for those running 2 batteries

i know most of you say to use an isolator and then there are a few who just use a switch. from what i have read so far is that the switch is the cheaper way to go but the isolator is easier and better.

i am planning on getting 2 optima yellow tops to run my system. i have a pair of B530's and the 4 speakers and 1 sub in my boat. i also the boss 5 light bar, but never use it. using my phoenix gold tantrum 500 amp and one of the stock clarion amps, i have 2 main questions.

2 questions... do you think the extra money for the isolator is worth it? also, how often do you charge your batteries? i should be ok with using the slow trickle charge during the week and then using the boat all weekend, shouldnt i?

also, any diagrams of the 2 battery setup would be great.
i already tried looking in past posts but couldnt really find the answers i was looking for. maybe i just didnt look hard enough.

thanks

(Message edited by mossy44 on March 14, 2003)

I use the stinger relay which works awesome and I bought for 15.00 at www.ampman.com

Matt,

I run two batteries with a 1 / 2 / all switch and it works fine for me. People will say that "human error" may leave you stranded if you forget to change to a single battery when you are chillin listening to music. However, human error can also sink your boat if you forget to put the plug in.

From you system it seems you will not be using too much juice. I'm running a single 400W amp to power tower speakers and a 10" sub. We can sit for hours with the music at normal volumes and the boat will still start off the accessory battery.

I never charge the batteries during the week. That said, we normally launch and boat about 12-15 miles before we stop and ride.

I just got some B-530s with a 3 light bar.••••••• 1 amp running the tower spkrs and another running the cockpit spkrs and 2 10" subs. Supposed to get it back this afternoon!!!! I can't wait. I did get another battery but I am not sure what the dealer installed. I'll put some photos up tonight. Providing that he gets it to me today. How do you guys like the b-530's???????

alex

I'm running two batteries and a simple 1/2/all switch. I got two of the biggest walmart marine batteries. I just leave the switch on one battery all the time with the other battery in reserve "just in case". So far I haven't needed it. Of course, you only need backup stuff when you don't have it. I flip the switch every couple of weeks to swap the main and backup battery just so they both get regular use. I also occasionally top them off at home with the charger.

The basic battery switch is about $25. You could always start with that and change it to an isolator later.

Check out westmarine.com for some good diagrams and discussions about dual battery setups. Its in the help section or howto section, or something like that.

Go with the isolator. The switch does not isolate the batteries in the "both" position. If you have one dead batt, and switch to both to charge the dead one, the good batt. dumps into the dead one, possibly ending up with two partial charged batts and maybe not enough power to start.

As far as wiring, there is a couple of ways to do it. I would call the manufacturer of the isolator and ask their tech. boys for help. If you use www.hellroaring.com they have e mail or phone in tech. help.

(Message edited by sdub on March 14, 2003)

Seriously...take a look at this.
www.ampman.com/products/details.asp?id=755

or look at the stinger website at them for a full wiring diagram.
it works like a champ.

I have never had a problem with the relay and I am just using two interstate marine batteries with the relay and have run the stereo for hours without the motor being started. FYI: I am running 1400 watts with orion amps.

we got an isolator in our new boat. there wasn't much price diff. and now it is idiot prof.

The problem with isolators is that they have a 0.7 volt drop across the terminals. This is pretty significant when you are talking about stereo amps.

In my research I've found that a "battery combiner" is the best choice. It only draws .00005 amps - that's only 1 amp hour every two years! The battery combiner allows the house loads to run off one battery, and the starting to run off another - with no need to ever touch a switch. When the boat is running they both charge.

Here's the wiring diagram for the battery combiner:
http://www.yandina.com/acrobats/C50Data.pdf

You can actually use one switch (1/2/both/off) with this system and it works great.

Here is a great article by West Marine on "creating a reliable battery system":
http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorDisplayView?storeId=10001&langId=-1&catalogId=10001&advisor=464-465.htm

relay has no resistence

Those Stinger relays look like a really simple, inexpensive option to isolate batteries. The one disadvantage they have to a a combiner is that there is no switching system as far as I can tell. With the combiner and a switching system if you ever have a problem you can:
1. Start your boat using both banks.
2. Run DC Power from both banks.
3. Take all power away from all electronics in case of a fire/short or whatever.

For the simplicity though, the Stinger looks like a great way to go - definitely way easier than setting up a combiner with switches.

ty - what do you mean "realy has no resistance"

stinger claims there is no voltage drop on the relays whereas you have voltage drop on isolators.

Here is the way they work.
when the ignition is on the batteries are bridged therefore charging both batteries with the alternator. when the ignition is off it isolates the two batteries...one for starting and the other for stereo.

the www.hellroaring.com , is not a regular isolator with the .7 volt drop, it is way superior to a standard diode isolator (dont have one yet but its on the list), the relay will allow the current from one battery to dump into the lower one (from sitting and running radio) so if you wind up shutting the boat back off shortly after you may still be stuck with two low batterys, the isolator will not allow current to flow from batt 1 to batt 2 unless you set it up with a switch that you throw to allow current to go from say your access/radio battery to a low starting battery

Relay contacts switching DC arc and carbonize and will develop a voltage drop over time until they eventually fail. They spark, so you should mount them somewhere where they won't ignite hydrogen from charging batteries or gasoline fumes.

psyclone - what will "a voltage drop over time" do to my boat? what does that drop effect? just the battery?

also, ty - where did you mount your isolator. did you mount it away from your batteries like psyclone said?

the drop means your batties will be .6-.7 volts lower then they should be (not charged fully), this causes the batteries(so ive heard) to not last as long

No, not with the Hellroaring Isolator. It is basically a short when turned on. It is a solid state relay device (safe, no sparks) that has very low resistance, .008vdc. Unlike a diode isolator that will drop .7 vdc by nature. The cool thing about the Hellroaring is that it can be configured so that it only turns on and combines the batteries when the input (charge)voltage is above a certain level, say 13.4vdc. That can prevent battery discharge through shorted alternator diodes, etc. Mechanical relays can do the same stuff, but they wear out much more quickly and there is more of a spark hazard. They develop a voltage drop over time, granted, smaller drop than a diode isolator. Either relays or SSR isolator is the way to go, SSR is more expensive but safer. Smaller than huge 80 amp mechanical relays, too.

porter, Thanks for the link to West Marine. They explained it well. I just bought a second battery a couple days ago and was just going to buy a 1,2 both switch. I think I will take West Marines advice and buy two more on/off switches and their Combiner 50.

I put a simple Bosch relay in the positive between the two batteries (different batteries, one interstate and a cheap one from wal-mart). When the ignition key is on, they are both connected so they will power the starter and they both charge, like in the diesel pick up trucks. When the ignition switch is off, the cheap battery powers the radio and amp. Cost: $4 for the relay + $1 for cables = $5, no voltage drop and no confusing signals to the alternator's voltage regulator. The easy place to hook the relay is the input side of the balast for the coil on the back of the engine. Has been working great for over two years. Never had to trickle charge the battery, even in winter! Send me an e-mail if you have questions.

Alejandro, i think you might have something there but id be sure to use one with a higher capacity then 30 amps. Im going to have to look into that.