Battery voltage

[dave110]

After a full charge, disconnected, and standing over night at about 55 deg., what should a battery hold it's voltage at? How low is too low?

[Me78569]

I would like to see over 12.4v+ after sitting with a full charge but @Mopar1973Man would know better.  I would have your batteries load tested if you are concerned

[Mopar1973Man]

Here you go...

[dave110]

Thanks. So I'm assuming the green range is considered good then? I had them load tested which is what brought this up. I charged them and let them sit overnight. Took them to Advance because they're under warranty and had them tested. They are 810cca and load tested OK putting out 440cca. Seems a little low to me. I asked how low they must be for warranty and was told the machine would know.They blamed it on a low charge when I brought them in, and I did probably take them off too soon. So after a full charge they settled in around 12.28 after sitting overnight. I'm no slop with battery maintenance having them usually last 8-10 years, that's why I'm concerned with these being on the low side after only 2 years.

[Me78569]

sounds like they are bad to me.  I'd be looking for a replacement.

[dave110]

I agree, but would like to get warranty out of them. Guess that's like wanting to get paid more for doing less

[dripley]

I bugs me that the machine supposedly knows but evidently the clerk does not. It does not surprise though.

[IBMobile]

Did the clerk ask if you wanted fries with that battery test?

I like to see 12.4 + volts, below that i feel the battery is on the weak side. 12.2 volts is a low state of charge for a 2 year battery but most wet cell batteries are only good for 3-4 years.  The warranty that you get with a battery is a scam. The company charges extra for that 60-72 month or more warranty with the knowledge that when most people replace the battery in their vehicle they either sell it before that battery gives them trouble or they don't keep the receipt so the selling store doesn't have to honor the warranty.  If you do happen to keep the receipt and the battery goes out in the last year of the warranty what they give you for the prorate isn't worth the extra you paid for that 60-72 month battery. 

[dave110]

These were a 36 month warranty but I get what you are saying. I'd never spend extra for a 72 month battery because of the pro rate scam, but I feel they should honor a 36 month warranty when they go bad in 26 months, especially when I have my receipt.

Now I have more info. While they held 12.3v disconnected they were down to under 12.2 in the truck over night. So I pulled the wire to the PDC, set my meter on 200mA, and put the leads in between the wire and the lug on the PDC. Reading went off the scale. I pulled all the fuses in the PDC and one by one put them back in and checked the amp draw. The engine control circuit was drawing 2.8, and the hazard circuit was 4.6. No draw on anything else except the battery fuse, which sent the meter off the scale. So I have a huge draw on the battery fuse with everything else disconnected. What does the battery circuit feed? What should I be looking for? I had the LH fender replaced recently and they may have removed the PDC to access the inner fender. Is it possible a wire is pinched somewhere creating the draw? Help! I hate electrical problems.

[IBMobile]

5 hours ago, dave110 said:

Is it possible a wire is pinched somewhere creating the draw? Help! I hate electrical problems.

If a wire was pinched then there would be either and open circuit with no draw or a shorted to ground circuit which would either blow a fuse or start a fire.

 

5 hours ago, dave110 said:

drawing 2.8, and the hazard circuit was 4.6.

Is this 2.8 and 4.6mA or 28 and 46mA, most normal parasitic draws I see around 50mA 

 

5 hours ago, dave110 said:

What does the battery circuit feed?

Is the fuse you're talking about here?

  

[dave110]

Pretty sure it was 2.8 and 4.4mA. I was never good with schematics but It is the 50A fuse right behind the 140A alternator fuse in the PDC labeled battery. The one in this schematic says junction block. Could that be the fuse panel in the dash?

What is the normal mA draw on one of these trucks sitting not running?

[IBMobile]

1 hour ago, dave110 said:

What is the normal mA draw on one of these trucks sitting not running?

Don't know, never had to measure it on the truck but it should be about the same as other vehicles to keep memory for radio, ECM, PCM (if needed) and clock going .  There may be a light on, a door or mirror switch stuck on.  A small light will draw 3+ amps.

 

2 hours ago, dave110 said:

The one in this schematic says junction block.

 

 

 

 

 

[dave110]

Thank You Much!! I now see what circuits it feeds. I'll pull the fuses (1,4,12,13,14) in the dash panel and measure across them to see which one is the culprit. Could very well be the glove box light. I seldom use the truck at night and it would be hard to see in the daytime. I have a copy the service manual but I never think to look there first. I appreciate you taking the time to look it up for me.

Edited February 7, 2017 by dave110

[dave110]

I got to do some checking and noticed a 17.5mA draw on my power window/door lock circuit. Fuse #13. What makes a parasitic draw on a circuit like that? I assume a partly stuck switch but not sure how to know.

[IBMobile]

The wire diagram shows three things on fuse #13, the two front window switches and the central timer module.    You can unplug the window switches and see if the draw stops but at 17.5mA I think it's the central timer module which is all so known as a body control module that's drawing the power.  The CTM is connected to the CCD data bus network and controls automatic door locks, central locking, chimes, timed illuminated entry, heated seats and a host of other things.  17.5mA  is what one would think a control module uses and I wouldn't worry about it.

[dave110]

Oh, I didn't see the CTM is on there. Yes that's probably the draw then. I plan to keep checking when it warms up a little.

[Chris O.]

Quote

17.5mA  is what one would think a control module uses and I wouldn't worry about it.

Amen to that, i bet your Radio is eating up more battery on standby.

[dave110]

@IBMobile. I put a new set of bats in today and noticed a .03V drop in voltage when I have the 50A battery fuse in. Take it out and the batteries climb up .03V again. Is this too much?

[IBMobile]

That's three hundredths of a volt.  This much voltage goes right along with the amp draw of 17mA.  Nothing I'd worry about.   if you want to find out what is using .03V start by removing, in the junction block, one fuse at a time:  #1, #4, #12, #13, #14, and circuit breaker #2.    

[dave110]

Thank you. That's just what I was hoping to hear, that it was similar to the 17mA. I'm pretty sure it's the CTM doing it's normal thing then as that's where the draw is. None of the rest showed anything. Now that I have these new Interstates in, I hold a charge of about 12.6-7 over night so I'm pretty sure that's where the problem was all along...... junk batteries. Just wanted to be thorough with it too though. Still steams me that a 3 year free replacement battery that puts out 1/2 it's rated amperage after 2 years is not eligible for free replacement .

Thanks for the advice!!