Auxiliary Power plug

[Yupster Dog]

it wouldn't surprise me to learn that there was some modification done to this leg of the 12 volt buss..

You just full of info after the fact.
And Sticker just added that connections will lower voltage and what Chris and I said (in his own words) and added a diagram of a previous generation expedition. might as well be looking at a diagram for a Tahoe.

How is that exactly what you looking for and what we said is not?

Your just grumpy. Do you need a hug? @07navi was acting nice on your thread maybe he will give you one.

 

[1970Maverick]

I have a 2017 Expedition EL. I wanted to use the right, rear auxiliary power plug (cigarette plug) to keep a floating charge across the battery. After connecting the float charger (13.2 VDC) to the plug I was only seeing a 12.5 VDC reading at the battery post.
My question is: why am I seeing a .7 VDC drop from the rear auxiliary power plug to the vehicle's battery post? It's almost as if it's going through a silicon diode before reaching the battery post but that doesn't make any sense because it shows a normal output voltage when measured at the plug!
Does anybody have a wiring diagram of the auxiliary plugs that would show the full physical route of the auxiliary plug?

Have you tried connecting the charger directly to your battery for 24 hours to see if it will charge up to 13.2 ? That would give you a clue as to whether it's a problem with the charger or something in the wiring from the aux power socket to the battery. If it works directly across the battery maybe you could wire a small 2 pole connector behind the grill.

 

[Plati]

Have you tried connecting the charger directly to your battery for 24 hours to see if it will charge up to 13.2 ? That would give you a clue as to whether it's a problem with the charger or something in the wiring from the aux power socket to the battery. If it works directly across the battery maybe you could wire a small 2 pole connector behind the grill.

Can you just simply use any old DC power supply to charge a battery anyway? I dunno, not in my wheelhouse. Me ... I would only use a battery charger since I dunno. I got an old 12V power supply I used in college to power the 67 Chevy Van 8 track player & speakers in my Dorm room. We blasted good tunes night & day. I would not use that to charge my Expy battery. Just me maybe.



MrYup. I disagree on one point. Yup it's a 2003 wiring diagram and you have to consider that the Expy in question is a later year (I think). However, some things haven't changed over the years - some have. It's info imperfect as it is but still good info. Right?

It would interesting to place a volt/ohm.meter at the rear power outlet with a long lead to the battery. This would be fun to troubleshoot. I hope we find out a final diagnosis!!

 

[Trainmaster]

I think Sticker makes the most sense. There are no electronics involved in the accessory jack circuit.

Connecting 13 volts at low amperage to a 12 volt battery isn't going to raise the battery's voltage to 13 volts instantly. Disconnect battery connector from the post, plug your charger into the rear jack and you'll see your 13 volts at the clamp.

The battery is moderating the voltage until it charges to the new value. Make sense?

Of course you can check resistance between the rear jack and the battery clamp, etc, etc.

 

[Yupster Dog]

Have you tried connecting the charger directly to your battery for 24 hours to see if it will charge up to 13.2 ? That would give you a clue as to whether it's a problem with the charger or something in the wiring from the aux power socket to the battery. If it works directly across the battery maybe you could wire a small 2 pole connector behind the grill.

Excellent idea Maverick But He won't tell what he is trying to accomplish and evidently it is some huge secret (only mother on the need to know)

@Yosemite Sam if you would say what it is you are trying to do There is no doubt in my mind someone on this forum can help. But forum members are not mind readers.

but still good info. Right?

Absolutely correct you can put up the wiring diagram from just about any vehicle on the road today and show Battery to fuse to power point. (of course I am talking about the power point that stays on after you cut the key off)

 

[ChrisRCNY]

You might try turning the supply up to 13.8, it's still a safe float voltage. I'll try hooking up my much cheaper regulated supply to the same port on my 08, see what I get.

I'm assuming you checked the voltage at the supply with the meter, just to make sure the meter agrees with the supply's measurement. Always fun to find out a $400 multimeter needs an out of warranty repair.

 

[Plati]

You might try turning the supply up to 13.8, it's still a safe float voltage. I'll try hooking up my much cheaper regulated supply to the same port on my 08, see what I get.

I'm assuming you checked the voltage at the supply with the meter, just to make sure the meter agrees with the supply's measurement. Always fun to find out a $400 multimeter needs an out of warranty repair.

How does a power supply like that determine the current to drive?
If it's a 50 amp power supply, will it try to drive 50 amps at 13.8V?
or is there an inherent resistance with the battery that determines supplied current?
I don't understand that piece of it.

update: I'll study this tonight while swilling Miller beer
https://www.itacanet.org/eng/elec/battery/battery.pdf

 

[ChrisRCNY]

The chinesium supply I used when set to the closest I could get was as follows:

12.4v .15a @ supply
12.12@ battery.

13.2v .52a @ supply
12.13 @ battery

Meter was within 0.01v of the supply, supply only gives me one digit after decimal.

 

[ChrisRCNY]

When I turned the supply up to 14.3v, I got 1.45a, and 12.15v at battery. Pretty noteworthy drop in there, somewhere.

Might be worth turning your supply up to the higher end of 6 cell lead acid float voltages. There's still a ton of drop, but it'll work.

 

[PeteinGH]

Attached is a diagram from the 2014 shop manual.




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