Charging voltage

2011 gtcs · Oct 6, 2019

Kinda a odd question, but I was wondering what you guys see for battery voltage on your LCD screen. My car starts off at 14.1 to 14.0 than after driving it (a lot last night) on my way home I noticed it was only reading 13.8 to 13.7, seemed kinda weird to me. Maybe my alternator is on it's way out.

Cman01 · Oct 6, 2019

It will jump around a bit like that, especially on my car since I ran it for a few years with my lightweight Odyssey battery that if I know I won't drive the car for a few days I would need to keep a tender on it so it doesn't die.

At night if you have the hdlts on and other things on causing a load on the battery the alt. will not be putting 14+ volts into it charging it it will probably keep the battery charging only at like <14V.

Tony

2011 gtcs · Oct 6, 2019

Cman01 said:
It will jump around a bit like that, especially on my car since I ran it for a few years with my lightweight Odyssey battery that if I know I won't drive the car for a few days I would need to keep a tender on it so it doesn't die.

At night if you have the hdlts on and other things on causing a load on the battery the alt. will not be putting 14+ volts into it charging it it will probably keep the battery charging only at like <14V.

Tony

Gotcha, I have a Motorcraft battery in it right now, and I always keep a battery tender on it. I'm not considered right now.

decipha · Oct 6, 2019

stock she should be at 13.3 volts when fully warmed up.

On the 13-14 gt500s I tune I always command 14.2 volts and get just over at 14.3 voltage on average.

That's unloaded. If you put a load on her im sure she'll drop.

2011 gtcs · Oct 6, 2019

decipha said:
stock she should be at 13.3 volts when fully warmed up.

On the 13-14 gt500s I tune I always command 14.2 volts and get just over at 14.3 voltage on average.

That's unloaded. If you put a load on her im sure she'll drop.

That makes sense, I spoke with my tuner earlier, is there any real reason to keep the charging voltage at 14.2 volts?

decipha · Oct 6, 2019

it depends on your battery. Lithiums don't like much more than .5 volts above their rating and gels shouldn't be pushed much harder than that. Acid battery's can take 16v with no problems.

As the battery warms up its charging voltage should be reduced as well. Thats how the stock ford code handles it going back to the eec-v days. In fact I just rewrote the alternator code in the marauder ecus earlier today.

biminiLX · Oct 6, 2019

Interesting, thanks men.
-J

merkyworks · Oct 7, 2019

My interceptor gauge shows 13.6-13.9 when idling but if I put a multimeter directly on the battery it reads 14.1+, IDK why it does but everything seems okay.

2011 gtcs · Oct 7, 2019

merkyworks said:
My interceptor gauge shows 13.6-13.9 when idling but if I put a multimeter directly on the battery it reads 14.1+, IDK why it does but everything seems okay.

Yeah I didn't put a DMM on the battery yet with the car idling, but I had the car out last night for a little joyride and the voltage stayed at 13.9 to 14.0 all night, so whatever at this point.

Cman01 · Oct 7, 2019

Nothing is wrong. Different factors will affect the actual # of voltage that is charging the battery.

me32 · Oct 7, 2019

decipha said:
it depends on your battery. Lithiums don't like much more than .5 volts above their rating and gels shouldn't be pushed much harder than that. Acid battery's can take 16v with no problems.

As the battery warms up its charging voltage should be reduced as well. Thats how the stock ford code handles it going back to the eec-v days. In fact I just rewrote the alternator code in the marauder ecus earlier today.

Great info. Thanks for sharing that.

Charging voltage

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