Usefulness of an external alternator regulator in this scenario

[3rdOrderEffect]

I have a Next Step NEXT-12P external alternator regulator currently installed in my boat. The boat is presently equipped with lead acid starter and house banks.

There is nothing wrong with the regulator (to my knowledge, although I admit to never looking at the status LEDs, it seems to work as intended). I am just looking to get rid of it as I don't see the need for it and would like the space for other components. and to simplify wiring. I have accumulated my whole box-o-Victron-parts setup for my new lithium house battery setup. In this new arrangement, my plan is to feed the start AGM battery by the (new) internally regulated single alternator. The start battery will charge the house bank via a 50A Victron Orion XS DC to DC charger.

The house bank consists of 2x 300AH Epoch 12V batteries wired in parallel, all connected thru the Lynx setup and monitored by a Cerbo GX. Beside what it gets from the dc-dc charger when the engine is running, the house bank will be charged by a modest solar array/victron MPPT, and via shore/gen power thru a Multiplus II.

With all that said, is there any reason I need this external regulator when I am just going to be sending alternator power direct to a lead acid AGM starter battery?

 

[Clark]

AGMs are sensitive to over charging. I had that problem when I ran long days and the battery bank was full by noon. It's worse for start batteries since they are already mostly charged. The internally regulated alternators hold a fix voltage like 14.2V and never back off to float. It caused the electrolyte to exit through the regulated valve and once it's gone, the battery has less capacity until it has none and doesn't start the engines. My AGMs lasted only 2 years until I put in the external regulator. I would keep an external regulator for your AGMs unless your internally regulated alternator can be adjust lower closer to the float voltage. Non-sealed flooded batteries are not as big a concern as long as you keep the levels up in all the cells.

 

[O C Diver]

If I were installing a new alternator in your described scenario, I probably wouldn't be using a regulator of that vintage.

To go a little further, what additional equipment will run off the start battery, besides the engine? Depending on how much other stuff is running, if it were all coming off the house bank, I would question if 50 amp charge rate was sufficient, and able to recharge the house bank.

While we all strive to keep power consumption to a minimum, electronics underway can consume significant amps. Should you have a water intrusion that you can't immediately rectify, bilge pumps can be substantial consumers depending on size. Not sure what size alternator you have, but I would be more comfortable with 100 amp house bank charging. If you already have a backup plan with the inverter / battery charger and the generator, please ignore my above thoughts.

Ted

 

[READY]

If you go with a modern smart regulator like a Wakefield you can integrate it with your cerboGX. Much better control and diagnostics.

 

[READY]

Wakespeed...

 

[3rdOrderEffect]

Thanks for the replies everyone.

Clark, acknowledge your point regarding the single-stage charging of an AGM versus the stepped charging that an external regulator can provide. That said I have run AGMs straight off internal regulated alternators my whole boating career (not on this boat), and my last two (an Odyssey and a diehard platinum AGM) lasted 10 and 8 years respectively. With the cost of a decent AGM starter battery at $300-400, half that if you're willing to risk amazon specials, I can absorb replacing that every couple years without too much emotion.

I am deliberately trying to avoid the whole wakespeed or balmar external regulator setup charging due to the cost of them and the wiring and the added complexity. If I was going to use one at all I might as well have forgone the DC-DC charging system altogether and fed the house bank from a high output alternator.

OC Diver, you raise a good point, is 50A charging of the house bank while underway enough? The answer is I dont know Not sure what my consumption would be, although with the current battery monitor (an ancient Xantrex) I've never seen anymore than ~30 DC amps being drawn at any time. Probably the radar wasnt running then though, and I'm sure other things. For context this is a 31' boat with pretty low demands, it has only a 60A alternator installed now (it has twins, but I'm pretty sure only one is wired in and the other is just spinning there for engine power and for the tach signal), it has both a diesel and gas backup 3.5kw gen. And soon to have some solar. Its not a passagemaker and it has spent and will spend probably 90% of its days hooked to shore power at my marina. I probably should have included that context in my original post.

I think my plan right now is to proceed with my setup as originally outlined and monitor the system's overall effectiveness via the Cerbo and see if I need more generation while the engine is running. I'll probably remove the external regulator and hang on to it for the time being.

 

[SteveK]

You have 600Ah of battery and a plan for 50A charger.
IMO, either the battery bank is too large or the charger is too small.
Using 30A~ leaves 20A charging. It is the 20A that will take forever to maintain or fully charge. At the dock you have the time, underway you are not going 24/7 or are you. With the 50A charger and nothing used a 50% depleted battery would take 6 hours minimum to charge.
Your setup as described only can maintain one 300Ah house away from the dock.

 

[J.T kearney]

You have 600Ah of battery and a plan for 50A charger.
IMO, either the battery bank is too large or the charger is too small.
Using 30A~ leaves 20A charging. It is the 20A that will take forever to maintain or fully charge. At the dock you have the time, underway you are not going 24/7 or are you. With the 50A charger and nothing used a 50% depleted battery would take 6 hours minimum to charge.
Your setup as described only can maintain one 300Ah house away from the dock.

