Remove the alternator - crazy idea?

[rslifkin]

Originally Posted by Fuss

in theory yes, but as the start battery only runs the instruments and starts… it has nothing to do and so a weak dc to dc charger is more than adequate

That isn't necessarily true. On some engines (such as anything with electronic controls or a gas engine) it requires power to keep the engine running and there's more draw. More importantly, if the start battery isn't charging due to a really low house bank or something, you're sitting there drawing down the start battery, which will shorten its life (assuming it's lead) and may mean you don't have enough power for the next startup.

[Simi 60]

We cruise full time
After smoking our second large frame alt trying to charge a large AGM bank I gave up and had no alt for about 2 years.

We charged the starts using a Victron ip67 24v 12 amp charger left on continuously
Worked ok during that time

But as our anchor windlass also runs off of starts we have now replaced it with a 100 amp @24v alt and run 2x 35amp dc2dc back to lifepo4 house bank.
Alt never gets above 75c

[hjohnson]

Originally Posted by Fuss

alternators charge house batteries… dc to dc charges charge start batteries

That’s exactly what i do. 18A DC-DC chargers keeps my starter battery forever on the float. Alternator charges my 460Ah house bank.

[Ballsnall]

Originally Posted by Rohan

They rely on solar or a generator to charge the batteries if needed.

This is a great idea, people have so many problems with alternators that removing it entirely and fitting a generator sounds like such a good solution it amazes me how it hasn't been done before.

[Simi 60]

Originally Posted by Fuss

alternators charge house batteries… dc to dc charges charge start batteries

Well that's one way.

The opposite is also true

[CaptainRivet]

Originally Posted by s/v Jedi

Because start batteries should be fully charged at all times and LFP hates being fully charged at all times, while AGM loves it.

You should go with the flow, use properties of battery chemistries to work in your advantage instead of forcing a way against them. There is nothing wrong with an AGM start battery, charged by an alternator.

a start battery needs only to be fully charged all the time because thats the requirement of lead to life long.
With LFP you have a very tight monitoring of your LFP and if you put the LCV on 3.0V or 12V (that disconnects all but starter and windlass) then you always have enough juice in your house LFP to start your engine. Even at 2.6V per cell that easily starts an engine 20x.

The typical LFP house is around 400AH, so at 3,0V you still have 60AH in them and thats more then a 100AH lead starter has avaliable if its full. And that discharged LFP can also start your engine more often then your full 100AH lead starter.
Additionally the starter lifes longer as the voltage drop is much lower and current deivery higher under load so less wear. You have to watch out that BMS is not FET based and can handle the start surge of a starter or windlass.


especalliy in a cat, the standard setup by all mass production company is having a combined starter&house bank in one hull (so perfect for a LFP bank) and a starter in the other (here a lead makes sense, or if both alternators are regulated anyhow to optimise charge rate i highly recommend to use a 30-80AH LTO, you will only buy one in your life)

And the 2nd starter can also always be used for the other hull by flipping a switch.
Much more important then a dedicated starter is to isolate your senstive electronics like chartplotter, Radar.... with an isolated DC2DC converter or even charger and have a small buffer battery at the navstation supplying them with power incase the LFP shuts off. Also enlarges live of all of them sigificantly as they don't get spikes from motors. I prefer a small LTO battery with an active balancer but other recommend a small AGM.

[CaptainRivet]

Originally Posted by Ballsnall

This is a great idea, people have so many problems with alternators that removing it entirely and fitting a generator sounds like such a good solution it amazes me how it hasn't been done before.

hope thats ironic....
another engine=gen is another one to buy and to maintain and needs much more space then your alternator.
With LFP charge rates and a big alternator on the existing engine you can avoid a generator in 85% of cases and use what you already have installed and which run anyway if you motorsail, go in/out of habour or an anchorage.
And having your daily usage covered when engine run the 30-45min when you get into haour/anchorage creates no more wear and tear and additional maintainance not existing and diesel consumption is neglectable.
with the Nordkyn VSR-200 Regulator you can regulate a lot of (especially newer) stock alternators like mitisubishi 115A one (can be found on all Volvo D1/2/4 and a lot small yanmars) without any modifiying.

[OceanPlanet]

The vast majority of the LFP installations we've done or seen UPGRADE the alternator, along with adding a smart regulator that communicates with the battery system.

Most often, the whole idea of the LFP upgrade is to take advantage of the faster charging capability, along with the PSOC cycling, etc.

This allows not needing (or disposing of) the generator(s).

Most of these upgrades also switch to 24V, and some now to 48V. Why? See attached output graph in kW of the popular APS HPI series alternators. These fit into the stock alternator position. Even the impressive-sounding 360A x 12V version pales in comparison to the 185A x 24V, and especially to the 48V (130A being the most practical due to lower rpm startup than the 160A).

