Formula Battery Setup
 

I have an 88 242LS with factory dual batteries. Currently, both batteries are cranking. I would like to set the boat up with one "house" and one "cranking" battery.

I would only need the house for anchoring and running two small cabin fans, however, I am concerned with killing that battery while sleeping. I don’t know much about house batteries and would like some suggestions/experience. Would it be wiser to have two cranking run in parallel and two house run in parallel and flip the factory switch depending on if I am starting the motor or using the fans?

Eventually I would like to add shore power only to charge the batteries and was looking for a suggested battery charger to use. My understanding is I would need a dual one for the house and for the cranking batteries?

Thanks for all the help.

Jed

Jed,

how are ya? hows that pretty boat doing?? I have no idea to your answer other then I have never killed the batteries on any of our Formula's and the current 303 I even run a fridge for 4/5 hours w/o worries, as far as a charger, i'd say buy a trickle charger and adapter and carry on,, just my opinion thou,

hope all is well havent seen u on here in a while

Sam

You could get a couple dual purpose deep cycle/starting batteries. when your on anchor just put selector on 1 battery then if it happens to die you still have battery 2. You can then switch back once running and charge with the alternator or with the battery charger once you get back.

This is what I do although I've never killed it, a good marine battery has lots of juice

Would it be possible to run 2 cabin fans off one battery for a night of sleeping?

Do you have any suggestions on batteries or a batter charger for shore power?

Thanks.

Jed

I have run a cabin fan all nite a just a small one that plugs into the lighter if that`s what you mean. I would think as long as one of your batteries is a deep cell you would be fine.

Suggestions for a battery?

I would just go grab a couple a decent dual purpose starting/deep cycle batteries (correct group size to fit your battery holder). Should be a 100 dollars apiece or so. I wouldn't over think it too much.

If you have an amp meter you could turn on everything you plan to run. Say it is 8 amps and you buy a battery with a 120Amp hour capacity, then you have 15 hours of use on that battery. Thats only a general guide.

A deep cycle will have better longevity but weaker starting power and a starting battery is the opposite. Thats why I would recomend a dual purpose. If you had a large cruiser you might want to consider a bank of house batteries, for a 24' performance boat I would stay with a 2 battery set-up, just my opinion.

I went to Sears they were close and a decent price, I think one is a cranking battery and the other is a deep cell group 24 size.

This will sound like a silly question, but with the exisitng stock dual battery setup can I keep the one cranking and replace the other cranking with a cranking/deep hybrid so I can switch between the two depending on what I am doing?

Thanks again everyone!!!

Jed

Yeah you can, I just wouldn't run the selector on "both" as the batteries will be different.

You should use a automatic charging relay if you are going to be using different batteries, or even one new and one old battery.

I run this one: http://www.bluesea.com/products/7610...12_24V_DC_120A

Jordan,

From what I see this would would be grounded and then a wire from each + battery terminal to to the separate terminals on the unit. Would this allow me to have the battery selector on both for charging purposes while running or even starting for that matter?

Thanks again.

Jed

I think that is the job the relay will do ...when running, both batteries are charging , even though you would have the battery switch on 1 or 2 .....the only reason you would run both is if you wanted to combine both batteries ....m

Offthefront

Are you sure of this? I was under the impression that with the factory isolator switch the boat would only run or charge whatever battery the switch was to. Meaning if switched to 1 it would start, run, and charge only battery 1 and same with 2 and same with both. This is why when starting I would start on either battery and switch to boat the charge both. When sitting on the hook I will switch to only one battery to preserve the other for starting only and then switch to both to charge both for the run home.

Thank you.

Jed

thats exactly how it works ...but your switch is a battery disconnect/selector switch .......I was referring to the Blue Sea charging relay Jordon is referring to ....it will allow both batteries to charge when running no matter what battery your running off of .....You select either 1 or 2 and forget it .....if you do a lot of overnighters and sandbar stuff I would add a 3rd battery ....if you forget to run "all" one battery is not charged if you forget to take it off of "all" you can drain both batteries .........I've had good luck with the ProSport chargers ....m

If you run an isolator connected to the alt output ,it doesn't matter where your battery selector is positioned, both batteries will charge

So if I am understanding this correctly I would wire this directly from my alternator (versus the alternator going to the switch to charge the batteries) and then to the batteries so it will charge both whenever the mototr is running and the switch will decide which battery I am running everything else off of?

Correct ,from alt to isolator, then the outputs split and run to the individual batteries. Nothing to do with the selector switch. To keep it clean you can hook the charge wires from isolator to the 1 and 2 post on back of selector. Keeps it neater at batteries.

Thats a really good idea with the outputs on the selector posts. So now the slector switch is only for if I want the house battery or if I want the cranking battery?