Battery Wiring

[felizcortez]

I have drawn a hookup diagram of how my batteries are currently connected and had a few questions. The connecting wires in the diagram are how things are actually wired. They represent the physical wires not a schematic.

1. The house bank and the starter battery negatives are hooked together as shown in the drawing. Should the start battery go to the boat ground bus bar separately from the house bank or is okay how they are connected?
2. The battery charger ground is only hooked up to the starter battery ground. Electrically that is connected to the House bank, but i've heard that you should put the positive charging wire at one end of the parallel bank and the negative at the other end to make sure that the current is flowing through the bank.
3. Do you see any issues with the attached? I'm converting to 4 x 6V golf cart batteries and want to make sure that I'm wiring this up optimally/correctly.

[smac999]

You can not directly wire the alternator to both batteries

[transmitterdan]

Originally Posted by smac999

You can not directly wire the alternator to both batteries

Why not?

[transmitterdan]

The main problems with that setup are there are no fuses on the house bank batteries as required by ABYC.

Also, the wiring to the house bank is not optimal. Check with the battery manufacturer and they will show the correct wiring sequence so that all parallel or series/parallel batteries are charged and discharged equally.

The alternator is wired directly to the starter and house bank. Therefore your battery switch is bypassed. Probably with too small wire size. This could be dangerous. Investigate getting a automatic charging relay or an eco-charger.

You should have an ABYC electrician look at this system and make the needed changes.

[Wotname]

^^ unless the alternator has two isolated outputs (unusual??), the 1/2/both switch becomes redundant as the house and start batteries are permanently connected at the alternator terminal.

[transmitterdan]

I guess it’s possible there are two sets of rectifiers inside the alternator. That would be unusual.

Would be interesting to know the make and model of alternator.

[felizcortez]

So I did a bit more investigating today on how the batteries are hooked up and drew a new diagram.

What I thought was an alternator cable is a power cable to the stereo so it doesn't lose it's presets. Tracing this wire took a long time.

There is a second cable which appears to go to the instrument panel/gauges in the cockpit. I need to investigate this one further when I head back to the boat.

The alternator appears to charge the system through the start cable which goes through the 1 both 2 off switch in the system. So it would charge whichever battery is currently selected. I believe I would rather have this dedicated to the house bank so that you can use a battery to battery charger to charge up the start battery.

[transmitterdan]

You need some fuses in that system. Are you leaving them out of the drawing or are there really no fuses at all?

[felizcortez]

I didn't see any fuses installed between the batteries and the switch. I know ABYC requires them within 7 inches of the batteries so I am going to rectify that.

If I parallel two batteries together do I need 2 separate fuses or just one for the bank?

[kmacdonald]

Originally Posted by felizcortez

I didn't see any fuses installed between the batteries and the switch. I know ABYC requires them within 7 inches of the batteries so I am going to rectify that.

If I parallel two batteries together do I need 2 separate fuses or just one for the bank?

Just one.

[Kelkara]

you have labled your batteries "house" and "starter", as long as you're aware that that's not really what they are ... you just have two battery banks, one twice as big as the other ... whichever is selected by the 1-2-both switch is serving as both house and starter, the other is just sitting there in reserve.

[dkenny64]

like others have mentions. fuses..
diode isolator on the alternator output.


what about 2 battery bank switches..?
my boat has 2 house banks and an engine/start battery..
depending on switch selection I can start the engine from
1. its own battery
2. combine with either house bank
3. combine with both house banks


not mentioned
how are monitoring the state of the banks?


are you thinking about adding Solar/ wind charging??


-dkenny64

[felizcortez]

Originally Posted by dkenny64

like others have mentions. fuses..
diode isolator on the alternator output.


what about 2 battery bank switches..?
my boat has 2 house banks and an engine/start battery..
depending on switch selection I can start the engine from
1. its own battery
2. combine with either house bank
3. combine with both house banks


not mentioned
how are monitoring the state of the banks?


are you thinking about adding Solar/ wind charging??


-dkenny64

I was just trying to get a baseline of my current system. I'm planning to move to 4x 6V golf cart batteries and a separate bank for the starter battery.

Since I have it all disassembled it's a good time to do it correctly.

We are adding solar panels - about 450 watts worth on our dodger and bimini.

I plan to add a battery monitor for the banks something like one of the Victron ones.

[felizcortez]

Originally Posted by Kelkara

you have labled your batteries "house" and "starter", as long as you're aware that that's not really what they are ... you just have two battery banks, one twice as big as the other ... whichever is selected by the 1-2-both switch is serving as both house and starter, the other is just sitting there in reserve.

Yes, I agree you can call them bank 1 and bank 2. You can start the motor off either bank. The second bank is a starter battery though and not a deep cycle one so that's how I think of it.

[transmitterdan]

It sounds like you are on the right track. Just one opinion, I would recommend against a diode isolator. Instead I would choose an automatic charge relay or an Eco-charger to keep the start battery charged then leave all the charge sources for the house bank.

Technically you don't have to fuse the start battery but I would. Lots of good information here: http://www.pbase.com/mainecruising/battery_fusing