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markus-e asked

LiFePo in a Yacht, how protect alternator

In a yacht I want to replace the 24v lead acid batteries (service batt) with a LiFePo Battery. There are two engines, one of them charges the service batteries which I want to be LiFePo.

Alternator has 55A max current at 24V, but engine runs little above idle RPM most of the time (900-1000 RPM). AFAIK I have to ensure that temperature of the alternator is monitored and current is regulated so the alternator does not overheat due to excess current drawn by the LiFePo.

I do not want to change anything at the alternator. Is there a product (DC/DC conv) suitable to connect in between which regulates the current accordingly?

lifepodc-dc charger
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pwfarnell answered ·

Victron DC to DC chargers do not monitor the alternator temperature. What I would suggest is you install a DC to DC charger and set the output current to a lower setting and monitor the alternator with a temperature probe or one of the small infra red thermometers or thermal camera and increase the current until you are comfortable with the temperature.


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markus-e answered ·

thanks! I would then need a 24/24 DC DC charger, cannot find that from victron, are there devices from other vendors?

Another thing, how is it managed that there is not a spike to the alternator at the moment the BMS switches off, I heard that could make trouble as well and needs attention?

I would also need to connect two or three 24v Lifepo batteries (each has its own BMS) in parallel, I assume that's no problem?

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pwfarnell avatar image pwfarnell commented ·

The alternator still charges a single 24V lead acid battery which then connects to the DC to DC charger input with the DC to DC charger output connected to the lithium. The Victron DC to DC chargers will not work direct on the alternator output, you must have a battery to stabilise the voltage control. This then means that if the Lithium BMS shuts down, tje alternator always has the lead acid battery connected which stops an over voltage.

https://www.victronenergy.com/dc-dc-converters/orion-24-12-5-10

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