the right battery for your outboard and why, a lesson from Iowaboy 1

With spring right around the corner a few of you might be thinking about your boat and possibly needing a new starting battery for it.
Which one do you choose?? the cheapest one out there because after all it only gets a few hours per year of use??
the biggest baddest 1000 ampere AGM job?? oh I know !! an Optima !! lets get one of those it looks like a six pack !! ya!! cool !! thats it !! when we see it in the boat it will remind us to check the cooler to see if we have plenty of beer !!

Sadly for those of us who own an outboard there is fewer and fewer right choices anymore, why??
Even todays outboards that do not have an automotive style alternator are woefully ill equipped to charge modern batteries and here are the reasons.
First off, most brands of outboards out there even ones with high amp stators are handicapped by either a rectifier or a combination rectifier/regulator as they were designed to use the battery as the final voltage regulator and that design hasnt kept up with the times.

AGM batteries, dry cell batteries and maintenance free batteries offer too high of a resistance within themselves that does not allow the charging system to see when the battery is full and lower the charging rate preventing itself from not only overheating but keeps on charging at full output until something cooks off and its usually the charging system that goes volcanic.
an old lead acid battery could be charged at full output and would absorb the extra voltage without harm to either the battery or the outboards charging system.
I have an article that does a good job of explaining what I am trying to say for those who want to study it further,just pm me and I will send it to you.

Thee most popular battery in America and one I have sold and stood behind since 1981 is not putting out a marine starting battery that is compatible with outboards after the battery reaches the two year mark in age, why not??
the paste that is used to bridge the batteries cell plates to protect them from road and wave shock begins to break down into small enough particles that lodge between the cell plates and shorts them out, shorting equals higher resistance and the charging system fails soon after even though the battery continues to crank the outboard just fine and will still pass a load test.

the attached pic is one of those charging systems that failed two hours after a brand new super start maintenance free battery was installed.
this is on a V-6 Johnson with a 35 amp stator and water cooled regulator on it.
this system went so volcanic that the voltage surge took out two of the ignition charging coils leaving it to run on only two cylinders !
this is the fifth time I have seen this kind of charging system failure in my shop in the last year and it hasnt mattered what brand of outboard, Mercury, Evinrude/Johnson, and a Honda !

this is occurring often enough even most outboard charging system manufacturers will not warranty a charging system failure due to the wrong battery being used.
so what do I use for a starting battery ?? believe it or not, Deka builds a starting battery that is about as old school lead acid as you can get and its the only battery that can be used and accepted for warranty claims.
I have contacted the battery manufacturer that makes the brand I sell ( I dont sell their cranking batteries for use in outboards ) and even with three electronics manufacturers who have provided proof positive that their batteries are at fault still continue to deny that there is a problem with their battery.

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Thanks for the post, I would love to see the article.

This article is a great read and has made me rethink my battery strategies!!

It also reminded me to check my battery water levels, something I am not very good at.

So, after 2 years can I drain the acid out of the battery and mix it with a little Margarita mix and toss in a Lime?

Eelpoutguy wrote:

So, after 2 years can I drain the acid out of the battery and mix it with a little Margarita mix and toss in a Lime? [/quote

It is weird how specific this would be. It would be the worst if you have a big charging system and top your batteries off all the time and use the outboard continuously for long periods?

Josh, you must understand that an outboard charging system that uses a stator and rectifier was never designed to charge a dead battery nor was it meant to be able to jump start another battery, it is meant to keep a charged battery charged replacing the amps used to start the motor and a minor electrical load like a graph.
the best thing you can do for your cranking battery is to have an onboard charger hooked to it and used to top the battery off overnight.

another point is that an outboards charging system really never quits charging especially if it uses just a rectifier and the lead acid battery is the voltage regulator as it can take a charge up to 17 volts.
remember though most outboard charging systems only put out anywhere from 3-15 amps and it takes a really long time to replenish the full charge so you can run the motor for hours on end and never hurt the battery.

the higher output charging systems that use a stator with a combination rectifier/voltage regulator are not perfect either as they still use and need a lead acid battery as the final voltage regulator.
these systems can put out up to and sometimes over 35 amps, and are designed to handle higher electrical loads such as graphs,pumps,and radios.
if it makes sense, the battery and the additional loads help handle the higher amps without harm to the charging system.
yes,its a bit complicated !!

edit to add: remember that the amps rating is at full throttle,most often you do not see motors ran full bore for hours on end so the charge output is most often at the lower end of the scale if at all at low rpms.

hope that helps !

