Mercury power tiller steering

Does the Merc power tiller steering require a stand alone battery, or does it run off the starter battery? Doing some scheming while the boat is in storage. Thanks

Just starting battery.

FYI big tiller install manuals say an accessory battery must be used, and all diagrams show the steering pump on an accessory battery. L4 Verado is the only exception, and the manual specifically calls out putting the pump on the cranking battery.

The steering pump should be ran to a second battery with a isolator or VSR/ACR for all Mercs currently being built. This is especially true for outboards 150HP and down because they have a lower amp output than some of the larger engines. If you’re trolling at or just off idle all day the pump can pull enough amps that the engine won’t keep up and the cranking battery could go dead, or at the very least throw low voltage faults. If you have the steering pump on a second battery the cranking battery will stay charged, and you can always get home.

May not have been what you wanted to hear but hope it helps

Good info. When I had mine 10 years ago I didn’t ever use except when running on plane. It was also on a two stroke.

Hillhiker, thanks for info. Thinking about new boat, and batteries that I will need for everything. I was thinking about 1 battery to run boat(including power steering), 1 battery to run electronics (3-4 solix, mega live, possible m360), and 3 tm batteries. What are guys doing that are Merc system? 6 batteries?

What you were hoping to do will function, but you will need to keep an eye on the voltage on your cranking battery. When starting the engine you will also likely see a delay in the pump starting as well due to the voltage drop when cranking. If you can be flexible with the number of batteries I would start with 5(one cranking, one for pump and electronics, and 3 for TM). If your electronics act up add the 6th specifically for the electronics. Depending on the engine you’re looking at 5 batteries may work. Assuming you’re looking at a Merc, a 175-300 will have a pretty good alternator output, and it may keep up depending on how much idling/slow trolling you do. I’d have my doubts a 150 will maintain a 5 battery setup with that many electronics on the same battery as the pump without low voltage issues on your graphs.

All of this depends on how you use the boat. If you’re not spending extended periods of time idling around and trolling the likely hood of voltage issues drops dramatically because alternator output ramps up pretty fast above trolling speeds. The additional loads on the battery like lights, stereo, livewell, etc all make a difference in how long that accessory battery will hold up as well.

I have a 300 verado with power steering. I run two AGM 31 series for running everything. 2 – 12″ screens, 2 – 10″ screens, livescope, marine vfh, livewells, and a stereo. Never have an issue even after 10-12 hours. Trolling motor I run 2 – 36v 60AH lithiums. My kicker is linked to the big motor, and whenever that was running the power steering was on. I did have issues with batteries going dead while trolling all day with just the kicker. I use the bow mount to steer and the kicker for propulsion, so I unplugged the wire that turns on the power steering when the kicker is running, and I never have had an issue since.