Alternator Differences....?

Our 2006 Ford Expedition Limited, started acting weird last night, it was hard to crank. Started up with no problems today, and I took it for a test drive, no issues at first. When I pulled back into the neighborhood I noticed the battery gauge was reading low. Pulled into the driveway, shut it off, tired to start it back up and no dice. Battery gauge was way down.

So I'm assuming (Famous last words) the alternator is taking a dive. Battery was installed in Oct 2020. So now, when looking at replacement alternators I see 3 different amps (110, 135 and some people talking about a 200 amp one). I'm assuming again, being I don't have the Nav System, mine would be the 110 amp one.

Is it better just to stick to the 110 amp one? Is there really any advantage to going bigger? Ours has no mods, and won't be getting any, just to much stuff to break and go wrong IMHO.

I'm just a keep it simple guy when it comes to vehicles, besides money not spent on upgrades and repairs, means more money for guns......

Edited to add:

It'll be getting done at a shop, with the heat and humidity in the Florida Panhandle and my health issues there is no way I could handle being out there right now doing this in this heat....Sucks!

If your Expy came with factory navigation you have a 135 amp alternator. If your Expy did not come with factory navigation you have a 110 amp alternator. Use the correct amperage or you will have the PCM throwing the "Battery" warning up on the instrument cluster. Get an alternator from a local NAPA dealer or Rock Auto .

Hamfisted said:

If your Expy came with factory navigation you have a 135 amp alternator. If your Expy did not come with factory navigation you have a 110 amp alternator. Use the correct amperage or you will have the PCM throwing the "Battery" warning up on the instrument cluster. Get an alternator from a local NAPA dealer or Rock Auto .

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Thank you, and yes we DON'T have and it DIDN'T come with the NAV System.

Are there any brands you would recommend going with or staying away from? I think our NAPA dealer is still in business here I'll have to check.

I did hook the charger up to the battery when we got back from our test drive. I just went out and checked and it fired right up. So when I bring it in, I'll have them check the battery along with the alternator.

I'd go with NAPA if buying locally, and Motorcraft if buying from Rock Auto.

Hamfisted said:

I'd go with NAPA if buying locally, and Motorcraft if buying from Rock Auto.

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Thank you for taking the time to share your knowledge with me........

Yes Sir, it sounds like your battery discharged due to a defective alternator. The open circuit voltage of a fully charged 12 volt battery should be at least 12.6 volts (engine off/ignition off). If you attach a charger (on boost) and charge it for a short period, it will have a surface charge, which could give an immediate/false indication of 12.6 volts, although it's still discharged. The best way to ensure a fully charged battery is to use a good hydrometer - one that reads the specific gravity of each cell, not just "good," "discharged," "bad," etc... There are some fusible links near the alternator, but they rarely fail. Remember. Just because an alternator (or any other "new" part for that matter) is "new," doesn't mean it's good/works, especially with aftermarket parts. Keep your airspeed and the blue side up!

BROKENPILOT said:

Yes Sir, it sounds like your battery discharged due to a defective alternator. The open circuit voltage of a fully charged 12 volt battery should be at least 12.6 volts (engine off/ignition off). If you attach a charger (on boost) and charge it for a short period, it will have a surface charge, which could give an immediate/false indication of 12.6 volts, although it's still discharged. The best way to ensure a fully charged battery is to use a good hydrometer - one that reads the specific gravity of each cell, not just "good," "discharged," "bad," etc... There are some fusible links near the alternator, but they rarely fail. Remember. Just because an alternator (or any other "new" part for that matter) is "new," doesn't mean it's good/works, especially with aftermarket parts. Keep your airspeed and the blue side up!

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The wife ran it to the shop, and on her way the "Check Charging System" light came on. She made it to the shop, and is waiting for them to check it out. Our SIL met her there, so he can give her a ride home.

We'll leave the beast there to have the repairs done. We've worked with this shop for years, and she's going to ask them to either go with NAPA or a Ford alternator. I'll keep yall updated......

Thank yall for all the help and advice.

Update:

The battery was completely drained, by the time they went to test everything. The battery was replaced, free of charge, since it's only been installed for 10 months.

After that they ran their tests, and the alternator came back as DOA......So barring any complications The Beast will be back home tomorrow.....

Oh, and while they are at it, they are going to check out the battery wires/harness/grounds and clean as necessary.

I lied, The Beast, is sitting in the driveway already.......According to my wife it seems it's running better. I'll see when we go to my doctors appointment tomorrow.

My 2006 Expedition is named "Beast" also...the wife named it that soon after she first drove it. She said it's a lot less tame than her Lexus 430LS!!!