question

infy avatar image
infy asked

Connecting a LiFePO4 bank to house & alternator

I am preparing to connect a Battleborn 600ah 12v battery bank to house power on board a powerboat. I'm wondering if any precautions need to be taken before I do that?

The house circuit is charged by shore power (Victron Multiplus 3000) or an alternator on the Starboard engine. That starboard alternator powers the 12V DC house circuit when the engine is running. It's the same circuit the lithium batteries would be directly connected to. I'm concerned about connecting the lithium batteries directly to the same circuit with the alternator.

Am I right to pause? Or is this perfectly normal?

Is there something I need from Victron to safeguard the lithium battery bank from any spikes or noise from the alternator?

Note - the port engine alternator is connected to the engine start bank (8D flooded). I'm not considering this port engine alternator as part of the 12V DC house circuit.

This is a 1989 alternator on a 400hp diesel.


-- Edit following replies:

Thanks guys - thanks for your patience and the responses are great. I'm continuing to research.

One clarification - Both engines start with the engine batteries. The port engine alternator charges the engine battery. The starboard engine alternator is not connected to the engine battery. (I'm simplifying this - there is a crossover switch to connect the house + engine banks in case of an emergency - which adds consideration as well as potential dangers. But let's continue to ignore crossover to keep this topic simple.)

One other thing I'm not yet clear on: The Lithium house bank is going to be directly connected to the house DC so it can power 12v electronics at all times. Typically, the entire house circuit will always be "hot" from the lithium source. Lights, radio, AIS, pumps, navigation, etc are all on the house DC circuit.

The starboard alternator is also directly connected to the house DC so it can power all of the above - at all times when the engine is running. Which is interesting because at this time the lithium and alternator are connected as voltage sources to the same circuit.

I've uploaded a crappy drawing to help illustrate:

1655172156801.png

If I install the Orion in between the Starboard alternator and the house bus.. would that resolve the problem? But the Orion would also be between the entire house load and the alternator too.

Lithium Batteryalternator
1655172156801.png (262.5 KiB)
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4 Answers
brando avatar image
brando answered ·

You need a DC to DC charger in between the Starboard engine battery and BattleBorn battery.

https://www.victronenergy.com/dc-dc-converters/orion-tr-smart

You'll want to also explore what type of alternator you have, and if its a smart alternator or regular style. You'll need to know if your starboard battery shares the same ground as your BatttleBorn battery to also determine if an isolated or non-isolated Dc to DC charger is needed for your application.

The Orion will supply your BattleBorn with the right charging voltage and selected current that otherwise your alternator would not. It will also disconect the two batteries when the ALT is not running.


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Trevor Bird avatar image
Trevor Bird answered ·

@infy ...Another consideration is the load the Lithiums will present to the alternator. It is possible the load of the lithiums may cause overheating of the alternator. In most cases like this, the alternator would have an external regulator and that would lower the alternator excition current in accordance with an alternator temperature sensor. If the alternator gets too hot, the regulator would back off the current to save the alternator from destrying itself.

I suggest you watch this video......https://www.youtube.com/watch?v=jgoIocPgOug

regards,

Trevor


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brando avatar image
brando answered ·

To low of a voltage coming from an ALT is useless to the BattleBorn because it requires a higher voltage for charging. The Orion boosts the ALT voltage to the parameters needed by the BattleBorn. The manual of the Orion would clarify a lot of your questions.

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brando avatar image
brando answered ·

I remembered a video from a while back that may interest you.


https://youtu.be/jgoIocPgOug

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