Another battery Question. Next Question.

[hitthebricks]

Thanks for all the input, the group 27 and 29 batterys dont comingile from what I hear!

Next question! A typical starting battery does not seem to be a enough power/voltage

to keep a larger graph running all day.

Towards the end of a full day on the water the graph will shut down when starting the main motor.

Would switching to a dual purpose type battery help this problem?

Thanks,

HTB

[Fish Head]

I called my boat dealership and spoke to the service department this morning. They recommended that I do not replace my starting battery with a dual purpose. Their recommendation was the same as what Sorgy had done. They recommended adding a 2nd starting battery strictly for the sonar, lights, etc., and install another on-board charger for the starting batteries. I think that's the rout I'm going to take. Thanks guys.

[BobT]

That would certainly work but sure seems like overkill.

Personally, if you're going to go through the expense of buying a second battery just for powering your console, accessories, and sonar buy a deep-cycle. It will be a better solution for that type of load and the console, navigation lights, bilge pump, livewells, and sonar use such a low amount of power you could easily get by on a smaller battery.

[Whoaru99]

I called my boat dealership and spoke to the service department this morning. They recommended that I do not replace my starting battery with a dual purpose. Their recommendation was the same as what Sorgy had done. They recommended adding a 2nd starting battery strictly for the sonar, lights, etc., and install another on-board charger for the starting batteries. I think that's the rout I'm going to take. Thanks guys.

If you don't mind footing the bill for all that, sure, a dedicated/isolated battery would be the ticket. However, I disagree with the dealer suggestion of using a starting-type battery for those auxiliary loads. I do agree with BobT that a dual purpose or deep cycle would be a better choice of batteries for those loads.

[aanderud]

They recommended adding a 2nd starting battery strictly for the sonar, lights, etc., and install another on-board charger for the starting batteries. I think that's the rout I'm going to take. Thanks guys.

[hitthebricks]

A 31 group starting battery? Who makes them? I have only ever seen a 27 size. As far as adding another battery, I only have room for one starting battery! I think my best solution would be a 3 bank charger or the occasional use of a portable type charger for the starting battery from the input I have received here.

thanks

HTB

[Whoaru99]

Not sure where you're going with that. There isn't really any need for a group 31 starting battery. If you're dual purposing the battery (starting plus accessories) then perhaps you mean a group 31 dual purpose?

In my boat I was using two group 31 deep cycles for the trolling motor and a group 27 (or was it 29?) dual purpose for starting and accessories. These were charged by a 3-bank on-board charger.

[BobT]

Got that right! If it was properly maintained the battery would die of old age long before it would die from over-use.

[CaptainMusky]

I have often wondered what the difference was between a deep cycle and a "dual purpose". I have a dual purpose battery for my outboard which also powers my electronics like everyone else. But my dual purpose battery is small. Really small. I believe its only a 24. I will be upgrading my trolling motor deep cycle batteries and plan to replace the one at my outboard as well. Do I really want to go to a deep cycle or just a larger "dual purpose"? I have heard that deep cycle batteries do NOT like the BIG draw that an outboard has at an instant when you turn it over. Obviously they can handle the drain of the electronics and accessories without issue, but I would be worried about this big hit to a deep cycle.

[aanderud]

A 31 group starting battery? Who makes them? I have only ever seen a 27 size.

I think you're right, they make 31 in both deep cycle and dual purpose. Probably not in "starting" only, however. I think if going to a dedicated battery, deep cycle should be used, not starting.

However, it's unfortunate to have to have a dedicated battery just for accessories. I still think that if you find the biggest dual purpose battery you can find (a big group 31 ought to work), you should be able to run those electronics AND start your engine without seeing power sag far enough to turn the graphs off.

[JumpStart73]

I also agree that adding another battery is overkill. Is your graph wired to a fuse panel that other accessories are wired to? Big graphs are very sensitive to power draws, example: when starting the big motor. So bypassing the accessories fuse panel and direct wired will eliminate that power draw. A roll of wire, inline fuse and couple hours is a lot cheaper than another battery and onboard charger.

[BobT]

I have often wondered what the difference was between a deep cycle and a "dual purpose". I have a dual purpose battery for my outboard which also powers my electronics like everyone else. But my dual purpose battery is small. Really small. I believe its only a 24. I will be upgrading my trolling motor deep cycle batteries and plan to replace the one at my outboard as well. Do I really want to go to a deep cycle or just a larger "dual purpose"? I have heard that deep cycle batteries do NOT like the BIG draw that an outboard has at an instant when you turn it over. Obviously they can handle the drain of the electronics and accessories without issue, but I would be worried about this big hit to a deep cycle.

There are three basic types of wet cell batteries that you would use.

Starting battery:

A starting battery is designed for delivering high current over short bursts but does not comfortable for low current draw over extended periods of time. A high current draw is what happens when you start your outboard. A starting battery is ideal for your car.

Deep Cycle battery:

A deep cycle battery is designed for lower current loads over extended periods of time but are not comfortable for high current short burst loads. Examples of low current loads are running lights, bilge pump, livewell pump, electric trolling motor, sonar units, etc. This type of battery is ideal for your electric trolling motor.

