Isolator Type and question on battery

Pop Addict · Criminal Joined: 25 Jun 2010 Posts: 79

From all the posts I've read on here, there seems to be a general concensus that a perko switch and isolator are the best way to go for a dual battery setup.

I currently have a Duralast marine battery (685 CCA) that I bought last year, and I want to add a second battery for some tower speakers and amp that I'm about to buy.

For both the switch and the isolator, can anyone recommend a product? I got confused in one of the posts when someone said some isolators also require a coil fuse or something??

For the second battery, I assume I should get a Deep Cell, correct? Do I need to get the same make and model as my Duralast? I hope not, since I don't think that my Duralast is a Deep Cell.

Brit Rider · Posted: Apr 24, 2011 12:54 pm Post subject:

Pop Addict, Actually, generally an auto relay solution tends to be the preferred method, unless you are running more than 2 batteries at which point more complex and expensive split-charge solutions come in to play: but you needn't worry about them right now.

For now, sit your new battery (in a battery box) in an area that you are happy with; next to you're current one is ideal.

Then simply run a ground cable between the neg posts on each battery (4AWG) and then a Power cable between the pos posts (again, 4AWG) - however, on this cable, fuse it with a standard inline fuse rated at around 60-80Amps, and throw an isolating relay on this cable too. The relay wants to be rated to around 180 amps continuous in my experience.

The relay will need a power feed and a ground. Ground it to either battery neg post and give it power from an ignition source in the boat (Generally found on the engines wiring loom - often purple, or at the ignition key). Fuse this to 5 amps and use 15 amp cable. A multimeter will be your friend in finding this cable and should be a staple in any boat users toolbox.

Fundamentally you want to be in a situation where when the key is in the 'on' position that the relay is receiving power so that it is in the closed position. This allows power to run between the two batteries (Inc charge from the alternator). As soon as you turn the key to off, or ACC (as you would when you're chilling, listening to the stereo), the relay should no longer be recieving power and thus you have 1 battery that is full and one (the originaly battery in your boat) running all your ancillieries such as stereo. You can then kill this battery, happy in the knowledge that when you go to start the boat that the relay will snap closed and provide juice from the fully charged (newly added) battery. The boat will gladly start with one knackered and one good battery and will then charge the dead one.

As for battery selection, you need a deep cycling unit, ideally gel type. Something like an Optimae Yellow Top will work but I know many on here have strong opinions on what batteries they have allegiance to s they can chime in with what they like.

Hope this helps! If you are uncertain at all about anything above please ask and I or someone will clarify.

Good luck!

Mike

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Mike, well done.
I was waiting for a response to this as well.

Brit Rider · Posted: Apr 25, 2011 4:10 am Post subject:

Ryan - No problem! Gad its useful to you.

Sidenote:
You'll still want to ensure you have an isolator between your boats electrical items and the battery (now 'battery bank' if you have added a second batt). This will stop the batteries getting drained.

The only things that should be permanently connected to the battery/batteries are:
- Stereo memory cable
- Bilge pump

Everything else should be on the isolator (inc Amplifiers).

Happy Boating guys!

Mike

Pop Addict · Criminal Joined: 25 Jun 2010 Posts: 79

Brit Rider, Thanks.

Here's the switch and isolator I've ordered: http://bluesea.com/category/2/productline/overview/329

I also got an Optima blue top deep cycle AGM battery (didn't get a gel).

I was going to install everything as shown here (look at the "INSTALLING THE ADD A BATTERY Dual Circuit System" section): http://bluesea.com/viewresource/1388

Finally, I was planning on setting the deep cycle battery only in a battery tray. I couldn't find a great reason why a box was necessary.

See any problems with this?

Brit Rider · Posted: Apr 25, 2011 7:17 am Post subject:

Pop Addict, Perfect! That's basically a kit with everything included so will work great for you.

And also, as a plus point, that blue top battery you ordered IS a gel battery... a very good one too! Very Happy

A battery tray isn't needed but a cheapo battery box or just some sort of basic tie down is needed. Fundamentally you need something that will hold the battery from moving.

Mikie

PimpinD2 · Posted: Apr 25, 2011 7:54 am Post subject:

Strnger makes a 200amp isolator which is water resistant as well and only $50.. but the one you bought hsould be great.

Okie Boarder · Ladies Man Joined: 03 Mar 2008 Posts: 10056 City: Edmond

Another solution...

http://www.allbatterysalesandservice.com/browse.cfm/4,2705.html

This is the route I went.

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

To all. So I thought about the whole isolator thing as well.
If you have the solenoid which is only "on" during run, why would you need an isolator as well?
I mean when the switch is off, the ACC batt would be disconnected from the Start battery.
So what is the need for the isolator? Why can't the amps be connected directly to the ACC batt?
When the boat is running the ALT will be charging both Batts.

PimpinD2 · Posted: Apr 25, 2011 8:32 am Post subject:

that puts more strain on the alternator. and also i dont have a solenoid

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

PimpinD2, Huh? Not having an isolator puts more strain on the alt?
So the isolator restricts the amount of current running to the second batt? I was under the impression that an isolator was just that, a diode.