Using these alternators (or the Balmar XT170/XT250 if on a budget) in the stock position negates the needing for adding a 2nd alternator at all.

The alternators are set up to charge the house bank, and a B2B charger (and our AC/DC charger) maintains the starting battery or batteries. B2B's are also utilized (if need be) to charge a bow windlass/thruster Pb battery, and/or a critical loads Nav/lighting/autopilot/etc. Pb battery.

Just saying how many yachts are setting up and utilizing their LFP systems these days.

[TPG]

Most of my power comes from solar. We have a cat that has 3YM30's on her that came with the standard 125 amp VALEO alternators. I have them set up with Balmar 618's and they charge the Lifepo4 house bank directly. The house bank charges the start batts via Victron DC-DC chargers. I also have the Balmar APM-12's on each alternator to protect them from quick disconnect. As a backup, I also installed a disconnect switch on each alternator to physically shut them out if need be.

So far this is working - I am told that you should never run an alternator without it being connected to something, so I'm guessing my Balmar parts are keeping them safe.

My whole point in trying this approach out was to see what I could get out of the stock alternators before I chukked 'em and installed fancy purpose-built ones.

[OceanPlanet]

Originally Posted by TPG

Most of my power comes from solar. We have a cat that has 3YM30's on her that came with the standard 125 amp VALEO alternators. I have them set up with Balmar 618's and they charge the Lifepo4 house bank directly. The house bank charges the start batts via Victron DC-DC chargers. I also have the Balmar APM-12's on each alternator to protect them from quick disconnect. As a backup, I also installed a disconnect switch on each alternator to physically shut them out if need be.

So far this is working - I am told that you should never run an alternator without it being connected to something, so I'm guessing my Balmar parts are keeping them safe.

My whole point in trying this approach out was to see what I could get out of the stock alternators before I chukked 'em and installed fancy purpose-built ones.

Seems like a good approach for now. Once they're cooked you can upgrade as needed...;-)

[CaptainRivet]

Originally Posted by TPG

Most of my power comes from solar. We have a cat that has 3YM30's on her that came with the standard 125 amp VALEO alternators. I have them set up with Balmar 618's and they charge the Lifepo4 house bank directly. The house bank charges the start batts via Victron DC-DC chargers. I also have the Balmar APM-12's on each alternator to protect them from quick disconnect. As a backup, I also installed a disconnect switch on each alternator to physically shut them out if need be.

So far this is working - I am told that you should never run an alternator without it being connected to something, so I'm guessing my Balmar parts are keeping them safe.

My whole point in trying this approach out was to see what I could get out of the stock alternators before I chukked 'em and installed fancy purpose-built ones.

Yes keep stock, most 115A Mitzi or the 125A Valeo deliver around 80-90A continuous. The nordkyn VSR200 is your choice here as you can regulate them without any modification on alternator and using the original alternator temp management which you losse when modifing to extrnal regulation.

On a lot small 10 to 50hp engines in org. Position you can only fit a small case and the balamar maybe delivers 20-30A more for 2k invest. 2nd on Volvos you have D+ issue when replacing the org. Alternator and need to factor in costs for that too. So with Volvo step 1 regulate Stock with VSR200, if you need more add a 2nd large case alternator, this one you can then also regear so it starts producing more low down as its 90% driven by a 2nd serpentine belt and pulley.

[Nicholson58]

You must change the alternator to a high end type with a continuous full load rating

OR

Install an external alternator programmable regulator such as Balmar and set the output to around 50%

You need the external regulator no matter what else.

[sinnerman]

I use a flux capacitor on my boat.

It also allows me to "relocate" the boat when there is no wind.

I purchase the plutonium online from Amazon and Alibaba.

cheers.

[OS2Dude]

To answer your question, YES. You could get away with removing the alternator from a diesel engine. But as others have pointed out, removing a charge source may not be the wisest thing to do.

DC-DC chargers are a middle of the road solution. Not as expensive as replacing the alternator and belt system on a typical engine but they and the 'start' battery do take up room. (Start battery can be any type except LFP, -AGM for example - if you don't want the maintenance hassles of a FLA battery)

BMS Cutout for under-current can be handled somewhat with multiple batteries in parallel via bus bars. It would be less likely that the BMS will cutout on all batteries at the same time. Over charge cutouts can be dealt with via an alternator regulator that can be shutoff via a signal from the BMS. These regulators (typically external) and related alternators tend to be more expensive than automotive style ones. They also tend to be larger and require more than the typical single V belt to drive them. These regulators will also help keep the alternator from burning out due to the excessive needs of large LFP banks.

[The Yacht Rigger]

Originally Posted by sinnerman

I use a flux capacitor on my boat.

It also allows me to "relocate" the boat when there is no wind.

I purchase the plutonium online from Amazon and Alibaba.

cheers.

I tried one of these back in 2054, but then I got stuck in 2023. Can't seem to reprogram it correctly.