Two Batteries and a switch

[Lrider]

My new toy comes with two batteries and a selector switch

Ohh soo many questions

1. why 2 batteries - no electric motor

2. I have a trickle charger how do I set them up to charge both

3. The batteries look like car batteries is there a difference between car and Marine?

4. How should the switch be set during normal operation?

5. Should the batteries be in battery boxes, currently they har just tied down inside of the center console compartment

I love this forum, it makes me think

 

[Bob's Garage]

Re: Two Batteries and a switch

Having 2 batteries permits the operator to use one battery solely for the starting process, and the other for the "house", i.e. radio, stereo, electronics, bilge pumps, bait well, lights, etc.

Do not try to charge both batteries at the same time with a single charger unless it is specifically designed to charge two batteries simultaneously. If you do, the charger will only charge to the weakest battery, and it may cause the good battery to be pulled down to the level of the weaker battery.

Put the selector in the #1 position (if that is the starting battery), then after the engine is running (but only if it is a "make before break" switch) you can select either "both" or "#2" (if that is the "house" battery.

Having 2 batteries will give you a back up starter battery if the primary battery fails.

WARNING - DO NOT LEAVE THE SWITCH IN THE "BOTH" POSITION WHEN THE ENGINE IS NOT RUNNING AND YOU ARE USING BATTERY POWER FOR ANYTHING. IT WILL DRAIN BOTH BATTERIES AND LEAVE YOU WITHOUT A BACK UP.

 

[RSR1010]

Re: Two Batteries and a switch

Bob's garage advice was very good, I just purchased a boat also having the same setup. My dealer told me switch selector from 1&2 whatever battery is stronger use that for the cranking one, or as I do leave selector switch in middle I have not yet had a problem with this, if your boat has an alternator you will not need to worry about using a charger.

 

[Lrider]

Re: Two Batteries and a switch

Ahh !!

That makes sense, I would have just left both of them on all of the time

Thanks

 

[Bob's Garage]

Re: Two Batteries and a switch

Ok, question #3, and #5;

#3
You can use car batteries but they are not really the same. The connectors are different (obviously) and they have different characteristics. Just what, I don't know but someone will explain.

#5
Battery boxes get mixed reviews. Some people like them, keeps thing neat, keeps moisture off the top.

However, some feel that they prevent the "gases" from dispersing which could lead to a build up and explosion. They also make it hard to get to the battery posts quickly and make a casual inspection of the condition of the battery difficult.

So, take you pick, your choice.

 

[Barnacle_Bill]

Re: Two Batteries and a switch

Coast Guard requires batteries to be covered.

 

[jdsgrog]

Re: Two Batteries and a switch

Is it a new boat or used? Is it a fishing boat or ski/recreational boat or a cruiser? What kind of batteries--deep cycle, starting? If it's car batteries, then they are probably starting batteries. The switch will allow one battery to be used if the other runs out. Do you know if you have a charging system on your motor? More info would help.

 

[Bob's Garage]

Re: Two Batteries and a switch

Bob's garage advice was very good, I just purchased a boat also having the same setup. My dealer told me switch selector from 1&2 whatever battery is stronger use that for the cranking one, or as I do leave selector switch in middle I have not yet had a problem with this, if your boat has an alternator you will not need to worry about using a charger.

Keep in mind that a battery will lose it's charge over time. Also, if you have any gear that maintains a "memory", it will use power and discharges the battery.

I know that reason says it is a very small amount, but as soon as you expect the batteries to be good, even tho the boat has only been sitting a short while, and you do not put a charge on them before starting your trip, that's when they will be dead or too weak to crank the engine.

Having the trickle charger to top off the batteries just before a trip, or when sitting for a couple months, is a good idea.

 

[Lrider]

Re: Two Batteries and a switch

Is it a new boat or used? Is it a fishing boat or ski/recreational boat or a cruiser? What kind of batteries--deep cycle, starting? If it's car batteries, then they are probably starting batteries. The switch will allow one battery to be used if the other runs out. Do you know if you have a charging system on your motor? More info would help.

This is a 1995 Sailfish 176, I suspect the motor (Johnson 88 SPL) has an alternator) not sure though- The boat is new to me and is still in the shop being inspected _ I will get the news next week (this is start-up season here and they are very busy.

It looks like interstate car batteries that are in there, the man I am buying it from says they are new.

So Much to learn thank you for the input

 

[reefrunner7]

Re: Two Batteries and a switch

Learned the hard way to have 2 batteries, just installed perko switch and 2nd battery, check your motor to make sure how many amps it puts back into the batteries while its running, my stator only puts 10 to 15 back and I now charge mine and have installed a battery gauge so I can see what the charge on each is. Bought a new battery from bass pro and could not get it to charge above 25% took it back and they gave me a new one. (these things do not charge like your car)

 

[Silvertip]

Re: Two Batteries and a switch

A little mis-information on charging two batteries in parallel (as is the situation with the switch set to BOTH). A single charger (just like the engine alternator and voltage regulator) monitors the electrical "system" and cannot differentiate whether there is one battery in the system, two batteries in the system or 10 batteries in the system. If there is one weak battery, the system will equalize at which point both batteries continue to charge normally. Diesel trucks can have as many as six very large batteries in parallel and they charge just fine. A "trickle" charger is just that, it is a very low output device that is not intended for keeping two or more batteries topped off. That's what on-board chargers are designed for. As for use of the switch, you can operate it any way you like as long as you understand the following:
OFF = Obviously everything on the boat is OFF except for an automatic bilge pump which should be connected directly to one of the batteries -- not through the switch.
BAT 1 = Battery #1 starts the engine and powers everything on the boat and it is the only battery being charged when the engine is running.
BAT 2 = Same as above but for battery #2.
BOTH = Both batteries power everything on the boat and both are being charged when the engine is running.

What's hard for people to understand is that all loads (circuits) are powered via the COM terminal on the switch. Anything less than that defeats the purpose of the switch.

 

[CharlieB]

Re: Two Batteries and a switch

Additional 'Notes' on Dual Batteries

Small outboard charging systems do not have much charging capacity, making for a very long runtime (at speed) to charge 'Both' batteries. If the batteries are very low as if you had to Pull-Start the motor or jump-start, charging both batteries could seriously overload a small charging system.

Most battery selector switches are NOT a 'make-before-break' and should NOT be switched while an engine is running. The momentary 'break' in the charging circuit will 'spike' the alternator charging circuit and can cause a rectifier/regulator failure. ONLY switch selector positions with the motor turned OFF.

If you are concerned about evening out the battery usage and increasing battery life, use battery one on the trip out, when you decide it's time to return simply shut down, switch to battery two to start up and make the run back in. Roughly even out the run/charging time between the two.