DC to DC charger - not needed for boats with proper alternators.

[Dockhead]

Originally Posted by Maine Sail

if you go back and look at my posting from the early 2000’s (CWBB days) you’ll see that once AGM’s hit the market we started seeing an increase in burned up alternators. This was back when AGM manufacturers were still actively marketing taking them to 80% DoD… AGM’s could not survive for long cycling to 80% DoD and they revised it to 50%. Once they stopped suggesting 80% DoD, as being ok, the alt burn-up rate dropped. Less common were burned up alts on flooded batts unless the bank was really big. The spike we saw when LFP hit was more pronounced than AGM likely because bulk is 98% of the charge cycle instead of a small percentage as it is with lead.

I can remember begging David Smead (we were an Ample Dealer at the time) toadd alt temp sensors when AGM came out. We were seeing a ton of Ample alts burned up with AGM. David even made outlandish claims of his alts being constant duty. they were not! Once we dropped Ample and became a Balmar dealer, our burned up alt issues with AGM stopped entirely. This was Due to alt temp sensing and “Amp Manager” Two features David and Ruth chose not to do.

Alt burn up is related to bulk duration. the alt has no clue what it is connected to.. LFP is all bulk hence the bad rap..

Indeed!

The issue is CONTROL over the voltage and output of the alternator. This is not only a matter of protecting the alternator from overheating, but also giving the batteries the right charging profile and shutting down charging when necessary. Then there's the issue of damaging the diodes in case one of the cutoffs in the BMS works while the alternator is running.

A DC-DC charger with the right program for LiFePo is only one way to solve these problems. This is pushed because it's the simplest and most straightforward way to do it. You can also do it with the right kind of regulator, plus something to protect the alternator in case loads are unexpectedly disconnected.

As to overheating -- I'm here to tell that even heavy duty large frame alternators, like my 110A * 24v Leece Neville, can be burned up if it's not properly regulated. Heavy load at low RPM will do it, even if the alternator will happily put out full load indefinitely, at normal operating RPM. Don't ask me how I know.

[Fuss]

Originally Posted by Dockhead

Indeed!

A DC-DC charger with the right program for LiFePo is only one way to solve these problems. This is pushed because it's the simplest and most straightforward way to do it. You can also do it with the right kind of regulator, plus something to protect the alternator in case loads are unexpectedly disconnected.

As to overheating -- I'm here to tell that even heavy duty large frame alternators, like my 110A * 24v Leece Neville, can be burned up if it's not properly regulated. Heavy load at low RPM will do it, even if the alternator will happily put out full load indefinitely, at normal operating RPM. Don't ask me how I know.

Thanks for this post, this is very interesting for me.
I also have a 24v leece neville that showed no signs of ever burning out and has run a full capacity for at least an hour sometimes , also with no alternator temp sensing.
Can you tell me what batteries and size they were.
What amps was it pulling and for how long
What regulator and wether battery temp sense or alternator temp sensed or none.
What have you done since to ensure this does not happen again.
Thanks John

[Dockhead]

Originally Posted by Fuss

Thanks for this post, this is very interesting for me.
I also have a 24v leece neville that showed no signs of ever burning out and has run a full capacity for at least an hour sometimes , also with no alternator temp sensing.
Can you tell me what batteries and size they were.
What amps was it pulling and for how long
What regulator and wether battery temp sense or alternator temp sensed or none.
What have you done since to ensure this does not happen again.
Thanks John

Hey John:

The regulator was an Adverc, which is not smart enough to dial down the power with higher temperature. A Balmar or Sterling is much better.

I asked you not to ask how I know! But anyway, the situation was I had accidentally left a heavy inverter load on while anchoring. Anchoring using the windlass and bow thruster at the same time with the main engine idling. Burned it right up; there was smoke coming out of the engine room.

I haven't changed the regulator yet, but I have so far avoided a repeat of this by being more careful with the inverter, and keeping the revs up while operating heavy DC equipment like thruster or windlass. Or often I simply start up the generator when I get ready to anchor.

Batteries are 8x Trojan T105s, which were run right down after an all night sail prior to this anchoring incident. It would be worse with lithium which is, as you said, "all bulk, all the time".


P.S. As I think about this, it seems to me that this situation would actually be WORSE with a DC-DC charger, as that will pull a load even when the voltage is pulled down by heavy DC equipment, because it boosts the voltage to whatever is needed for charging. In my case, the batteries weren't drawing any current, because they won't when the voltage is below whatever is needed at that moment for charging. I guess this can be solved by properly programming the DC-DC charger, to stop charging when system voltage is below x.

