Dual batteries

[dazza]

Hi All,
we have a dual battery set up in our boat. 1 battery has the bait tank, deck wash and christ knows what else hooked up to it and the other one has nothing hooked up to it apart form the outboard.
My question is
when we go fishing should we run out on the battery with all the gear on it or run out on the standalone battery.
I think we should be runing out on the one with the gear on as it will be fully charged to run everything when we are out there and home on the standalone, but the other one will be run down for the next time.
Hope this make sense
cheers
dazza

[Jack_Lives_Here]

My set up is similar to a car system. While I'm running, both batteries are charging. The electric and other bits run off the deep cycle when stopped etc. The solenoid does not allow the cranking battery to be drawn upon, that way I have full power in my starting battery.

[jaybee]

Am thinking of a dual battery myself, know where i can get a wiring diagram.thanks

cheers

[Lucky_Phill]

Just keep in mind folks that the 2 stroke outboard ( non efi ) has a rectifier and puts minimal charge back into a battery. Whereas, the new 4 bangers have an alternator and will put up to 45amps back in.

I don't know how many times people have said to me " but I thought when the motor is running, it'll charge my batteries ". Yes, it will, if you have 13 or 15 plate batteries, use them all night while fishing, and then drive 4,784 kilometers home, sure they'll be charged.

Your electrics are one of the most important items on your rig. Don't 'think' they are OK before a trip.

Always, always charge them before hand, and if you have dirty great car batteries, they need charging for a couple of days.

That's my experience, and opinion, for what it's worth 8) ???

[Jack_Lives_Here]

Yeh, important point there Phil. Mine is a 4 banger and pumps plenty of charge back in while running.

[jaybee]

going back a long time now when i had a cat, both motors charged both batteries, it was setup with a switch so if i was fishing nite i only used one battery, start one motor, then flick the swith and start the other,or from the 1st battery, both motors were 2 stroke the run home from the 9 mile charged both batteries sufficiently for the next trip. would like a setup like this in a mono with one motor, the cat was setup when i bought her.
cheers.

[Heath]

Jaybee,

I have diagrams for wiring up dual batteries on my webpage that should help you get started.

My suggestion is that you shouldn't have anything running of any battery full time. Both batteries through an isolator switch so that one battery runs everything at any given time. We've been out & flattened a battery, just switch over to the other to start the donk & then switch back. We usually run out on 1 batt, use it, run in on the same battery, run out again & when we get to our spot change over. Never had a prob. The only small thing is that short trips such as when we go to Palmy for mackerel, the round trip is only 9 km, so after a dozen trips or so we top the batteries up for good measure.
also the advantage of wiring the batteries like that is you can turn switch them off when you get home so no probs with electrolisis etc.

[jaybee]

thanks heath but i must be a dumb B* i found it really hard to understand waaaaaaaaaaaaa specially after

Installation to select a starter battery and auxillary battery Manually isolates each battery, parallels both batteries for start, master disconnect, manually selects batteries for charging.

oh well guess i need to find a elecie that knows what this means, greatly appreciated tho.
cheers
joe

[NQCairns]

Hi, just to muddy the water a bit, one way of setting up a dual battery that is good and easy to make, can also help to overcome the human forget factor with switches as well, but like all systems it has its own drawbacks.
#It is also is a good idea with this system as with all others to keep the biggest and best battery for starting only. #
#Try this - the number 1 battery is connected ONLY to the starting circuit. The number 2 battery is connected to ALL accessories bar none. Between these two batteries there is an industrial solenoid. The 1st and 2nd battery will automatically charged when running and when stopped the 1st will be automatically isolated from any accessorie drain ready for the next start. This setup can also be tarted up a bit with isolation switches as well but there is really no need. NQCairns

[jaybee]

gee ta nq,now i am totally confused not to worry thanks anyway. just a bit too much for my grey matter eh.
cheers

[dazza]

Hi All
Touch wood I haven't had a problem yet, just wanting to avert any problems that may arise.
Phil,
how slow do they charge? Most of my trips are to around the Cape or M1 and to the north. Surley after a hour or so run they would be getting to full charge?
the volt meter tells me that everything is well charged.
Currently running Century Marine Pro 600 batteries. Change them every 18 months to 2 years, as I don't think they have much life in them after that. No battery shops 20 mile out to sea either
Have an isolator switch but no soleniods. How do they go in the marine enviroment??
Cheers
dazza

[Lucky_Phill]

I'm no sparkie nutter, but I know from experience that your 2 stroke doesn't put a lot of charge back in.

After stop starting of motor while drifting, colour sounder drawing mega amps, lights, GPS, live bait pumps, radios ( 3 ) the batteries took a hammering.

But, now with the 4 banger, no probs at all.

[NQCairns]

I'm no sparkie nutter, but I know from experience that your 2 stroke doesn't put a lot of charge back in.

Just had a look for interest at some specs for 9.9 to 50hp 93 model Johnsons 2st and they charge 4 amps. Can only assume the bigger ones charge more. Nqcairns
Ps. Just testing the 'quote' so if it comes out strange please forgive.

[Heath]

Jaybee,

Installation to select a starter battery and auxillary battery

- This means that you can select either battery 1 or battery 2 to start the boat or run electronics.

Manually isolates each battery

- Basically means if you select battery 1 then battery 2 will have nothing connected to it & visversa.

Parallels both batteries for start,

- Means you can select BOTH batteries at the same time so you can start the motor if required.

Master disconnect

- Means you can have the switch in a position so NO battery is connected.

Manually selects batteries for charging

- Means you can switch to either battery 1 or battery 2 to charge while you have the motor running

[jaybee]

thanks heath, that makes it a little easier to understand.
cheers.