Outboard Electrical

[scruffy95]

So I started off with 2 deep cycle batteries that I alternated plugging into a battery charger that plugged in at the dock and alternated wiring into the panel that I have. I know not the best solution. The outboard that I had was stolen, but charged back to the battery that was wired into the panel.

Now I purchased a new outboard that has an electric start. So the need for a starting battery. So now I have three batteries (2 deep cycle/house batteries and 1 charging battery), a panel to control the house (i.e. running lights, cabin lights, vhf, stereo). I just bought a switch with 1,2, both and am wondering how others would wire this taking the following into consideration:
1. I would like the outboard to start off the starting battery
2. I would like the outboard to be able to charge back to the starting and/or house batteries.
3. I would like to be able to still use the battery charger to charge the house batteries when in the slip since I am guessing the charge back on the starting battery will be quicker and the deep cycle will take longer to charge back.

I am guessing I should wire the house batteries in parallel but have read that there is some debate on whether this is a good idea if the two deep cycles are at different stages of live (i.e. one worn down over the other).

Any advise or guidance would be greatly appreciated as I have an idea of this stuff, but not a full comprehension and everything I read refers to alternators and inboard engines for recharging and not the simpler charging from an outboard which recharges at a much lower rate.

 

[Benny17441]

If it was me, I'd keep it simple. I would get a group 24 starting battery and connect it to the engine leads and control panel. The engine would cranck of this battery and recharge it while motoring. I would go back to the store and return that 1,2,Both,Off switch and instead get a simple On/Off switch. The two deep cycle batteries I would connect in parallel and connect to the boat's electrical panel with the On/Off switch in between to cut power in an emergency or when needed. To charge there is no need to alternate the batteries since they are connected in series and both would recive charge from the shore power charger. I would probably hardwire a dedicated inboard charger but any portable smart charger would do. Vector sells a rather inexpensive smart charger with 2/10/20/35 amps steps. It also offers a battery reconditioning cycle. My reasoning behind is that the alternators in small outboards are not very strong and it would be a far strech to expect it to charge the starter battery and the house bank. Also there will be a marked difference between the starter battery and the house bank and they should not be combined. The purpose of the 1,2, both switch is 1) to combine batteries 2) to select the battery that will be supplying power to the loads or getting charge from the alternator. Since I would not be combining batteries and I would not be selecting the alternator to charge the house bank there is no need for the 1,2 both switch. When the two deep cycle batteries are connected in series basically the two batteries turn into a single larger one. So for all practical purpose the boat would just have two batteries, a starter and a house. There are many advantages to connect the two deep cycle batteries into one.

 

[Maine Sail]

You do not need a starting battery for your outboard. Your house bank will start it just fine. If you want one as an emergency reserve bank that's fine but be careful switching the switch with the motor running because if you pass through the OFF position you might fry the alt in the outboard...

 

[thinwater]

My opinion on electric start outboards has long been that they don't need a separate starting battery at all, since they can also be pull-started. Some have a handle installed, some it is a simple matter of pulling the cover and wrapping a rope. Outboards have many shortcomings; this is a major advantage.

If you watch your charge, this shouldn't happen, but it seems more likely if I need to be fusing with switches all of the time. I would rather just watch the charge and link all of the batteries. The load is not that high.

 

[Ron20324]

.... should wire the house batteries in parallel but have read that there is some debate on whether this is a good idea if the two deep cycles are at different stages of live (i.e. one worn down over the other).

Yes, preferably batteries should be the same, the same age, but you can live with it. Contrary to some of post #2, the batteries should be in parallel, not series.

 

[Benny17441]

The advantage of having a dedicated starting battery for your outboard is that it will start the engine and charge right back providing fair assurance that you will have power to restart it no matter how low you may have to draw your house bank. It would keep the starting circuit totally independent from the house circuit. To expect the alternator of the outboard to recharge a modest house bank is not realistic and would probably place more strain on the alternator components that it was designed to handle. You mentioned you have three batteries and this setup for me seems would work the best. Having to worry on a trip about the state of charge of the house bank so that it can start the engine is not fun.

 

[scruffy95]

So upon further inspection this evening I came to find out that the two house batteries I have are rated for different amp hours. Is that a problem in wiring them in parallel? Right now I wired the outboard directly to the starting battery and the two house batteries are wired in parallel and directly into the house panel. I am thinking the next step is to wire the battery switch so that I can send charge to all three batteries. I understand that the charge from the outboard is pretty minimal but any charge going back to a the house bank and to the starting would be good right? I am not powering anything heavy like a refrigerator or the like so my house batteries should last pretty long when all sailing but I guess I should definitely add a meter into the house bank so that I know what their charge is at all times. Any suggestions on the inexpensive side? Any and all advise is greatly appreciated.

 

[Ron20324]

If your batteries are too deeply discharged they may blow the fuse in your charging circuit. You DO have a fuse in there, right? It may be under the engine cover.

 

[scruffy95]

There is a fuse in the charger that I plug into shore power. I am not aware of a fuse in the outboard that would protect that circuit. The panel which is powered by the house batteries are all fused for each switch and then the VHF radio and stereo are each individually fused.