Adding 3rd Battery

[Dirtysidedown]

2021 MXZ 24 w/M6 and Stern turn.

Battery Option 3(ACR), 170 AMP alternator.

Currently have 2 group 24 Interstate Cranking batteries.  Not sure why it's not a cranking and a deep cycle?? 

I get a low house bank warning(have read others have dealt with this too)if using the stern turn too much.  Volts drop a ton even just bumping it off/on for short burst.

 

At a minimum I want to upgrade to a Group 31 AGM(X2, Lifeline,Odyssey)for the house and then a group 27 AGM for the Starting side.  But ideally I would like 2 31's in parallel and a 27 for starting.

 

A couple questions:

Haven’t measured yet, can I fit 2 group 31s and a 27 into the bow compartment on the new MXZ?

Will 31's fit at all?  Worst case would like to have 2 31s in the bow and a 27 in the observer storage area by the amps.

Anything special in regards to wiring with the ACR?  Wire the 31s in parallel on one side for the house and keep the 27 alone for starting?

 

Imagine I would also need to upgrade the Noco Genius Gen 2 Mini, 2 Bank, 8A on board charger?

I'm sure 4A/bank is fine if I did a group27/31 2battery set up, but not sure how 4 Amps would work on 2 31's in parallel. If I'm looking at it right, 2 31s in parallel would make an approximate 200A bank(using X2 Batteries for example), if discharged to 50% it would take almost 25 hrs to recharge?? Not that it would be that low on a normal basis, but probably down in the 20-40% discharged range so 10-20 hours to recover and run through the recharge process.

Maybe go with a 2 bank 20A, so each bank is getting 10A??

Am I thinking about all this correctly?

Thanks

 

[csleaver]

I doubt you will get anything other than two 24 series batteries in the bow without some modification. 

The factory battery option, and the batteries used for testing by Malibu, are the NorthStar NSB-AGM-24M which are rated at 840 CCA and 160 minute reserve capacity.  The optional charger is a PowerMania Turbo M215E2 two bank 15 amp charger.  That setup, or a similar one, should allow the system to function as intended.

[Dirtysidedown]

Went by and measured the bow compartment yesterday. Strictly by the numbers, 2 31s and a 24 will fit, but not sure of the reality of it when it comes time with compartment lips, bump outs, wire lengths, natural spacing, etc.  Going to have to make some sort of insert/filler for the  compartment floor where the factory cut out for the current batteries. 

I bought the 31's last night, gonna give it a shot today🤞🤞

[shawndoggy]

Following.  Take some pics of your progress please!

[Dirtysidedown]

Well right off the bat, they fit!

Went with Interstate 31M AGM.

Now need to figure out the fine detail, like hold down trays and getting them wired.  Appear to have plenty of length in the cables.

May rotate the 31s 90* to allow for some more work space.

Had to disconnect the bilge vent hose, and if I had about 1/4" more space on the back ledge this would be a piece of cake.

 

But as of now this seems like it should be pretty straightforward.

Need to fill the void that the rear battery box sits I  and secure the new 31s.

Back to work.....

[Dirtysidedown]

Rotating 90* appears to give alot more room to be able to secure them down and I can keep the factory bilge vent hose intact as designed, and the battery trays I have ordered will bridge the orginal box recess.

Edited February 15, 2022 by Dirtysidedown

[shawndoggy]

Are you going to put the AGMs in a box (or individual boxes), or just secure as-is, without a box?

[Dirtysidedown]

Don't think a box will work.  Think it would be too tight to be able to manipulate the lid under the walk through lip.

I plan to secure the AGMs to that battery tray I posted a picture of.  I can secure the tray to the floorboard and then the tray comes with a tie down strap.

The 24 wet cell starting will go back in the orginal location in its box.

The fitment is about perfect. I won't have to worry about any bow/stern movement. The only possibility would be for some port/starboard movement, but i think it needs to be secured for sure.

[shawndoggy]

1 hour ago, Dirtysidedown said:

Don't think a box will work.  Think it would be too tight to be able to manipulate the lid under the walk through lip.

I plan to secure the AGMs to that battery tray I posted a picture of.  I can secure the tray to the floorboard and then the tray comes with a tie down strap.

The 24 wet cell starting will go back in the orginal location in its box.

The fitment is about perfect. I won't have to worry about any bow/stern movement. The only possibility would be for some port/starboard movement, but i think it needs to be secured for sure.

