Just double checking my planned LifePo4 set up

[john61ct]

Excellent that there are more DCDC options coming into the market, Victron may give Sterling a run for the money.

Also have a look at Kisae, their 50A unit allows you to set the current limiting in 10A increments, while Sterling only offers 50%

If you have multiple alternators upgrading both to external VR gets pretty pricey.

Another point for DCDC is that it "front-ends" the LFP bank itself, filtering / massaging the charge input, feeding the exact voltage and current you want for that pack, from **any** old charge source.

Particularly valuable for powerpaks that can be moved between multiple boats, e.g. powering a dinghy, vehicles, off-grid homes or used for camping, beach parties etc.

No need for expensive upgrades to user-adjustable gear for mains chargers, solar SCs, and of course stock alternator setups, just the one piece of kit and all your LFP-specific charging needs are covered.

Some units also throw in an integrated solar charger as well, but have yet to see A/B testing against say Victron MPPT to compare.

[mbartosch]

I chose to implement "option A", alternator directly charging the LiFePO4 house bank controlled by a Balmar MC 614 regulator.
The MC 614's "belt manager" in combination with the alternator temperature sensor takes care of limiting charging current to acceptable limits.
Our Balmar 6 series 150 A alternator typically puts out around 110 A when cold at moderate cruising speed (~2000 RPM) and is limited to about 90 A after a while when hot by the MC 614. Overall it works very well.

Charging the starter battery is done via a Sterling B2B charger from house bank, triggered by ignition and using a timer relay to make sure the battery gets at least one hour charge even if ignition is on for a few seconds. I chose a B2B charger in order to avoid slowly destroying the LA battery due to never reaching full charge if it were directly connected to the alternator output via the traditional battery isolator.

The entire setup works great so far for us.

[john61ct]

Great setup.

The cost of the DCDC for getting better longevity out of "just a Starter" would be a personal preference / calculation.

There are cheaper DCDC options these days too, since 10-15A would be plenty for that purpose.

Another option would be fitting a Starter whose mfg spec charge voltage was within range of the output you configure the Alt for House.

[Q Xopa]

Originally Posted by mbartosch

I chose to implement "option A", alternator directly charging the LiFePO4 house bank controlled by a Balmar MC 614 regulator.
The MC 614's "belt manager" in combination with the alternator temperature sensor takes care of limiting charging current to acceptable limits.
Our Balmar 6 series 150 A alternator typically puts out around 110 A when cold at moderate cruising speed (~2000 RPM) and is limited to about 90 A after a while when hot by the MC 614. Overall it works very well.

Charging the starter battery is done via a Sterling B2B charger from house bank, triggered by ignition and using a timer relay to make sure the battery gets at least one hour charge even if ignition is on for a few seconds. I chose a B2B charger in order to avoid slowly destroying the LA battery due to never reaching full charge if it were directly connected to the alternator output via the traditional battery isolator.

The entire setup works great so far for us.

Great setup.
As you say the Temp compenstation function is my preferred method. I hear people talking about current limiting. To me this is half of the story. Current per se isnt what kill Alternators. It's temperature which is a factor of current and ambient temp.

So this where using a B2B to limit current is not ideal. Apart from the fact that operating a B2B at its design max current will mean it is running hot and wont live so long.

A B2B being used to charge up your Start batt from your house bank is exactly the intended purpose and a great use for them. I have mine setup this way and agree it is great.

I also hear others suggestion of using B2Bs for charging 'aux' battery packs. I dont think this is what the OP, is asking about. In fact all of the boaties I have met I have never heard of anyone doing this. Elec dingy motors are still reletively quite small numbers, but the ones I have seen use the Torqueedo etc chargers. I agree it could be a good use for a B2B but I would say this is a rare/ obscure use case.

[smac999]

Originally Posted by Q Xopa

Yes true, indirectly.

Belt manager is usually for a set initial start up period. You could also use Small engine mode, if it is connected with a switch and programed. It reduces output, when selected, to approx 50%.

