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Author Topic:   Jump Box versus Second Battery
Scott Grey posted 02-06-2007 03:59 PM ET (US)   Profile for Scott Grey   Send Email to Scott Grey  
[Moved to the SMALL BOAT ELECTRICAL discussion.]

I want to add a second battery to Boston Whaler 190 OUTRAGE [which apparently has a Verado propulsion system] for backup. I have read several articles about doing this, but nothing on adding it to a boat with a Verado [propulsion system]. The manual says not to use a deep cycle battery for this. Do I use a automotive type battery with the correct cranking amps? Any recommended brand? Any info would be helpful. I believe the OptiMax [requires the same battery]. I should have had it added when I had the electronics added, but [a second battery] slipped the mind.

Jordi posted 02-06-2007 05:30 PM ET (US)     Profile for Jordi  Send Email to Jordi     
You might also consider a portable battery start up unit. I keep mine on a milk crate in the console so it does not move while cruising.
podosky posted 02-06-2007 06:12 PM ET (US)     Profile for podosky  Send Email to podosky     
Jordi: I just got the same advice from my dealer. I also was considering a second battery for our boat with a 150 Verado [propulsion system], and was told to consider a portable starting unit.
Scott Grey posted 02-06-2007 06:13 PM ET (US)     Profile for Scott Grey  Send Email to Scott Grey     
Is that the same as a jump box (jump start box with 2 battery clamps)?
Scott Grey posted 02-06-2007 06:20 PM ET (US)     Profile for Scott Grey  Send Email to Scott Grey     
Using a "Jump Box" is less expensive than adding a second battery. I think this is the way to go.. Thanks!
Jordi posted 02-06-2007 08:48 PM ET (US)     Profile for Jordi  Send Email to Jordi     
Yes, this is the same as the " jump box". Another benefit of having this set up is you can help fellow boaters that are stranded because their boats wont start.
jimh posted 02-07-2007 12:36 AM ET (US)     Profile for jimh  Send Email to jimh     
There is nothing particularly magic about a Verado propulsion system or an OptiMax regarding needing a particular brand of battery. They both need a cranking battery that can stand up to the task of turning their starter motors while not dropping the voltage too low. The concern is that the battery voltage remain high during cranking. Apparently the Verado propulsion system and OptiMax do not tolerate low voltage during engine cranking. Both those engines have sophisticated electronic engine controlers. Those controllers may not operate properly with low battery voltage during cranking, leading to problems in starting. If you use a battery with the proper rating, you should be fine. It may be difficult to obtain a battery with the necessary rating except in a cranking battery. If I recall, the figure is 1,000-Amperes. It takes one heck of large deep-cycle battery to supply that many amperes for cranking. If the engine manual recommends using a cranking battery, I would follow their recommendations.

If you need advice on choosing a battery or on other aspects of a small boat electrical system, please us the SMALL BOAT ELECTRICAL discussion.

jimh posted 02-07-2007 12:38 AM ET (US)     Profile for jimh  Send Email to jimh     
I would not use a "jump-box" battery. There is too much risk for damage to very expensive electronics in the engine if any sparking occurs during cranking.
Perry posted 02-07-2007 01:32 AM ET (US)     Profile for Perry  Send Email to Perry     
I know of many people who use a "jump box" to jump start boats. The marina where I keep my boat uses theirs all the time to start outboars in their fleet of rental boats when someone leaves the key on or there is a just a dead battery.

jimh can you explain how sparking can occur in the motor when a jump box is used compared to when a boat's fully charged battery is used to crank the motor?