Height clearance is enough with the box added?  Or will you have to modify the existing group 24 "cupholder" to accommodate?

[Dirtysidedown]

I do not think the 31s would fit in a box height wise under the lip of the walk through. My trays just got hear from Amazon and I got them mounted and batteries are sitting in them with just enough clearance to hook up cables and slide them into the trays and tuck under the walkway.  It got too dark to finish tonight.

The 31s are so long I just bridged them over the orginal group 24 recess.  I was able to secure the tray with 6 of the 8 mounting screws.  I plan to fill the small amount of space between the sides of the battery and the ballast with fileted pool noodles to prevent any side to side movement.

 

Edited February 15, 2022 by Dirtysidedown

[shawndoggy]

did you investigate how hard it would be to pull the "cupholder" piece out to enlarge it or just cut it off altogether after the first battery hole? curious whether you might be able to get yourself some additional room by getting rid of unnecessary spacer on the floor.

 

[Dirtysidedown]

2 hours ago, shawndoggy said:

did you investigate how hard it would be to pull the "cupholder" piece out to enlarge it or just cut it off altogether after the first battery hole? curious whether you might be able to get yourself some additional room by getting rid of unnecessary spacer on the floor.

 

To get the "cup holder" as you say or recess out to enlarge it, it appears you have to get the bow ballast hard tank out.

If you just enlarged it in place eventually you would expose  the  center ballast tank. 

Not sure if you can see in the pictures, but for easy numbers, lets say the "cup holder/recess" is 6×12, then there is a "10x 16 " piece at the bottom of the cupholder/recess" that sits on the top of what must be center ballast or fuel tank.

You can kinda see the white lower tank exposed on the left edge of the first few pictures, Or through the circular vent tube.

To do what I think you are suggesting, you would need to pull the bow ballast, enlarge the "cup holder/recess", enlarge the base plate on top of whatever tank that is and then reinstall everything.

 

Edited February 16, 2022 by Dirtysidedown

[JeffK]

On 2/13/2022 at 6:09 PM, Dirtysidedown said:

2021 MXZ 24 w/M6 and Stern turn.

Battery Option 3(ACR), 170 AMP alternator.

Currently have 2 group 24 Interstate Cranking batteries.  Not sure why it's not a cranking and a deep cycle?? 

I get a low house bank warning(have read others have dealt with this too)if using the stern turn too much.  Volts drop a ton even just bumping it off/on for short burst.

 

At a minimum I want to upgrade to a Group 31 AGM(X2, Lifeline,Odyssey)for the house and then a group 27 AGM for the Starting side.  But ideally I would like 2 31's in parallel and a 27 for starting.

 

A couple questions:

Haven’t measured yet, can I fit 2 group 31s and a 27 into the bow compartment on the new MXZ?

Will 31's fit at all?  Worst case would like to have 2 31s in the bow and a 27 in the observer storage area by the amps.

Anything special in regards to wiring with the ACR?  Wire the 31s in parallel on one side for the house and keep the 27 alone for starting?

 

Imagine I would also need to upgrade the Noco Genius Gen 2 Mini, 2 Bank, 8A on board charger?

I'm sure 4A/bank is fine if I did a group27/31 2battery set up, but not sure how 4 Amps would work on 2 31's in parallel. If I'm looking at it right, 2 31s in parallel would make an approximate 200A bank(using X2 Batteries for example), if discharged to 50% it would take almost 25 hrs to recharge?? Not that it would be that low on a normal basis, but probably down in the 20-40% discharged range so 10-20 hours to recover and run through the recharge process.

Maybe go with a 2 bank 20A, so each bank is getting 10A??

Am I thinking about all this correctly?

Thanks

 

Sorry I'm late to the party!  I have a group 31 and a 24, both in boxes, in the bow of my 25.  It is a tight fit but I was able to make it work.  I run the stereo and the thruster off of the 31 and along with the HO alternator, I haven't had any issues since.

Edited February 16, 2022 by JeffK

[Dirtysidedown]

It's done

 

 

Edited February 16, 2022 by Dirtysidedown

[Dirtysidedown]

I agree

3 hours ago, JeffK said:

Sorry I'm late to the party!  I have a group 31 and a 24, both in boxes, in the bow of my 25.  It is a tight fit but I was able to make it work.  I run the stereo and the thruster off of the 31 and along with the HO alternator, I haven't had any issues since.

I agree, getting one 24 and one 31 in a box up there is doable.