[Jerry Woodward]

My cat has two small diesels, 2GM20f and two alternators. About 4 yrs ago I upgraded one alternator to a Balmar 6 series 120 amp, a serpentine belt kit and a MC614 regulator (with the help of Main Sail). This really helped my lead acid bank, giving it a full charge when motoring. This season, I swapped the lead acid for lithium and wired the Balmar directly to the lithium bank and programmed the MC 614 appropriately with belt manager set to 3. I also have an alt protection device and alt temp sensor attached. This works very well and puts about 80-90 amps into the batteries for an extended period when I am underway. My other stock Hitachi alternator is wired to the start/reserve SLA battery. Thus, the reserve battery will maintain charge if I need to switch over to it. So, in my setup, I don't see the need for a DC-DC charger.

[s/v Jedi]

Originally Posted by MWGDVC

A concern I have not seen discussed with the current fashion of all electric galleys and increasingly power hungry sailboats is crankshaft loading.
With the alternator fan cooling load, belt and bearing friction and the load of power generation, assuming a rather generous 50% alternator efficiency, a 2070 (150Ax13.8V) watt alternator will consume 6-10 horsepower.
We use, in most sailboats, what are essentially modified compact tractor engines. In intended use form, they are equipped with 35-50A 12V alternators expected to operate at peak output for short times, to replenish current used for starting, then maintaining such minimal power as required for lighting, instrumentation, etc.
Front main bearing sizes and crankshaft noses are sized for this application.
Factory pulley and belt sizes are also calculated off of this much lower load.
As we add more power draw from the front of the engine, we must increase the belt tension to avoid belt slipping, or increase the belt surface area to transmit the power required to the alternator.
Wider belts move the load further away from the engine main bearing, increasing the leverage of the belt and alternator load upon the crankshaft.
I have personally seen 2 crankshaft failures due to increases of crankshaft loading at the nose.
Given a battery bank of 8280 watt hours (600AH at 13.8V) , a 2070W alternator would charge, at maximum output , .25C.
My point to all of this, is we may be reaching the limit of easily bolted on electrical power solutions for the engines currently utilized.

Indeed. When Steve Dashew designed the Sundeer series he was well aware of this when he added 450A alternator charging. For this reason he kept the standard belt driving the water pump and standard alternator, then added a massive custom bracket to mount two additional 225A alternators inline and at opposite sides of the crankshaft, so that they canceled out each other’s sideways pull on the bearings.

For the distance from bearing to pulley, it isn’t just that a serpentine belt moves this pull further from the bearing… for additional alternators, a second pulley is bolted onto the first one, making this much worse and I think it’s crucial that the sideways pulls on such extra pulleys must cancel each other out.

I have never seen anyone repeating that. We actually removed all those alternators (my engine mounts loved that!) and switched to solar charging. I did replace the standard pulleys and belt to a serpentine belt and put an upgraded Balmar alternator and regulator with temperature control in. It is a 170A alternator that I’m happy to run at 100+ Amps shortly after starting to replenish the start battery, then use dc-dc chargers to feed some charge to house batteries with a maximum of 60A. My standard alternator was 85A.

[Dockhead]

Originally Posted by s/v Jedi

Indeed. When Steve Dashew designed the Sundeer series he was well aware of this when he added 450A alternator charging. For this reason he kept the standard belt driving the water pump and standard alternator, then added a massive custom bracket to mount two additional 225A alternators inline and at opposite sides of the crankshaft, so that they canceled out each other’s sideways pull on the bearings.

For the distance from bearing to pulley, it isn’t just that a serpentine belt moves this pull further from the bearing… for additional alternators, a second pulley is bolted onto the first one, making this much worse and I think it’s crucial that the sideways pulls on such extra pulleys must cancel each other out.

I have never seen anyone repeating that. We actually removed all those alternators (my engine mounts loved that!) and switched to solar charging. I did replace the standard pulleys and belt to a serpentine belt and put an upgraded Balmar alternator and regulator with temperature control in. It is a 170A alternator that I’m happy to run at 100+ Amps shortly after starting to replenish the start battery, then use dc-dc chargers to feed some charge to house batteries with a maximum of 60A. My standard alternator was 85A.

Those with Yanmars should be particularly careful about the issue of side pull on the crankshaft pulley, and max permitted HP takeoff. The ratings are quite low and should be followed carefully.


Serpentine belts need less tension, so cause less trouble with main bearings.


Mounting two alternators opposite each other helps with side pull but won't solve the problem if you are tapping too much HP off the front end.

[Stu Jackson]

FUSS,



It's not your "opinion" that's wrong.

It's your engineering, both in how each battery chemistry accepts charge and how alternators work and are protected.

Jedi's reply answers you completely.

Originally Posted by s/v Jedi

It doesn’t work like that. Alternators have been designed for a specific purpose and that is to charge LA batteries while also supplying energy for the normal operation of the vehicle.

The important part is that the thermal design was for the expected RPM and for the charge characteristics of LA batteries. They have never been designed to output full rated capacity continuously.

