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thebarold avatar image

Addition of Orion Smart DC to DC Charging

Here is my configuration thus far: LiFePO4 House bank, AGM (or SLA) Start Battery. Alternator is 120A non-smart (one option considered is the Balmar retrofit kit but cost is more than the Orion Smart DC Charger) The House was an AGM bank before and both batteries were connected through an electronic battery isolator for charging (diesel engine alternator and shore powered charger and Solar MPPT).

I've read that it may be advisable to keep the Lead-acid start battery from a starting CCA capability AS WELL as a safety consideration -- should the BMS ever disconnect the LiFePO4 bank (over or undervoltage) and say the engine is running, I am concerned the alternator could burn out or excess voltage be pushed through my DC system, damaging electronics.

Since I will have to disconnect one bank from the shore power charger (it can only be set to Lithium or Lead Acid charge profiles) I was wondering if the Orion Smart Charger would help to provide Alternator charging to the House bank through the Start Bank.

The rationale for leaving the Lead Acid connected to the alternator is that 1. Serve as protection from overcharging as it is cheap(er) to replace, 2. the chemistry prefers to be at a higher SOC and can sustain higher/longer levels of charge should we motor for longer periods.

Thoughts? I've seen others who charge from house to start bank. Or is there a product that provides 2 bank DC to DC Charging (using different charge profiles)?


orion-tr smartOrion DC-DC Converters not smartalternatorsystem integration
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1 Answer
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two-rocks answered ·

I have:

Isolated Start AGM battery, 30A 120v charger (AGM settings), also isolated to only the start AGM battery. And an Orion DC-DC that charges the lithium.

House Bank is LiFePO4, charged with solar and the Orion DC-DC only.

That is what the Orion is supposed to do. My AC charger is not isolated - so pick a bank - I put in on the start. This way the LI only sees the charge profile of the Orion and MPPT and protects the system from an alternator voltage spike in the case of a disconnect.

Isolation is both + and - wiring ... if you want a parallel 'emergency' option you need a battery switch for both poles de-isolating the batteries.

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Thanks! I never thought to put(leave) the shore charger and the alternator to the Start battery and isolate the LFP bank but that makes sense. The LFP profile of my shore charger is 14.4V which is higher than I'd like so the Orion would allow the tailoring of the charge voltage to the LFP bank. Originally I was thinking I'd separate the banks but charge the house with the Shorepower and the start with the alternator -- the current system is two AGM banks, connected through an Isolation device charged by 'dumb' alternator and Shorepower and I will be replacing the AGM house bank with an LFP battery.