2017 190 Montauk Electrical System

Electrical and electronic topics for small boats
Tacky79
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Joined: Wed May 03, 2017 1:49 pm

2017 190 Montauk Electrical System

Postby Tacky79 » Sat Jun 03, 2017 12:40 pm

We just picked up our 2017 190 Montauk a few weeks ago and have one short day, and one long day out on the local lakes. The boat came with one battery and I don't know the Ampere-hour rating (I should go check). We have a Humminbird 5-inch fishfinder that we'll probably keep on as we float around fishing and the like. We don't (yet) have a trolling motor, radio, or any other electrical usage except for Navigation lighting (that we won't use often).

The FishFinder has a low-battery warning alarm that I set for 12-Volts and it went off a few times. That got me thinking:

First, I don't see a battery switch. All switches are "hot" all the time. Should I have one?

For redundancy and safety, should we have two batteries? We only have small(ish) lakes here in Colorado.

For this boat;s present electrical load, do you think I'd run down the battery using the fishfinder for four hours?

We'll probably use the boat twice a month. Should I store with a battery maintainer during the summer? Maybe a solar one?

Also, the Mercury Tachometer reads about 500-RPM when the engine is off. That can't be normal, can it? Bad tach?
2017 Boston Whaler Montauk 190 w/ 150 Merc/Fish Pkg/Bowrail delete/aft seating
1979 Boston Whaler Harpoon 5.2 sailboat with sails and a tiller :D

jimh
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Re: Tachometer Dial Pointer Position When Engine is OFF

Postby jimh » Sat Jun 03, 2017 5:24 pm

I'll reply separately to each question.

TACHOMETER READS 500 WHEN ENGINE OFF
It is quite normal for a tachometer dial pointer to indicate some RPM reading of more than ZERO when the engine is switched off. This occurs from the nature of the instrument's design and the nature of the voltage pulses on the tachometer signal itself. Do not be alarmed by this.

jimh
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Re: Battery Switch

Postby jimh » Sat Jun 03, 2017 5:30 pm

BATTERY SWITCH

I am surprised the primary 12-Volt power connection is not switched. To see if this is normal, check the Boston Whaler website. Under WHALER OWNERSHIP --> RESOURCES, you will be directed to

https://www.bostonwhaler.com/boat-ownership/resources/

From there, select YEAR, FAMILY, MODEL, and DOCUMENT TYPE to be 2017-->MONTAUK-->190--> OWNER'S MANUAL

This will get you eventually to

http://bostonwhaler.com.s3.amazonaws.com/resources/190-Montauk-Owners-Manual-2017.pdf

Read owner's manual. Find SECTION 4, ELECTRICAL SYSTEM. Note entry under heading BATTERY SWITCH (CE OPTION).

My inference: a battery switch was an option on this model. My preference would be to have a battery switch that was able to disconnect the battery from all normal loads.

jimh
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Re: Two Batteries

Postby jimh » Sat Jun 03, 2017 5:32 pm

TWO BATTERIES

I would base the need for a second battery on this condition: can you pull-start the engine and will it run if the battery connected to it has insufficient charge to turn the cranking motor and insufficient voltage to run the engine once it tries to start.

If the answer is no, then install a second battery. Since your boat seems to lack a battery switch, you won't have to replace a single battery switch with a dual battery switch.

Alternative: can you row to shore from the center of the lake?

jimh
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Re: Battery Loads

Postby jimh » Sat Jun 03, 2017 5:35 pm

LOAD OF A SONAR DEVICE OR OTHER ELECTRONICS ON BATTERY

The primary purpose of the single battery is to crank-over the engine. If you shut off the propulsion engine and run some electrical accessories, the battery will be discharged. A typical SONAR device may consume about 3-Amperes of current. If allowed to run for 4-hours, the drain will be about 12-Ampere-hours. Generally the cranking battery storage capacity, assuming it was fully-charged when the engine was shut off, would be at least 40-Ampere-hours. Thus you'd consume about a quarter of the stored energy in the battery. The remaining energy should be sufficient to re-start the engine, but there are many variables. The following would affect this relationship:

--general condition of the battery; its storage capacity; its state of charge; its quality and type of construction
--temperature (lower temperature means less storage capacity in general)
--actual power consumption during period of non-engine charging (add up all the loads)

On my boat, I isolate all electrical accessory loads to a second battery, so I never draw stored energy from the starting battery if I run electrical loads while the propulsion engine is shut off. I use an 80-Ampere-hour battery for the electronic loads, which is probably a bit excessive, but it also runs the cabin lighting.

jimh
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Re: Float Charging

Postby jimh » Sat Jun 03, 2017 5:44 pm

USE OF FLOAT CHARGER OR BATTERY MAINTAINER DURING STORAGE

I don't see a need for continual float charging of a boat's battery, assuming the last voyage ended with the propulsion motor running and charging the battery. The self-discharge rate for a lead-acid battery in good condition is small. I just got my boat out of winter storage. It went into storage in mid-October. The batteries were not charged by any sort of charger for about 7-1/2-months. I connected 120-VAC to the built-in charger on the boat. The charger went immediately to float mode, not bulk charging mode. Within a few minutes the battery terminal voltage was above 14.4-Volts. This demonstrates that a modern lead-acid battery that has no load on it other than self-discharge can easily tolerate several months of sitting without significant loss of charge due to self-discharge.

My normal practice, when the boat has not been used for several weeks, is to connect the built-in charger to 120-VAC at the house before heading out to the launch ramp, and let the charger have 30-minutes to top-off the batteries. In that way, when I get to the ramp and the boat is in the water, I know the engine will be able to crank over rapidly and start quickly.

Tacky79
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Re: 2017 190 Montauk Electrical System

Postby Tacky79 » Sat Jun 03, 2017 11:39 pm

All great answers. Thanks JimH.

I think it'd be pretty straighforward to add a second battery and a OFF-1-BOTH-2 battery switch like I'm accustomed to on sailboats.

Thanks again.
2017 Boston Whaler Montauk 190 w/ 150 Merc/Fish Pkg/Bowrail delete/aft seating
1979 Boston Whaler Harpoon 5.2 sailboat with sails and a tiller :D

jimh
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Re: 2017 190 Montauk Electrical System

Postby jimh » Sun Jun 04, 2017 8:05 am

You'll need to go a bit further than just adding a second battery. You should re-configure the wiring so the non-engine-starting loads are isolated to the second battery, and then use an automatic-combiner-relay (ACR) or voltage-sensitive-relay (VSR) or (if your engine provides one) a second charging output from the propulsion engine to keep the isolated second battery supplied with charging current.

Actually, I'd get out and run the new boat for a while before tearing it apart. It may work just fine for your needs, as long as you don't run the battery down too far to get the engine cranked over. I do find in handy to install a 120-VAC operated charger in the boat and have it available to recharge the battery when the boat is not in use and on the trailer. You can find them for about $100.