Q's on putting in 2 Batteries

I have a 1987 sunsport w/ 454 in it. I am going to install 2 batteries in it this weekend. I will be using the 1315 Sure Power that everyone is using. I am wondering what kind of batteries to use in this application. I am on a budget so I was thinking of for know buying one Optima Gel Cell. So I guess the Question is do I use the Optima for the Starter or the Stereo. Also what color Gel Cell. I was thinking of using the Red top for the Stereo but I dont know. I have heard that people like to use the blue top but that just seems like to much for what I need. I am only hooking my Stereo to it I have no amps or anything that needs lots of power. Just have Cd/Mp3 and 4 Alpine speakers. Also some tips on how to hook up the 1315. Thanks

I am going to post up some pics to. I have been meaning to so I am going to just do it here.

I plan to watch this thread closely. My motor home has two batteries, one for the chassis, and one for the house. These two electrical systems are completley independant from each other, with nothing in common other than the power source (alternator). The alternator charges the two electrical systems via a solid state electronic thingy-mabobber. if one battery is discharged to a dramatically lower voltage than the other, this thingy-mabobber will make make clicking sounds, as I assume it is accomidating the low battery in some way. What I am getting at is that indipendant multi-battery 12v systems can be somewhat complex, and may involve more parts and cost than just a second battery and some wire.

Of course you could just add a second battery in parrallel, which will add battery capacity. This would allow you to run the stereo longer before you can't start the engine, but run the stereo long enough and eventually you will end up with a dead battery. Two separate systems means that running the stereo will never prevent you from starting your engine.

I am hoping someone with experience in creating such a system will chime in...

just installed 2 batteries in mine last weekend. bought a battery Isolator from northern tool Model# B-120A1B2E $39.95. put a deep cycle from napa $83.00.
you will have about $15.00 in cable and wire. the deep cyl only runs the amps and stereo

There are a few ways of going about a 2 battery system. I'll just mention the two I have experience with. Both have pros and cons in my mind. I have not used the Sure Power 1315 but I did a little reading about it and have a few comments and observations.

1. Isolator Setup

The first setup I had utilized a battery isolator as mentioned by angus above. I wired only the audio to the second battery. The batteries are wired in parallel with the isolator being on the + wire between the batteries. The isolator is wired to the ignition switch. With the key off, the second battery is "isolated" from the cranking battery. So, you aren't running down the cranking battery while listening to some tunes with the motor off. As soon as the key is switched on, the isolator closes the circuit. You'll be cranking off both batteries and both batteries will be charging off the alternator while the motor is running. This sounds great at first blush, but there is a down side. If the second battery is low, as soon as the key is switched on and while cranking, the second battery will draw from the cranking battery. The end result is that you'll have less cranking power than if the cranking battery was not also connected to the second battery. With all that said, I have used the isolator set up and never had a problem starting the boat even with a dead second battery. In this setup I would certainly recommend a quality cranking battery as it will be working over time on occassion. This is the cheaper of the options as the isolators aren't that expensive.

The Sure Power 1315 will alleviate some of this problem in the event the second battery is lower in charge than the cranking battery. But, if the cranking battery is lower than the second battery, it appears the 1315 will close the ciruit and crank off both. This would give you more cranking power than if you only had the cranking battery, but not as much cranking power as you'd have if you could simply crank off the second battery. Also, with the 1315, if the second battery is so low that it causes the system voltage to drop below 12.8 volts while the motor is running, it will isolate the second battery to avoid excessive drain on the craking battery. As a result, the second battery will not be charged. However, the Sure Power 1315 would help avoid being left on the water without a sufficient cranking battery as compared to a standard isolator. Again, I haven't used the Sure Power 1315 but these are my observations from reading the product information.

