Most efficient way to charge batteries?

YYZRCYYZRC Member Posts: 5,142 ✭✭✭✭✭
edited July 2020 in Electrical Discussions
This has been bugging me.

What is the most efficient way to charge the house batteries assuming no other requirements (eg: at anchor, don’t need any other AC power so the decision to use engine(s) vs genny is purely efficiency based)

1) run the generator to power the battery charger
2) run one engine (70 amp alternator)
3) run both engines (2 70 amp alternators)

Efficiency would be in terms of quickest charge and also fuel burned/environmental impact. 

Thoughts?
2008 350 EC on Georgian Bay

Comments

  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    what is the isolator rated at? ... it may make sense to run both engines, or, it may not depending... 

    if you're charging and not just tending (meaning you're tossing max voltage at it.... 14.5vdc as opposed to 13.5vdc) and you have shore power available, a smart charger on the battery side of the isolator is the way to go... throw maximum 'smart' charge at it and charge them in no time.... the 'smart' part is it fluctuates and between bursts it reads the drift... if it drifts a lot it will blast it again- if it doesn't drift much it will reduce the amperage and the voltage and checks it again.... flooded cells charge slower, but even so they still do the majority of the charging in the first 20 minutes of charge. 

    i have a dewalt charger that can toss 80a at a battery... with it a battery is charged to a decent amount in less than 20 minutes.. it's 'smart'... i may be wrong but i don't think most on-board chargers can do that... they can 'tend' or trickle all day long, but they won't burst charge... and an alternator can toss max amperage (depending on isolator) but not do it 'smartly', UNLESS it goes through the computer/ECU- which almost all newer cars do but i'm not so sure mercruiser or volvo's do. 
  • YYZRCYYZRC Member Posts: 5,142 ✭✭✭✭✭
    I have the original isolator right now but the proisocharge on the way. Flooded batteries. 
    2008 350 EC on Georgian Bay
  • raybo3raybo3 Administrator Posts: 5,508 admin
    The genny fuel burn is pretty low. IMO I would not run the engines just to charge the batteries. Seems like a lot of wear and tear on them plus it will increase your engine hours. Run the genny as the more you use it the better it will run............. Just say'n
    2002 342 Fiesta Vee PC Point Of Pines YC Revere MA. popyc.org     raybo3@live.com
  • PickleRickPickleRick Member Posts: 4,038 ✭✭✭✭✭
    The genny is like a muscle. Use it or lose it.
  • YYZRCYYZRC Member Posts: 5,142 ✭✭✭✭✭
    I agree with running the genny and it's getting plenty of use running the AC (over 20 hours in the past month).  
    2008 350 EC on Georgian Bay
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