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Author Topic:   Engine Not Cranking: Bad Battery Switch Suspected
boatdryver posted 08-17-2014 09:51 AM ET (US)   Profile for boatdryver   Send Email to boatdryver  
On my 2007 200 Dauntless with a 4 cylinder 175 HP Verado equipped with two batteries and a Perko Model 8501 (no field disconnect feature) 4 position battery selector switch, the following occurred:

With selector switch on battery #1, attempted engine start resulted in a low frequency clicking sound from the engine, indicative of a low battery voltage.

Immediately switching to battery #2, the result was a normal engine start.

After shutting down the engine to check battery cables for looseness and finding all tight, I repeated the engine start with selector switch on battery #2: same low clicking sound as just previously had occurred on battery #1, and engine would start on battery #1 this time.

Multimeter readings then showed 12.6 volts on one battery and 10.5 on the other. Both are Marine cranking batteries, one 3 months old and one 5 years old (24 month battery) with 800/1000 ratings.

I will of course replace the older battery with the 10.5 volt reading, but my concern is that the selector switch is defective ( it is only 2 years old, the original seized up ) or that the boat came from the factory with the two batteries not isolated from each other.

Any ideas on this? I'd like to understand what is going on here.

thank you


Jefecinco posted 08-17-2014 11:48 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
JimL--on this type system it is recommended to start the engine with the battery switch position set to "Both" and to leave it in that position while operating the engine. This provides the maximum cranking power from your battery bank to start the engine AND allows both batteries to be charged while the engine is running. Switching between switch positions with the engine running reportedly damages the engine alternator and may be harmful to any operating accessories/electronics.

While aboard with the engine shut off the switch should be switched to whichever battery you designate as the "house or auxiliary" battery. This provides a freshly charged battery to power any accessories/electronics you are using while drifting or at anchor/mooring/slip. This also provides you with a fully charged battery in reserve for engine starting when it is time to move.

Before replacing the older battery, battery#1, I would give it a long slow charge to see if it will come back. Have you been running the boat with the switch on battery #1, or #2 or both. If it was last run on battery #1 it is probably done given it's age but may be wort a try.

Personally I prefer AGM batteries from Sears installed and treated as a set. They are costly but have an excellent replacement warranty and warranty service is available virtually everywhere. A search on this site will provide many perspectives of the batteries.


boatdryver posted 08-17-2014 12:41 PM ET (US)     Profile for boatdryver  Send Email to boatdryver     
Butch, thanks for the reply.

On this boat, unlike our previous Hatteras 58, there are only minimal electronics and no "house" loads, so it came new equipped with two starting batteries.

We use the boat about once a week so I have been alternating between the batteries each use for 6 years now.

We are never aboard with the engine off more than an hour or so and when the key is turned off, the electronics get no power.

With this additional info, do you still recommend changing the way we operate to starting and running with the selector switch on "both" or "all"?

I know not to switch to "off" while the engine is running, especially with this model of Perko unit which has no field disconnect feature. I was shocked to see that the Whaler dealer installed this model after the previous one failed. Maybe the Verado alternator has its own protetcion.

thanks, JimL

jimh posted 08-17-2014 02:02 PM ET (US)     Profile for jimh  Send Email to jimh     
Based on your narrative of the starting problems and the battery switch, a reasonable deduction is a problem in the battery switch. I would temper that with the advice that it can be difficult in some circumstances to make really good voltage measurements with the temporary leads of a portable voltmeter. The measured voltages may have been affected by poor connections to the battery cables by the leads of the voltmeter. On the other hand, the behavior of the engine is a very good indicator. The engine showing difficulty starting on both batteries tends to point to the source of the problem being a component that was common in both instances. In addition to the battery switch, consider the engine starter motor solenoid, too. It could be erratically operating, and it may have been just a coincidence that it failed on both batteries in the sequence you described in your narrative.
jimh posted 08-17-2014 02:12 PM ET (US)     Profile for jimh  Send Email to jimh     
I cannot comment with any authority on the recommended position of the battery switch when starting a Mercury VERADO engine. I believe the VERADO engines will need a strong battery to start and to run immediately after starting, as they do not produce much battery charging current at low engine speeds.

Re having a battery switch with an alternator field disconnect circuit, such a battery switch is used with alternators that have a separate circuit to connect their field with the battery. I do not believe the Mercury VERADO alternator has such a circuit available. On that basis, the lack of an alternator field circuit in the battery switch is not a serious defect in the switch in this application.

Mercury has taken the unusual step of requiring (or very strongly recommending) the use of an absorbed glass mat battery (AGM battery) with the VERADO. I believe they have done that in order to get better battery life from the charging characteristics of the VERADO. The VERADO can deliver a lot of charging current when running at higher engine speeds, but the VERADO charging current at low speeds is not great, if any at all. Also, at idle speeds, as in maneuvering around the dock, the VERADO power assisted steering pump will be drawing very high current, as much as 60-Amperes. This is a further load on the battery, and it comes just when a stalled engine would be very inconvenient. I think all of those factors have affected Mercury's stance on insisting on an AGM battery (or "batt" as all the Verado owners seem to insist on calling their battery).

boatdryver posted 08-17-2014 02:36 PM ET (US)     Profile for boatdryver  Send Email to boatdryver     
I've followed the factory recommendation to use AGM batteries for Verado, however, mine is a four-cylinder with simple hydraulic steering. It's my belief that the recommendations to use AGM batteries were aimed at the in-line six-cylinder engines that are installed with power assisted hydraulic steering.--JimL
jimh posted 08-17-2014 06:22 PM ET (US)     Profile for jimh  Send Email to jimh     
The next time you encounter the engine not being able to crank over on either battery, you can expeditiously test the solenoid to see if it is involved as a cause. Without disturbing the battery switch position, try to jumper across the high-current terminals of the solenoid. If the engine cranks over, you have an indication that the solenoid was the cause, not the battery switch.

I keep a short jumper of 4-AWG cable with ring terminals in my spares box just for the purpose of serving as an emergency replacement for the solenoid, should it fail. You can connect one end of the jumper to the cranking motor terminal on the solenoid. Then, holding the jumper in your hand, touch the other terminal to the battery terminal on the solenoid to crank the engine. After the engine starts, insulate the loose end of the jumper and stow it away under the cowling. That will start your engine in the event of a solenoid failure. Or, carry a spare solenoid. They are not very expensive.

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