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DC-DC converter for use with engine alternator

ArranP

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Nov 5, 2020
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I am looking at installing solar setup for the 240V AC circuit, it uses a 48V DC inverter / battery.

The boat has an existing 24V DC circuit for the starter motor, windlass, winches and alternator.

Having a 24V and 48V requires two battery banks, I'm considering dispensing with the 24V battery bank.

This would require a DC-DC converter to convert from 48V battery bank to the 24V circuit, aside from checking if there are any issues regards to amperage which I am yet to do, this seems fine for the starter motor, windlass and winches..... However, I not sure how it stands in regard to the alternator... are these DC to DC converter bi-directional ie. would the 24V alternator still provide a charge the 48V batter via the DC-DC converter ?

Regards
Arran.
 
A typical DC-DC converter is unidirectional. There would be no charging as it is likely diode protected to prevent reverse flow. You would need a suitable separate step-up converter or charger designed specifically for this. Converters make bad chargers because they tend to operate at a fixed voltage that is practical for loads, but ineffective for charging. One never charges a 24V battery at 24V.

If your 240VAC power needs do not warrant a 48V battery bank, 24V might be more practical.
 
I am looking at installing solar setup for the 240V AC circuit, it uses a 48V DC inverter / battery.

The boat has an existing 24V DC circuit for the starter motor, windlass, winches and alternator.

Having a 24V and 48V requires two battery banks, I'm considering dispensing with the 24V battery bank.

This would require a DC-DC converter to convert from 48V battery bank to the 24V circuit, aside from checking if there are any issues regards to amperage which I am yet to do, this seems fine for the starter motor, windlass and winches..... However, I not sure how it stands in regard to the alternator... are these DC to DC converter bi-directional ie. would the 24V alternator still provide a charge the 48V batter via the DC-DC converter ?

Regards
Arran.
Dc/Dc converters are not bidirectional ,also you would still need to keep your 24v battery as a reference point/voltage for the dc/dc to work!
 
I would expect those 24V loads to take a current far higher than any DC-DC converter that I would consider affordable.
But you may well be able to reduce the size of your 24V bank to just one good battery.
 
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