Scott Grey posted 02-07-2007 08:01 AM ET (US)     Profile for Scott Grey  Send Email to Scott Grey     
when jumping a car the ignition should be in the off position when connecting the cables, if not it could damage the computer on the car. I would think in the case of jumping a boat motor would apply the same way.
Jordi posted 02-07-2007 08:22 AM ET (US)     Profile for Jordi  Send Email to Jordi     
Are you saying that the only option we have is to have a second battery installed for those of us that want the extra security. If you are following the proper battery starting instructions, why would sparking occur? The Optimax 135 owners manual states “Do not use deep cycle batteries, engines must use marine battery with 1000 MCA or 800 CCA rating”. I have a Vector Start-It Jump-Start System with a boost power of 400 instantaneous cranking amps and 900 peak ampere power. Are you suggesting the amperes are not sufficient in the Jump-Start System and the risk of sparking is not worth the potential electronics damage? The marina and dealer both recommended the Jump-Start System to me, should those of us that have them discard them? I have started many other stranded boats while fishing and have never had the need to start my own engine with the Jump-Start System. Offering to help a stranded boater with starting their engine and knowing the potential damage I may cause raises some real concerns. Your suggestions are appreciated.
fno posted 02-07-2007 12:47 PM ET (US)     Profile for fno  Send Email to fno     
Jordi, when you are twenty miles out, the fog is setting in and your jump box doesn't start your motor, are you going to call your dealer or the marina for help? I don't think they will be much help to Scott. If Scott is boating inshore or on a lake with lots of others, I guess the "cheaper" jump box is logical choice. If he is going offshore with a jump box then he is being cheap with his life and his wife should "invest" in a good life insurance policy. No offense Scott, but you did not state the intended usage of your boat, and that fact has the most influence on your choices.
mfclapp posted 02-07-2007 03:03 PM ET (US)     Profile for mfclapp  Send Email to mfclapp     
Just went through the same thing on a 20 ft Outrage. I installed dual Interstate Marine cranking batteries set up through a Perko battery switch. Works like a charm.

Tight Lines

PS: I also carry a jumper box in the tow unit.

Scott Grey posted 02-07-2007 03:06 PM ET (US)     Profile for Scott Grey  Send Email to Scott Grey     
Most of my use will be inshore and intracoastal. I do plan on using in the florida keys (go twice a year for lobster and diving. Maybe the best would be to have both. Again, thanks for all your imput!
Jordi posted 02-08-2007 08:09 AM ET (US)     Profile for Jordi  Send Email to Jordi     
If you are twenty miles out with fog, etc...The "cheaper" jump box works just as well. When did the jump box become less reliable the farther you go out? "Logical choice".... Some folks choose the second battery set-up for the added security which makes sense no mater where you are and particularly in offshore "desolate" locations. Calling the marina or dealer for help.... (I assume you are kidding). If offshore is your game many folks with single outboards will go out with another boat, have two batteries, VHF, Sea Tow Membership, etc....for the added security. For offshore the best life insurance is sound judgment and if that fails....twin outboards.

highanddry posted 02-08-2007 02:05 PM ET (US)     Profile for highanddry  Send Email to highanddry     
I installed a blue top Optima, it is OptiMax and Verado [propulsion system] compliant and meets the required specs. I installed a dual battery switch and the additional cable. The extra weight up in the front of the console helped the boat actually and adds tremendous security knowing there is another battery up there and the flick of a switch puts it on line.
jimh posted 02-09-2007 12:40 AM ET (US)     Profile for jimh  Send Email to jimh     
Using any kind of jumper cables with their pinch-on connectors can create a spark.
Perry posted 02-09-2007 01:15 AM ET (US)     Profile for Perry  Send Email to Perry     
I know a spark can be generated at the battery but I still don't know how a spark generated at the battery can do damage to very expensive electronics in the engine.
jimh posted 02-09-2007 09:29 AM ET (US)     Profile for jimh  Send Email to jimh     
The spark is an indication of a momentary interruption in current flow, and a high current flow at that. In a circuit in which there is an inductive load, energy is stored in the magnetic field surrounding the inductor. When the circuit is broken, the field collapses, and the inductor becomes a source of voltage. The voltage generated by the collapsing field can be higher than the voltage which created the field because the voltage depends on the rate of change of the field, and in a circuit suddenly opened, the rate of change is nearly instantaneous. There are two inductive loads in the engine: the starting motor itself and the windings of the alternator.

Well, you might say, this happens all the time in engine starting when you shut off the starting motor. Yes, but two big differences. The motor is shut off by being disconnected from the rest of the 12-volt system, and the battery remains connected. The transient voltage is isolated to the motor because it is not connected anymore. Any inductive kickback is absorbed by the battery. The battery remains connected to the engine, and the very low impedance of the battery, usually about 2 or 3 mOhm (1/1000-th of an ohm) is a very big load and absorbs any transients, limiting the voltage.

But if there is a spark at the source of the voltage, that is, the battery is momentarily disconnected, things are much worse. The inductive fields collapse, and any spike that is induced does not have the shunt of the battery to suppress it. So the transient voltage will be much higher.

The situation is exactly the same as switching the battery switch to OFF while the engine is running. And everyone knows that is not a good practice. If you see a spark in the jumper cables while cranking, look out.

Jordi posted 02-09-2007 09:33 PM ET (US)     Profile for Jordi  Send Email to Jordi     
I appreciate the explanation. It seems that the best choice is the second battery followed by the jump start battery used very carefully.