AFAIK there is no alternator on the market that was designed for LFP battery charging.

There are alternators designed for higher loads, I have sailed many years with 3 alternators bolted to my engine: the oem one plus two Lestec 225A Brute alternators which were beasts. Still, they were designed for charging LA house batteries at RPM’s for normal use of the engine, not high idling like we all want. So I had to de-rate them to be able to use them at lower RPM’s and of course they quickly reduced output when the long absorption charge phase of the LA begin.

Then there’s the question if the engine or the belt is overloaded at the RPM’s used for charging from the alternator. Many problems on that front as well.

Today, when using an alternator for charging a LFP house bank, the two main concerns that must be addressed are:

1 - the temperature of the alternator must be monitored and controlled by the regulator.

2 - the rectifier diodes must be protected against a HVC event.

That’s it. Hope we get LFP alternators soon

[CaptainRivet]

Originally Posted by sailingharry

I have 800Ah of AGM charged by a pair of 120A alternators excited by a pair of Balmar regulators. Nothing anywhere is "Lithium."

If I'm well down in the morning, say 60% SOC, I won't reach acceptance voltage for over an hour, probably close to 2. The alternators will be pushing 100% of what the "system" (alts + regs) can do. A combination of alternator limitation and regulator protection (if that comes into play) limit my charge rate -- the battery is NOT limiting charge rate in this region.

So, what I don't understand. If I swap out my AGM for LFP, and am down that same 300Ah, what would be different in the first hour+? My assumption is "nothing." The batteries won't be limiting charge, and the "system" will be pushing all it can.

And, if I had LFP, even though I already have solar, I'd still want to get every bit of the 150-200A I currently charge at (although as things heat up, that continues to drop.) Especially if I was only running the engine for a 30 minute trip out of the harbor. Even more so if the only reason I was running the engine was at anchor after a few days of poor solar output!

Using the theory that says alts need to be protected from the charge rates of LFP, I'd say it applies equally to large AGM. Fortunately, I don't buy the theory....

In very Short words:
All lead based battery have a high resistance that naturally limit the current, in charge and discharge.
A LFPs internal resistance is between 10 and 20 mOhm so you basically charging a short so nothing is limiting the current and the resistance the alternators oem regulator sees are the wires, fuses and connections (so underrated cables and corroded connection saved thousands of alternators from burning up when newbies and incompetent installers install LFP drop ins, the stories you hear „I installed LFP drop ins and didn’t change anything else and even after 2 years all works fine“, no it didn‘t…).
As Jedi Said correctly all alternators available are made for LA charging, so at minimum their regulation need to be modified as the OEM regulator expects LA characteristics.
Next is the environment the alt is installed…the nearly unventilated holes where in a lot monos the engine and therefor alternator is installed plus the low RPMs the alt is forced to work as no big crank pulley fit the engine in its mounted location gives the alternator no cooling, it actually heats it up additionally so even your large case alt would loaded with its rated amps burn through when not limited in output.
Then add the additional hp plus loads on the bearings you big alternator needs (see posts above 33 and 35), the higher the load, the higher the hp draw and load on the bearings…
To avoid all that just add a DC2DC to your existing system which as an additional benefit isolates the starter circuits from house circuits. You can add as many DC2DC charger so you reach your current capability of your existing alternator in your existing environment without changing anything else. And in most cases that’s cheaper then modifying your existing alternator or even install a bigger heavy duty alternator which won‘t deliver its rating also…

[CaptainRivet]

Originally Posted by s/v Jedi

Indeed. When Steve Dashew designed the Sundeer series he was well aware of this when he added 450A alternator charging. For this reason he kept the standard belt driving the water pump and standard alternator, then added a massive custom bracket to mount two additional 225A alternators inline and at opposite sides of the crankshaft, so that they canceled out each other’s sideways pull on the bearings.

For the distance from bearing to pulley, it isn’t just that a serpentine belt moves this pull further from the bearing… for additional alternators, a second pulley is bolted onto the first one, making this much worse and I think it’s crucial that the sideways pulls on such extra pulleys must cancel each other out.

I have never seen anyone repeating that. We actually removed all those alternators (my engine mounts loved that!) and switched to solar charging. I did replace the standard pulleys and belt to a serpentine belt and put an upgraded Balmar alternator and regulator with temperature control in. It is a 170A alternator that I’m happy to run at 100+ Amps shortly after starting to replenish the start battery, then use dc-dc chargers to feed some charge to house batteries with a maximum of 60A. My standard alternator was 85A.

Why didn’t you went for 24V alternator instead 12V with this massive setup? 10-15% higher alternator efficiency 24V compared to 12V and your house is 24V too, was the perfect opportunity to go to 24V. Just switch the one starter to 24V wouldn’t have been so expensive.

