Dual battery or booster pack?

[carlos515]

The marina where I bought my boat suggested that instead of a second house deep cycle battery, to get a booster pack. I was thinking to put a second battery in for the stereo. Not sure which way to go. Looking for suggestions, or real world scenarios.

 

[Scott Danforth]

2nd battery and switch will be cleanest

 

[carlos515]

Thanks,
I have 6 feet from the switch to my house battery. Looking on the chart, could I use 2awg? My alternator only outputs 65 amps and my draw would be for lights and stereo.

 

[Scott Danforth]

2AWG should be fine. I personally ran 0000 in my project because i hate voltage drops of any kind.

 

[alldodge]

What are you going to use to charge the Bat, ACR, isolator or switch?

 

[carlos515]

What are you going to use to charge the Bat, ACR, isolator or switch?

I was going to use BLUE SEA SYSTEMS #9001E switch.

 

[carlos515]

I have a Stingray isolator, but I am not sure if I can use it. It is not a marine one.
SGP32 is the model.

 

[alldodge]

I have a Stingray isolator, but I am not sure if I can use it. It is not a marine one.
SGP32 is the model.

That model list as marine rated
https://www.amazon.com/Stinger-SGP32-Battery-Relay-Isolator/dp/B001HBYXVS?th=1

But I would recommend a ACR because they protect both Bats and charging is better
https://www.bluesea.com/products/category/35/Automatic_Charging_Relays

 

[airshot]

I would consider a LifePo4 battery, far longer run times between charging, lighter weight. I only charge my house battery after 3-4 all day trips....it runs everything except starting the main engine. And they recharge much faster.

 

[carlos515]

I would consider a LifePo4 battery

I just looked up a LifePo4 battery. Interesting battery.

That model list as marine rated
https://www.amazon.com/Stinger-SGP32-Battery-Relay-Isolator/dp/B001HBYXVS?th=1

But I would recommend a ACR because they protect both Bats and charging is better
https://www.bluesea.com/products/category/35/Automatic_Charging_Relays

ACR seems to be a good starting point. Would I be able to remove my dash electrical panel from the starting circuit, including the ignition?

 

[alldodge]

I just looked up a LifePo4 battery. Interesting battery.

ACR seems to be a good starting point. Would I be able to remove my dash electrical panel from the starting circuit, including the ignition?

No, the Helm the Helm is run from the motor, so "most" everything there connects thru the 10 pin motor harness

You could run a separate wires (+/-) from the house Bat up to Helm to run things like radio, fish finder, plotter, etc

If you do use a LikePO4 Bat than don't use a ACR and don't let your motor(s) charge in directly, it needs a special charger. The Bats are great and last a long time, but should be charged using shore power with specific charger type

 

[Scott Danforth]

the way I wired my boat. the key switch operates a set of electro-mechanical contactors that provide ignition power. the fuel pump relay, ignition relay, and gauge cluster run off that. the accessory terminal on the key switch operates a pair of 100 amp SSR's to power the house loads.

a 00 cable runs from the two house batteries to the buss bar. one SSR feeds all the lighting, charge sockets, and the head unit. the other SSR is strictly the amps.

the only thing going thru my key switch is the coils for the contactors or the signals for the SSR.

if running LiFePo4 batteries, you would need a separate DC to DC charger for them.

 

[carlos515]

Thanks for the info on the LiFePo4 batteries. I will stick with a conventional.
Scott, your setup is good, but I have a small area to work in. The boat has a fibreglass inner lining which makes for a more difficult working environment.

No, the Helm the Helm is run from the motor, so "most" everything there connects thru the 10 pin motor harness

You could run a separate wires (+/-) from the house Bat up to Helm to run things like radio, fish finder, plotter, etc

I was thinking of just running pair of 4awg from the house battery to the port side pedestal. Making a fuse block and run my amps and aux off this.
Now I do have an 8 awg cable running from the main battery to the fuse block under the helm. That is why I thought of putting the wire to the house battery.

 

[alldodge]

8 awg is more than enough for what you mentioned, most likely 10 would work

 

[boscoe99]

No, the Helm the Helm is run from the motor, so "most" everything there connects thru the 10 pin motor harness

You could run a separate wires (+/-) from the house Bat up to Helm to run things like radio, fish finder, plotter, etc

If you do use a LikePO4 Bat than don't use a ACR and don't let your motor(s) charge in directly, it needs a special charger. The Bats are great and last a long time, but should be charged using shore power with specific charger type

Mercury Marine has issued a service bulletin that approves a number of their models for use with lithium starting/dual purpose batteries where the alternator of the motor does all of the charging.

I suppose that on the basis that Mercury says it is OK, many Yamaha, Suzuki, Honda and Evinrude owner's are doing likewise to no ill effect. The need for motor maker approval not being needed.

Many of the lithium battery suppliers state their batteries are suitable for use with outboard motor alternators.

 

[alldodge]

Mercury Marine has issued a service bulletin that approves a number of their models for use with lithium starting/dual purpose batteries where the alternator of the motor does all of the charging.

I suppose that on the basis that Mercury says it is OK, many Yamaha, Suzuki, Honda and Evinrude owner's are doing likewise to no ill effect. The need for motor maker approval not being needed.

Many of the lithium battery suppliers state their batteries are suitable for use with outboard motor alternators.

The "Only" LIFEPO4 Bat approved for starting by Mercury Marine for there OB's are made by Relion
Bulletin