DC to DC Charger Sizing for Yanmar

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Hans Retterath asked Jan 1, '24

DC to DC Charger Sizing for Yanmar

My sailboat has a Yanmar 3JH40 with an alternator rating of 125 amps. I am upgrading house bank to 400 amp hours of lithium iron phosphate. As Victron's maximum DC to DC charger is 30 amps, I am planning to get two for 60 amps total. I have heard that a good rule of thumb is to keep DC to DC at about half the size of the alternator. Is 60 amps DC to DC safe for my 125 amp alternator?

I have also heard you can run just one DC to DC charger if worried about alternator burnout. What is the situation when this might occur? High ambient temperatures? Boat engine running a long time?

Thanks!

dc isolators in parralell system

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Answer 1 · 2024-01-02T01:10:41Z

dc4me answered · Jan 02 at 01:10 AM

I would suggest you look at the Balmar MC-618 external regulator. You will have more options for your own charging needs. You will find that you will never have the ability to harness 125 amps out of that alternator. As soon as it heats up output goes way down without an external regulator. With the Balmar you can regulate output to control temp of alternator to get the most output without damage from heat. It also has nice monitoring abilities if one chooses to use them.

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Answer 2 · 2024-01-02T01:32:49Z

klim8skeptic answered · Jan 02 at 01:32 AM

@Hans1961 You might be better of with an Orion XS 12-12-50.

With the new Orion you can adjust the output current in 0.1a increments.

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