Recommendations on how to properly use dual batteries

[Puddleracer]

I've only had the boat for a few months but have always used battery #1.  I figured I should switch to #2 to make sure it works.  We float around with the stereo on and use ballast pumps so am always worried about killing a battery.  #2 would barely start the boat.  I've got a 600 CA and a 1000 CA, so will look to replace the dying 600 with another 1000.  Is the best practice to switch between #1 and #2 every now and then?  I've avoided using 1+2 as I would worry that I could run them both out.

 

Thanks for your help.

[cmargosi]

I was told it's best to run 1 and 2 when under motor to simultaneously charge both batteries.  If floating around or listening to tunes, switch to one battery or the other.  Then back to 1 and 2 when motoring home.  

[RTS]

Here's what I always did with my manually switched 2 battery setup.

Beginning of the day....Start boat with battery 1, run for 15 minutes or so getting to 'spot' and getting ropes out etc. to ski.  Switch to battery 2 to make sure it would start the boat and ski for a while. 

Switch back and forth between 1 and 2 every hour or so if I remembered when the engine was off to pickup skier, float around, etc..  If I forgot, no big deal.

On the way home, switch to BOTH to charge them up by running 30 minutes or so to the dock....this was the only time I would use the BOTH position.

Turn the switch to OFF when I got the boat on the trailer.

Edited July 29, 2019 by RTS

[Bozboat]

1 hour ago, Puddleracer said:

I've only had the boat for a few months but have always used battery #1.  I figured I should switch to #2 to make sure it works.  We float around with the stereo on and use ballast pumps so am always worried about killing a battery.  #2 would barely start the boat.  I've got a 600 CA and a 1000 CA, so will look to replace the dying 600 with another 1000.  Is the best practice to switch between #1 and #2 every now and then?  I've avoided using 1+2 as I would worry that I could run them both out.

 

Thanks for your help.

Do you have access to electricity when not using the boat?    With my simple 1/2/both perko switch, I run on 1 or 2.  Never combined.  The idea is to keep a spare battery to use when the first battery fails.  To keep the batteries charged I have a prosport battery charger mounted on the boat.  It keeps both batteries charged and conditioned when plugged into shore power.

If you don't have a smart charger, then the only way to charge the second battery is to follow RTS suggestion.   My concern with combining a dead battery with a good battery  using the "both" selection is that the good battery may drain into the dead battery leaving you with two weak batteries or worse.  Also, never switch to off with the engine running.

Edited July 29, 2019 by Bozboat

[Puddleracer]

I do not have power unless I remove the battery Bozboat.  It is either on a buoy or tied to a dock.  Thanks for the advice everyone.

[AzAxisA22]

Seems you are going to get a wide variety of answers as I do it a little different than posted above.  I don't live on a lake so we are stuck making weekend or extended weekend trips to the lake.  The first start of a weekend I put the switch to 1+2 figuring that's the best chance to get the boat started first try.  I then leave the boat on 1+2 the first few hours of run time to charge both batteries.  Once we stop and are going to be running the stereo floating with the engine off, I switch to either 1 or 2.  This way if the stereo kills the battery I should have a charged and untouched battery to get me started.  To keep use relatively even on the batteries, I alternate which battery I use each day.  

[MLA]

The biggest take away is to not anchor with the switch in the BOTH or 1+2 position. 

If both banks are identical, then you can rotate usage between them. If you have a cranking and a deep cycle, then ideally, you start/run on cranking and anchor on the deep cycle. However, its not a bad idea to switch to 1+ 2/BOTH or the deep cycle after restarting, to put some charge back into it. 

[ejwestman]

https://www.bakesonline.com/images/MediaLibrary/Malibu_2012manual.pdf

starts page 4-11, actually kinda interesting stuff...had same ?'s few weeks back. 

[RTS]

5 minutes ago, MLA said:

The biggest take away is to not anchor with the switch in the BOTH or 1+2 position. 

If both banks are identical, then you can rotate usage between them. If you have a cranking and a deep cycle, then ideally, you start/run on cranking and anchor on the deep cycle. However, its not a bad idea to switch to 1+ 2/BOTH or the deep cycle after restarting, to put some charge back into it. 

Yes....I should have mentioned that both my batteries were identical 'cranking' batteries.  Did not have a large sound system to feed with a deep cycle battery.  I was slumming it with just the standard Sony head unit and 4 cabin speakers.