I don‘t see any LFP alternators in 12 or even 24V being released as the high amp uses cases like EV already running on 48 till 96V. I expect to see 48V LFP alternators (which the integrel system offered basically is) as the alternator efficiency in 12 and 24V is too low to allow to offer the current capability LFP alternator needs to be offered at an acceptable price and boats will also go longtermed to 48V as cars will too as the is the new announced standard in the future.
The beta hybrid engines are actually the most economical way for bluewater cruisers for LFP charging with big LFP banks and high amp needs plus it offers you to use part of your anyhow oversized house bank for propulsion too to enlarge range or actually do the big amount of engine use Short in/out Marina or anchoring spot on e-power while motorsailing and long distance motoring on combustion engine.

[s/v Jedi]

Originally Posted by CaptainRivet

Why didn’t you went for 24V alternator instead 12V with this massive setup? 10-15% higher alternator efficiency 24V compared to 12V and your house is 24V too, was the perfect opportunity to go to 24V. Just switch the one starter to 24V wouldn’t have been so expensive.

I don‘t see any LFP alternators in 12 or even 24V being released as the high amp uses cases like EV already running on 48 till 96V. I expect to see 48V LFP alternators (which the integrel system offered basically is) as the alternator efficiency in 12 and 24V is too low to allow to offer the current capability LFP alternator needs to be offered at an acceptable price and boats will also go longtermed to 48V as cars will too as the is the new announced standard in the future.
The beta hybrid engines are actually the most economical way for bluewater cruisers for LFP charging with big LFP banks and high amp needs plus it offers you to use part of your anyhow oversized house bank for propulsion too to enlarge range or actually do the big amount of engine use Short in/out Marina or anchoring spot on e-power while motorsailing and long distance motoring on combustion engine.

I don’t see much use for the alternator for charging. I would seriously consider switching to electric propulsion when the Yanmar gives up the ghost. Of course I still have a genset to extend motoring range in that case.

Also, I am focused on easy, self reliance, expedition style cruising. I can take a sailboat auxiliary diesel engine and plug it in to our system as it is, in OEM default version. My updates with belt and pulleys is all OEM on current models, I just modernized ours because it’s still going strong

[s/v Jedi]

Originally Posted by s/v Jedi

I don’t see much use for the alternator for charging. I would seriously consider switching to electric propulsion when the Yanmar gives up the ghost. Of course I still have a genset to extend motoring range in that case.

Also, I am focused on easy, self reliance, expedition style cruising. I can take a sailboat auxiliary diesel engine and plug it in to our system as it is, in OEM default version. My updates with belt and pulleys is all OEM on current models, I just modernized ours because it’s still going strong

Let me add to this the two scenarios that I use alternator charging:

1. A backup for a backup. Very unlikely that both my solar and my genset stop working but alas here’s another charge source, why not.

2. In case I am underway and it is night and there absolutely is no wind at all and I have a schedule. This is hard to believe but I may even get antsy without a schedule and want progress during the dead calm night so I use the diesel. For this case I like to have plenty power because when this happens we tend to make heavy use of the galley, entertainment systems etc.

Both of these are very unlikely because I simply don’t leave when there’s no wind. But I can remember a couple of cases in the past 20 years of sailing Jedi so it does happen. Also, we are lucky with our boat because even in only 7 knots wind on the beam we can sail 4 knots STW on working sails and I can tolerate that

[Fuss]

Originally Posted by Stu Jackson

FUSS,



It's not your "opinion" that's wrong.

It's your engineering, both in how each battery chemistry accepts charge and how alternators work and are protected.

Jedi's reply answers you completely.

Thank you Stu, If I don’t follow your opinion, what will happen?

[sailorboy1]

such an interesting battle

[CaptainRivet]

Originally Posted by Fuss

Thank you Stu, If I don’t follow your opinion, what will happen?

Simple, you will pay for your lesson
Some just need to find it out the hard way

[CaptainRivet]

Originally Posted by s/v Jedi

I don’t see much use for the alternator for charging. I would seriously consider switching to electric propulsion when the Yanmar gives up the ghost. Of course I still have a genset to extend motoring range in that case.

Also, I am focused on easy, self reliance, expedition style cruising. I can take a sailboat auxiliary diesel engine and plug it in to our system as it is, in OEM default version. My updates with belt and pulleys is all OEM on current models, I just modernized ours because it’s still going strong

I got that, otherwise you wouldn’t have swapped out 450A for 170A.
I am just curious why you didn‘t go with a 24V 90-100A alternator instead of a 12V 170A when you have a 24V house. Old yanmar means your engine doesn‘t need 12V for ECU so swapping the starter would be the only mod to go to 24V on the starter circuit too. More backup as you can start from house too and more efficient as your cables have less voltage drop.