But this is not the intended use and has limited adjustable parameters so is not ideal to use for this.

But if it works for your application great.

that is the exact intent of the belt manager. to perminatly limit alternator amps to protect the belt. and has 10 levels of settings in ~5-7% increments.

they also have a start up delay / ramp up if you are thinking about that. that is different.

[Q Xopa]

Originally Posted by smac999

that is the exact intent of the belt manager. to perminatly limit alternator amps to protect the belt. and has 10 levels of settings in ~5-7% increments.

they also have a start up delay / ramp up if you are thinking about that. that is different.

Yes I agree with what you are saying. However the suggestion was to use this funtion to save Alternators, not belts. Again I agree that saving belts with less load will also save your Alternator.

All I was saying is that function is specifically meant to save your Belts, hence the name. So I agree it does save your Alternator but there is IMHO possibly better ways of doing this.

Specifically Im not actually as concerned as output as the operating temperature. For example if it is colder weather or your engine bay is better vented then you can run your alternator at a higher output with out overheating it.

Of course there are many ways to skin this cat.

But if it work for you great.

[john61ct]

The Wakespeed / American Power progeny of Al Thomason's open source "Very Smart Regulator" / "Smart Alternator Regulator" project*

allow for programmable derating levels based on temp sensor feedback, both of the alt/diodes, and the battery pack.

[Q Xopa]

Originally Posted by john61ct

The Wakespeed / American Power progeny of Al Thomason's open source "Very Smart Regulator" / "Smart Alternator Regulator" project*

allow for programmable derating levels based on temp sensor feedback, both of the alt/diodes, and the battery pack.

I have Al's SAR regulators and they are great. So that is what I am more familar with. I'm not completely up to date but unfortunately I dont think he is selling them any more.

I am not as familiar with 614s but I think you can temperature derate them as well. Just my opinion but this would be my preference.

But using Belt manager functions is certainly also a good way to manage your output. I think this is way ahead of what the vast majority have that are blissfully unaware of any of these factors.

[sailingharry]

I don't have Lithium yet, but I have been giving much thought, and have considered how to deal with two of your questions. My opinions, not based in actual practice.


First, how to charge the start battery. This battery requires essentially no charge current (it is rarely down even 5%). It also can be charged over long periods of time, because it is so rarely used. My thought is that in today's world, inverters are run often, or even always. I would think that using the inverter to power a small (10A or s) smart charger would keep your battery in tip top condition. And, since the LA start battery has an entirely different charge regiment than the Li house battery, a dedicated charger for when attached to shore power is appropriate anyway -- and so you already have/need that. Note, I often think that if I had a dedicated windlass battery (I don't), this would be better than DC charging there too.


Second, how to disconnect the alternator. Not only is the alternator a challenge cutting the output, but the relay needs to be beefy to handle that 200+ amps you could see. I think I would prefer to hard wire it to the battery (through busses and fuses, of course), and manage the overcharge protection by interrupting the power to the field (or the regulator).


Neither thoughts are mainstream. But I tend to be not mainstream. LOL.


Harry

[mbartosch]

Originally Posted by sailingharry

First, how to charge the start battery. This battery requires essentially no charge current (it is rarely down even 5%). It also can be charged over long periods of time, because it is so rarely used. My thought is that in today's world, inverters are run often, or even always. I would think that using the inverter to power a small (10A or s) smart charger would keep your battery in tip top condition. And, since the LA start battery has an entirely different charge regiment than the Li house battery, a dedicated charger for when attached to shore power is appropriate anyway -- and so you already have/need that.

Well, running an inverter 24/7 from DC to power an AC to DC battery charger just to keep the starter battery topped up is quite inefficient and will likely consume more than 40 Ah @12 V per day. The proposed approach with a DC/DC charger such as the Sterling B2B or the new Victron chargers, actived by Ignition is vastly more efficient.