A high amp sound system and extended floating would change the way I did things.  

What type of stereo you running Puddleracer?

Edited July 29, 2019 by RTS

[Puddleracer]

The sound system is a stock Rockford system with 13 speakers all over the place powered by 3 massive-looking amps.  It is extremely loud.  I've always just drawn off of the CCA battery without a problem to date.  I'd hate to get 2 different types and have to worry about switching every time I turn the boat on / off.

[eubanks]

1 hour ago, cmargosi said:

I was told it's best to run 1 and 2 when under motor to simultaneously charge both batteries.  If floating around or listening to tunes, switch to one battery or the other.  Then back to 1 and 2 when motoring home.  

This is what we do except I don't switch it off 1/2 unless we are going to be using the stereo while floating for a significant period of time.  Never had an issue.

[RTS]

11 minutes ago, Puddleracer said:

The sound system is a stock Rockford system with 13 speakers all over the place powered by 3 massive-looking amps.  It is extremely loud.  I've always just drawn off of the CCA battery without a problem to date.  I'd hate to get 2 different types and have to worry about switching every time I turn the boat on / off.

In that case, please disregard everything I said!

[csleaver]

An onboard charger, or at least a portable charger, is a necessity on a boat with multiple amps, power wedge, surf gates or other high draw electrical equipment.  Starting out with fully charged batteries, then selecting battery 1 for normal operation, selecting battery 2 for non-running stereo use or as a backup, and only selecting 1+2/Both for emergency starting is the ideal way to use most single circuit dual battery setups with four position switches.  The engine's charging system is simply not robust enough to charge two batteries at the same time, especially if they are already partially discharged.

[AzAxisA22]

I'm not an electrical engineer, but I believe the alternator can charge both batteries at once although the batteries may recharge at a slower rate than if you were just operating one battery.  Each battery should still be getting the 14.4V (charge voltage) at half the normal amps.

Edited July 29, 2019 by AzAxisA22

[MLA]

Unless there is a large battery bank, in terms of Ah, and that bank has been run very deep, I dont have any concerns about running the switch in 1+2 position. 

[csleaver]

31 minutes ago, AzAxisA22 said:

I'm not an electrical engineer, but I believe the alternator can charge both batteries at once although the batteries may recharge at a slower rate than if you were just operating one battery.  Each battery should still be getting the 14.4V (charge voltage) at half the normal amps.

You are right, but it may just take three or four tanks of gas to fully charge the batteries if the rest of the electrical load is low enough.

If, for example, the alternator can produce 95 amps at 3000 RPM, and the ignition, fuel and electrical system uses 30 amps, the stereo uses 40 to 100 amps (or more), and the wedge, or surf gates are using 20 to 40 amps at a time, the system is essentially running off of battery reserves when all of those systems are being used simultaneously.

[TallRedRider]

I have a unique approach.   I have a battery charger, so both batteries are always charged fully from the beginning, and they are identical batteries.  I have enough crap to remember as captain of the ship, so remembering to fiddle with the battery switch is something I don't want to do.  I keep a costco battery jumper in the boat at all times and it has been useful, mostly for other boats.  I run the batteries combined all the time and will use the battery jumper if I run them dead.   I do not run the stereo full blast for extended periods with the motor off, so that also plays a role in my thought process.  

It will some day be a winter project to upgrade to the Perko automatic charging relay, which will hopefully take away the risk of needing my jumper battery for myself.  

And my batteries are charged to 15.3 Volts, so they are way more powerful than your usual batteries.  

[MadMan]

11 hours ago, TallRedRider said:

 I keep a costco battery jumper in the boat at all times and it has been useful, mostly for other boats. 

This is an excellent approach.  I keep a lithium ion battery jumper in my boat too, even though I already had a battery isolator.  The jumper has "rescued" other boats.  Since we don't do the sandbar thing, listening to music for extended periods of time, I'd be confidant heading out with a single battery and the jumper.

[minnmarker]

Stereo on one battery alone.  If stock it probably is already.  Then a Blue Seas ACR setup and forget about it.  No switching anything ever.

[Nitrousbird]

Blue Sea add a battery.  One battery for the stereo and another for the rest.  

This makes full use of both batteries and keeps them separate unless the boat is running.  No worry about switches.  No worry about starting of anchored with the stereo blasting for hours.  It's such a simple, logical approach that I don't understand why more people don't run this setup.

