300 Amp Alternator Upgraded 0AWG Cable Question

[drodio]

I just installed a new DCPower SPX 300 Amp Alternator in my truck.

Here's a question: By default, the stock 2003 F250 alternator doesn't start charging the batteries until 120 seconds after start. By bypassing that system via upgraded 0AWG + and - cables, I'm now charging the batteries immediately upon start. Everything seems to be running fine, but am I causing some type of long-term damage to the engine or electrical system? I figure there *must* be a reason it was engineered not to charge the batteries for the first 120 seconds (I know the batteries are used to run the glow plugs, but not sure how/why that relates to not charging them).

My thought process (here are two pics: http://drod.io/image/3z0I2z2h2z2S and http://drod.io/image/0q1E290p3B44): Since this is a 300amp alternator, I upgraded both the positive and negative lines with 0AWG cables. I attached the positive cable to the positive terminal on the alternator (with a 250amp fuse inline) and attached it to the positive terminal of one of the two batteries. And then I attached a negative cable to the base of the alternator where it screws to the engine block, and attached that to the negative terminal of the battery.

So now, immediately upon start-up, I get a 14.4-ish voltage showing on my Insight CTS, because the alternator is charging the batts immediately.

Can you please let me know:

1) Is everything OK as-is?

2) Should I *not* have the negative 0AWG cable attached, and only have the positive 0AWG cable attached? (I was thinking maybe if I took off the negative cable, the system might go back to its previous state of not charging for the first 120 seconds -- i.e., if I'm not completing a full positive and negative loop, but only the positive side of things, then the default charging system would take over, but I'd still get the benefits of the upgraded positive 0AWG cable

3) Other?

Thanks,

DROdio


Sent from my iPad using Autoguide

[Snake]

Where did you get the information that the OEM alternator doesn't begin charging for 120 seconds? I may be wrong, but I don't think that's accurate. If it IS true, changing the cable configuration won't impact that. It would have to be linked to the PCM / ECM.

Personally, I'd just run the positive cable from the alternator to the battery and pull the ground cable you added. Use that to add another ground elsewhere, either battery to frame or frame to engine block. I don't think I've ever heard of someone running the ground cable the way you have and don't know what benefits or drawbacks it has, if any.

[drodio]

@Snake, I've just seen that around on the forums; pretty sure it's right.

Here's what Ed at FICMRepair.com said (I had asked him the same question):

=================


---------- Forwarded message ----------
From: Ed Stefan
Date: Fri, Sep 14, 2012 at 10:38 AM
Subject: Re: Ed - question about + and - upgraded cables
To: DROdio


What you've done is fine.

By default, the 2003 F250 alternator does not start charging the system
until after the glow plugs are off, which can be up to 120 seconds
depending on ambient temps.

This was due to an engineering call at Ford that it would be better to not
overtax the alternator each and every day, instead taxing the batteries
each and every day.

Given that your new and shiny alternator can more than handle the demand,
you are no longer taxing your batteries and, for that matter, don't have a
taxed alternator either!

Hope this helps!

Ed

[Snake]

I'm trying really hard not to derail this thread already, but it's hard.

Ed's a smart guy (probably smarter than me) and I understand what he's saying, but did you monitor your voltage before making your changes and afterwards? I already had an upgraded alternator on my truck when I began watching battery volts, and right after start up (less than 5 seconds) I still see over 13v, usually 13.7 - 14.1v. With the truck off, I read 12.6v or less. How does the voltage increase without the alternator contributing?

The only other related mods I have are a 2/0 cable between the alternator and the passenger battery (alternator to pos) and a second 2/0 cable between the two batteries (pos to pos). I didn't eliminate the factory wires. I just added the 2/0 cables.

Again, anything related to how the alternator when the alternator is providing amps comes back primarily to the ECM / PCM. Adding extra grounds or power leads will certainly make things more effective, but it won't change if the alternator is "on" or "off."

Taking a step back, and if Ed's information is accurate, I think you already have an answer to your first question. Per Ed, the alternator does not come on for the first 120 seconds to reduce wear on the alternator.

On a side note, you could / should swap out the 250a inline fuse with a 300a or slightly higher. Otherwise your 300a alternator can only provide 250a of power before the fuse blows.

...

[juzatheman]

i'm sure that your stock alt did start to charge right after start, but the amps just wasn't enough to charge while the glow plugs was on.

i know my -03 did but the voltage didn't rise but drop a bit cause of all amps what was use and that stock alt coud provide only 75 amps at idle.

no issues after i install the very same alt you did

[Dante04SRT]

Originally Posted by Snake

Where did you get the information that the OEM alternator doesn't begin charging for 120 seconds? I may be wrong, but I don't think that's accurate. If it IS true, changing the cable configuration won't impact that. It would have to be linked to the PCM / ECM

My truck does this. Doesn't charge for somewhere between 60-120 seconds after starting. I verify this every morning as I have a digital volt gauge in the truck.

[1995ps]

I have noticed that on my 7.3 as well. Right when i fire it up the stock voltage gauge reads a little to the left and after a minute or so it pops a bit to the right of center. I have the 215amp ambulance alternator on there.

[Snake]

Originally Posted by Dante04SRT

My truck does this. Doesn't charge for somewhere between 60-120 seconds after starting. I verify this every morning as I have a digital volt gauge in the truck.

How many volts are you seeing with the truck off, in the 60-120 seconds after starting, and after the 60-120 seconds?

[juzatheman]

Originally Posted by Dante04SRT

My truck does this. Doesn't charge for somewhere between 60-120 seconds after starting. I verify this every morning as I have a digital volt gauge in the truck.

the volt gauge wount tell the whole truth!

you need to put amp plier to alt positive cabel and see if there coming any amps from alt. if there comes amps you know that your alt is chargin right away and if your voltage is not rising the amps is not enough to charge cause of glow plugs use all of it and no amps left to charge system.

[Dante04SRT]

Originally Posted by Snake

How many volts are you seeing with the truck off, in the 60-120 seconds after starting, and after the 60-120 seconds?

My truck: Truck off: 11.7-12.x
60-120 after staring: 13.7