Second, how to disconnect the alternator. Not only is the alternator a challenge cutting the output, but the relay needs to be beefy to handle that 200+ amps you could see. I think I would prefer to hard wire it to the battery (through busses and fuses, of course), and manage the overcharge protection by interrupting the power to the field (or the regulator).

Agree, dropping field current is the safest way to properly shut down alternator charging. A simple NC relay in the field does the trick, but IMO it's better to cut power to the external alternator regulator. I remember that e. g. Balmar recommended against cutting field directly, and as field is driving a coil I definitely see the reasoning behind this.

[john61ct]

A killswitch for cutting alternator output is bog standard, and yes how wired depends on the specific alt/VR.

Starter should be kept topped up by a small VSR/ACR from the House side, or an Echo Charger, Yandina combiner etc.

If your inverter(s) are kep on all the time, IMO you're doing it wrong, or have a surplus of off-grid power sources.

[john61ct]

If you are cruising living on the hook powered mostly by solar, then it is worth investing in every bit of extra efficiency you can.

Redneck engineering kludges like a mains charger feeding off the House bank to charge another battery while there are no actual energy inputs active

will "work OK" for some contexts, but really are far from ideal.

[john61ct]

If your time and attention is required, rather than being fully automated, that qualifies as a kludge afaic.

Inverter efficiency ratings are pure fiction, notice the "up to", at best they cherry pick one point out of hundreds.

In the context I cited inverters are to be avoided completely, or at least as much as possible.

There is no need for us to agree, differences of opinion are the norm. . .

[CatNewBee]

Originally Posted by ablefollower

What you need to see, is a house 400AH LifePO4 is a MASSIVE energy store, and your little start battery is a tiny one, of which you will likely pull ONE amp-hour from during an ordinary start, and also that it will likely do 20-30 of those ordinary starts without any recharging at all.. Different story if you run it out of diesel..

You could trivially use a 5A mains battery charger from your house inverter to recharge your start battery after it had done its' daily starting duty, and likely it would accomplish this task in minutes, or less.

Long story short, there is no need for a large and complex charging system for your start battery. Don't be tempted to install all sorts of complicated and risky junk to do a 2 minute, 5 amp job.

Dedicate your alternator to charging your main house bank.

There are many ways to do it, I opt for keeping it as simple as possible.

In my world, alternators, starter and start batteries belong to the power train. Solar, wind and water generators along with the house battery are another independent circuit, interconnections with or without electronics can be done of course.

In general, the alternator remains always connected to the start battery, no need for special protection, it is a AGM.

Charging one battery from another always generates heat and energy losses, less with B2B charger, more with inverter and regular charger. But doable.

[sailingharry]

A lot of strong opinions on the matter. Frankly, I don't see it as a redneck kludge that requires management. It's not far removed from my old boat where for years I had NO underway charging for the start battery. I could, of course, close the 1-2-All switch, but rarely did. I just ignored it. When I was at a dock, I plugged in (with no solar and limited alternator, shorepower was a godsend!), and the battery got charged. With no cruises over a week, the start battery was called on to do maybe a dozen starts (we often anchor and get underway under sail), and it was pure simplicity.

I'm simply suggesting a similar approach. On a boat with LiFePO4 batteries, there is significant consumption going on, probably including an inverter - and it probably runs an hour or more a day. The boat probably also has a mains charger, already set for the right battery chemistry, and already installed. If you simply set it and forget it, every time you turn on the inverter (coffee, microwave, whatever), the start battery gets charged. And every week or two, it gets a shorepower 100% charge.


B2B are expensive. If you set it up to be "the" answer, at least you don't have to worry about installing a shore power charger too. And if you don't have a shore power charger already, it's not that much money.


Echo charges, combiners, ACR's, etc, are all unequivocally a BAD answer. Lead Acid (of any chemistry) is an entirely different charge regimen from LiFePO4, so simply connecting them (intelligently, yes, but still just connected) is truly a redneck kludge.


I will agree that, with money, time, and labor no object, ripping out the mains charger and installing a true B2B, is the best answer.