I also run an onboard charger and plug in after every use, partly due to my use case where I may be hard on the batteries right before shutting the boat off and this ensures full, happy batteries after every outting.

[Nacibound]

I was just reading the axis manual and came across this, which I'm not sure I agree with, but I understand it:

OFF means that all power to the battery is shut
down. The battery will not be able to re-charge while in the OFF position. This is the appropriate setting for periods of inactivity with the boat, un- less the boat is in the water. When the boat remains in the water, it will be necessary for the bilge pumps to periodically and automatically pump out residual water in the bilge system. See above description of how the bilge system operates automatically. Battery 1 is the “house” battery or main battery.
It should be rated at least 800 cold cranking amps
(cca), and a spiral cell battery is preferable. Battery 2 is the back-up battery (used as a back-up, the smaller 500 cca battery is acceptable; however, you may prefer that your back-up also be 800 cca).
Normally, when the battery switch is not turned to OFF, it should be set on “1.” However, if Battery 1 is somewhat drained or sluggish, turning to “1+2” can be very helpful in providing
Axis Owners Manual 2019 Page 76
  
     Axis Owners Manual 2019 Page 77
sufficient power to start the engine and begin the natural recharging process. After the engine starts and runs for a few moments, return the battery switch to “1.” The electrical system is not designed to run at optimum efficiency on “1+2.” The “1+2” setting is intended for limited use. For example, if the boat has not been running, but the boaters have been using the stereo, lights or other electrical components for a period of time, the running battery may not have sufficient power to return to shore. In that instance, by combining the batteries there may be sufficient power to continue underway while the batteries recharge.
On rare occasions, it may be necessary to turn the switch to “2.” For brief periods of time, especially if Battery 1 is non-functional, you can run on “2” for limited periods of time.

[jjackkrash]

6 hours ago, Nitrousbird said:

Blue Sea add a battery.  One battery for the stereo and another for the rest.  

This makes full use of both batteries and keeps them separate unless the boat is running.  No worry about switches.  No worry about starting of anchored with the stereo blasting for hours.  It's such a simple, logical approach that I don't understand why more people don't run this setup.

I also run an onboard charger and plug in after every use, partly due to my use case where I may be hard on the batteries right before shutting the boat off and this ensures full, happy batteries after every outting.

Agree 100%.  One "house" and one "starter" with the Blue Sea set up is the only way to go; you also want a dual-bank on board smart charger if you are running anything more than a modest stereo or you will kill batteries pretty quickly.

OP, if you need to pull the batteries and bring them to shore to get them fully charged, it is what it is.  

https://www.westmarine.com/buy/blue-sea-systems---add-a-battery-dual-circuit-system--8646275?mrkgcl=481&mrkgadid=3085587794&cm_mmc=PS-_-Google-_-GSC>NonB>Product%20Type-_-8646275&product_id=8646275&adpos=1o2&creative=108421552324&device=c&matchtype=&network=g&gclid=EAIaIQobChMI__-R_Ozg4wIVCv5kCh0QtwvCEAQYAiABEgIlT_D_BwE 

[Txstoj]

This is going to be a dumb question but our 2019 is the first one I have had with the factory onboard charger.  Plugging the boat in with the onboard charger, is the charger wired to both batteries directly, like the switch can be “off” and the batteries still charge or do I need to turn the switch to 1+2 to charge both batteries?   FYI - I have not changed any factory wiring of how the boat came.

[wedge88]

54 minutes ago, Txstoj said:

This is going to be a dumb question but our 2019 is the first one I have had with the factory onboard charger.  Plugging the boat in with the onboard charger, is the charger wired to both batteries directly, like the switch can be “off” and the batteries still charge or do I need to turn the switch to 1+2 to charge both batteries?   FYI - I have not changed any factory wiring of how the boat came.

If your charger is anything like mine (https://www.amazon.com/gp/product/B00JQE31K2/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1) it is recommended to charge while switch is in the OFF position.  Both my batteries charge fine.

[phinz]

I run mine on 1+2 when the motor is running so both batteries are getting charged up. Then switch to 1 or 2 for floating. With that I alway have 1 fully charged battery to start the motor.

Also I am looking for someone with a 2017 21" VLX factory installed ProSport charger. Where did the factory mount it? Any pictures? 

The manual for the ProSport charger states "Do not install charger on carpeted, upholstered, vinyl, or varnished areas.... Install this unit on a hard surface."