Perry posted 02-09-2007 11:03 PM ET (US)     Profile for Perry  Send Email to Perry     
Thanks for the explaination jimh. Doesn't this risk also exist when jump starting your car or truck? If so, wouldn't you think that if it is okay for your car that's it's okay for your boat?
fno posted 02-10-2007 09:19 AM ET (US)     Profile for fno  Send Email to fno     
As usual, Jim explains the technical stuff with great clarity. Yes Jordi, I was being facetious and only kidding about the dealer coming to the rescue. That would be a miracle in itself. I just wanted to point out that Scott had not given us enough information for any one of us to answer his question specifically. What we wind up with is a slew of opinion and conjecture not directly related to Scott's original question.
jimh posted 02-11-2007 11:44 AM ET (US)     Profile for jimh  Send Email to jimh     
I really try to avoid the "jump start" situation, even with cars. Chris's car was stranded last winter when the battery failed. Rather than try to jump start it and risk blowing something out in the process, I just bought a new battery and drove over and installed it. I figured the old battery was a goner, anyway, so why blow up a $150 alternator and who knows what else jump starting it--just to drive over and get a new battery anyways.
mfclapp posted 02-12-2007 09:28 AM ET (US)     Profile for mfclapp  Send Email to mfclapp     
jimh hit it dead on the money but one of my main concerns is not there may be a field collapsing induced voltage but that there may be an explosion produced when the hookup is made. I know this is rare but it does happen.

Tight Lines

sail16 posted 02-20-2007 04:52 PM ET (US)     Profile for sail16  Send Email to sail16     
Jimh: Do the risks associated with jumpstarting or using jumpacks decrease if you turn the battery selector switch to "Off" before connecting jumper cables?
Bulldog posted 02-20-2007 07:01 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
I think the second battery installed with a proper switch is the way to go, that switch can be thrown in seconds and a start attempted before a drifting boat gets into trouble. The jump boxes are a great idea, but getting a battery cover off and hooking up the cables correctly,in a hurry can be a pain! It sounds like your motor requires a large starting battery, is a 400 "instant crank" jump box, the same as a 400 CCA battery, and is it enough? If you go the jump box route try it sometime and see how it goes before relying on it in the boat...............Jack
jimh posted 02-21-2007 01:26 AM ET (US)     Profile for jimh  Send Email to jimh     
I was somewhat of a skeptic about the potential for inductive kick back in circuits until one night about 25-years ago. I was working on a control circuit which involved a lot of 24-volt relays and indicator lights. The relays were old telephone-style relays, which meant they had coils with many windings to make them sensitive and not need much current. (The whole remote control system in this plant had been built with telephone relays because they were very high quality and plentiful on the surplus market after the telephone company went to solid state devices for switching.) I had my hand in a relay rack with a voltmeter probe, checking on some point in the circuit. Somehow another relay in the system dropped out. I got a shock from the collapsing field voltage. Man--I will tell you that 24-volt relay must have generated about a 400-volt spike. My arm came flying out of the relay rack.

The goof-ball who designed the control circuit had not included a suppressor diode across the relay coil to absorb the kick back voltage, and my hand absorbed all of it.

That was the day I learned first-hand about how much voltage can be generated by inductive kick back. I have been a believer ever since.

jimh posted 02-22-2007 08:53 AM ET (US)     Profile for jimh  Send Email to jimh     
The importance of the battery on a small boat is directly related to how easily the engine can be pull-started. In the case of the Mercury Verado propulsion system or Mercury OptiMax, these engines cannot be started without a battery connected because their ignitions systems are not self-powered.

The Mercury Verado propulsion system and Mercury OptiMax engines MUST have a battery connected to them to start. This is not because they must be cranked by an electrical motor, but because their ignition systems are not self powered and their alternator charging systems are not self-excited. Even if the motor is mechanically cranked over by some other means other than the electric starting motor, it will not start unless there is a battery attached. The alternator on these motors is not a permanent magnet type alternator so it depends on the battery to supply the initial current to generate the magnetic field in its windings. Without a battery there will be no current generated from the alternator.

Further, the electronic controllers of the Mercury Verado propulsion system and Mercury OptiMax motors appear to be intolerant of low voltage conditions, and therefore the battery voltage MUST be maintained at a high level during cranking. The starting motor will crank the engine even if the voltage sags somewhat during cranking, but if the voltage falls below a threshold the electronic devices will not operate properly and engine start up will be impossible. I do not know the precise voltage threshold. Mercury recommends a very large cranking battery for the Mercury Verado propulsion system and Mercury OptiMax in order that the cranking voltage does not fall too low during engine start-up. The starter motor does not really draw 1,000-amperes during cranking, but they want a battery with that sort of capacity in order to assure that the voltage does not drop very low.

