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Dual battery question
Posted: Tue Jun 14, 2016 8:19 am
by djmodifyd
Hi all, I'm new to boating...so bear with me.
I've been reading about dual batteries, but I'm not sure what the advantages are. I did search, is it basically just to be able to run the stereo/accessories without the motor running for a longer period of time?
What about master battery switch, my premier doesn't have one from the factory that I know of. Is it a big enough deal to try and install one? I'm on the boat a few times a week.
Thanks!
Re: Dual battery question
Posted: Tue Jun 14, 2016 1:22 pm
by jediger
You've basically got the idea. I've got a single battery right now, but am considering adding a second. My thinking isn't much because I listen to the stereo all that much, but because I'd like to add another fish finder or two and the bigger ones pull more power and are more finicky about their power source. I also like the peace of mind that comes from having back up power. We had a dead battery when we opened up the boat this year, but had to jump through a a couple of hoops to confirm that. If I'd had the second battery installed, I could have just combined power sources at the switch and tested with the second battery.
You can install a master switch pretty easily. You just might need to alter your cabling a little bit.
Re: Dual battery question
Posted: Tue Jun 14, 2016 2:03 pm
by rob28
We installed our second battery so that we can be anchored up all day, have the radio on, fish finder on, charge up phones, ipods etc and know we have a fully charged battery ready to start the motor at the end of the day.
Re: Dual battery question
Posted: Tue Jun 14, 2016 5:38 pm
by Crest_02
+1 with rob28. I just finished our add a battery install last month. It is nice to know all house loads are on one battery and starter has its own battery.
Re: Dual battery question
Posted: Tue Jun 14, 2016 6:54 pm
by Capt Sully
Here ya go.

- StandardBatterySwitchWiring.jpg (27.35 KiB) Viewed 13869 times
Re: Dual battery question
Posted: Tue Jun 14, 2016 8:26 pm
by tadams
I've always added a second battery & perko switch to every boat I've owned. I also installed an on board dual battery charger/maintainer that I plug in every time we come off the lake. Also have the longest jumper cable that I could find. The only thing I don't have is a jump box. All it took was one time having a dead battery & I told myself that this won't happen again.
Re: Dual battery question
Posted: Wed Jun 15, 2016 6:44 am
by rancherlee
I ALWAYS add a second battery and leave the starting battery to do its ONE job. I just run a simple 50amp kill switch that I can flip on or off to charge the 2 battery while the engine is running, only need to run 8 gauge cables that way since a deep cycle rarely takes in over 15amps of juice while charging, typically only 10 amps with a 14.4v charging source. My second battery is a pair of G27's mounted up front in one of my benches and powers everything on the boat.
Re: Dual battery question
Posted: Wed Jun 15, 2016 9:14 am
by rsscoggins
I always add a second battery and set it up just like the picture that Capt Sully posted.
I alternate which battery I used. One day on battery 1 - driving and parked at the cove. Next day on battery 2 - driving and parked at cove. If I wear down one battery, I have a spare to get me home. Knock on wood, never been stranded in the party cove due to a dead battery!
A second battery give you piece of mind!
Re: Dual battery question
Posted: Thu Jun 16, 2016 4:09 pm
by djmodifyd
Thank you everybody!!
Re: Dual battery question
Posted: Mon Jun 20, 2016 7:23 pm
by tka
Another option is to use an acr add a battery kit. It comes with the traditional switch allowing you to use either of the two batteries and an acr switch. The acr switch allows complete separation of the two banks preventing accidentally running down your house and cranking battery,but also allows you to charge both batteries from your engines alternator at one time. The links below do a much better job of describing it than I can. I will be adding one over the next few weeks. Hope this helps someone.
https://www.bluesea.com/products/7650/A ... Kit_-_120A
https://m.youtube.com/watch?v=B4830QsybbM
Re: Dual battery question
Posted: Tue Jun 21, 2016 5:36 pm
by Crest_02
+1 on the add a battery by blue sea.
Re: Dual battery question
Posted: Wed Jun 29, 2016 1:42 pm
by gmdfst
I just added a second battery one start battery and one house battery, instead of a switch I used a battery Isolator by Battery Doctor the 150 amp PT# 20092 both batteries will charge when running and when the motor is off and the house battery volts drop it will isolate from the start battery and if you need extra to start you can push a button and it will jump both together to start.
seam to be working good.
Re: Dual battery question
Posted: Sat Jul 02, 2016 11:43 pm
by tuned
gmdfst and tka are both on the same page, but with different products. Although fancy, an ACR (automatic combining relay) is really a fine system. I don't even use a Master Switch any more. I can run my house batteries (2) to nothing and my start battery stays full charge-all fully automatic! I just monitor one LED from the helm.
Now the downside. A fair amount more expensive and certainly quite a bit of work to get it all right. I love it tho.
Re: Dual battery question
Posted: Sun Jul 03, 2016 5:56 am
by MH Hawker
i run just one battery but i added a perko switch so if i ever need one its a easy add. i use a group 31 battery works and it fine for what i do plus i only have a 15 hp motor so i can easily pull start it if needed