

All electrical conductors have some amount of resistance. Electrical resistance is measured in OHMS. Resistance is simply resistance to the flow of electricity. Similarly, all water pipes have some resistance to water flow. The resistance in both cases depends largely on diameter (of cross section really) of the pipe or conductor, the length, and in the case of electrical current the resistivity of the conductor material i.e. units of resistance per foot of length.

All three of these properties apply to any electrical circuit. They relate to each other in a simple equation known as Ohm's Law.

Simply stated V = I X R.

V = voltage in VOLTS
I = current in AMPS
R = resistance in OHMS

Understanding these measurements and their relationship to each other will take you a long way in understanding any electrical system, including automotive systems.