Charging voltage

[Lays]

Hi all, I noticed my voltage has a mind of it's own while driving around / idling, if I don't turn my headlights it seems to sit between 12.3-12.5v, if I turn the headlights on it sits at 13.4-13.6, and occasionally it will sit ~14.4v whenever it feels like it.

I believe we have some sort of "smart-charging" system on our cars. Is there a way to bypass that? Maybe through Forscan or maybe an inline resistor on the alternator wiring?

I plan on getting another subwoofer and want to make the most of my 2300w RMS amplifier. Figured if I can get the charging voltage up a little, less likelihood of voltage dropping as much and causing clipping.

 

[TyphoonFiST]

Hi all, I noticed my voltage has a mind of it's own while driving around / idling, if I don't turn my headlights it seems to sit between 12.3-12.5v, if I turn the headlights on it sits at 13.4-13.6, and occasionally it will sit ~14.4v whenever it feels like it.

I believe we have some sort of "smart-charging" system on our cars. Is there a way to bypass that? Maybe through Forscan or maybe an inline resistor on the alternator wiring?

I plan on getting another subwoofer and want to make the most of my 2300w RMS amplifier. Figured if I can get the charging voltage up a little, less likelihood of voltage dropping as much and causing clipping.

Quit monitoring it on a Anxious port* or shove it in the glove box. The car is smart enough that if there is a problem it will notify you VS. Worrying yourself to death.

Sent from my SM-S908U1 using Tapatalk

 

[Lays]

Quit monitoring it on a Anxious port* or shove it in the glove box. The car is smart enough that if there is a problem it will notify you VS. Worrying yourself to death.

Sent from my SM-S908U1 using Tapatalk

You didn't read my whole post
My amplifier outputs more wattage at higher voltage. I want to bypass the smart charging stuff for that reason.

• RMS power, 1ohm : 2000w @ 12v | 2300 @ 14.4v
• RMS power, 2ohms: 1000w @ 12v | 1300 @ 14.4v

 

[D1JL]

The FiST (as most newer cars today) uses a smart alternator.
That is, the voltage regulator is built within the alternator.
You are going to get what you get.

 

[Lays]

The FiST (as most newer cars today) uses a smart alternator.
That is, the voltage regulator is built within the alternator.
You are going to get what you get.

I may try unplugging the harness that goes to it, seems like one of the wires is for PCM to monitor what voltage it's outputting. Curious if it'll just run at 100% if I unplug it, and it'll just throw a CEL.

Figured I'd ask beforehand if someone knew if another work-around before I tried strong-arming it lol.

 

[D1JL]

The PCM does not control voltage regulator in the alternator.
The best you can do would connect directly to the battery.
You of course, can do whatever you want.
I always check the official Ford workshop manual.
Maybe an Amp that controls its input voltage better would be a good choice.

 

[koozy]

Read the manual to be certain before committing. Think I read something about the potential to fry other sensitive components. Not worth it in my opinion, but I know how sound enthusiasts can be about getting the most power.

 

[Lays]

The PCM does not control voltage regulator in the alternator.
The best you can do would connect directly to the battery.
You of course, can do whatever you want.
I always check the official Ford workshop manual.
Maybe an Amp that controls its input voltage better would be a good choice.

Thanks for the help, if all else fails I will just order an aftermarket alternator. I'll probably need one anyways with higher amperage output to combat voltage droop with the second sub. Seems like most of them have options to charge at 14.4-14.8v constant.
About the amp thing, I think most amps increase output as their input voltage goes up, usually up to ~15-16 volts you see an increase in output. Like a more-in more-out type of deal.

I'll look into getting a workshop manual, will come in handy at some point down the road I'm sure!

