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Author Topic:   Battery for Mercury VERADO
NSWhaler19 posted 11-10-2008 10:23 AM ET (US)   Profile for NSWhaler19   Send Email to NSWhaler19  
I never knew battery selection could be so confusing! I have a 2008 Outrage 19 with a Mercury Verado 135. I bought it new and it came with only one battery. I would like to install a second battery. I know how I will do this, not a problem. Here's what I do know: My manual and stickers on the boat say "DO NOT USE DEEP CYCLE BATTERIES". I think it has something to do withthe DTS (Digital Throttle System). I wrote to Mercury to inquire about battery type and here is their response "We recommend the AGM battery. We have tested and found it to be the best for our marine application".Batteries must be the same.

Any suggestions or comments?

Casco Bay Outrage posted 11-10-2008 10:40 AM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
What is the brand/type of your current battery? Mercury is recommending AGM type batteries going forward. If you have an AGM, buy another of the same brand/rating. Shop around, prices vary a great deal from store to store.
glen e posted 11-10-2008 11:18 AM ET (US)     Profile for glen e  Send Email to glen e     
[Recommends the] Sears Marine AGM.
jimh posted 11-10-2008 01:36 PM ET (US)     Profile for jimh  Send Email to jimh     
I believe that DTS is an acronym for digital throttle and shift.
Jordi posted 11-10-2008 07:00 PM ET (US)     Profile for Jordi    
On two battery applications, can a deep cycle battery be used as the second battery to run the livewell.
jimh posted 11-10-2008 09:16 PM ET (US)     Profile for jimh  Send Email to jimh     
Follow the recommendation of the engine manufacturer, even if it goes out the window. You'll have fewer problems with warranty support if you follow their recommendation. Considering the cost of these modern motors, a few bucks extra spent on a fancy battery is insignificant.

Jordi posted 11-10-2008 09:38 PM ET (US)     Profile for Jordi    
There are NO recommendations for the second non starting battery. Many dealers that I know recommend a deep battery on the Verado for livewell, etc as the second battery.
Jefecinco posted 11-11-2008 08:51 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
If one knows the answer why ask the question? Maybe reinforcement?


Jordi posted 11-11-2008 12:13 PM ET (US)     Profile for Jordi    
The original set up for the 210 Outrage with dual batteries is series 27 cranking batteries. This is how Marinemax delivered the boat. The manual states not to use deep batteries as the starting battery. When my batteries needed replacement a reputable marina recommended to go with two series 27 batteries one for starting (cranking) and the other (deep) for "fishing". Would you go with the original set up or the "improved" recommendation? Batteries get a lot of discussions on these forums, yet I have not been able to read a reply that answers the question. If I knew the answer I would not be asking or wasting my time
Jefecinco posted 11-11-2008 07:27 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     

Sorry. I thought you had made a decision.

If it was my boat I would use two identical AGM batteries of the size deemed best by Mercury Marine for the Verado on the transom.

I've been using twin AGMs on my boat for approximately six years with no problems. I don't have a Verado I have a small FICHT which requirs little cranking power compared to a Verado.

The reason I use AGM batteries is that they provide superior life and performance. I believe a properly sized AGM battery can do a very reliable job of powering a livewell or starting a Verado.


jimh posted 11-11-2008 10:12 PM ET (US)     Profile for jimh  Send Email to jimh     
I don't think the choice of an AGM battery for use with a Mercury Verado motor has much to do with the Verado's cranking requirements. It probably has to due with maintaining a high terminal voltage during cranking so that the microprocessor power supply voltage and other electronic circuitry supply rail voltage does not sag too much during cranking. In the old days of cranking over a simple motor with magneto-powered ignition and no solid state controls, an engine would crank and fire even it the battery voltage was low during cranking. Not any more. Many engines, even relatively old engines like my 1992 Evinrude, won't fire the spark plugs until a particular cranking speed is reached. And in engines with microprocessor controllers, the supply voltage needs to be maintained above certain minimum levels to keep all the processors and other digital circuitry happy. The battery not only has to supply cranking amperes, but it has to hold its terminal voltage high while doing it. This is related to the internal resistance of the battery. AGM batteries tend to be able to have a lower internal resistance than flooded-cell lead-acid batteries of the same size.

A second consideration: the Verado motor is a heavy consumer of electrical energy because it uses an electro-hydraulic boost pump to help with the steering. The Verado motors are very heavy and greatly benefit from having a power-boosted steering sytem, but this imposes additional electrical drain on the battery. A lot of electrical energy is needed by the boost pump to provide all that power steering energy.

Also, the Verado motor does not have high charging current available at low engine speeds, so at extended low-speed operation, and particularly when a lot of steering is being done, the battery may not receive much charging current. When the Verado motor speeds up, it can provide much higher charging current, perhaps as much as 50-amperes. However, a conventional flooded-cell lead-acid battery may not be able to accept such a high charging rate. This is where the AGM excels. An AGM battery can accept a high charging current, thus in a short time the Verado motor will be able to re-charge the battery.

It has also been speculated that real-world experience shaped the recommendation from Mercury. Apparently field results showed that boats rigged with other types of batteries more frequently had electrical problems than boats rigged with AGM batteries.

Another advantage of the AGM is its ability to tolerate physical damage without leaking acid. This makes the AGM popular with the military. And, since it is sealed, the AGM can be operated in any orientation, which comes in handy in a military aircraft during a dog fight. A battery retailer told me that one of the reasons for rising prices for AGM batteries of a particular brand was heavy buying by the U.S. military.

The disadvantage of the AGM is its relatively short life span. AGM batteries are valve-regulated sealed lead-acid batteries. My experience with over 160 AGM batteries has shown that four years is about the limit for a top-grade AGM battery before internal resistance begins to increase. In contrast, a well-maintained flooded-cell lead-acid battery can last ten years or more.

In summary, there are valid electrical reasons why an AGM may be preferred with a Verado, and there are equally valid reasons why you should just follow the manufacturer's recommendation--the warranty coverage being the most significant. The cost differential is marginal, so there is hardly any reason not to get an AGM for your Mercury Verado motor.

Jordi posted 11-12-2008 06:37 AM ET (US)     Profile for Jordi    
After a few phone calls it does not matter which set up you use as long as both are series 27 with the correct cold cranking amps. The advantage of using the deep battery while fishing is the discharge rate is lower than the cranking battery. AGM's are considerably more expensive than using the Marine Interstate 27 series which cost $100 bucks.
tmann45 posted 11-12-2008 07:27 AM ET (US)     Profile for tmann45  Send Email to tmann45     
From the Verado Service Manual:

Charging and Starting Specifications
Alternator Output (Regulated)
Output @ Battery (@ 1000 RPM) 37 - 44 Amperes
Output @ Battery (@ 3000 RPM) 53 - 69 Amperes
Output @ Alternator (@ 1000 RPM) 48 - 54 Amperes
Output @ Alternator (@ 3000 RPM) 65 - 72 Amperes
Voltage Set Point 14.5 +/- 0.25 Volts

Looks like pretty good output from the alternator.


Power Steering Specifications
Current Draw Shall not exceed 75 Amps

Looks like the power steering can draw more than the alternator output, even at 3000 RPM.

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