Sterling regulator

[Bob 04 H260]

I have the Electromaax 140 Amp alternator, with Sterling Pro-Digital regulator, I do not have the remote control for the regulator. I have about 400 Ahr AGM house bank.

If I am in the slip with the Sterling battery charger on, with the bank fully charged, so it is floating at 13.3 volts and few mA's going one way or the other. Then when I start the engine (the battery charger is off of course) and the alternator voltage goes quite high around 14.7 volts, with about 8 amps being accepted by the battery bank, the voltage and current seems to jump around quite a bit like the regulator is analyzing the battery. After a bit, the voltage is reduced to 14.5 V and about 2 amps are being accepted. It has stayed like that for a half hour or more until the engine was shut off.

From the owners manual it appears the regulator has entered a timed period of 1 to 6 hours at the high charge rate before it will go into "float" mode and reduce the voltage to 14 volts. I have the regulator on the AGM setting.

The battery label indicates it should be charged at 13.8 to 14.6 v and floated at 13.2 to 13.6 v. I am concerned if this could hurt the batteries by running them at such a high voltage when they are already fully charged ?

Bob

 

[Rick D]

Same

I have a Balmar with a Xantrex regulator and it does something similarly. It will be at float, but when I get the engine going, it will go up to 14 volts and charge for a while before it settles back down (wet cell 500 amp hour).

 

[Stu Jackson]

Yes, that's normal. Really. The regulator is programmed from the factory to do a 14.+ at startup for a certain timed period, which is adjustable.

What you really need to do is think differently: When you're on the hook, you WANT the alternator to put out at bulk when you first start up because the house bank will have been used overnight.

Start thinking: what do I need to fast charge after depleting the house bank, NOT what's the condition after I've been plugged into a shorepower charger all week.

The higher voltage won't hurt, since the house bank is full it won't accept much current, regardless of the voltage.

 

[Bob 04 H260]

I'm sorry my original post has caused some confusion. I guess it was not clearly written. I think the regulator is running as designed. I have run the bank of batteries down and the alternator does a good job of quickly bringing it back up.

Actually according to the manual you can't adjust the time the Sterling regulator outputs 14.5 volts, it is determined by the regulator itself and is not adjustable. It may in fact decide to hold this high voltage for up to 12 hours after engine has started.

My question was and still is will it hurt my new fully charged AGM batteries to keep them at 14.5 volts when the battery manufacturer says float them at a max. of 13.6 V once they are charged. As I mentioned the bank is only accepting a couple of amps. at the 14.5 V output. I would like to hear from someone who actually has done this to their AGM's for a season or two and if it has had any negative effects. We use the boat on the ICW so it could be motored for 12 hours some days. My understanding is that AGMs are sensitive to being over charged or having too high a float voltage.

The Sterling battery charger does not behave this way at all. It starts up does a battery check and quite quickly drops down to 13.3 V and keeps adjusting the voltage up and down as things on the boat turn on and off so the batteries are always sitting with a few mA going in or out.

Bob

 

[Stu Jackson]

Then, Bob, you "have it made."

 

[Maine Sail]

I'm sorry my original post has caused some confusion. I guess it was not clearly written. I think the regulator is running as designed. I have run the bank of batteries down and the alternator does a good job of quickly bringing it back up.

Actually according to the manual you can't adjust the time the Sterling regulator outputs 14.5 volts, it is determined by the regulator itself and is not adjustable. It may in fact decide to hold this high voltage for up to 12 hours after engine has started.

My question was and still is will it hurt my new fully charged AGM batteries to keep them at 14.5 volts when the battery manufacturer says float them at a max. of 13.6 V once they are charged. As I mentioned the bank is only accepting a couple of amps. at the 14.5 V output. I would like to hear from someone who actually has done this to their AGM's for a season or two and if it has had any negative effects. We use the boat on the ICW so it could be motored for 12 hours some days. My understanding is that AGMs are sensitive to being over charged or having too high a float voltage.

The Sterling battery charger does not behave this way at all. It starts up does a battery check and quite quickly drops down to 13.3 V and keeps adjusting the voltage up and down as things on the boat turn on and off so the batteries are always sitting with a few mA going in or out.

Bob

Bob,

What brand of AGM? It may be temp compensation doing its job on a colder morning. I don't recall whether Charlie has programmed it for compensating "up" in cold weather or just down in hot and his manual is rather "scatter brained" so I have a tough time even reading it..... The easy way to test is to disconnect the battery temp sensor.

The long and short is you will be fine. You can always program it for a lower absorption voltage too. The Pro-Reg D regulator calculates the time it took to come up to voltage and then adjusts the absorption time, or should. You should never see 12 hours at absorption with the Sterling reg unless the batts need it.

That said there are millions of cars on the road using AGM batteries and millions of car alternators pumping out 14.4V - 14.6V constantly with no float what so ever. These batteries are not cooked. Personally, for sailboats, I think float on a regulator is more of a "selling feature" than a useful feature. For shore chargers float is useful...

Also the term float has wide definitions. Some manufacturer consider floating as days or months and others want to see no more than 10 hours at absorption etc....

Keep in mind that a battery charger has a known amperage thus it can tell better than a regulator when to go into float mode as it can assume it has been properly sized..

A regulator has no clue what size alternator it is connected to, or the bank, thus it can't base going into float on such things as % of field current etc. and has to run on-the-fly time calculations to determine absorption time..

The Balmar's do have many more programming options and can be very well tailored but the MC-614H is about 2X the cost of the Pro-Reg D, and that is without temp sensors. The Pro-Reg D is a decent low cost external regulator but not programmable....

 

[Bob 04 H260]

thank you Maine, good information........just what I was looking to get.....I will feel better now when I look at that voltmeter !

Yes the manual is a bit scattered. He states that AGM and Gel batteries are not recommended because "they have a limited ability to absorb high charge currents" , so it made me question some of the rest of his advice and recommendations.

I bought the AGM's at Sams Club, they are group 31's I have 4 in the house bank, the specifications on the label are in the photograph below.

We are about halfway down the east coast of Florida, it has been quite warm and we have not started the engine before 10 am so I don't imagine temperature was an issue. I do have the temperature probes on both the battery and alternator for the regulator.

thanks again, Bob

 

[SailingHarry]

Bob,
A regulator has no clue what size alternator it is connected to, or the bank, thus it can't base going into float on such things as % of field current etc. and has to run on-the-fly time calculations to determine absorption time..

This is a real frustrating point for me. As far as I know, the old Xantrex 2000R was the only "smart" regulator ever sold that understands the battery that it is connected to. If you look at the charge profile of a Balmar, you quiclky realize that it is not very smart at all -- if you rarely run your engine more than an hour at a time (most sailboats typically run 1/2 hour or so per start cycle), it is almost identical to a dumb regulator. Here's the cycle:

* Regardless of battery state of charge (ie, unplugging after a week on shore power is the same as 50% discharge), it will immediately go to "Bulk" for 36 minutes (or longer).
* After 36 minutes, it will reduce to "Absorption", about a .2V drop, for another 36 minutes.

If you had a "dumb" regulator at about .1V below "Bulk," it would look very much like a Balmar for the first 72 minutes! And if you shut the engine down for 10 minutes to check the wind or some such, then started it again -- you'd do it all over again! Now, granted, we've all spent 8 hours on the engine, but we'd like to think that's a rarity. If you do an hour motor out from your slip, and an hour motor into the anchorage -- and the same thing the next day -- a "smart" regulator is of little value.