The Official Dual Battery Thread

[JimN]

Jim if I run an isolator or relay instead of the perko switch will I be able to run the cranking and deep cell? Or should I try to just get another deep cell or go all cranking? The deep cell I have is huge and gives me 710 CCA with 150 mins at 25 amps that is why the cranking is more of a back up.

If you get to the point where the big deep cycle is low (never kill it completely), just switch over to the cranking battery and run it back home. When you do this, use a charger on the deep cycle.

[JJMorris3]

Planning for dual battery - but have question

I have a 1994 Prostar 205. I installed a sony marine receiver (just a simple head, no amp, etc) and powered it from the harness that was labeled behind the dash. It powers when the key is in acc or ignition is on. I hooked up the memory thru the acc1 switch so I could control it - leaving it on during outings so I can set presets at the beginning of the day and they stay, but I can turn it off and know that I have zero drain.
I would like to add a dual battery with the relay setup because it seems like great piece of mind. In reading the instructions, I see that they say to move accessories to the second battery. Well, I went to the battery and expected to see additional wires for the accessories. But there is just one big cable on each battery terminal. There is an accessory wire dangling with a fuse on it that is not attached to the battery. it runs up the drivers side and under the dash. It is cut and capped there.
Do I need a dual battery setup for such a small radio? Should I wire just the radio to the second battery using the unused wires rather than the dash/harness? And leave all other things as they are? Then the second battery will be for JUST my radio?
I was hoping I could feed all accessories somehow by using the harness. I would need to know where the harness gets its power for the accessories and hook the secondary battery up there. Then I would have the dual battery protection when I used lights too while floating at night with the motor off.

[rspiecha]

Having owned a 1994 Prostar 205, there no convenient place to put a second battery. I would get one of those portable jump battery pack and keep it under the seat for situations where a second battery would come in handy. With your stereo configuration, it would take a very long time to drain the battery, unless you have a weak battery to start off with.

Rob

[JJMorris3]

Thanks for the reply. I might just do that. I am also a bit nervous about adding a relay in the compartment behind the back seat where the gas tank is. If that thing arcs while there are fumes built up in that compartment that would not be good!

[brucemac]

there are plenty of ignition safe combiner seperator options out there. just be sure to make sure it is and is rated for your alternator and you're golden.

[5280Hawk]

Wow, there is alot to take in, in here. I have a few comments, as i am about to install another battery.

I am doing a Perko switch the "1/2/both/off" type. Someone earlier in the thread said they fried their voltage regulator in their alternator by trying to start their boat with the switch set to "off" how is that possible? In the "off" position BOTH batteries should completely isolated from the Boat, so you'd have no power,...right?

I understand you can do damage by switching the Perko to "off" if the boat is running, but not the other way.

Also with the switch you are isolating the Batteries from each other, but (at least the way im doing it) the rest of the boat's systems are going to be connected by the comm. post on the Perko. So I will be able to start the boat, run the stereo, lights, pumps, etc. with either battery, or both at the same time (not practical, or likely).

If you are on the "both" position, the Batteries are connected in parallel, and that will cause them to "equalize" the weaker drawing charge from the stronger which can be damaging if one is way down and pulls very rapidly, but what don't get is .....How does that efffect the Alternator as someone mentioned earlier??? Thanks guys this is a great thread.

[brucemac]

i'll take a shot at this. it's usually not an issue with the alternator unless you are running a larger stereo system with multiple batteries. if the stereo bank of batteries is constantly being drained down to low levels and the combiner combines both banks because the starting battery is full, then the alternator is constantly overworked with the engine on. stock alternators are not capable or designed to recharge multiple heavily drained batteries while maintaining electronics, guages, ballast and bilge pumps, etc. that's why if you're serious about your tunes and your stereo, you need to protect your investment by having a recharging routine off the water with a battery charger. most people don't consider upgrading their boat's charging system unless they're working with fairly large stereo system.

if you're going to go to the trouble of installing a second battery and a manual switch, i'd definitely consider adding a combiner/seperator. it will give you peace of mind, elminate the need to have to mess with the switch to charge and you'll still have the switch to turn everything "off" and manual combine in an emergency start situation.

someone else will probably come along and put in their two cents, but that's how i understand it.

[TX.X-30 fan]

Nice Bruce. More alt. is a good thing with these over-the-top stereo systems.

[thatsmrmastercraft]

i'll take a shot at this. it's usually not an issue with the alternator unless you are running a larger stereo system with multiple batteries. if the stereo bank of batteries is constantly being drained down to low levels and the combiner combines both banks because the starting battery is full, then the alternator is constantly overworked with the engine on. stock alternators are not capable or designed to recharge multiple heavily drained batteries while maintaining electronics, guages, ballast and bilge pumps, etc. that's why if you're serious about your tunes and your stereo, you need to protect your investment by having a recharging routine off the water with a battery charger. most people don't consider upgrading their boat's charging system unless they're working with fairly large stereo system.

if you're going to go to the trouble of installing a second battery and a manual switch, i'd definitely consider adding a combiner/seperator. it will give you peace of mind, elminate the need to have to mess with the switch to charge and you'll still have the switch to turn everything "off" and manual combine in an emergency start situation.

someone else will probably come along and put in their two cents, but that's how i understand it.

Very well said.

[5280Hawk]

The big reason Im Adding a Battery and the switch is peace of mind on the water. I dont have a BIG stereo - Im running basically two 6" speakers in the bow, and two in the aft and one sub, all from a single amp. I plan on adding two 6.5" speakers on the tower, and another amp. I also want to add a Light bar, possibly some underwater LED's.

I plan to use the switch to go to the second battery to play music, run lights ect. while floating around on the lake while the boat is off, saving the primary battery to ensure i have starting power when its time to go home. The perko was the best deal, and the easiest to wire up.

Have any of you guys used a bus bar set-up to manage the wiring when you have alot of "add-ons"?

[brucemac]

adding a combiner along with that switch isn't all that much more difficult and can used to achieve exactly what you're after with one great benefit: you don't have to mess with the switch or remember to change positions. get in your boat, turn it to "1" and enjoy your day. come home turn it to off, charge your batteries, etc. just saying it's not much more money and well worth it imo.

[BriEOD]

Nice Bruce. More alt. is a good thing with these over-the-top stereo systems.

Don't forget to increase the charging lead as well.

[bturner2]

I did the Blue Seas "add a battery" kit. If it wasn't for the poor wiring that I started with (see attached link for the details) this would have been an easy job that I could have completed in a couple hours.

http://www.mastercraft.com/teamtalk/...hlight=battery

There have been several other members that have installed this system and seem to be happy with the results.

[JohnE]

So I've read this thread once or twice a year for almost 4 years now....Each year I plan on installing it, then end up with a new boat instead.

I'm going to do Diesel's relay before the season starts. I think I am going to install a pushbutton switch in series with the purple ignition wire. Essentially the same as the OP, but when I know I've been floating for a while I can push the button while starting to keep the current from rushing from one battery to the other until the boat is started. Simpler than a timer/ relay combination. If someone else happens to start the boat or I forget to push the button, no harm done. But I'm sure I can get in the habit of using it when I think I've drained the battery substantially.

I just need to find a decent (normally closed) push button switch.....

[BriEOD]

Hey John the path to he'll is paved with good intentions...I guess we'll see if you do this.