I have had a rectifier catch fire while on the water. Nearly lost my boat. One must keep their head and have an fire extinguisher onboard.

So you’re recommendation is a Deka lead acid? Is that a “marine starting”? Or dual purpose or deep cycle or dual purpose? Just so happen to be in the market for a new one this spring.

Red Eye wrote:

So you’re recommendation is a Deka lead acid? Is that a “marine starting”? Or dual purpose or deep cycle or dual purpose? Just so happen to be in the market for a new one this spring.

Deka SRM 24
I have to be honest and say I personally dont care for the Deka line but currently it is the only battery CDI electronics and others say to use and will warranty their products ONLY if this brand is used.
they do dont recommend it because of kickbacks or anything of the sort,they recommend it because it works with outboard charging systems that use stators, rectifiers and rectifier/regulators.

Sheldon i assume your talking about batteries for the newer OB that have an ECM and all the headaches that go with it.I would think the wet cells would still be ok for the older OB like my 95 evinrude.

chuck100 wrote:

Sheldon i assume your talking about batteries for the newer OB that have an ECM and all the headaches that go with it.I would think the wet cells would still be ok for the older OB like my 95 evinrude.

Chuck, the old school lead acid battery is what I am talking about for use with ANY outboard regardless of age that uses a stator type charging system.
do not use an AGM, maintenance free or dry cell battery on these motors.

Thats what i thought.I was looking at it again this morn and read it again and i thought it all goes back to old school.If it ain’t broke don’t fix it.

Paul in Iowa wrote:

have you looked in to the expensive ion batteries?
most of those have a charge controller built in now.

also a charge controller is a great idea to limit how much current can be demanded from the boat motor charge circuit.
match it to the alt or generator system on the boat motor.

and yes perko battery switches for the batteries!
as well as marine fuses and marine manual reset breakers…

use the perko switch to disconnect the boat power when charging at shore power.
that saves the electronics for the harsh charging voltages.

I will look into the charge controller after while.
an ion battery for most boats would be a waste of money as it would most likely never be used to its full potential.
I also feel using the charge controller side of it would be another thing that could go wrong, call me old school if you will but I like the KISS method as it has worked well for years with the way the system is set up now.

Iowa Boy, what is your source for this statement? “ AGM batteries, dry cell batteries and maintenance free batteries offer too high of a resistance within themselves that does not allow the charging system to see when the battery is full and lower the charging rate preventing itself from not only overheating but keeps on charging at full output until something cooks off and its usually the charging system that goes volcanic”.

Iowaboy1 wrote:

Deka SRM 24
I have to be honest and say I personally dont care for the Deka line but currently it is the only battery CDI electronics and others say to use and will warranty their products ONLY if this brand is used.

Is this battery called out in the owners manuals? If a dealer puts in a different battery are they not liable? They would be considered the SME and not you.

Buzz wrote:

Iowa Boy, what is your source for this statement? “ AGM batteries, dry cell batteries and maintenance free batteries offer too high of a resistance within themselves that does not allow the charging system to see when the battery is full and lower the charging rate preventing itself from not only overheating but keeps on charging at full output until something cooks off and its usually the charging system that goes volcanic”.

Buzz, my information comes from manufacturers and a lot of people who are smarter than I am.
a lot of it is experience itself.
if it helps let me put the resistance another way.

outboard charging systems that use a stator type charging system cannot even at full throttle offer enough of charge output to overcome what is necessary to charge the batteries mentioned.
the resistance lies in the material the battery is made up of, gel in a maintenance free battery, the material in a glass mat battery ( AGM )
nor can they overcome the material in a dry cell battery.

