Alternator and Battery Over charging issues

[Tkenopic]

Hi everyone
I have 2 batteries that were purchased in 2016. One smelled bad so I popped caps and the water was very low. I topped that up. When I tested voltage the bad battery was 13.5 and it is the house. The starter was 13.0 . Our new radio is displaying an error message saying “high battery”. I’m wondering if my alternator is overcharging? Wondering how I test for that? And what to do about it? Can you adjust an alternator easily? No knowledge in this area. Hi hanks!

[joe_db]

First thing:
With the engine not running and the battery charger off, run a load like some lights for a few minutes and then shut everything off. Let the batteries sit for half and hour and check the voltages. 12.6 (wet) to 12.8 (gel/agm) is full.
Second thing: Turn your battery charger on. If it is a 3-stage charger, it might charge wet cells at 14.4-14.6 volts if they are low, but it should settle down to around 13.X for float, probably around 13.8 or so.
Third thing: Repeat the first step and then run the engine. Assuming you have a stock one-stage regulator and alternator, at cruise RPM with light loads and batteries near full you should see around 13.8 to 14 volts.

"High Volt" warning should not be on at 13.x volts and probably not at 14.x. Some systems will charge as high as 14.6-14.8 depending on how low the batteries are and the type of regulator. I would expect that warning at 15 or higher. Your low water and smell do indicate overcharging.
Can you tell us what kind of batteries, what kind of charger(s), and what kind of alternator and regulator?

FYI - My 3 stage charger runs around 14-14.1 in the summer flat out and drops to 13.2-13.4 for float. My alternator is currently set to 14.1.

* just thought of something - Make SURE you don't have "equalize" turned on either on the charger or regulator. This will run the voltage way high, maybe close to 16, and is only to be done in specific circumstances.

[Tkenopic]

Thank you very much! I’m currently cruising and headheading to port and will run the tests as instucted. I can confirm that running a voltage test with the engine running right now it is charging at 16 volts! If you’re able to post a pic of the regulator so I can look for the equalize” function?

[Tkenopic]

Ok I think I attached photos of the charger battery and alternator

[joe_db]

16 volts under power
You have the standard Motorola alternator and regulator that has no equalize or adjustments of any kind. It must be defective.
Disconnect the wire shown and then check the voltage.

[Tkenopic]

Ok awesome thanks. Did that. Now not charging either battery. Voltage on both batteries is 12.95. Ok so now the question is what is the recommended replacement set up? Is there a rebuild kit i can install myself?

[Tkenopic]

Also, is this disconnect/reconnect a reasonable solution to get me thru this cruise?

[joe_db]

Sort of. Wait until the batteries get low, connect it, and *disconnect it again* when the voltage passes about 14.2-14.4 or so.
I had to do this flying once. The alternator wiring had a short to ground that drove the regulator to full output. The overvoltage warning went off, we truend the alternator off, and when the battery got low we turned it on for a bit. Managed to keep the lights on until we landed (this was after dark

[sastanley]

Joe's advice is good.

The nut with the orange wire is the (+) wire charging your batteries out of the alt, and guessing by your wiring probably going to the ammeter, unless you've wired it somewhere else.

You can connect your (+) meter to this and to a good ground to see what's happening with the charging voltage. There are still a few sources for voltage regulators for the old 35A Motorola alternators. I bought one earlier this summer. Off the top of my head Google "M5-197A Transpo" and see if that helps. OMB Warehouse in Pennsylvania, if I recall correctly, for about $35.