2. Perko

The second option I have experience with utilizes a Perko. It was installed on my current boat when I purchased it. The Perko allows you to select which battery you will be drawing from or charging. There is a setting for battery 1, 2, or both. While some still wire the audio exclusively to the second battery, my system is wired such that the entire boat will be powered by which ever battery is selected. The up side to this system is that if you run a battery down, simply switch the Perko to the other battery and fire up the boat. The Perko can isolate the batteries while cranking so you won't have the low battery drawing from the charged battery during cranking. Once the engine is running, you can select which battery (or both) to charge. I like this set up but it requires a little more attention from you. I'll explain. When I am cranking I generally select battery 1. If we stop to swim or just float around, I'll select battery 2 to listen to the audio. Then, I'll switch back to battery 1 to crank back up. After the motor is running I'll either select both batteries or just battery 2 to be charged by the alternator. Unfortunately, from time to time I'll forget to switch the Perko after we are underway and battery 2 will not be getting charge. So, in my opinion, you'll have to be more attentive to the system with the Perko. It's certainly more versatile and when used wisely it provides the best assurance of having a strong cranking battery. Again, keep in mind, you could still dedicate a battery to the stereo with the Perko. It's up to you.

On boats, I feel like quality batteries are a must. Boats can provide enough headache on the water without having dead batteries. A cheap battery is just another thing than can leave you floating aimlessly. I like Optima batteries (although I had one fail in less than a year in my last boat - I'll chalk it up as a fluke). For the second battery I'd recommend a deep cycle. Many may recommend a deep cycle for both batteries. But, I've had good results with a standard battery as the primary cranking battery. These are simply my opinions and take them for what they are worth.

I hope this helped a little and didn't just further confuse the issues.

Shannon

Timely question 87 - add me to the curious list.

I've got the 1315 sitting on the shelf (for when I reach that point in the rebuild) plus an Optima blue top that came in the boat. Looking for ideas for the second battery, as well?

Another question is should I run all the accessories (stereo, amps, bilge, blowers, lights, etc.) off the auxillary 2nd batt & leave the primary solely for starting? Or just the stereo & amps (~1000 watts) off the second? How do you guys have it all split up?

Also for those with the 1315, do many of you tie the "auxillary assist" circuit to the ignition key for automatic boost starting (I saw one poster? that went the manual switch route)?

Thanks.

I installed the Sure Power 1315 and a dual battery setup before the 4th and it worked out great. I ended up useing (jonyb is gonna shoot me in the head!) an Interstate SR-29 deep cycle and already had a standard marine Insterstate for the starting battery. Setup was very simple just daisy chain the ground and run the hot wires to the 1315. The stereo is wired up stock to the cranking battery then I ran all the amps and fat sac pumps off the deep cycle. I have 2 amps one is 900 Watt RMS and the other is 400 RMS.

I did not hook up the auxiliary yet but I plan to just run a switch. I'd rather not mess with my ignition switch, but thats just me.

Last weekend we ran the stereo with the motor off for about 6 hours straight. The I ran it at the camp site for about an hour or 2 every night. The only charging I did was with the stock alternator so I might just charge the deep cycle over night before I go out again.

I run two batteries with the Perko switch. both are deep cycle, and have 1000CCAs. They never hesitate to start the motor, and can last a darn long time. They do however cost over $100 a piece, which was a swift kick in the wallet, but worth the piece of mind.

They're the Duralast Marine dual purpose batteries. They can be charged as a normal battery, and don't require a trickle charge (per Autozone recommendation). They also have a few years of warranty, so you're set to go for a while.

I put this in. Isolator and selector switch. Therefore, it charges both batteries when running, separates when not, and I have the option to put on 1,2,both,off. By selecting the battery, it chooses what one is monitored to stay full.

http://www.amazon.com/714-100A-Batte.../dp/B000NI5FAE (shop around for price as I got it cheaper).

Both batteries are deep/cycle/starter (with CCA 650 I think).

I don't have a huge stereo system, but we do listen to it while on the hook.

Positive wire from switch to both batteries. Stereo/Acc's are wired to one battery. I leave the switch turned to then monitor the other battery for the starting one and leave it set.

Advantage over the Perko alone is no longer needing to remember to switch off of all or alternating which battery it is run on which day.

