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isabella avatar image
isabella asked

Charge a flooded lead-calcium starting battery with LiFePO4 house bank via DC-DC 12/12-18 charger

I charge my LiFePO4 house battery bank from the alternator via the start battery and a Victron DC-DC charger. All works great with that setup. I have solar and a wind generator that charge my house bank when not running the engine. I want to charge the start battery indirectly from my solar and wind through the house battery bank using a DC-DC charger. It would look something like this:

Lithium house bank bus bars -> Victron 12|12-18 DC-DC charger -> Flooded Lead-Acid Start Batt

My questions are:

1- Would I put a circuit breaker between the house bank and the DC-DC charger or between the DC-DC charger and the start batt?

2- The manual recommends a 60A fuse/breaker, but the 12|12-18 DC-DC charger has specs: cont output 18A, max output 25A, short-circuit output 40A. I'm confused whey the manual specs a 60A fuse when it seems the charger specs are lower current.

Thanks for any help!

orion-tr smart
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2 Answers
kevgermany avatar image
kevgermany answered ·

Put the circuit breaker between the house bank and the Orion. If you need one.

Fuses... They're there to protect the wiring. They also need to sustain max current of the equipment. Generalising. Some fuses will blow as soon as the target current is reached and will only sustain a continuous current of half the target. Personally I'd stick with the Victron recommendation and replace the circuit breaker with the fuse positioned as close to the house bank as you can.

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isabella avatar image isabella commented ·
Thank you, that makes sense. I was forgetting that the fuse/circuit breaker is to protect the wire more so than the devices. I appreciate your help!
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isabella avatar image
isabella answered ·

I have another question that is related to my original question asked here and I'm not sure if I should create another question or create an answer here to my question or somehow edit my original question.

My question is this:

I don't want my Orion-Tr Smart DC-DC charger that charges my starting batt from my house bank to charge when the engine is running and thus charging the start batt from the alternator. I found a question asked here on the forum but the post is a few months old and details weren't fully given as to what I am asking. It said the the charger will see that the start batt is being charged by the alternator while the engine is running and will disable it's output to it won't also charge the start batt. Is this true? If so, do I need to make any settings changes on the charger to make sure this happens? I was thinking about adding a manual switch to disable the charger before I start the engine but if the charger does this automatically all the better.

Thanks.

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pwfarnell avatar image pwfarnell commented ·
Set the charging voltage of the Orion 0.1V below the alternator charging voltage then the alternator will stop charge current from the Orion.
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