help with installing second battery

[natedog]

hey guys i want to install a second battery in my ss, i have a 600 watt and 500 amp and running it on one battery has been fine but i usually turn the boat on every 30 minutes so it doesn't drain all the way. Do i need a perko switch? if i dont when installing my second battery should i just run the negative of the new battery to the negative to the first and positive to positive, that would be "parallel"? correct?

[vr6mole]

Just add another battery in the other locker.

Negative to Negative.

Put a SurePower http://www.adventurerv.net/unidirect...or-p-4010.html between the positive cables.

Stock battery -> Positive cable -> SurePower -> positive cable -> extra battery.

All you need to do is ground the Surepower.

Hook all your stereo stuff up to the extra battery and leave the normal boat stuff on the starting battery.

When the boat is off the batteries will disconnect.

When the boat is started and you hit 13.2 volts on the starting battery the SurePower will connect both batteries and charge the stereo battery.

[natedog]

do i need the surepower between the posititives, i wanted to install the battery today but don't want to wait for the surepower.

[vr6mole]

you don't need it right away but your stereo stuff won't be "isolated" from the starting battery. You could run your stereo while the boat is off and be fine. You'll have more "capacity" so the both batteries would just drain slower.

[EarmarkMarine]

Yes, for now and in the most basic scenerio the Surepower will only interrupt the positive cable that links the two batteries.
It will have no impact on the interconnecting grounds.
However, when you get around to facilitating dual bank AC charging it will get more involved. And, you will be separating ALL stereo electronics from the helm buss and starter/alternator feed.

David
Earmark Marine

[ckdollar]

Do you need to upgrade alternators for this?

[TX-Foilhead]

Depends on whether or not you want the alternator to do some charging. My system is about the same size and the stock 50 amp alternator was about tapped out with all the other additions. I upgraded it to 105 amp which will enough charging to add to the battery so I'm good when we're running with just a single battery. A few times a year we do sit for extended periods so I went ahead an added a couple of stereo batteries to handle those situations as well.

[EarmarkMarine]

ckdollar,
There is no set answer. Whether or not you need an upgrade alternator will be determined by a number of factors including the output of your existing alternator, the size of the audio system, the total battery reserve capacity plus your typical stereo play at-rest duration and other boating habits. There are charging system schemes designed specifically to avoid an alternator upgrade. And, for some boaters the alternator upgrade is the only route that will match up with the boater's usage.

David
Earmark Marine
Lewisville Texas

[cdrymalla]

I am in the same situation as the OP, and I had a couple of additional basic questions.

1) Will the sure power allow you to run two different types/age/condition of batteries? In the past when I looked into doing this, it seemed like many people suggested waiting until I could buy two new batteries at once, so as to avoid connecting up two batteries with different conditions - expecting that the worse of the two would negatively affect the better of the two...However, this seems like it would overcome that potential issue as it addresses/charges the batteries almost seperately - one after the other.

2) Charging - Right now I have a sinlge C-Tek that has been great, and so I am looking at my options: (a) manually swap the C-tek back and forth (not too difficult b/c it is in my garge, but still something to remember) (b) buy a second C-tek Charger and run them at the same time on the two batteries (c) buy a dual bank charger....In each of these options, what disconnects need to be made - hard disconnect the negative and the positive? To me it seems like leaving the surepower alone as the disconnect may allow the batteries (and possibly the two chargers operating at the same time) to connect once the primary hits 13.2v.

Thanks in advance.

[EarmarkMarine]

cd',
If you are running two batteries on the same stereo bank then they need to be identical in every respect including age. If they are on separate banks then the issue is not critical as they are used very differently and will represent a different value very soon regardless. The fact that a single alternator will be charging two dissimilar battery banks is inherently flawed but an unavoidable conflict that comes with the territory. An alternator is limited to a maintainer and really isn't effective as an effective recharger. However, an AC shore charger should be viewed differently. An ACR/VSR serves to circumvent the dual battery isolation allowing for independent profiling and conditioning.
You have to have a manual provision to separate the starting battery from the dedicated stereo battery during shore charging. This is a must with any ACR/VSR unless its already built in. The SurePower requires a separate battery switch.
Ctek makes a good charger. Because of their use of pulse technology you can get the desulphation impact of a larger amperage capacity charger. The 3 amp model is good for a starting battery. For the stereo battery I would go with the 7 amp model.

David
Earmark Marine

[wake_fun]

For my SS I went with two Optima blue tops, a Perko battery switch, and an onboard Minn Kota (HERE) battery charger that hooks up to both batteries. When I get home after a day on the lake I just plug my boat into an outlet in my garage and it keeps the batteries charged up. I also bought the Correct Craft GT40 100amp alternator upgrade kit. Everything works perfect!

[EarmarkMarine]

^^^^^Its tough to beat the simplicity of the above set up. The charger is hooked up to the batteries permanently. Change the battery switch when you put the boat on the trailer and plug in the AC cord when you get to storage.

David
Earmark Marine

[cdrymalla]

cd',
If you are running two batteries on the same stereo bank then they need to be identical in every respect including age. If they are on separate banks then the issue is not critical as they are used very differently and will represent a different value very soon regardless. The fact that a single alternator will be charging two dissimilar battery banks is inherently flawed but an unavoidable conflict that comes with the territory. An alternator is limited to a maintainer and really isn't effective as an effective recharger. However, an AC shore charger should be viewed differently. An ACR/VSR serves to circumvent the dual battery isolation allowing for independent profiling and conditioning.
You have to have a manual provision to separate the starting battery from the dedicated stereo battery during shore charging. This is a must with any ACR/VSR unless its already built in. The SurePower requires a separate battery switch.
Ctek makes a good charger. Because of their use of pulse technology you can get the desulphation impact of a larger amperage capacity charger. The 3 amp model is good for a starting battery. For the stereo battery I would go with the 7 amp model.

David
Earmark Marine

That being said, would it be ok to have two different batteries (e.g., buy a new battery and link it up with my current an Optima Blue Top that is several years old and still seems to be strong) keeping in mind that I will charge them seperately. Thus, sure power connects the alt to both batteries in parallel when underway and over 13.2V, and when at home, simply flip a perko switch to completely isolate them and charge them sperately - whether it be two seperate chargers, a dual bank or whatever?

I guess what I am trying to decide is go ahead and buy a second battery and surepower now, or wait until my current one starts to suffer before going the two battery route. I want to make sure adding a surepower and combining a good battery wiht an old battery is not going to cause more trouble than it is worth.

I like the simplicity of the above too, but from what I read, both batteries are not charged by the alternator.

Thanks!

[wake_fun]

I like the simplicity of the above too, but from what I read, both batteries are not charged by the alternator.

Thanks!

I drive around with the Perko switch set to "Both", so I think it is charging both while running.

[EarmarkMarine]

ACR/VSR/combiner-separators or whatever you want to label them are generally misunderstood. There is lots of misinformation on this subject as well. It is precisely a depleted battery after a long duration at rest in combination with a large stereo and continued play that will bounce a voltage sensing solenoid back open after a trial and a failed attempt to close. While these are certainly convenient and can serve to protect your alternator, ACR/VSRs also can increase your dependency on AC shore charging. There is a ratio between alternator capacity, collective amp/hour reserves plus audio system wattage and current draw that will dictate the right scheme for a particular boat. One size does not fit all.
Yes, a properly wired and set Perko switch will always charge both batteries when underway.

David
Earmark Marine