Dual purpose battery:

A dual purpose battery is a compromise between the two types mentioned above. "Compromise" is the optimum word here. Like anything else, because it is not specialized for either use, there is some sacrifice that takes place. Because your boat is typically wired with the bilge pumps, livewell pumps, navigation and console lights, and other accessories connected to the same battery used for starting your outboard, this battery is ideal for this application. It provides reasonable ability to deliver high current to start your outboard while maintaining a reserve capacity for the low current loads for your accessories without suffering for it.

[CaptainMusky]

BobT, thanks. I am going to look for a larger dual purpose to replace that one. I saw some guys saying to replace that battery with a deep cycle and that was against what I always thought and your detail supports my thinking.

[Fish Head]

I'm rethinking my decision of going with 2 starting batteries. Instead I'm thinking about replacing my size 24 battery with a DieHard Platinum Marine Battery Group Size 31M. It has 1150 cold cranking amps and 205 min reserve capacity. This may solve my problem right there.

Would there be any issue using this battery and having it charged by my 2004 Suzuki 140's alternator.

[Whoaru99]

Would there be any issue using this battery and having it charged by my 2004 Suzuki 140's alternator.

Depends.

Do you have a charging bank for that battery or relying on just the alternator?

I'm sure the alternator in my 90hp isn't as big as that one, but after a day (or night) of fishing the charger always indicated the (dual purpose starting/auxillary power) battery was taking a pretty good charge. When fishing I seldom run the main engine for long periods of time, usually just a sequence of fairly short bursts which doesn't put all that much charge back into the battery.

[Fish Head]

[Do you have a charging bank for that battery or relying on just the alternator?

No I don't have a charger for the starting battery. It would just be charged by the alternator when I'm running the motor.

[delcecchi]

If you don't charge it periodically then my experience says it will run down gradually. But you might run the big motor more than I do as a percent of the time. If you draw 5 amps from the accessories for 10 hours and run the big motor, charging at 30 amps, for 1 hour you ran a deficit of 20 amp hours. Do that a few days and toast, no matter how big the battery.

One way to tell is to display the battery voltage on the screen of the graph. It is one on the items on the menu of stuff to display. If it starts to drop during the day that means you are discharging the battery.

[BobT]

I would not recommend relying on your outboard to maintain your starting battery. We typically don't run our outboards for extended time periods adequate to completely refresh the battery and wet cell batteries are not very happy when left partially charged for any period of time. My recommendation is to install an on-board smart charger that provides all the leads necessary for all the batteries you have on board.

For example, if your boat is set up to handle up to two deep cycle batteries and one starting battery, get a 3-bank charger and connect it per installation instructions. Note that they typically have dedicated leads for the starting battery unique from the others.

Also, verify with the manufacturer but of those that I have used to date, if you have a 3-bank charger and only one starting battery and one deep cycle as I have, you connect both sets of deep cycle leads to the one deep cycle battery and the starting leads to the starting battery.

The nice thing about the on-board charger is I installed a plug on my console that I can reach while standing on the ground. Every time I get home I just plug in my boat and the batteries are fully charged and ready to go when I am every time.

The on-board charger was probably the best investment I ever made on my boat.

[Fish Head]

The DieHard Platinum Size 31M battery I was thinking of getting is an AGM battery. I don't know if that makes a difference when charging. I currently have 2 deep cycles with a dual bank charger that I plug in every time I get to the dock. I have always relied on just my alternator to charge the starting battery which is only a size 24.

[CaptainMusky]

Thats an enormous battery. I would hope it would be good for you in your application but only time will tell.

I, like you, usually relied upon my motor's alternator to charge my battery back there, but I did peridically hook up a charger to it. It amazed me how it was often not fully charged.

On days where I was predominantly using the trolling motor with radio, lights, etc I made sure to hook a charger up to the motor battery.

I just replaced my "marine starting" battery with a larger "dual purpose" battery and am eager to see if I run into the same problems I had before.

[Whoaru99]

Some chargers have settings for standard/wet-cell, AGM, or gel batteries as they each take a unique charge profile to be fully optimized.

AGM and wet-cell are by most accounts close enough that the standard curve works well for both. A true gel battery should be charged with a a gel-specific charge profile.

If you're in the market for a new charger, by all means get a three-bank. However, often single bank 5A chargers can be found on sale. Since you do get some help from the engine, a 5A usually works fine for keeping that one charged up in a reasonable timeframe. Two chargers means two cords to plug in, but there are multi-outlet plug adapters to fix that if you can locate both chargers reasonably close together.

[JumpStart73]

I thought my motor(Suzuki 225) would also charge my starting battery. After 2 yrs the battery was junk. So when purchasing a new battery, also purchased a single bank charger for it. Like I posted above, when I installed the new battery I ran separate wires for the graph, going on 3 yrs with no graph or battery problems

[delcecchi]

How many hours are on the motor compared to how many hours you have fished?