Well i got the new system all hooked up. I couldnt have picked a hotter weekend ,107 degrees all weekend. It must have been 115 in the garage! Anyway the 1315 worked great out on the sand bar this weekend. I ran the radio all the way up for about 4 hours and it then started to cut out (Bad Battery). I hopped in the boat and she fired right up, man did that feel good cause it does always end up like that... I do have more Q's thow. How do I hook every Accessory up to that battery? run another switch or something ? Because when I want to run the radio I have to push in the power button next to the key and the accessory button too. The radio power line coming out of the radio is hooked up to the 2nd battery. In the future I want to run amps and subs. So I guess now I am curious as to how you all hook up your amps,subs and pumps along with anyother extra things you are running.

Quote:

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Originally Posted by 87sunsport454

Because when I want to run the radio I have to push in the power button next to the key and the accessory button too. The radio power line coming out of the radio is hooked up to the 2nd battery.

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Hi 87,

I am a little confused. You stated that you power your radio from the new auxilary battery, which makes sense. But you also stated that you need to energize the master systems, and the accessory circuit to run your sound system, which I presume are still connected to the main battery. I get the sense that you may not have connected your stereo to the aux battery, that it might still be connected to the main battery via the accessory bus. Your stereo may have more than one electrical input, such as power antenae, or memory circuits. I am speculating that you may not have all of them connected to the new aux battery?

As far as the rest of the accessories, you could disconect the circuit breakers/fuses from the main battery, and wire them to the new aux battery. I wonder if this is a good idea though. Most every accesory that I can think of probably should be energized when you are driving (lights etc), and therefore powered by the main battery. Maybe you have some auxilary deck lighting (LEDS etc) that could be run from the aux battery. In that case, I would create a new circuit by installing a new curcuit breaker or fuse and a control switch, powered by the aux battery. If these aux circuits didn't function it wouldn't ruin your day, and you could still get home.

That is what I was thinking is that there must be another power wire coming off the radio. It was way to hot to go digging around under there to have a good look.

If I can get the radio to run without the master button pushed then I would not move any of them. To run amps and such do you still use a circuit breaker or just a on/off switch so when you park you just turn a switch off? Are breakers/fuses needed for this stuff?

The circuit breaker and the fuse accomplish the same task. You can user one or the other. Fuses work one time, but they are cheap. Circuit breakers are re-settable (reusable) but cost a lot. The function of circuit protection is to protect the wire, not the equipment (most modern equipment feature built in protection) from excess amperage (current flow). If something caused a hot short, the wire would quickly overheat and ignite if something wasn't able to remove the flow of electricity through the wire. The fuse or circuit breaker offers this protection. To design an electrical system correctly, it should feature circuit protection of some sort.

In order to size the circuit breaker properly, you need to know what size wire you should use on the circuit. To do this you determine the load that the equipment draws, and you factor in the length of the wire (to account for voltage drop). The result describes the wire size. Then the circuit protection can be determined to protect the wire size/length chosen for the given load.

Try this calculator, as it will select both the wire size and the circuit protection value required for the circuit: beta.circuitwizard.bluesea.com

If you have equipment that you wish to control by one common switch, such as amplifiers and the stereo deck, they could be wired in parallel on a common circuit and switch if the combined loads are not to large. Otherwise, you may wish to use a relay on the switch circuit which in turn energizes the larger circuits that feature their own circuit protection.

Most modern stereo decks feature outputs that will energize the amplifiers so that they turn on when you turn the deck on. This simplifies your life, as you don't have multiple switches, and you won't accidently leave your amps powered unintended. But, this output probably will not be adequate to power large or multiple amplifiers. This circuit could be used to energize a relay, which could then energize a properly designed circuit featuring circuit protection for each amp. This concept would not feature any switches, as your deck already has the on off switch built in, but it would feature seperate circuit protection for the deck, and each amp.

I hope this helps, hit me with any additional questions...

With the combiner in my system, I have a 1/2/all/off switch that has a common post. The stereo is directly wired to battery, the accessory is wired to the common post. Therefore, it will work off whichever battery is selected. Hope that helps.