Dual-battery DC-DC charging kit

Description

Charge a second battery from the engine the right way: Victron Orion-Tr Smart 12/12-30 isolated DC-DC charger, two ANL fuse holders (one near each battery), a SmartShunt for the house bank and 8 AWG ring terminals.

Bring your own battery: this kit is everything around it.

Add all parts to cart. Already own a part? Set it to 0 below.

What’s in the box

Not in the box

• The batteries
• Cable for the charger runs, sized from the Orion-Tr manual for your lengths
• The two 60A ANL fuses
• A negative busbar on the system side of the shunt, if you don’t have one
• Ring terminals for 6 AWG, if your runs are long enough to need it

Who it’s for

Boats, vans and trucks with a start battery and a separate house battery, especially lithium. The charger stops a big house bank from running the alternator flat out and keeps a flat house bank from draining the start battery.

Good fit if: Your boat, van or truck has a start battery and a separate house battery, especially lithium, that you want charged from the engine.

Not the pick if: You only charge from shore power: get the shore charger + battery monitor bundle instead.

How it goes together

You can do this. Here’s how.

1. Turn everything off and disconnect the battery, negative first.
2. Start battery positive through a 60A fuse close to that battery, then to the Orion-Tr input.
3. Orion-Tr output through a 60A fuse close to the house side, then to the house positive.
4. Negatives: start battery and charger negatives go to the system side of the shunt, never the house battery post.
5. House battery negative to BATTERY MINUS on the SmartShunt. Connect its fused red wire to the house positive, and the second one to the start battery if you want to see that one too.
6. Reconnect the battery (positive first, negative last), then set the Orion-Tr’s charge profile to your house battery in the VictronConnect app.

Read next: Charging lithium from a boat alternator · DC-DC charger for a camper van

Fit rules

• One fuse near the start battery on the input side and one near the house side on the output side. Victron gives a 60A fuse for a 12V input or output on the Orion-Tr 12/12-30. (Victron Orion-Tr Smart manual)
• The Orion-Tr has screw terminals for flexible stranded copper up to 16 mm2 (6 AWG), no lugs. Victron’s cable table for the 12/12-30 gives 10 mm2 for a 1 to 2 m run one way and 16 mm2 for 5 to 10 m. (Victron Orion-Tr Smart manual)
• It senses the engine running from the input voltage, so no extra signal wire is needed. (Victron Orion-Tr Smart manual)
• The start battery negative joins the busbar on the system side of the shunt, not the house battery post. (Guide 2)
• Run the SmartShunt’s second fused red wire to the start battery positive if you want to see its voltage in the app. (Guide 2)

Maker’s pages: Victron Orion-Tr Smart · Victron SmartShunt · Egis ANL holder

Questions

Why a DC-DC charger and not a battery combiner?

A combiner joins the two batteries when the voltage is up. With lithium on one side and lead-acid on the other, a DC-DC charger gives each its own charge and limits what the alternator has to deliver.

Is 30A enough?

For most single house banks, yes. How much your alternator can safely give up is a question for its maker or a marine electrician.

Do I need the SmartShunt?

It’s how you see what the charger is putting in. If you already have a shunt monitor, set it to 0 before you add to cart.

Each part ships from the maker’s distributor, so a kit can arrive in more than one box.