Alternator Needs Replacement?

[Space Fox]

Been dealing with some electrical gremlins lately.

I first bought the car over two years ago. Upon reading the codes the car had a bunch of low voltage codes - instrument cluster, foot module, seat electronics, passenger junction box, tire pressure control, etc. I didn't think much of it as many say there is often a number of 'ghost' codes that stick around.
After about a year of ownership the battery died on me. Couldn't start the car one morning after increased battery discharge warnings intermittently. I kept the car on a trickle charger at all times while not in use to help promote battery longevity. Nevertheless the battery died. I checked the date and it was from 2018, just about three years old. I thought that was a little young but replaced anyway with an Odyssey ODP-AGM48 H6. Everything was fine for about 8 months then boom, car won't start again. Battery completely drained even with the same trickle charger treatment. Worth mentioning that even after spirited drives it would take the trickle charger hours to read 'full charge' on the battery.

I took the battery to an Advanced Auto. They charged it and tested it in front of me and it passed with flying colors.
At this point I had already expected it may be an alternator issue but I hadn't had any electrical issues with the car running i.e. dimming lights, etc.
Fast forward to now. I just got done checking the voltage. While running, the alternator holds a steady 13.8-13.9V. From my understanding that should be closer to 14.5V. Is this a big enough delta to warrant a full alternator replacement? I've read that the voltage regulators have issues as well and can be bought and replaced separately (and for less money) than a new unit. Does anyone know how to tell one from the other?
Lastly, I used Carly to code the new battery to the car but have been told that does not work as expected/advertised. Could not coding or coding the new battery improperly lead to excess drain and eventually a dead battery? That quickly?

Any help is appreciated! I'm at a bit of a crossroads here with which route to take next.

[Space Fox]

Originally Posted by Theodore

If I were in your shoes I'd start with replacing the battery again. The battery you purchased was way under spec as compared to the original OE battery. I'm guessing you simply matched the specs from the replacement battery the previous owner put in not knowing it was significantly under powered.

Original OE battery: Absorbed Glass Mat (AGM), 900 Cold Cranking Amps (CCA) and 90 Amp Hours (Ah)

Replacement battery: Absorbed Glass Mat (AGM), 720 Cold Cranking Amps (CCA) and 63 Amp Hours (Ah)

Fair point. When tested the battery was running closer to 780 CCA (most replacements are 850) and I did a good bit of research before buying seems the H6 battery is a decently common replacement (many from the z4M). I figured I live in warm weather Florida and keep it on a trickle charger. Not ruling this out though! Still doesn't quite explain the early demise of my OEM battery from previous owner and the constant low voltage codes stemming from the day I purchased the vehicle.

[happydude]

Scan for codes to see if you have one related to alternator before replacing it. When my alternator was failing it was intermittently. I would get code but it wasn’t present. I would check the voltage and see it working so I cleared and ignored it. But the code kept comimg back every week when I scanned it. Eventually after awhile I was able to see the voltage of it initially not working after starting the car and after about 10 mins having it kick on. And vice versa. And after regularly monitoring the voltage and seeing it not working and voltage getting low I replaced it and never had the issue come back.

When it wasn’t working the voltage would read around be 9-10v range with engine running. When alternator decided to work it would read 13.5+ With engine running.

[Space Fox]

Originally Posted by happydude

Scan for codes to see if you have one related to alternator before replacing it. When my alternator was failing it was intermittently. I would get code but it wasn’t present. I would check the voltage and see it working so I cleared and ignored it. But the code kept coming back every week when I scanned it. Eventually after awhile I was able to see the voltage of it initially not working after starting the car and after about 10 mins having it kick on. And vice versa. And after regularly monitoring the voltage and seeing it not working and voltage getting low I replaced it and never had the issue come back.

When it wasn’t working the voltage would read around be 9-10v range with engine running. When alternator decided to work it would read 13.5+ With engine running.

Thank you! This is what I was looking for. Wasn't sure what the drop in voltage while running would be with a bad alternator. Seems to be much more significant than the .4-.6 drop I'm seeing. I haven't gotten any alternator-specific codes yet. Just a bunch of electrical/low voltage codes. I would think it is the battery but the same thing was happening with the old OEM battery. I still don't think the battery is being charged while driving. Every time I come home and throw it on the trickle charger it takes overnight and then some to get to a full charge read out on the charger. I'm going to try re-registering/coding the battery without using Carly and see if that helps at all.

[TheLuky8]

I wish I could remember more of what was going on when my alternator was going out. I don't recall the voltage numbers when running. The big thing I remember was the "increased battery discharge" error code. I don't think there were any other lights or codes. I assume I went to get the battery and alternator checked at Autozone and we decided to try the alternator. Luckily that was it. Sorry I couldn't offer more info.

[Space Fox]

Originally Posted by TheLuky8

I wish I could remember more of what was going on when my alternator was going out. I don't recall the voltage numbers when running. The big thing I remember was the "increased battery discharge" error code. I don't think there were any other lights or codes. I assume I went to get the battery and alternator checked at Autozone and we decided to try the alternator. Luckily that was it. Sorry I couldn't offer more info.

All good. I have been getting the increased battery discharge code. Battery is new and was just tested and passed inspection so I think I've narrowed it down enough. Already ordered the alternator. For $300 and a couple of hours of work it's worth a shot. Will report back on whether or not that does the trick.
Still scratching my head as to why my battery tender won't reach a full charge..

[TheLuky8]

Originally Posted by Space Fox

All good. I have been getting the increased battery discharge code. Battery is new and was just tested and passed inspection so I think I've narrowed it down enough. Already ordered the alternator. For $300 and a couple of hours of work it's worth a shot. Will report back on whether or not that does the trick.
Still scratching my head as to why my battery tender won't reach a full charge..

Originally Posted by Space Fox

All good. I have been getting the increased battery discharge code. Battery is new and was just tested and passed inspection so I think I've narrowed it down enough. Already ordered the alternator. For $300 and a couple of hours of work it's worth a shot. Will report back on whether or not that does the trick.
Still scratching my head as to why my battery tender won't reach a full charge..

Yeah I remember it not being too bad. I think I fought the bottom bolt or something on the alternator. It was just stuck on there. Other than that wasn't bad. But yeah I'm curious to see if that fixes it all or if there's something else. That battery tender issue is interesting.

[Denny347]

My car was acting very strange when my voltage regulator malfunctioned. I replaced the alternator and never an issue again. I replaced the alternator from the top of the engine bay and it wasn't too bad. There is a good DIY for it here.

[Space Fox]

Got the new alternator installed over the weekend. Pretty straightforward job once you learn you have to tap the bottom bolt out. So far the car is running great. Need to perform some tests to see how everything is holding up and confirm this solved my electrical gremlins.