Lithium house battery with a Yamaha F150

Yamaha is a trademark of its owner. Amp Hour Supply isn’t affiliated with Yamaha.

The short answer. Check which F150 you have first. Yamaha lists 50 A at wide open throttle for the 2.8-liter digital F150 and 35 A for the 2.7-liter mechanical one. Either way, charge the lithium bank through a 30 A DC-DC charger, not straight off the engine or the isolator lead.

The F150’s numbers

The manual we used is Yamaha’s European edition for the F150CA and LF150CA. Yamaha’s US manual lookup needs your serial number, so pull your own copy too and check the battery table against it.

Can a Yamaha F150 charge a lithium battery?

It can feed one, through the right box. Here’s how Yamaha set it up. The F150 can charge an accessory battery separate from the starting battery using an optional isolator lead. Yamaha’s electrical page says the starting battery gets charged first, then the charge switches over to the house battery.

That lead was drawn for a second lead-acid battery. A lithium bank barely pushes back while it charges, so it will pull whatever the alternator gives. Victron’s Orion-Tr manual says that kind of direct charging can overload an alternator. Our parent guide walks through why: Charging lithium from a boat alternator: 3 ways compared.

So on an F150, the DC-DC charger is the piece that turns Yamaha’s output into a lithium charge.

Is 50 amps enough for a 30 amp charger?

On paper, yes. Look closer, though. The 50 A figure is at wide open throttle. Victron’s manual says an alternator at idle can drop to about half its rating, and less again when it’s hot. Most F150 hours aren’t at W.O.T.

Here’s what that means on the water:

• 2.8L digital, 50 A: a single Orion-Tr 12/12-30 is a sensible match. At idle, with the fridge, plotter and pumps running, it may pause. That’s the charger protecting the engine side, not a fault.
• 2.7L mechanical, 35 A: one 30 A charger asks for most of what the alternator makes at full throttle. Expect it to cycle at idle. Keep house loads light while you troll, or accept slower charging.

Don’t stack a second charger on an F150. There isn’t room in a 50 A number for two.

You’ll need

• Victron Orion-Tr Smart 12/12-30 isolated DC-DC
• A fuse near the start battery and one near the house busbar, sized from the Orion manual
• Tinned cable sized with the Wire gauge calculator
• Victron SmartShunt 500A on the house negative
• Your lithium battery maker’s charge voltages

Steps

1. Find your engine. Check the cowl or manual: 2.8L digital or 2.7L mechanical. It sets your output, 50 A or 35 A.
2. Leave the start battery alone. Keep a starting battery that meets Yamaha’s table. Low voltage there means the engine won’t start, per the manual.
3. Ask about the isolator lead. If your F150 already has one, it was meant to charge a second battery directly. Ask your Yamaha dealer how to wire around it so the lithium bank is only fed through the charger.
4. Feed the charger from the start battery side, fused close to that battery.
5. Run the charger output to the house busbar, fused close to the busbar.
6. Land the house negative on the SmartShunt’s system side so you can see the amps going in.
7. Set the lithium profile in VictronConnect from your battery maker’s numbers.
8. Run it and watch. At cruise, you should see close to 30 A going in. At idle, watch whether it pauses.

Shore power and any AC charger are a job for a licensed electrician.

Does this page fit your boat?

It fits if: – You run a single Yamaha F150, 2.8L digital or 2.7L mechanical, on a 12V boat. – Your lithium bank is a house bank. The start battery stays the type Yamaha’s table calls for.

It doesn’t fit if: – You run twin F150s. Yamaha’s manual shows a separate twin-engine wiring layout; follow it and your dealer. – Your F150 is a tiller model or a different code than the manual covers. Check your own manual’s battery table. – Your lithium battery maker says something different. Their manual wins.

Products for an F150 lithium setup

Prices show live from the store. Full parts list: Boat lithium upgrade kit.

Bundles for this job: Dual-battery DC-DC charging kit, Boat lithium upgrade kit, large

Quick answers

What size alternator does a Yamaha F150 have? Yamaha lists 50 A at W.O.T. for the 2.8-liter digital F150 and 35 A for the 2.7-liter mechanical F150.

Can I hook a lithium battery to the F150 isolator lead? Not straight on. The lead charges a second battery directly, with no current limit. Put a DC-DC charger between, and ask your Yamaha dealer how to wire it.

Does Yamaha say anything about lithium on the F150? Not in the F150 owner’s manual we read. It gives lead-style ratings (CCA, MCA, reserve minutes), so keep a starting battery that meets them.

Sources

• Yamaha Owner’s Manual F150/LF150/F175/LF175/F200/LF200/F200G/FL200G, 6DV-28199-79-E0 (Nov 2021): https://cdn2.yamaha-motor.eu/prod/owner-manuals/Outboard%20Engines/6DV-28199-79-E0.pdf
• Yamaha Outboards F150 (In-line 4) specifications: https://yamahaoutboards.com/outboards/350-150-hp/in-line-4/f150-(i4)
• Yamaha Outboards, Electrical System Maintenance: https://yamahaoutboards.com/maintenance-matters/electrical-system
• Victron Orion-Tr Smart DC-DC Charger Isolated manual (Rev 14, 02/2026): https://www.victronenergy.com/upload/documents/Orion-Tr_Smart_DC-DC_Charger_-_Isolated/34439-Orion-Tr_Smart_DC-DC_Charger-pdf-en.pdf