Getting 2 31s and a 24 all in boxes would take some talent

Edited February 16, 2022 by Dirtysidedown

[alcoprop]

11 hours ago, Dirtysidedown said:

It's done

 

 

I am going to be doing this same thing to my 2021 and have a couple questions. Your group 24 is just your starting battery, correct? You plug the boat in every night, turn the switch to say 1, start the boat and then turn the switch over to 2? Did you have to do any rewiring in order to achieve this? I am unaware of how the factory wiring is in these boats. I just know that right now I can obviously start and run my boat on any position of the switch. If this has been covered before I apologize and please lead me to a post! Thanks

[Dirtysidedown]

10 hours ago, alcoprop said:

I am going to be doing this same thing to my 2021 and have a couple questions. Your group 24 is just your starting battery, correct? You plug the boat in every night, turn the switch to say 1, start the boat and then turn the switch over to 2? Did you have to do any rewiring in order to achieve this? I am unaware of how the factory wiring is in these boats. I just know that right now I can obviously start and run my boat on any position of the switch. If this has been covered before I apologize and please lead me to a post! Thanks

I don't have the same battery switch as you, I have Option 3, which does what you are asking/saying, but does it automatically. My switch simply has an On/OFF/ Combine(Only time you would ever use combine is for some reason the "Starting" battery was dead, then you "Combine" the "House" battery into the "Start" circuit and you get the motor started.

Yes, I plug the boat in with the switch in the Off position. 

With my set up, as it came installed, I did not need to do/change any wiring.  I simply upgraded the size of 1 of my batteries and added an additional matching battery and wired it in parallel (+/+ to -/-)to the new upgraded battery. 

The group 24 is my "Starting" battery. It only starts the boat and has the auto bilge wired to it.

The 2 larger group 31s are the "House" bank.  They run everything but the starter and auto bilge. 

 

You can do what I did 100%, you just have to be the one that flips the switch between start or house, Bat1 vs Bat 2.

If you want the auto function,  research Blue Sea System ACR.  Tons of youtube videos, and posts on that.  

[alcoprop]

4 hours ago, Dirtysidedown said:

I don't have the same battery switch as you, I have Option 3, which does what you are asking/saying, but does it automatically. My switch simply has an On/OFF/ Combine(Only time you would ever use combine is for some reason the "Starting" battery was dead, then you "Combine" the "House" battery into the "Start" circuit and you get the motor started.

Yes, I plug the boat in with the switch in the Off position. 

With my set up, as it came installed, I did not need to do/change any wiring.  I simply upgraded the size of 1 of my batteries and added an additional matching battery and wired it in parallel (+/+ to -/-)to the new upgraded battery. 

The group 24 is my "Starting" battery. It only starts the boat and has the auto bilge wired to it.

The 2 larger group 31s are the "House" bank.  They run everything but the starter and auto bilge. 

 

You can do what I did 100%, you just have to be the one that flips the switch between start or house, Bat1 vs Bat 2.

If you want the auto function,  research Blue Sea System ACR.  Tons of youtube videos, and posts on that.  

Ahhh, I understand now. So basically everything for the boat is wired to the switch and then I will manually turn the switch to lets say 1 to start the boat then after it is started I will switch it over to 2. The boat could start, run and operate on the starting battery technically. Thanks for the clarification! 

Edited February 17, 2022 by alcoprop

[Surf4FamFun]

11 hours ago, alcoprop said:

Ahhh, I understand now. So basically everything for the boat is wired to the switch and then I will manually turn the switch to lets say 1 to start the boat then after it is started I will switch it over to 2. The boat could start, run and operate on the starting battery technically. Thanks for the clarification! 

I would NOT switch the battery switch with the engine running.  You might get by with it but there will be an instant where there is no battery connected to the alternator which could result in voltage spikes and damage to anything turned on.  When we had an 1/2/1&2 switch I would start on the battery that had been draining, if that would not start would combine and run for a while then switch to the weak battery with the engine off, crank and charge.  Installing an ACR switch is a much better solution.  

[Surf4FamFun]

On 2/13/2022 at 6:09 PM, Dirtysidedown said:

2021 MXZ 24 w/M6 and Stern turn.

Battery Option 3(ACR), 170 AMP alternator.

Currently have 2 group 24 Interstate Cranking batteries.  Not sure why it's not a cranking and a deep cycle?? 

I get a low house bank warning(have read others have dealt with this too)if using the stern turn too much.  Volts drop a ton even just bumping it off/on for short burst.