Hi 3OE
That's a lot of amp hours for a 31 foot trawler. Are you planning on only drawing it down 50 % at anchor or on the mooring ball ? With a small solar array you could easily keep up with the refer. what do you think your daily consumption (amp hr) will be?
Cheers J.T

 

[O C Diver]

Its not a passagemaker and it has spent and will spend probably 90% of its days hooked to shore power at my marina. I probably should have included that context in my original post.

You answered the question. If you plan to spend 90% of the evenings at the dock, 50 amps of charging will be sufficient. Further, solar would be a poor investment.

There's a general guideline that says, buy based on 90% of the time, not 10%. If you plan to have all the kids and grandkids over for Christmas, do you and your spouse need to live in a 15 bedroom mansion the other 360 days of the year? That's what they make hotels for. If 90% of the time you are leaving in the morning with full batteries, there's no point in worrying about recharging the battery bank or solar. On the rare occasion when you anchor out, fire up the generator for an hour in the morning.

Ted

 

[Clark]

Internally regulated is fine if the use case is primarily short trips and most of the time the batteries are at the dock with a 3 stage charger, especially for smaller alternators with larger banks. Some AGMs are more tolerant of this. If the use case is full days running the ICW, you may find shorter AGM battery life. As we cruise extensively, my back and my wife's back don't like swapping out 8Ds in far off places, so I'll always opt for the complexity.

 

[Jeff F]

With all that said, is there any reason I need this external regulator when I am just going to be sending alternator power direct to a lead acid AGM starter battery?

The only concern I would have is for alternator health. It's quite possible that the alternator could be running at an output of 50a for extended periods of time.

Choose your alternator with this in mind. If there isn't any heat regulation on the alternator you'll risk cooking a standard 60a alternator.

Everyone thinks external regulation is for battery health, but IMO with lithium it's more about alternator regulation to manage heat.

 

[Jeff F]

I am deliberately trying to avoid the whole wakespeed or balmar external regulator setup charging due to the cost of them and the wiring and the added complexity. If I was going to use one at all I might as well have forgone the DC-DC charging system altogether and fed the house bank from a high output alternator.

I'm generally supportive of this approach. Alternators - leave them alone and forget about them

But that said, I'd suggest a modern regulator just to get full systems integration . Replace your ancient regulator with a Wakespeed and keep the existing alternator maybe? Send that to the house bank and use a smaller dc-dc charger for start bank.

 

[Barking Sands]

I think your set up will be fine. You state you have both a diesel gen and gas back up gen. I assume that will power your primary method of AH replacement when at anchor via your Multiplus II which is a 120 amp charger (set absorption to 14.2 and float to 13.5 for the Epochs)
The 50 amp dc2dc is just supplementary in nature IMO and just used to hedge losses while underway. You will likley be able to add some AH under most circumstances. Or at least break even. Keep in mind with a 60 amp alternator you will likley need to throttle the dc2dc back to around 30-35 amps being sent to the house bank.

For comparison on my 31 foot Trawler with a 920ah Epoch lifepo4 bank:
As an experiment on my Westerbeke 4.4kw gen with a Hitachi 55 amp alternator I set the Orion dc2dc at 30 amps and measured temps. Alternator maxed out around 190F. I am ok with that.
I also have another DC2DC for my Balmar 100amp alternator with MC618 that will provide another 50 amps.
So thats 80 amps coming from alternators via Victron DC2DC chargers.
120 via the Multiplus II being powered by the Westerbeke at anchor (or underway)
30 amps additional from a Victron IP22 plug in with Gen running as well. The IP22 is there for "supplementary and back up"

So thats about 230 amps charging possible on a 920ah Epoch battery bank (2x460 Marine batts). But of course its unlikely to be using all of these at once.
Typically it will be the 50 amps from the dc2dc while underway
150 amps from the multiplus ii and gen alternator /dc2dc (120+30) and can add another 30 if needed from the IP22 for a total of 180 while on gen at anchor.

 

[CharlieO.]

I use a little over 10 amps of power while underway with the refrigerator running, charging a phone or two and my son playing his Xbox. I have an 18a DC-DC charger with an old rated 51-amp alternator.

The only thing that runs on my house bank is an inverter with the refrigerator plugged in and I let my son play the Xbox while cruising, and USB charging ports.

So, if I leave the slip with my house battery 100% charged, I'll arrive at my anchorage with the battery at 100%. My 100ah LifePo battery will get us through the night and then some without my son on his Xbox. Without the Xbox running we use just over 5 amps. I plan on adding another battery in the spring to carry us through the weekend.

We are not fulltime cruisers but weekend warriors, so this setup works for us.

 

[sunchaser]

A few things. First, it is not uncommon that all the vessel’s instruments run off the engine start battery and alternator. There are several devices like dc-dc that allow sharing but instruments can be a surprisingly heavy load.

Second, I agree with barking sands, your current setup is ok keeping in mind that monitoring running amp draw to both house and start banks is a good idea. Removing the regulator you pictured could create unintended consequences . A good old fashioned in place amp meter (common on 20 year old boats) is a worthy tool. As example, I was amazed at the highly fluctuating power draw of an auto pilot.

Thirdly, AGMs are not necessary for start batteries. A sealed lead acid is equally good and considerably cheaper.

Lastly, are you happy with your onboard monitoring systems? These can, will or are telling in real time what is happening and point out problem areas, if any.