Dual Batteries good idea or overkill?

[nerys]

Re: Dual Batteries good idea or overkill?

Just got my first boat. Traded a 75 300D for a 74 larson 186 with 140 erude and trailer. I Love it. looks like its going to be some work (ripped out the putty wrotten wood floor already but I can still run it by tossing a sheet of ply in there)

I am short on cash so for now I carry a 1gal fuel can with mix in it and a "jump" box with me. so I have back up electricity and backup fuel (just in case the fuel gauge is fickle and I have no idea how much gas this thing is going to eat though it has at least a 20 gallon tank (just put 15 gallons into it

I plan to go dual batt and STILL take the jump box with me (run a laptop chartplotter so its hungry)

I also have a 2hp little outboard I am working on getting running. got it years ago brand new never ran. Trying to make it run would be a nice "backup"

I also found out I can pull start this motor. when I removed the cover I found a pouch with a pull cord in it!

Paddling would really suck so I am preparing to avoid having to but I keep 3 paddles on the boat as well just in case (3 cause I know someone will drop one eventually

Just did the math on a 4.5 day 9 amp draw. Your battery bank has over 1000 amp HOURS of capacity? holly crap man thats a massive battery bank!

I also have 2 solar panels on the back of the boat to keep the batteries tickled when out of the water. just little 5 watt units.

 

[bgseib1]

Re: Dual Batteries good idea or overkill?

OK - dumb question I guess - I have a 2000 larson with 5.0 and single battery. If I want to go with a dual battery, do I just buy another battery the same size and specs as the original, and purchase a switch like the perko with the 1, 2, off, both options. And if this is so, how do I wire up the batteries? Also should I leave on just to the starter and all other hook ups to the second battery, and if I have the switch on 1 or 2 will both batteries get charged while the engine is on?

I know a lot of questions... : )

Thanks,
Brian

 

[Goundworks3]

Re: Dual Batteries good idea or overkill?

I have a little 16footer, but I always carry a spare, no fancy switches or anything, just another to switch to, just in case, I currently don't have a radio or anything yet either, but every time I go out the night before, I check the charge on the newer battery & charge up my older one, but both are good to go the next day.

I'm still at that paranoid stage though so I've got the trolling motor,3-plugs, 2-batteries, a 2-gal reserve of gas, (plus I always top off before I go), I've, (knock on wood here), NEVER had an issue so far, but heard too many stories from others, so If I get stranded it will me a mechanical issue, not something simple that I just forgot, at least gives me some piece of mind.

 

[Thajeffski]

Re: Dual Batteries good idea or overkill?

OK - dumb question I guess - I have a 2000 larson with 5.0 and single battery. If I want to go with a dual battery, do I just buy another battery the same size and specs as the original, and purchase a switch like the perko with the 1, 2, off, both options. And if this is so, how do I wire up the batteries? Also should I leave on just to the starter and all other hook ups to the second battery, and if I have the switch on 1 or 2 will both batteries get charged while the engine is on?

I know a lot of questions... : )

Thanks,
Brian

Not to be rude, but check out the search function and the instructions that come with the switch - all your answers are there.

 

[Handegard]

Re: Dual Batteries good idea or overkill?

I haven't upgraded yet, but I intend to very soon. I ran my battery down last week on the lake, and needless to say it wasn't very fun.

Thankfully, some kind guy got jumper cables from his car and drove out to use to jump us. I keep jumper cables in the boat now

 

[Shadow66]

Re: Dual Batteries good idea or overkill?

Boat came with two, with a Perko switch. I never had to use them but I always put them both in before going out fully charged. Not sure why really...except for the reasons everyone has already covered. Just in case I suppose.

 

[4JawChuck]

Re: Dual Batteries good idea or overkill?

I run dual batteries wired in parallel with a BEP marine switch to handle charging/switching duties, it disconnects the primary battery at 12.8VDC so it never runs down from accessory usage. The second battery is used for the trolling motor and Lowrance sounder.

I can't tell you how nice it is to go out and fish and not have to worry about battery's, the BEP switch cluster was the best $100 I ever spent for the boat and the best part is it charges the second battery when the engine is running once voltage to the primary battery reaches 13.7VDC. Now when I am done fishing all day and have run the second battery down I just take the long way home and charge it up before docking for the night...no more hauling battery chargers when we camp and paying for a powered campsite. During one long day I ran the secondary battery down and recharged it with the motor running in neutral-TWICE!...how many people can say they trolled with an electric trolling motor for 12 hours with only two batterys!

http://bepmarine.web03.co.nz/Single-Engine%2C-Two-Battery-Banks-180-1460.html

They also make 24Vdc and 36VDC clusters for those running three or more battery's, great product and well constructed.

 

[deadstick]

Re: Dual Batteries good idea or overkill?

how about this. use a continous sylenoid. hook it to your second batt so it only comes on when you turn the switch on or try to crank it. when you are running the engine you will be charging both and if you are sitting still and it runs the main batt down when you turn the switch on to start your boat it will crank from the charged spare batt. this setup requires no switching. its all auto. this is very cheap and easy too install!

deadstick

 

[jdlough]

Re: Dual Batteries good idea or overkill?

Usinga 2 battery setup with a switch...

Starting a cranky motor, setting the switch to two batteries will definitely give it some extra punch to start.

Once your motor is running, flip that switch to just one battery (to charge THAT battery, and NOT use the other). Then, the next time out, while running, switch the switch to the OTHER battery, to charge that one. Don't leave the switch on both while running, thinking that you'll charge both at the same time. If set to both, any bad things while running will just drain both batteries.

If you get in the habit of running with the switch set to both, you may be stupid like me and leave some accessory switch on at the dock, MOSTLY draining both batteries. This MAY leave you enough juice to start the motor next time, with two mostly dead batteries, but will leave you stranded 5 minutes later when you try to restart out on the water.

So, run the boat on ONE or THE OTHER, but not BOTH.

 

[allen6634]

Re: Dual Batteries good idea or overkill?

i have 3 batterys ,one for the starting and ***. ,and the othert two for my trolling motor. i have been thinking about switchingaround some of my wiring, so i can use one of my troling batt for the acc.i think it is better safe than sorry!

 

[ifallsguy]

Re: Dual Batteries good idea or overkill?

The marine shop I visit frequently has told me that the battery switch can also be used to charge both batteries when underway (I hope they are correct!!). So I start up using the dedicated OB battery and turn the battery switch to both batteries once I am up and going.

I would really recommend getting an isolator. It allows each battery to charge, but keeps them isolated from each other. I also have a switch, but the isolator controls how the batteries charge (normally your primary (starting) battery, then the house).

Also think about this. You spend money to insure your car. Waste of money until you need it. Same with a two battery setup, a spare to get you started and home.

 

[bruceb58]

Re: Dual Batteries good idea or overkill?

Just don't use diode based isolaters. Your batteries won't fully charge with them. Best method is a combiner. Also, these device have no idea which battery needs to get the charge. That is only determined by how discharged each is.

 

[stylesabu]

Re: Dual Batteries good idea or overkill?

I'm also thinking of adding a third battery. the extra wieght won't slow me down enough. I go fishing were I have no access to 120 volts, that less than 45 minutes away.

 

[bruceb58]

Re: Dual Batteries good idea or overkill?

So how are you planning on charging this 3rd battery?