OopsUpsideYerHead

I'm considering some mods that will somewhat tax the battery & electric output. I have some questions regarding upgrading the alternator.

1) is there a preferred alternator (part number)?

2) what are the implications vis-a-vis BMS? Does BMS work fine with a higher output alternator? Only particular alternators? Or does it need to be disabled?

3) any other caveats to upgrading the alternator?

The vehicle is a 2017 Screw 157" 502a with tech & 3.5 EB.

tvsjr

What are you planning to run? The factory alternators are quite beefy... good enough to support most car audio systems, and even extensive public safety communications/equipment installs. You may be overengineering.

Napalm

I was going to ask do you have an alternator in mind or are you talking about taking your's off and going to an overhaul shop and having it "overbuilt"

LIke TVS above said there is plenty of capacity stock, I don't know of a higher spec OE alternator - there might be one on the F250/350 but I'm not sure it would bolt in. maybe it does.


As far as BMS is concerned - provided the upgraded device has the harness input for field voltage from the computer - there shouldn't be any warnings or issues. BMS is really only going to monitor the current going in, or coming out of the battery - and the battery voltage vs vehicle status voltage. So it shouldn't matter. If it was way more capable - like say 50 more amps, then I would hope you are using a larger battery while also installing something that will draw that much current all the time, or most of the time.


SO now curious - what are you planning to run?

Gordy49913

The F150 does have one higher output alternator, the trucks with the snow plow option have it, I want to say it was 40 amps higher, but its been awhile since I looked at this. I wanted to put a plow on mine and was looking at the differences. I did buy one from a scrap yard out of a wrecked truck. I don't know if it was used on any of the Auto start/stop trucks. I just looked at Car-part.com and they show a 200amp and a 240amp. Guess I should mention this is for the 5.0 engine, they list several different ones for the 2.7 and 3.5, turbo/non turbo, 110v inverter/no inverter

BareBonesXL

Do you know what you have now? Always good to know your starting point before "upgrading".

If you are going to run substantially more amperage you'll need to upgrade wiring also, to the components that are pulling more current.

Most people "upgrade" their alternators based on maximum output when the real problem is at idle when output is low. You might get the same results with a pulley change.

You could even go backward, look at 75 versus 95 here - https://www.fullsizebronco.com/forum...ins-agian.html

And here, just picked some images from Google search - http://www.forwardlook.net/forums/fo....asp?tid=53499

tvsjr

Correct. The SSV (special service vehicle) gets the 240A alternator as well. Mechman and a few others have upgraded alternators for the 12th gen trucks... but I know of nothing for 13th gen. You could always do something completely custom, if you're good at fabrication and are comfortable reworking the belt.

With the capabilities of the alternators these days, there just isn't much need to upgrade. It's not like 10+ years ago, when vehicles often had ~100A alternators that performed very poorly at idle.

BareBonesXL

Don't the newer vehicles also have PCM's that raise engine RPM to meet electrical demand? Even before the battery management systems I think that this was a thing.

Might be best to do the mods first, then see if a new alternator is needed. Be ready, but don't assume.

tvsjr

Not really. On the Super Duty side, you have to use the included wiring to engage charge protect. Fortunately, the alternators these days deliver a lot more power at idle RPMs.

The best solution is to engineer it properly. Understand what the load is (peak and average) then design the electrical system to match.

BareBonesXL

Interesting. Nissan's can get a high idle if the battery needs charging. Since the late 80's. It's described as one of the factors that the ECM uses to set idle speed.

BareBonesXL

I guess that Ford just produced high output alternators instead.

Interesting comment in this test procedure, below, about using a different alternator with a "smart charge" system.

"Smart charge systems can be highly intolerant to any alternator that is not manufactured to the original specifications."

https://www.picoauto.com/library/aut...rt-alternator/