question

amauryaile7 avatar image
amauryaile7 asked

Is it possible to connect an alternator directly to the 50A victron DC DC Buck-boost?

Hello everyone,

I am new to the community

On my boat, I have a Lithium service battery .

I want to be able to recharge via the boat's alternator (volvo penta D2 75 engine and a volvo 115A alternator)

I know that you can't connect an alternator directly to a lithium battery because of the non-resistance of Lithium batteries.

I have a Victron 50A Buck-Boost DC-DC Converter and I wanted to know if I could directly connect the alternator to the buck boost before connecting to the battery ?

If this assembly is not possible, how could I do to avoid adding a lead battery upstream of the buckboost?

Thank you in advance for your answers


Have a good day

Amaury

Lithium Batterycharger
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2 Answers
yachtingearth avatar image
yachtingearth answered ·

Hey mate,

Short answer, yes you can.

Additional information, we’ve been running a single Li bank for quite some time now charging it directly from the alternator without any devices between.

The alternator deliver 14.4’ish volt and the BMS accepts up till 14.8 in our configuration so when the battery get closer to 14.4 the charging slowly gets filed down by itself to just a few amps. The built in temperature regulator in the D2-75 alternator adjust the charging by itself.

Mine happily deliver 80-90A till the engine room gets warmer then it lowers the output to just below 50A or so.

Best of luck!

Tony @ yachting.earth

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Kevin Windrem avatar image
Kevin Windrem answered ·

A DC-DC CONVERTER doesn't regulate charging current in the same way as a CHARGER does. It will attempt to supply maximum current until the set output voltage is reached. This could result in over or under charging the battery depending on the output voltage.

I'm not sure you can connect the alternator to the DC-DC converter without a battery in parallel with the alternator.

There are some smart alternator controllers that will interface directly to lithium battery banks but I don't have any details. This might be your best approach.

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