Installing a second deep cycle battery for accessories and a starting hot spare

[BoyzFunBoat]

I have a 2005 Sportster Le DI with the ROTAX 947, 2-stroke direct injection.

I bought the boat used, and the previous owner had an aftermarket stereo installed on the aft side. The stereo is fused and wired directly to the starting battery's posts. I want to put in an on/off switch so I don't have to mess with the unscrewing the battery post's wingnut each time I want to add or remove power from the radio. Also, I want to install a USB charging port (for cell phones) and a 12-volt power outlet for plugging in my portable 12-Volt (120 watt) inflatable tube pump.

I'm considering adding a second battery, the deep cycle kind for running these accessories and also so I have a hot spare battery in the event that my starting battery dies. My current battery is an Autocraft M24-3 starting battery. I want the option to be able to charge both batteries with the boat's alternator, so I'm going to get a 4 position battery switch, like:

1.) Off
2.) 1
3.) 2
4.) 1+2

I'm looking at these two battery switches:
https://www.bluesea.com/products/9002e/e-Series_Selector_Battery_Switch_with_AFD
https://www.bluesea.com/products/9001e/e-Series_Selector_Battery_Switch

My question is four-fold.
1.) Do I need a battery switch with the (AFD) Alternator Field Disconnect circuit?
2.) Can my boat's charging system handle charging both battery types simultaneously?
3.) Weight balance is my biggest concern, so where is the recommended location to install the second deep cycle battery?
4.) Where is the recommended location for installing the USB charging port/12-volt power outlet, such as this one http://a.co/aXWwacK

 

[snikwad003]

You need the blue sea add a battery kit, it has the switch and an isolater so that your accesory battery doesnt drain your starting battery like it would with just the switch. It also allows the motor to charge the acc battery once the starting battery is full. They also have one with a charger built in, our boats dont have a big charging system so depending on your accessories use you may need to charge your acc battery from time to time.

 

[Seadoobuddy]

You need the blue sea add a battery kit, it has the switch and an isolater so that your accesory battery doesnt drain your starting battery like it would with just the switch. It also allows the motor to charge the acc battery once the starting battery is full. They also have one with a charger built in, our boats dont have a big charging system so depending on your accessories use you may need to charge your acc battery from time to time.

Do you have link to this blue Sea kit?

 

[snikwad003]

No charger:
https://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A

Built in charger:
https://www.bluesea.com/products/7655/Mini_Add-A-Battery_Plus_Kit_-_65A

I plan on going the built in charger route because in going to add multiple amps to the stereo along with 6 more speakers. The stator output of these engines may be enough if you drive at high rpms for hours at a time, but I would rather plug the boat into an extension cord the day before an outing from time to time to top off the acc battery and never worry about getting stuck with a dead battery that you arnt supposed to junp start to prevent burning up the mpem. The key is the isolater that keeps the acc batery from sucking on the starting battery while youre jammin with the anchor out and you loose track of time[emoji106]:cheers:

 

[BoyzFunBoat]

No charger:
https://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A

Built in charger:
https://www.bluesea.com/products/7655/Mini_Add-A-Battery_Plus_Kit_-_65A

I plan on going the built in charger route because in going to add multiple amps to the stereo along with 6 more speakers. The stator output of these engines may be enough if you drive at high rpms for hours at a time, but I would rather plug the boat into an extension cord the day before an outing from time to time to top off the acc battery and never worry about getting stuck with a dead battery that you arnt supposed to junp start to prevent burning up the mpem. The key is the isolater that keeps the acc batery from sucking on the starting battery while youre jammin with the anchor out and you loose track of time[emoji106]:cheers:

Thanks for the info. The spec sheet on my boat's Magneto generator output is 270 W @ 6000 RPM, so that's 22.5 Amps. (270 watts/12volts = 22.5 Amps). Do my calculations look correct?

I'm usually going fast (5000-6500 RPM) to and from my destination, so I think I'll be OK without charging batteries via an extension cord prior to leaving the dock.

