on board battery charger question

[fish hook]

my boat has a primary battery connected to the motor, alternator, etc. -- and a second battery that stands alone that has a trolling motor and my stereo connected to it. I usually charge this battery at the end of the day with a standard wall charger and never have to worry about the primary battery that is just for starting as it charges from the alternator. I'm thinking of adding an on board charger but have a couple questions. If I add a dual bank charger (thinking of also reconfiguring the batteries and adding perko switch in the future) will it harm the primary battery if it is always charged when connecting to charge up the secondary battery? Or as another option, can I leave one of the banks unconnected and capped until I need it in the future? Maybe I should just buy a single bank charger for the secondary battery and be done??? Not sure what to do. Any input would be great. Thanks

 

[JASinIL2006]

Re: on board battery charger question

I've got a second battery that I've thought of hooking up as well (mine is charged manually before I go out). From what I've read, this is the way to go:

Add a battery kit


If it wasn't for the cost, I'd have done it by now...

 

[alldodge]

Re: on board battery charger question

my boat has a primary battery connected to the motor, alternator, etc. -- and a second battery that stands alone that has a trolling motor and my stereo connected to it. I usually charge this battery at the end of the day with a standard wall charger and never have to worry about the primary battery that is just for starting as it charges from the alternator. I'm thinking of adding an on board charger but have a couple questions. If I add a dual bank charger (thinking of also reconfiguring the batteries and adding perko switch in the future) will it harm the primary battery if it is always charged when connecting to charge up the secondary battery? Or as another option, can I leave one of the banks unconnected and capped until I need it in the future? Maybe I should just buy a single bank charger for the secondary battery and be done??? Not sure what to do. Any input would be great. Thanks

A dual bank battery charger will charge both batteries and will not harm either battery. The charger has internal circuitry which will not allow the batteries to be connected together. If one goes bad it will not take the other down. I will guess that you have an outboard motor and not an inboard which has a larger alternator, correct?

Tell me more about your setup and I can suggest other options

 

[UncleWillie]

Re: on board battery charger question

A dual bank battery charger will charge both batteries and will not harm either battery. The charger has internal circuitry which will not allow the batteries to be connected together. If one goes bad it will not take the other down. I will guess that you have an outboard motor and not an inboard which has a larger alternator, correct?...

+1 ^^^

The charger will charge both batteries only the amount needed without overcharging.
Once the battery is fully charged, the charger will go into a maintenance mode and only charge the battery for a second every few minutes, if needed. Your situation is very typical and present both ends of the battery charging spectrum at the same time.

The starter battery is used only for starting. A very high current is drawn,but only for a few seconds.
A starting type battery is recommended and and will need very little to top it off again.
The alternator will complete the job in well less than an hour while the engine is running.

The trolling motor is used for long periods at a time and will be much more discharged at the end of the day.
This will needs to be a Deep Cycle Battery for that reason.
It will usually require a charge that will take many hour to complete.
Even if attached to the alternator, unless you take many hours to get back to the dock after fishing,
the battery is still going to need to be attached to a shore powered charger to complete the job.

The two bank charger solves both of these extremes.
The Starter Battery will essentially only be "Maintained", and the Trolling Battery will be Charged and then also Maintained.
The Best of both worlds.

 

[fish hook]

Re: on board battery charger question

My boat is an 04 tahoe q4 with 4.3 v6

 

[alldodge]

Re: on board battery charger question

You can use an isolator from your alternator output to charge the batteries while the engine is running, and the dual battery charger when docked. Both connections for isolator and charger would be the same connection

Edit: I TRIED TO POST PICS BUT ****** iboats still has an issue

 

[cjjjdeck]

Re: on board battery charger question

I have the setup AllDodge mentions with an on board charger and an ACR unit. The ACR helps in not having to charge my trolling batteries quite as long with the battery charger after a long day. Most better quality chargers have a microprocessor in them that performs like UncleWillie states, so no harm to the battery no matter what charging state either one is in. The better chargers actually have separate charging units in one enclosure. For example, I have a Dualpro three bank on-board charger that has three 15 amp chargers in one unit; this is the kind of design I recommend (this is the second boat I've had this kind of charger on with great reliability and service). There are other good manufacturers as well (like Minn Kota, Guest, etc.), that other members can share their experience on.