House Batteries

[houstoncajun]

I have 2 house batteries, believe they are 90 AH (about $150 each at west marine) I have shore power with a onboard dual battery charger. I can leave the slip, go out for the day and have my battery switch on all. I stop and play and flip it to 1 or 2. when I go to start it wont, so I flip it to all and I can crank up and leave. I thought my fridge might be taking too much power so I turned the breaker off when I'm not on shore power but it doesnt help.

Anyway I thought I need a cranking battery for the starter to be hooked to, not a house? And if I add one and just put the starter to it can I connect my alternator to it and the other two house batteries? since I have a dual onboard charger it wouldnt get charged either....

Or

Do I get larger house batteries? (One is new last month the other old and dont want to waste what I have) or could I add anothe 90 AH and run with them and how to hook that all up and charge withe the altenator??(I have plenty of room in the engine capartment) I'm carrying an extra dual purpose battery now that I used to use for my trolling motor on my other boat for a "spare in case battery" I wish I didnt need to. I dont know how many AH i use in my 25' boat with all the bells and whistles, is there a rule of thumb? I like camping out at night on her and having my lights and stuff.

Sorry for the long post, just trying to wrap my head around this?
Thanks in advance for any help....

 

[Boatist]

Re: House Batteries

I think the starting battery should be just for starting and running the gear needed for running the boat. This would be the starter, bilge blower, Navigation lights, dash lights, horn, wiper. GPS, VHF Radio and depth finder can usually be supported by the starting battery or be put on the house battery.

All the rest of the gear should be on the house battery.
Any high drain gear like a fridge, big stereo, trolling motor, Live wells, TV should not be connected to the starting battery.

You boat with a 5.7 L engine will have a alternator of at least 60 amps and should be capable of charging the starting battery and putting some charge back in the house batteries.

I would suggest you never use the all or both setting on your switch. When you do the house battery can drain the starting battery. Only time I would use all is if the starting battery is dead and the house batteries are charged.

My Boat like yours has a 65 amp alternator and I charge both batteries thru a battery isolator with no problem. When the key is off and the engine is not running the only drain on my starting battery is navigation lights when required. Also the bilge blower before starting on a day with no wind.

 

[Silvertip]

Re: House Batteries

The start battery is rarely deeply discharged so using the BOTH or ALL while under way will indeed keep everything charged. However when parked, you need to switch to "1" or "2" (whichever is the house bank). When you are ready to go, then switch to the Start battery. When started, you can then again switch to BOTH or the HOUSE bank to charge it/them. The switch is versatile. Take advantage of its capabilities. If you are having load/draw issues, you need to determine what the high current draw item is and upsize the battery bank or downsize your useage of those items. Batteries are like a bucket of water. It only holds so much juice and then needs to be refilled.

 

[houstoncajun]

Re: House Batteries

Thanks for the responses,
So from what I get is using the switch can put all of my alternator charging to either bank or split the charge between the 2 depending on what I think I need. Thats great to know, maybe I need to switch some wiring around for critical and not critical components and name my banks for future reference.

but one question is I have 2 house battries, should i trade one out for a cranking battery and put the starter and maybe th radio, gps on it? or is the 2deep cycle house batteries ample to be starting and stopping?

What I'm tryint o figure out is if I need to carry my extra trolling motor battery (from other boat) on as a spare because of the problems I've seen so far as start and stop.

If I could leave it at home and get a jump box it would make more sense to me. So 2 house batteries ok or shopuld I have a cranking and a house bank??

Thanks again

 

[Silvertip]

Re: House Batteries

If the switch was wired correctly at installation, you should not have to rewire anything. However, for correct installation, EVERYTHING except the bilge pump(s) should be connected to the COM terminal on the switch. The bilge pump should be connected directly to any of the batteries. Why would you want to use one of the deep cycles with the start battery? That's what the switch is for. Yes -- the switch allows powering everything on the boat from the start battery, house batteries, or both. It also allows charging the start battery, house batteries or both depending on the switch setting. It makes no sense to have a switch and then have accessories wired directly to one battery bank or the other.

 

[Boatist]

Re: House Batteries

Slivertip's way is probably the way most switches are wired.

I wire mine completely different.
Only thing on the common post is the Starter.
Battery one is my starting battery is connected to post 1 along with everything need to run the boat.

The house battery is connected to post 2 along with everything that is not needed to run the boat.

I charge both batteries thru a battery isolator.

I leave the switch in the one postion all the time so the house battery and gear can not discharge my starting battery.
The ONLY time I would switch to 2 or all or both would be if for some reason the starting battery was dead and I needed to use the house battery for starting.

This way does require a battery isolator or battery combiner to charge both batteries.

The thought of having to go back and switch the switch to 1 every time I start and then when running switch to both or all to charge both batteries and then switch to 2 every time I stop is something I would never set up or do.

If you do go Silvertip's way make sure you have a good make before break switch and never switch thru off with the motor running. If you do switch thru off with the motor running it will blow your alternator.

 

[houstoncajun]

Re: House Batteries

The thought of having to go back and switch the switch to 1 every time I start and then when running switch to both or all to charge both batteries and then switch to 2 every time I stop is something I would never set up or do.

This is my thought too, even though I would try and remember I like to sit for 30 minitues then take off again, getting stuck offshore because I forgot to turn a switch or turnd it off in the dark while running would be a disaster.

I would like to seperate my essentials from my non esentials and use the isolator, thanks for the info, I'll dig more

 

[Boatist]

Re: House Batteries

A little more information on the battery isolator and combiner.

Battery isolator will start charging the batteries as soon as it starts. With large alternators like I am sure you have this is not a problem as the alternator has plenty of current to charge the starting battery and the house battery. The battery isolator will drop about .7 volts accrosed the isolator so if your alternator output is over 14 volts it will work good. If your alternator output is less than 14 volts then for some a battery combiner works better.

The battery combiner charges the starting battery first. When the battery voltage of the starting battery gets to a certain voltage then the combiner kicks in the house battery. With large alternator like you have this time to where the conbiner kicks in is a short time, 1 to 2 minutes.

On my boat I have a external voltage regulator so ever thou the isolator drops .7 volts the battery voltage stays the same as if the isolator was not there. This is because the voltage regulator uses the battery voltage as the input to the vlotage reglator. Alternators with internal regulators will use the alternator out as the voltage regulator input so the voltage to the batteries will be .7 volts less.