Q's on charging multiple batteries in the boat

[projectcop]

Hi all;
I am used to automotive charging systems, so don't know if this can be done with a boat or not.
My new-to-me 1984 Bayliner Capri has one battery to run everything on the boat. What I would like to do is have a two battery system where one battery would be used to start the engine and the second battery would be used to run all of the accessories such as trollong motor, radio, lights, fishfinder, etc. I would like to charge both batteries with the boats alternator.

Is it possible (advisable) to use an automotive style battery isolater for a boat? If so, how would it be wired?
I can get everything I need; battery box, wire, cable, connectors, fuse blocks, etc.

Any suggestions? Have any of you done this?

George

 

[Silly Seville]

Re: Q's on charging multiple batteries in the boat

Hi George! There is a very simple remedy for your situation. It's called a dual/multi battery switch. Most larger boats come equipped from the factory with this device. It does exactly what you have mentioned wanting to do.

http://www.westmarine.com/webapp/wc...51_10001_112765_-1____ProductDisplayErrorView

 

[projectcop]

Re: Q's on charging multiple batteries in the boat

Hi SS;
Thanks for that link! That looks to be exactly what I need for the charging system. Now all I have to do is crawl in there and figure out where to mount the switch. Then I need to figure out how to "split" the wiring up so all the accessories are fed by the #2 battery.

George

 

[5150abf]

Re: Q's on charging multiple batteries in the boat

Heres an even better one http://www.iboats.com/Single-Engine...6454088--**********.939492861--view_id.342282

 

[JoLin]

Re: Q's on charging multiple batteries in the boat

Hi SS;
Thanks for that link! That looks to be exactly what I need for the charging system. Now all I have to do is crawl in there and figure out where to mount the switch. Then I need to figure out how to "split" the wiring up so all the accessories are fed by the #2 battery.

George

Read up on how to install and operate the switch. You don't need to split any wiring- the switch does that for you. Basically, you'll disconnect your present + cable from the battery and attach it to the 'ALL" terminal on the switch, instead. Then you'll run a new + cable from switch terminal #1 to battery #1, and another new + cable from switch postion #2 to battery #2. Add a new negative cable to wire the negative terminals of the 2 batteries together and you're finished.

Whichever switch position you turn to, your current draw will be only from THAT battery- the other is isolated. So, you can start and run from battery #1, get to your destination and switch to battery # 2. Now all your accessories are drawing current from #2. When it's time to go back home, switch back to battery #1 (which is still fully charged because you've been drawing only from battery #2), start your motor and be on your way. Once you're running, you can switch back to battery #2 (or ALL) to charge it while you're going home.


They work

 

[Jerryh3]

Re: Q's on charging multiple batteries in the boat

This is what I'm going to use. Maybe one of these days I'll get to hooking it up.

http://www.charlesindustries.com/main/battcom.html

 

[Scott Danforth]

Re: Q's on charging multiple batteries in the boat

the easiest thing is to use the two battery switch. However with that stated, there may be a need or desire to completely separate hotel loads from power train loads. in that case, a battery isolator from companies such as Sure Power would be needed.

A battery isolator is nothing more than two really really really large diodes bolted to a heat sink and encapsulated in epoxy. did I mention that they are large diodes. they have to be to handle up to 400 amps

All the information on separating the circuits is there, however only a 3rd party supply company that sells and installs battery isolators would have a packaged deal. ASE supply would be one

for fuse holders, etc. Cole Hearsey would be my suggestion.

In the end though, the two battery switch is about $50 total cost and 2-3 hours to install and a battery isolator circuit is about $200 total cost and 6-8 hours to install.

 

[Silvertip]

Re: Q's on charging multiple batteries in the boat

This is what I'm going to use. Maybe one of these days I'll get to hooking it up.

http://www.charlesindustries.com/main/battcom.html

That's fine, but it does not allow starting the engine from either battery. If you kill the starting battery you are still dead in the water unless you carry jumper cables. And you still must split the loads. Dual battery switch is far more versatile.

 

[j_martin]

Re: Q's on charging multiple batteries in the boat

If I understand the OP's question, he wants to operate the engine on it's battery, and trolling motors etc. on their own battery, just like any normal fishing boat.

Charging them can be done a couple of ways. If you have a mercury outboard with the dual 20 amp (40 amp) system, you can route the output of each regulator to a separate battery. That works very well.

If not, there's this voltage sensitive relay that works real well for maintaining both systems.

http://www.iboats.com/Single-Engine...5575061--**********.946238800--view_id.342282

If the link don't work, put the description in it into iBoats search link.

Note to iBoats. You'd get a lot more advertizing routed through the forums, like this, if it were a little easier to share a link.

 

[Jerryh3]

Re: Q's on charging multiple batteries in the boat

That's fine, but it does not allow starting the engine from either battery. If you kill the starting battery you are still dead in the water unless you carry jumper cables. And you still must split the loads. Dual battery switch is far more versatile.

How would the start battery drain down if all of the house loads and on the second battery?

 

[bruceb58]

Re: Q's on charging multiple batteries in the boat

My suggestion is to get a switch and a BlueSea ACR or equivalent. Put the trolling motor on the second battery and just leave everything else the way it is now. Hardly worth the effort on a small boat to separate all the electrical loads.

 

[Silvertip]

Re: Q's on charging multiple batteries in the boat

How would the start battery drain down if all of the house loads and on the second battery?

There is an old saying that goes like this: S#@t happens. Brand new batteries go bad. Electricral gremlins in the engine can suck a battery dry. It happens.

 

[j_martin]

Re: Q's on charging multiple batteries in the boat

How would the start battery drain down if all of the house loads and on the second battery?

In my boat. Starter battery charged by 1 20 amp regulator. Trolling bank has 12/24 automatic relay that puts the two batteries in parallel any time the ignition switch is on. Second 20 amp regulator charges those 2 batteries.

The negatives are bonded together with a 6 gauge wire. I carry a 3 foot piece of 6 gauge wire with jumper clamps on each end so if for some reason the engine battery lets me down, I can jump from the trolling batteries. The 12/24 relay is a 50 amp beast, so it can take the short time jump without damage.

If all the batteries fail, I have VHF radio and flares.

If that fails I can swim.

any other questions?

 

[projectcop]

Re: Q's on charging multiple batteries in the boat

Wow folks;
A lot of great answers, and some that are thought provoking. All I want to do is start my motor with one battery, run all my accessories off a second battery, but charge them both at the same time. I am thinking the Perko switch would be the way to go for me, but I've got other work to do first. I just wanted to get an idea of what I was going to use so I can figure out the "perfect" spots to place everything while I am re-doing the floor and seats and figuring out why this boat has no bilge pump in it (and putting in one with a float switch); but that is a subject for another thread.
Thanks all for your replies;
George

 

[Silvertip]

Re: Q's on charging multiple batteries in the boat

The Perko switch (or Guest) does all of this and more WITHOUT dedicating things to specific batteries. It is the simplest, cheapest, and most versatile setup there is but if you are switch challenged, then an ACR may be what you need.

 

[bruceb58]

Re: Q's on charging multiple batteries in the boat

The Perko switch (or Guest) does all of this and more WITHOUT dedicating things to specific batteries. It is the simplest, cheapest, and most versatile setup there is but if you are switch challenged, then an ACR may be what you need.

Even if you aren't switch challenged, the ACR and the switch is the way to go. You don't have to worry about forgetting to switch out of the "Both" setting ever and risk draining down both batteries.