trying to install second battery

[bigbotes]

By looking at diagram #1, this indicates that I would be starting the motor on both batteries correct?? Also would I just run a hot wire from the battery switch, lets say number 2, to a gang bus and then connect my accessories to the gang bus?? In a nutshell, PO had two batteries and the bat switch. When I bought the boat there was only one battery in there with the switch. I just want to run basically a house and starter battery. This crap is SO confusing. I have looked everywhere for a SIMPLE drawing, you know elementary style. Any help would be GREATLY appreciated.

http://www.overtons.com/assets/prodman/31620.pdf

[Capt. Bob]

First, fixed your link.

Second, from our Resource forum
http://classicaquasport.com/smf/index.php?topic=9053.msg79506#msg79506

These diagrams help you under stand what is happening with the different switch positions.

Diagram #1 (your link) is not what you are trying to achieve. You are correct on both batteries providing power when switched to "Both". Only one would be used in "1" or "2".

That stated, you want to wire the switch as follows:

Starting battery (let's call it #1) positive lead to post #1 on the switch.
House battery (let's call it #2) positive lead to post #2 on the switch.
Positive battery lead to engine from "common" post. (this allows starting from either battery or both depending on switch position.
Feed to you positive buss is connected to the "common" post also. This allows power to your accessories with the switch in any position except "off" (duh).

Now if the start battery is weak, you can switch to #2 or "both" to start ("both" using both batteries,again duh).
How you do your switching underway is a matter of preference. Some switch over after after starting while others switch when they reach their destination.

Wiring an accessory(think bilge pump, clock,stereo memory) off the #1 or #2 post ("not common") will provide constant power to the accessory even with the switch in the off position (recommended when keeping the boat in the water for storage(slip).

Use this link for ideas on wiring.
http://classicaquasport.com/smf/index.php?topic=9053.msg79505#msg79505

Simplest diagram I could find.
https://www.google.com/search?q=wiring+perko+dual+battery+switch&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwi0roDwrZ3MAhXEKCYKHVMhDeMQsAQIKQ&biw=1366&bih=659#imgrc=0FaIB_pDDBevBM%3A

Good luck.





 

[Capt. Bob]

I run two batteries but this is old school.

Gleaned from old thread:

A deep cycle combo start and "house" will work fine. I run two batteries but both are combos meaning I start and run accessories off one all day long. Stuff like the VHF, depth sounder, GPS and live well wash down pump and do fine. I just switch between batteries each time I go out. Key is a battery in good condition that is maintained between trips with a good charger. Personally I like the two batteries for a sense of security when offshore or if spending several days on the boat. Still, I can't recall switching over for some time. Batteries have gotten much better for this style use over the years.

Good reading:
http://classicaquasport.com/smf/index.php?topic=6643.msg47450#msg47450

[Brendanpd28]

Hey Capt. Bob is this basically what you are talking about? I know it's not pretty but this is a very basic setup. Please ignore the fact that in this drawing they are ALL switched accessories. You will obviously have a different layout for your gauges, bilge pump, etc... This is just to show the connections to the battery switch, fuse block, and motor.

Thanks!

[Brendanpd28]

And does this mean you need a separate fuse block for the accessories you want to remain hot all the time? bilge, clock, etc...  Because the main fuse block is connected into the "common" post.

[love2fish]

I think your negative leads on the batteries need to be looped together in addition to what you have drawn there. but double check that!

[Brendanpd28]

Ya the negative terminals are supposed to be connected. Oops

[love2fish]

normally if you have an auto-bilge pump- you run your hot lead directly from the battery and you have some kind of in-line fuse in a high and dry spot in the bilge (relatively speaking)... and if its a new (non-modified) wiring harness with your radio... usually the "clock" wire which will keep your time and preset stations has a small inline fuse also. could make things easier for you to run a secondary "constant" fuse block" SeaSense has smaller 4 and 6 post options.

your main fuse block will run off the output line on your battery switch so it runs on either 1, 2, or BOTH settings...

[Capt. Bob]

Also, don't forget what the purpose of a fuse is; to protect the wiring (not so much the device) from an over-current event. You would like the fuse to be as close as practical to the power source (battery).

The feed coming off the battery switch (common post) to your helm buss should be fused (say 40 amp,depending on the wire size of course) and if you run another wire from the switch (let's say #2) to a stern/cockpit buss, you'll want to fuse that as close as possible to the battery, again based on the size (gauge) wire you run.

Good luck.

[bigbotes]

Thanks everyone. I will go knee deep into it this weekend. If you see smoke billowing from the Jacksonville area that's just me catching something on fire lol

[wingtime]

You are describing a basic two battery system with a three position switch. It allows you to select which battery you want to draw from (and charge while the engine is running) and allows you to combine them if one or both batteries get low. Very simple batt 1, batt2, both, or off options. This is a good setup that has been the standard for years. However it requires strict battery management on your part. ie you start the boat on #1 and head out to your fishing spot. Once you get there you switch to #2 to run your livewell pumps radios etc on while you fish saving #1 so you can switch back to it to start your motor and go home right? Well not to confuse you but there is a much better automatic way to do it today. Take a look at a Blue Seas automatic charge relay and battery switch kit.

https://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A

 This will allow you to keep your house loads and engine batteries separated at all times automatically. This prevents power spikes to your electronics when you start your engine, keeps your starting battery separate from your house loads at all times, and it charges both batteries for you when it senses a charge voltage on either battery. Of course you still have the option of combining them in a pinch too.

[love2fish]

brilliant! definitely doing this upgrade soon.

[wingtime]

I actually have the mini add a battery kit.

https://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A

The switch is smaller as is the relay. You determine the amperage based on your alternator output. 65 amps is more than enough for an outboard powered boat.

Here is a pic of my install:


And basic wiring diagram:


Note this system will also disengage the relay from your house battery when you are starting your motor. (Yellow wire) This protects your electronics from voltage drop while cranking and spikes when the engine first starts.