Alternator Upgrade, Crusader 6.0 MPI CES

[kwkirkwood]

I'm about to have an extensive electrical power upgrade performed on my 2012 41 CMY. New LiFePO4 house bank, Victron Inverter/Charger, Solar panels, electronic monitoring system, etc. My budget couldn't afford alternator upgrades mainly because there was an unknown mounting challenge for a higher output alternator. I have two questions: 1) has anybody found a good solution for a high output (200A) alternator from a mounting and reliability point of view? 2) Has anybody had issues with mechanical power or load burdens placed on the Crusader 6.0 engines from a higher output alternator? These 6.0 engines are slightly underpowered for this boat in the first place, or my props aren't pitched correctly, because I have to trim the tabs full bow-down to get on plane ever since I added our davit and tender on the swim step last summer. I do not have a planing problem when the tender is not onboard.

[tomschauer]

With the pending upgrades you are planning, I would assume you spend a lot of time on the hook and do not plan on running your genny.
Others that do the same will be able to provide more info, but the factory alternators on your engines should provide at least 80 amps each X2. Not sure how big of a bank you plan to install, having more charging capacity than your bank can take at any given time really does no good.
Do you have a 400 amp battery charger? If not no reason to have 2, 200 amp alternators.

[Rocketman]

If you plan to run your AC units on the inverter while engines are running, you will definitely need more alternator power than the 80 amps each in my mind.
I did this on another boat and running the alternators at full load for hours at a time burned them up.
I had to install the largest alternators I could find.

Good luck.

[km1125]

Curious to know more about your LiFePO4 house bank and how you will be using it.

However, to address your concern about the larger alternator and "mechanical power or load burdens placed on the Crusader 6.0 engines from a higher output alternator":

A 200A alternator at full output would be around 3,000 watts or 3kW. That's not a huge amount when you compare it to the gensets that are installed on boats of this size. (how large is yours?). Now, comparing that load against the engine's output at cruise speed, Those Crusaders are each capable of about 375HP or 280,000W (280kW). So even at 75% of rated output, which is where you might at cruise, you're adding -at most- 3kW load to a 210kW engine.

I don't think you'd EVER notice it.

[bud37]

Used to be when you needed a much higher output alternator some of the considerations were, the mounting bracket and the drive belt ( size etc ), belt and pulley tension, wire and cable size and so on. Can you just run your generator while travelling and try the existing and see whether it is needed or not ?

Now maybe the new serpentine systems can handle it to a certain point, will be interesting to find out what the specs actually are for loading.

[Viper]

What are you reasons for needing HO alternators? What are your boating habits or plans?

[kwkirkwood]

km1125, that’s perfect information, thank you for answering my question so clearly and understandably. I also appreciate the comment about 75% load being an acceptable cruising speed. I’ve been wondering what load is considered good for extended durations.

Bud37, you arrived at the exactly same place I did. I’ve opted for a dual inverter-charger solution and no new alternator. The dual 200A chargers will charge the lithium batteries using both legs of the 7.5kw genset at a nice match of generator capacity, getting a boat load more charging amps per hour of run time (nearly 400) out of the generator compared to my whimpy 60A charger that I have now. So, for now the plan is to run the generator while underway as needed and save my money on the alternator, custom bracket, etc.

Thanks everybody, super helpful.