 

At a minimum I want to upgrade to a Group 31 AGM(X2, Lifeline,Odyssey)for the house and then a group 27 AGM for the Starting side.  But ideally I would like 2 31's in parallel and a 27 for starting.

 

A couple questions:

Haven’t measured yet, can I fit 2 group 31s and a 27 into the bow compartment on the new MXZ?

Will 31's fit at all?  Worst case would like to have 2 31s in the bow and a 27 in the observer storage area by the amps.

Anything special in regards to wiring with the ACR?  Wire the 31s in parallel on one side for the house and keep the 27 alone for starting?

 

Imagine I would also need to upgrade the Noco Genius Gen 2 Mini, 2 Bank, 8A on board charger?

I'm sure 4A/bank is fine if I did a group27/31 2battery set up, but not sure how 4 Amps would work on 2 31's in parallel. If I'm looking at it right, 2 31s in parallel would make an approximate 200A bank(using X2 Batteries for example), if discharged to 50% it would take almost 25 hrs to recharge?? Not that it would be that low on a normal basis, but probably down in the 20-40% discharged range so 10-20 hours to recover and run through the recharge process.

Maybe go with a 2 bank 20A, so each bank is getting 10A??

Am I thinking about all this correctly?

Thanks

 

Did the dealer have an excuse for the battery voltage dipping?  Our 2021 23 MXZ will get a low battery warning if I just sit on the switch for a very long time but in typical use (even with a bunch of new riders and lots of turning back) the charge while running with the 170A alternator keeps things topped up.

My concern is that you have increased your stored energy but the Stern Turn pulls like 210 - 220 amps, two batteries will last longer but will it be long enough?  Especially if you are at the lake for a week and don't charge the batteries fully every night.

Edited February 18, 2022 by Surf4FamFun
added thought

[ahopkins22LSV]

5 hours ago, Surf4FamFun said:

I would NOT switch the battery switch with the engine running.  You might get by with it but there will be an instant where there is no battery connected to the alternator which could result in voltage spikes and damage to anything turned on.  When we had an 1/2/1&2 switch I would start on the battery that had been draining, if that would not start would combine and run for a while then switch to the weak battery with the engine off, crank and charge.  Installing an ACR switch is a much better solution.  

Don’t think that is true. The battery switches have a make before break system. Pretty sure @shawndoggy confirmed this in another thread. 

[Dirtysidedown]

6 hours ago, Surf4FamFun said:

Did the dealer have an excuse for the battery voltage dipping?  Our 2021 23 MXZ will get a low battery warning if I just sit on the switch for a very long time but in typical use (even with a bunch of new riders and lots of turning back) the charge while running with the 170A alternator keeps things topped up.

My concern is that you have increased your stored energy but the Stern Turn pulls like 210 - 220 amps, two batteries will last longer but will it be long enough?  Especially if you are at the lake for a week and don't charge the batteries fully every night.

Didn't go to the dealer.  I bought this used. Going to try this route before I do. I don't think I have an underlying issue, just improperly equipped in the battery department.

You are right that ST pulls a huge load.  As soon as I saw I had two cranking batteries installed, to me, that was a problem and something I wanted fixed.  I don't feel there should be a cranking battery running the "house" with all the electrical load that is on this boat, I wanted a cranking and a deep cycle, especially with an ACR installed, it makes life is so easy.  Then,since this is America, if 1 is good, 2 must be better, and Super Size it while you're at it! I know the 2nd 31 in parallel is overkill probably.

We live on a lake, boat will be on a lift, plugged in 100% of the time its not in use, so that makes maintaining the large battery bank easy.

[Surf4FamFun]

1 hour ago, ahopkinsVTX said:

Don’t think that is true. The battery switches have a make before break system. Pretty sure @shawndoggy confirmed this in another thread. 

That would be great if I was wrong.

[alcoprop]

7 hours ago, Surf4FamFun said:

I would NOT switch the battery switch with the engine running.  You might get by with it but there will be an instant where there is no battery connected to the alternator which could result in voltage spikes and damage to anything turned on.  When we had an 1/2/1&2 switch I would start on the battery that had been draining, if that would not start would combine and run for a while then switch to the weak battery with the engine off, crank and charge.  Installing an ACR switch is a much better solution.  

Yeah this has been proven to not be true. 

[hethj7]

IIRC, the manual used to state not to switch while running but that has since been removed I think.