Alternator not regulating charge

[sailorboy1]

Another thought is that it may not be a regulator problem at all. If the sense wire is on the regulator and there is any cortisone between the regulator and the batteries, the regulator will see that as a low battery voltage.

When the alternator is putting out 14.8, what’s the actual battery voltage at the battery? ( I have my sense wire connected right at the batteries)

[Mike OReilly]

OK, thanks guys. Lots to test and ponder now. So thanks.

It’s late, and I’m tired (and a bit drunk). I’ll get back to it tomorrow, and come back for more wisdom.

Don, I do have sealed (“maintenance-free”) FLA batteries. I’m not happy that this is the case, but it is. So I can’t top them up.

[belizesailor]

Sounds like at least a partial failure to me (Ive had them fail in the past and go way above 14.8V...different models though).

I assume you noticed it tapering to less than 14.8V in the past?

How many amps is it outputting (high V + high amps = not good for batteries)?

Are you somewhere you can get a replacement easily?

If so, just disconnect the field wire, output will go to zero (your tach will likey quit working too), and order two replacements (1 as spare...suxs when they go out somewhere remote). You can reconnect the field wire when you need a brief high V charge.

You can also make up a manual regulator from available bits & pieces (I made one up with a rheostat pulled from the stereo system a few years ago). But given you are not very familiar with this, and if you can easily get new...then why risk frying something.

Other things could cause high output, like failing batteries, but sounds like they are good (solar/wind charge is working).

[Mike OReilly]

I want to thank you all for all your excellent advice. It turns out the only real problem was me . The regulator seems to be working to spec. It’s just that the voltage is set a bit high. Now I know how to change this.

Bottom line is I probably never before really paid any attention to the alternator output. It charged the batteries, and I never really thought about. When I noticed recently the high voltage while running, and that it never changed, I panicked.

What I forgot to check was the actual current. Some of your comments woke me up to this failure, so when I checked it turns out it is ramping down just fine as the batteries charged. Idiot (me).

Anyway, I now know how to set the voltage. I plan to lower it a bit, but it seems like I’ve been running like this for years now, and the batteries seem fine.

Again, many thanks to all your help. I now know a little bit more about all this DC electrical stuff. If I live to 200 I might learn enough .

[kenbo]

Mike,
Honestly I wouldn't change the setting of the regulator. 14.8v is not overly high.
Ken

[Mike OReilly]

Originally Posted by kenbo

Mike,
Honestly I wouldn't change the setting of the regulator. 14.8v is not overly high.
Ken

Even with a closed wet cell battery (“maintenance free”)? With these silly batteries I can’t check the electrolyte, nor can I add more water if needed. The alternator could be charging for hours at times. Still OK at 14.8v?

[kenbo]

How long have the batteries been in service?

[Mike OReilly]

Three years now. They seem fine, but I haven’t done a proper 20 hr test or anything. Assuming the alternator/regulator has always been operating like this (and I just never noticed ), I’ve not seen any issues with the batteries.

It just seems a high voltage for hours and hours. But clearly I don’t know much about this stuff...

[kenbo]

3 years is definitely long enough to have destroyed those batteries if 14.8 was too high of a vSet.

To be comfortable, can you look up what the battery manfacturer specs as the absorption voltage?

[sailorboy1]

I would turn it down to 14.4

But that’s me knowing I had a well charged dry sealed start battery from the 14.8

[Bleemus]

Turning it down a bit wouldn't hurt because I believe you have solar and wind to get you all the way.

[kmacdonald]

If the batteries aren't requiring a lot of water and you don't run the engine for days at a time, I'd not adjust it. 14.8 will get the batteries charged faster, maybe. Most vehicle regulators work the same and don't go to a bulk or float voltage----single stage only and the batteries seem to last over 8 years. Don't kick the sleeping dog.

[Mike OReilly]

Thanks guys. I’d feel better if it was a bit lower. My solar absorption is set to 14.4v, so that makes sense. My batteries are branded Magnacharge. They are Group 31 (31DC-205). I’ve not been able to find much info them. They are sealed (“maintenance free”). I can’t check or add to the electrolyte levels.

The seller claimed they were true deep cycle batteries. So far, they’ve served us well, but my next batch will be a set of 6v golf cart.

Bleemus, you’re correct. Solar and wind maintain our batteries most of the time, with the very occasional boost from our portable gas generator. In fact, I ran for the last two months without the use of the alternator at all. I guess if I were moving more than this would change, but we tend to stay put for long periods.

But I’d still rather have the use of the engine alternator.

[kmacdonald]

Originally Posted by Mike OReilly

But I’d still rather have the use of the engine alternator.

You still have the use of it. It won't hurt the batteries enough to make a difference. Negligible if any harm IMHO unless you run it for weeks or months non-stop.

[belizesailor]

Originally Posted by Mike OReilly

...
What I forgot to check was the actual current. Some of your comments woke me up to this failure, so when I checked it turns out it is ramping down just fine as the batteries charged. Idiot (me).

...

If your batteries are already at a high SOC from solar/wind then yes the regulator should raise V and lower current. Thats normal.

Check manufacture's spec for V set points...14.8V would worry me on a sealed FLA battery, but best to confirm per specs. Note that max V varies with battery temp. Does your regulator have a temp sensor?