I'm leaning towards the 120A boxed version (part number 7650003), because it's only about $21 more than the 65A version on Amazon and I may add more accessories later. For my USB charging port and 12-volt power outlet, I'm looking at this one from Amazon http://a.co/hsdri3e . It has extra rocker switches that I don't need right now, but I figure I'd rather install a larger panel now, have a few extras for future use, then have to cut another fiberglass hole later.

Now, I just need to figure out where in the engine compartment to mount the extra Deep cycle battery and where to install the USB/12-volt Power/switch panel. Any suggestions?

Also, do I need to buy a bus bar, or is there already one in my boat that I can use?

 

[snikwad003]

On my twin engine boat there is a bus bar inside the mpem box but i dont want to add any holes to the box, so I'll likely add my own buss bar. The 120 amp version is massive overkill for your boat but it will work just the same, I'd save the 21ducks for your battery, adding a bus bar or the beer youre gonna want while working on your boat upside down on your head:cheers: Some guys mod the stock battery tray to hold 2 batteries sideways or simply add a battery tray to the other side of the boat. Your calculation looks right altho at 6k rpm you may be a little higher in voltage than 12v but that is a marginal difference. The reason behind me wanting the charger is im going to add ALOT of stereo and a well discharged battery takes hours to recharge fully, and after seeing that switch panel I want some zombie lights!

 

[wheatfield8301]

You can use the negative battery stud as a bus bar.

 

[BoyzFunBoat]

On my twin engine boat there is a bus bar inside the mpem box but i dont want to add any holes to the box, so I'll likely add my own buss bar. The 120 amp version is massive overkill for your boat but it will work just the same, I'd save the 21ducks for your battery, adding a bus bar or the beer youre gonna want while working on your boat upside down on your head:cheers: Some guys mod the stock battery tray to hold 2 batteries sideways or simply add a battery tray to the other side of the boat. Your calculation looks right altho at 6k rpm you may be a little higher in voltage than 12v but that is a marginal difference. The reason behind me wanting the charger is im going to add ALOT of stereo and a well discharged battery takes hours to recharge fully, and after seeing that switch panel I want some zombie lights!

You're right about the 120 amp being over kill, so I ordered the 65 amp one. Now, I just need to find a battery tray for the second deep cycle battery and figure out exactly how to attach it to the hull without too much damage. I really needs to be mounted securely, because I do a lot of wave/wake jumping in the ocean.

https://www.youtube.com/watch?v=JYUasALMMnU&feature=youtu.be

 

[snikwad003]

I love these jet boats, I may get a small one one day to mod out for peformance. Ive aired out my 18fter a few times and its a wild ride, my wife hates those kind of rides. You have a tether of some sort for your light pole/camera? Depending on your engine bay you may need to fiberglass in a block of wood or something to achieve a flat spot and somewhere to screw in the hold down. Keep us posted for sure, not enough people follow up what their soultion winds up being, and we want fotos too.

 

[BoyzFunBoat]

I love these jet boats, I may get a small one one day to mod out for peformance. Ive aired out my 18fter a few times and its a wild ride, my wife hates those kind of rides. You have a tether of some sort for your light pole/camera? Depending on your engine bay you may need to fiberglass in a block of wood or something to achieve a flat spot and somewhere to screw in the hold down. Keep us posted for sure, not enough people follow up what their soultion winds up being, and we want fotos too.

I don't have camera tether yet, but I definitely need one for my rough rides. I'm using the AquaStickPOWER [USBx2] by YOLOtek for the camera mount. It's pretty neat how it fits into the stern light socket and gives USB power to your action cam. If the pole snapped, I would probably lose my action cam

I guess I'll be making a wood/fiberglass block for mounting my 2nd battery. I'll post pictures of the project. The Blue Sea Add-A-Battery Kit looks like exactly what I need. Thanks for all your help! :thumbsup:

 

[howie099]

I glassed in some wood in my boat to added a 2nd battery and just I just used an AB switch. I followed instructions on AB switch. I am pretty sure all the charging wires went To the common post on the switch. The Marie grade battery cable is where the cost is. I physically charge the batteries before I go out. The 2 stoke systems cant keep up if you add extra power devices in your boat. Just make sure you have the power off before you charge the batteries off bye bye MPEM.