I am sorry that I cannot explain it better than that.

gizmoguy wrote:

<div class=”d4p-bbt-quote-title”>iowaboy1 wrote:</div>
Deka SRM 24
I have to be honest and say I personally dont care for the Deka line but currently it is the only battery CDI electronics and others say to use and will warranty their products ONLY if this brand is used.

Is this battery called out in the owners manuals? If a dealer puts in a different battery are they not liable? They would be considered the SME and not you.

gizmoguy, that specific battery brand is not called out in the owners manual to my knowledge.
a lot of times when a new boat is rigged it is up to the buyer to pick what batteries they want in the boat, it is my guess most often the batteries end up being what the selling dealer has on the shelf.

I can only hope that installing dealers are aware of this problem as it has been around for years and sadly the operator/owner of the boat gets the blame.
I made this post to make folks aware of what will happen when the improper battery is used and am trying to prevent you the boating enthusiast a lot of expensive headaches down the road.

DANG IT !!

please forgive my old brain !
the starting battery that you want to use is a Deka DP27 or DP31

So I have been running Interstates only until recently, the shop I am running now stocks Napa Legends so after seeing minimal warranty issues I replaced my weak starting battery with one of there DP24, it is all I have room for in the compartment. They are the pop cap add water style lead acid battery. Are they still not recommended? This is the first time I have heard anyone saying the Deka is different from them in anyway. Also it sounds like there is almost nothing you wont work on Sheldon, a man of many skills.

Well the info from Evinrude is that AGM is one of the listed battery types for my Etec.

John Rasmussen wrote:

So I have been running Interstates only until recently, the shop I am running now stocks Napa Legends so after seeing minimal warranty issues I replaced my weak starting battery with one of there DP24, it is all I have room for in the compartment. They are the pop cap add water style lead acid battery. Are they still not recommended? This is the first time I have heard anyone saying the Deka is different from them in anyway. Also it sounds like there is almost nothing you wont work on Sheldon, a man of many skills.

I cannot give you any intel on the Napa, and yes, you want to have a battery that you can add water to.

Buzz wrote:

Well the info from Evinrude is that AGM is one of the listed battery types for my Etec.

Buzz,does your Etec have an alternator on it?? if it does then yes,you can run an AGM battery.
I will be honest and say I know nothing about an Etec motor as there are not many if any in my area.

Iowa
The V-6 E-TECs have a fully regulated 50 amp charging system for the battery. The engine puts out the full amperage as low as 1200 rpm and at 500 rpm idle, it still generates around 15 amps.<br /><br /> If you use the built in isolator, that circuit charges a maximum of 25 amps.<br /><br />The rest of the engine runs on 55 volts, not 12volts, and the engines do not use the full capacity of the alternator, but it is available if ever needed.

This isn’t good for me. I have 2 – 31AGM’s for my starting batteries and electronics. I have an PERKO A B switch and run it normally pulling on both batteries. Am I better off switching out one battery and leave the other for reserves for when my electronics drain the main down trolling all day? It is on a Verado 300. Thanks

It looks like the Verado has an 70 amp alternator so I should be okay.

I am still old school and happy. I use all lead acid batteries. Engine is a 1996 moded Mariner Magnum III 150 HP 2 stroke. Puts out a bit more than 150HP as measured on dyno. Compression is good still. Block has never been opened. She still runs like a raped ape. I have 1 battery that I use for starting, electronics (which use very little juice), bilge pump, livewell pumps, dash components, etc. And I have 3 batteries dedicated to the trolling motor. I use an onboard charger, and always charge to full charge, after using my boat. I normally get about 5 years out of my batteries. I do carry jumper cables in my boat, have never used them to jump myself. But I could. I have jumped a few other boats over the years, those folks are always grateful, and it saves me from having to take the time to tow them in. Food for thought here. So, even though I have not progressed with the times, I have a rig that works, so why fix it. Plus she is paid for. Hull is a 1996 Skeeter Bass rig. She still looks pretty good too, but has her scars. Some came before I owned her, some are my fault. She is a good girl. Great Post btw, thank you. I know, I rambled again……

Robby it looks like your motor has an alternator. I’m not sure how many outboards still only have a stator and no alternator.