Incredible stupid question about my Volvo Alternator

[dougxn]

Okay, I can handle your abuse, but I have examined the wiring of the engine and the starter battery, I am just not seeing where the alternator comes back and charges the battery :cry: Besides, pulling the engine and tracing every wire out of the engine?
:?

I have a 2015 R-27 classic.

Perhaps someone can explain to this simpleton, how the alternator is wired in my boat to charge that’s battery? I see how it works for the house and Thruster - two acr’s off the starter battery. At some pointy I am going to add a dc-dc charger for the future lithium batteries. I suppose one can just take it off the start battery directly to the dc-dc charger . Anyway, I am clearly confused.

Thanks

 

[Texas Tuggernaut]

One possibility is the alternator output wire goes to the starter solenoid and from there alternator charging current goes to the engine start battery on the large red cable. The ACRs would then allow alternator current to charge house and thruster batteries. Just a guess…


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[jimv]

On my 2011 R27 with the Yanmar Engine / Valeo(BMW) alternator, the alternator was wired to the house bank, not the starter battery. Two ACRs - one between the house bank and start battery, and one between the house bank and thruster battery.
The previous owner had replaced all the batteries with AGM's, so I cant say if the alternator was wired this way from the factory, or if it was modified.
Either way, I'm not thrilled about the alternator wired directly to AGM's as this is just a 'basic' alternator and could easily overcharge the batteries - and with AGMs' if you lose electrolyte, it can't be replaced, e.g. lost capacity.
My winter project is to add a regular flooded wet cell starter battery, as that will be a better match to the alternator. I am then putting a smart DC-DC charger between the new start battery and the house bank, which will be all four of the existing AGM's (I'm going to tie the thruster battery into the house bank). Having a smart charger that I can setup with the correct profile for AGMs should help prolong the life of my house bank. New dc-dc charger also has LiFePo profiles, so I'm future proofing as well for an eventual switchover to lithium for the house bank.

 

[dougxn]

Thanks, this is what I sort of assumed, but since I cannot disconnect the battery from the alternator while it is running, I was feeling a bit constrained.

Thanks again!