 

[Intuit]

If you mess with the Battery Monitoring System (BMS) there may be unintended consequences. (like not charging) More information here...
https://www.fiestastforum.com/threads/2014-ford-fiesta-st-1-6-ecoboost.29091/post-474638
The grounding system is engineered to handle all the potential options that came with the initial car design; probably with some overhead. Your equipment may overtax the existing ground. Be sure to voltage drop test your grounding back to battery with all accessories running, including tail lights, hazards, high-beams, max-AC, etcetera. Voltage drop tests without putting the circuit at its potential, will provide misleading results. Six percent or higher is considered excessive voltage drop.

 

[Intuit]

Yes, what you're observing is the "smart charging" system. Running the alternator at or near capacity runs it hotter and shortens its life. (Also negatively impacts mileage since alternators under load provide some drag on the engine.) Alternator replacement may require draining and disconnecting the A/C lines. The charging system relies on good grounding to provide accurate charging.

 

[Lays]

If you mess with the Battery Monitoring System (BMS) there may be unintended consequences. (like not charging) More information here...
https://www.fiestastforum.com/threads/2014-ford-fiesta-st-1-6-ecoboost.29091/post-474638
The grounding system is engineered to handle all the potential options that came with the initial car design; probably with some overhead. Your equipment may overtax the existing ground. Be sure to voltage drop test your grounding back to battery with all accessories running, including tail lights, hazards, high-beams, max-AC, etcetera. Voltage drop tests without putting the circuit at its potential, will provide misleading results. Six percent or higher is considered excessive voltage drop.

I’ve already upgraded the charging wire, grounding wire and engine ground with 1/0 OFC wiring, “big 3 upgrade” in other words, so I think that part is alright.
I’ll give that a read when I get back from vacation, thank you!

 

[Intuit]

I’ve already upgraded the charging wire, grounding wire and engine ground with 1/0 OFC wiring, “big 3 upgrade” in other words, so I think that part is alright.
I’ll give that a read when I get back from vacation, thank you!

Gotta a thread on it? I may eventually redo (or augment) the rusted ground underneath the battery tray. Ford pulled that same chit with a prior car. Stop sticking important ground cables underneath batteries Ford! They leak acid. 🤦‍♂️

 

[Lays]

Gotta a thread on it? I may eventually redo (or augment) the rusted ground underneath the battery tray. Ford pulled that same chit with a prior car. Stop sticking important ground cables underneath batteries Ford! They leak acid. 🤦‍♂️

I didn’t make a thread but all I did was get some quality 1/0 off Down4sound website, they have preterminated kits that you can buy for like ~100ish bucks.

I went from alternator bracket to strut tower for engine ground, and from battery ground to the chassis ground right by the battery, then ran one from positive batt to the terminal on the alternator for charging wire.

I left all the OEM wiring in place too, just added my new stuff on for ease of “back-to-stock” if I ever decide to.

I also updgraded the oem battery with a same size beefy AGM from XSPower batteries. Helped a lot with keeping voltage up during really bassysongs

 

[Intuit]

Yeah 'augment' is the route I took last time too since it's soooo much more work to try and redo a ground point that was badly rusted from battery acid. I had run wires off the alternator bracket in that case as well.

One part of the manual reads something similar to:
* when charging the battery in-vehicle connect one lead to positive terminal and the other to a grounding point on the body
* do not connect the ground directly to battery because the the BMS won't be able to monitor charge and this can cause problem

DIdn't say that precisely but that's the gist of it, memory serving. I got the impression that they want everything to go past a little module or whatever that they have attached to the ground cable clamp. It might be in that stuff I linked to.

 

[Intuit]

I had drilled holes into the frame rail. I've noticed over the years that running electricity through metal, accelerates its decomposition process. So I avoided attaching wires to structure points like the strut towers... as convenient and tempting as it was. But I can see the manufacturer did exactly that on this vehicle so it's kind of moot.

 

[M-Sport fan]

One part of the manual reads something similar to:
* when charging the battery in-vehicle connect one lead to positive terminal and the other to a grounding point on the body
* do not connect the ground directly to battery because the the BMS won't be able to monitor charge and this can cause problem

I do this as a matter of course/standard procedure, whether the manual says to or not.