Connecting 2 12v's, TM, Graph, Battery switch together

[gixxer01]

OK...I will be wiring up the boat this week and had a question. I will do my best to explain.

I would like to add a second 12V battery to the 12v system already in place. It includes: 12V trolling motor, bow graph,MK deckhand anchor, battery selector switch, and MK-230 onboard charger. I have STRICT orders not to wire the batteries in parallel.

My question is: Is it possible to run all these add-ons by using the selector switch, and only pulling juice from one battery. I can't look at the switch, currently, and don't know if it has a positive output in which to connect the positive TM,Graph,Anchor leads to.

Question 2: I am fairly confident that I can connect all negative leads together, and still keep the batteries isolated from one another?

Qustion 3: Can I use the Battery 1&2 position of the switch to attach one lead of the mk 230 in order to charge both batteries at one time from one bank of the charger? I've read that charging two seperate batteries that are not in parallel will lead to overcharging if one battery is not working.

What possible advantages are there to keeping the batteries seperate? This would be much simpler if the old man would let me wire them parallel!!

[marine_man]

Can you explain your setup a little more?

The battery you currently have is a starting battery or a deep cycle battery?

The battery you're going to add is a deep cycle battery or starting battery?

What are you trying to gain by adding another battery? Longer trolling motor life, longer accessory life / etc?

Sorry to answer a question with a question.. but some clarification would help.

marine_man

[gixxer01]

The second battery will be an addition to the trolling motor battery. It currently has a marine deep cycle/starting battery. The hopes is to double the life of all the above mentioned accessories, which currently run off of the trolling battery.

[Esox_Magnum]

Trolling motor should be on a designated battry, everything else should be hooked up to the starting battery.

[marine_man]

If possible.. I'd put the trolling motor on it's own battery and the rest of the accessories on the starting / motor battery.

You could use the battery switch to charge both batteries from the same charger... depending on the amps on your charger that could be a slow process.

marine_man

[ScottsShopInHawl]

I'd connect the alternator from the boat to the trolling battery so the charging current does not affect the accessories (mainly locator/GPS) you have connected to the starting battery (they draw very little). If using an isolator switch then if you run out of cranking power, switch it to ALL to start the motor then leave it there until the starting motor is also charged.

[morepower02]

I'd connect the alternator from the boat to the trolling battery so the charging current does not affect the accessories (mainly locator/GPS) you have connected to the starting battery (they draw very little). If using an isolator switch then if you run out of cranking power, switch it to ALL to start the motor then leave it there until the starting motor is also charged.

The engine should never be wired to the trolling batteries. The trolling batteries should only be hooked to the onboard charger and the trolling motor. All boat accys should be hooked to the starting battery.

[ScottsShopInHawl]

Quote:

The engine should never be wired to the trolling batteries. The trolling batteries should only be hooked to the onboard charger and the trolling motor. All boat accys should be hooked to the starting battery.

Why should the engine never be connected to a single trolling motor battery?

The charging system adds junk lines to your locator & I've seen it cause issues with GPS's as well.. Much clearer if the digital electronics are NOT on a battery being charged

[jeffreyd]

why not use a battery isolator that way you can hook up to one battery and save the other for starting etc.

[Esox_Magnum]

25 years and many different locators hooked up to my cranking battery without any having any interference.

[ScottsShopInHawl]

25 years and many different locators hooked up to my cranking battery without any having any interference.

35 years and I never noticed interference until the past 6 years. When sensitivity is cranked while searching for bait pods @ higher speeds, there is a difference in clarity.

An isolator is the way to go if looking for the spot on the spot.

[morepower02]

Why should the engine never be connected to a single trolling motor battery?

Most deep cycle batteries do not have high enough marine cranking amps [MCA's} for larger outboards. For example a Optimax requires 1000 MCA.

The other reason is the deep cycle battery will not last as long if it is hooked to the engine and always being charged without the battery ever running low.

[ScottsShopInHawl]

For some reason I assumed this was not a big outboard and Chris is right for larger higher output alternators.

I run 4 batteries (5 this week when my new Terrova 101 I-pilot gets here:) and 1 is for starting, 1 for accessories and 2 for (24v trolling motor). I use a Guest switch to continuously charge the starting battery, plus the acc. battery if needed. Trolling has their own.

Here's a good link Battery wiring diagrams