Remove the alternator - crazy idea?

[Kettlewell]

As I mentioned earlier in the thread, I like the safety feature of having a separate dedicated starting battery so no matter what I know that I can turn the key and the engine will fire up in an emergency, which has happened more than once! Just use the alternator to keep that topped up and if you want you can then also use that battery to run a few critical electronic items, like maybe the GPS, the radio, and the depthsounder. I like to keep critical stuff off of the main house circuit just for the situation like we had once where one of our flooded house batteries developed an internal short while offshore, almost creating a fire onboard. I then had to disconnect the various battery cables and reconfigure the house battery bank while offshore, yet all the time I had the separate starter battery hooked up and ready to go if I needed it. Redundancy is good!

[s/v Jedi]

Originally Posted by Fuss

why wouldn't they use lithium for starting?

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.

[Fuss]

yes of course you could use AGM but smac999 wrote than no one would ever use lithium as a start batter and I wondered why.

[s/v Jedi]

Originally Posted by Fuss

yes of course you could use AGM but smac999 wrote than no one would ever use lithium as a start batter and I wondered why.

You obviously didn’t read my post because I explained it in detail.

[sailingharry]

Originally Posted by The Yacht Rigger

Or you could go the other direction, since you'll have a lithium system, and really maximize your charge rates, and also be able to just turn off the alternator when you wish to... like this setup. https://youtu.be/_XM4W0enlzg?si=zHEqWYonwesuy4Iz

I'm not sure what, if anything, that regulator adds over a conventional smart external regulator like a Balmar. The super high charge rates that they allude to can only be accomplished with a new alternator. My Balmar regulators already draw every amp my alternators can give.

A conventional regulator assesses how much is needed from the alternator. It then cranks up the field to get that amount. There are two limitations. The first is the maximum power of the alternator - no regulator can get more out of an alternator than full field. The second is overheating the alternator - any good regulator dial back output to protect the alternator. Within those necessary limitations, you can't get more than that.

[The Yacht Rigger]

Originally Posted by sailingharry

I'm not sure what, if anything, that regulator adds over a conventional smart external regulator like a Balmar. The super high charge rates that they allude to can only be accomplished with a new alternator. My Balmar regulators already draw every amp my alternators can give.

A conventional regulator assesses how much is needed from the alternator. It then cranks up the field to get that amount. There are two limitations. The first is the maximum power of the alternator - no regulator can get more out of an alternator than full field. The second is overheating the alternator - any good regulator dial back output to protect the alternator. Within those necessary limitations, you can't get more than that.

For me it's mostly the simple bluetooth programming, yes, combined with a high output alternator - and generator mode. Being able to fully engage (full output) the alternator at lower RPM's when the engine is in neutral is awesome for when wanting a quick boost on anchor. We run AC on our lithium system, so just fire up the engine (or engines depending on charge needs) for 30-45 min in the evening, make some hot water, fully charge up the batteries, then can sleep with the AC on. If it's a cloudy day the following day, run the engines for another 45 min in the morning and then let the batteries do the work again.

This Florida weather is so nasty in the summer - it's either charge batteries fast, or run the generator all day and night.

[Fuss]

Originally Posted by s/v Jedi

You obviously didn’t read my post because I explained it in detail.

yes, I did but we are slightly different wave lengths.
of course I would also not buy a lifepo4 starter battery with their limited specs 1000cca for 1 second and not more than 3 times a minute… or something like that but they are out there… Dakota, race car starters, emergency jump starters etc so it’s not that others don’t think drop ins are not possible and winston makes a bms less starter .

[Bowdrie]

The regular old SLA batteries, sold by the millions for vehicle starting duty do great for what they were designed to do, and they're inexpensive, available everywhere in the world, and operate just fine without any sophisticated electronic gizmos.
There is no need to spend time and money working to shovel sand against the tide.
You can dedicate the alternator to the fancy house bank and use a DC>DC device to keep the starting batteries charged.
Or do what some others do, (and it ain't a bad idea,) mount two alternators, the little job that comes on the engine works just fine for the starting batts, and an additional big one for the house.
Then you can have more peace of mind.

[Fuss]

but people are buying these drop in lifepo4 starter batteries or they would not be made
don’t dedicate an alternator to charge start batteries… it’s not smart, use a dc to dc charger

[Fuss]

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

[Fuss]

a 12v eve 280 costs now 500€ including BMS …the same price as a quality AGM…. so we are now at the same price point nearly

[rslifkin]

Originally Posted by Fuss

but people are buying these drop in lifepo4 starter batteries or they would not be made
don’t dedicate an alternator to charge start batteries… it’s not smart, use a dc to dc charger

If you've got an engine that requires power to run (such as a gas engine or an electronic diesel), then in my opinion there needs to be a guaranteed source of power to the start battery whenever the engine is running. I don't love a DC-DC from the house bank in that situation, as if you start the engine with very low house batteries or a problem in the house side electrical you may not be getting any charging to the start battery (which will instead sit there discharging as the engine runs).

Not as much of a concern with a mechanically injected diesel that only needs power to start though, as the draw from the engine instruments will be minimal.

[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… an alternator for this task is silly as the battery does nearly no work.
however my future post on lithium starting is going to show that this concept is about to change

[badadim]

Setting aside redundancy and conventional wisdom, I would argue that completely removing the alternator is not efficient, especially when equipped with an LFP battery bank capable of absorbing high charging currents (in most cases, up to 100% of the alternator's capacity).


When examining the output graph of the Yanmar 4JH-TE and the Caterpillar table displaying maximum power output versus propeller demand, it is safe to assume that in over 90% of cases (when the engine is not operating at its peak power output), more energy is produced by the engine than is required for propulsion.


Keeping the alternator on board allows for the harvesting of this excess energy into the LFP battery bank. In particular, using a high-output alternator permits the capture of all that wasted energy, as LFP batteries can be charged with high currents (up to 100% of the alternator's output in most cases).


This concept becomes even more attractive when the engine is used rarely and for short periods of time. Additionally, it offers a more cost-effective and technologically simpler means of partially achieving the results of INTEGREL, especially in comparison to Nigel Calder's more complex and expensive system.

[Fuss]

absolutely… do not remove the alternator unless you have one of those plastic ones that 70% of forum users seem to have… but that’s another story.