Considering the absolute necessity of having a fully charged and powerful battery for engine starting on small boats with a Mercury Verado propulsion system or a Mercury OptiMax engine, I think it is imperative that such boats have a dual battery system in order to assure reliable starting.

As I explained above, I do not think it is wise to make temporary connections with clip-on leads or "jumpers" for engine starting boosting of battery capacity due to the risk of damage from transient voltage spikes.

[NOTE: The first response to this inquiry was a recommendation to seek advice elsewhere. With all due respect to that person offering that advice and to the source he recommended, I have removed that recommendation. I think this discussion provides an example of the sort of advice one can receive here on CONTINUOUSWAVE on this topic, and I do not believe that the level of advice one can receive elsewhere is in any particular way more qualified or more cogent. People seeking advice are always free to use GOOGLE to locate information, and in the case of the topic of "verado cranking battery", this article is the number one recommended resource.]

andygere posted 02-22-2007 11:51 AM ET (US)     Profile for andygere  Send Email to andygere     
The most reliable system is one with 2 batteries, where the house loads and the outboard are connected via a switch or switches along with a voltage sensing relay. The idea here is that if the start battery is connected to the outboard only, it probably won't go dead in the first place. The VSR sytem allows both batteries to be charged automatically without fussing with switch settings, etc. If the starting batter does somehow get weak, you can "jump" start the motor by simply closing the emergency parallel switch. BEP Marine and Blue Seas manufacture these devices, which work quite well. There are several articles in this forum with a lot of detail on these systems. They are easy to wire and install, and come with good, detailed directions.

Mambo Minnow posted 02-22-2007 12:48 PM ET (US)     Profile for Mambo Minnow    
JimH - you and your website are my "go to" source for all things electrical. I don't think Whaler owners can thank you enough for this tremendous boating resource!

Yes - I'm sucking up! :)

bullwinkle posted 02-22-2007 05:08 PM ET (US)     Profile for bullwinkle  Send Email to bullwinkle     
In regards to the Optimax needing a battery to start, I believe the Nissan and Tohatsu smaller hp motors use the same technology. I know on the 40 hp Nissan there is NO provision for pull starting the motor. Will these motors run without a battery connected after the starting process? Will the alternator still produce electricity if the battery is disconnected?
Mudkap1 posted 02-24-2007 10:06 AM ET (US)     Profile for Mudkap1  Send Email to Mudkap1     
Are the new (2007)4 Stroke Mercury engines, 90 & 115HP, able to be started by hand crank? How difficult would it be? Thanks.
contender posted 02-24-2007 09:48 PM ET (US)     Profile for contender  Send Email to contender     
Quit trying to squeeze the indian until he rides the buffalo, spend the bucks get a second battery and connect it correctly with a shut off switch...
jimh posted 02-25-2007 12:11 PM ET (US)     Profile for jimh  Send Email to jimh     
First, there are no such things as "2007" Mercury motors. Mercury has dropped model-year identification from their products.

From what I can tell the alternator system is the same as with the Verado and Optimax, so a Mercury "FourStroke" AKA "Veradito" AKA "L4NA" will need a battery to get the charging system going.

I assume the same situation applies to the ignition--not self powered and needs a battery.

sternorama posted 03-01-2007 04:08 PM ET (US)     Profile for sternorama  Send Email to sternorama     
Another benefit of the switch (properly installed) is that it eliminates the potential of "operator error" which in the alligator clip scenario would be polarity reversal. A buddy gave a jump to a fellow boater, but screwed up the connection and fried our boat!
Scott Grey posted 03-08-2007 04:44 PM ET (US)     Profile for Scott Grey  Send Email to Scott Grey     
Does anyone have the wiring diagram for the second battery for 150 Verado? I'm sure i know how to do it just don't want to over look something critical in the installation and do any damage. Again, thanks in advance!
bluewaterpirate posted 03-08-2007 06:03 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
It's pretty simple to do. I would recommend the BEP 716. 11514712/file.jpg 11514713/file.jpg 11514709/file.jpg 13517372/file.jpg

Here's what the final install looks like ......

All you've wanted to know about the BEP 716 Battery Distribution Cluster


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