PimpinD2 · Posted: Apr 25, 2011 11:07 am Post subject:

i guess there is a difference between isolators. The one i looked at were "smart" and would only charge 1 battery till it his 13.2v then switch to the charging the second battery.

Nor*Cal · Ladies Man Joined: 12 Jan 2003 Posts: 9479 City: Sac

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Nor*Cal, If you trigger the solenoid to be activated in the "RUN" position only and not on during "CRANK" it would be OK. But really for the 2 seconds that the ACC batt would try to drain the Starting batt I doubt you would see any noticeable power loss.
So if you do use the 12v trigger for the solenoid in the RUN as soon as you let go of the key from CRANK the solenoid would activate and start charging both batts.

Pop Addict · Criminal Joined: 25 Jun 2010 Posts: 79

What exactly is a Common Bus Bar? Is it a steel bar that grounds several things together? Where do I get it? I see it here: http://bluesea.com/files/resources/technical_briefs/Technical_Brief_upgrading_battery_switching_and_charge_management.pdf

jjaszkow · Posted: Apr 26, 2011 6:22 am Post subject:

Pop Addict, I use a distribution block for this, but you could simply tie the grounds together using cables if you so desired.

http://www.amazon.com/Stinger-HPM-Gang-Distribution-Block/dp/B001HC76NE/ref=sr_1_1?ie=UTF8&qid=1303827644&sr=8-1 is the one that I use.

Hollywood · Posted: Apr 26, 2011 11:20 am Post subject:

Brit Rider · Posted: Apr 26, 2011 1:27 pm Post subject:

ryan351w, you need an isolator so that when you leave the boat you can breka the circuit. Even when everything is switched off power is used and thus you'll end up with a dead battery unless you open the circuit. That's why you shouln't hook amplifiers etc directly the battery.... Always through an isolator.

Nor*Cal, Exactly. Though this is worst case sceanrio assuming you killed one battery. 9.9 times out of ten you'll just have one battery that is marginally down on power compared to the other. As soon as you start going to multiple batteries (more than 2) you want to go to a smarter system but this also comes at a financial cost. My way is simply what we use for customers when they want a simple, cost effective way of ensuring they can play tunes etc and guarantee the boat will start when they want ot head home.

Pop Addict, A 'bus bar' is simply a strip of metal where you can bring lots of connections together and run one large main cable back to the battery rather than having to connect stacks. You'll doubtless find a couple around your boat hidden away if you look for them.

Hollywood, It's certainly not instantaneous, but the power draw from the dead battery to the powered battery can be large (this is why you must fuse the supply cable). 60Amps is a sensible level as if the battery is trying to pull more than this then there is something wrong, for example:
1. you totaly discharged the battery... which would be hard with stereo equip and it generally shuts down at 11v'ish
2. The battery has failed.
BY fusing it, then the fuse will automatically close down the donnection leaving you still with 1 good battery and 1 dud. Voila - you can still get home Very Happy

All, Sidenote - NOt sure if I mentioned this but ideally with this setup you want ot be running identical battery types. NOt a must but it's much better to do so. 2 Optima Yellow Tops would be a good shout, or 2 generic deep cycling leisure batteries. Many go out and buy 1 posh battery and keep 1 chitty cheapo one... this, for many uninteresting reasons is not ideal.

Hope this helps,

Mike

Nor*Cal · Ladies Man Joined: 12 Jan 2003 Posts: 9479 City: Sac

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Brit Rider, wow ok something isn't clicking with me.
I looked up batt isolator relay for a schematic , here is what I found...
http://www.hifisoundconnection.com/Shop/Control/fp/SFV/30046/view_page/Battery_Isolators

Now this makes perfect sense to me.

What I'm not getting is this. If I were to run say one amp to the BATT 2 side of the Iso/Relay I would not be running directly to the batt, I would be connecting to the ISO/Relay. (I/R) ( Laughing

which is also 2/3 of Ohms Law) But just because the amp isn't directly connected to the batt how would it then be protected from draining that battery? Because really it is connected to BATT 2.

2nd related question; say I were to have another isolator connected off BATT 2 post of I/R. Then connect my amp to that. The isolator is a diode correct? Which allows current to flow in one direction. Which means it is still allowing current to flow to the amp.
I guess what I"m getting at is that in cars, people install an amp or two, connect directly to their one and only battery without ever having an issue.

Ryan.

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Nor*Cal, yup, fuse inline with the aux batt.

Brit Rider · Posted: Apr 27, 2011 12:47 am Post subject:

ryan351w, Great diagram! That's exactly what I've been talking about. Only differences would be that instead of grounding the batteries to the chassis (we don't have one in a boat), ground them to each other to complete the circuit.ALso remember that you're puttng all your power draw items on one battery and leave another with nothing ulling form it (the new battery).

Nor*Cal, Exactly. Just as shown in the diagram. Though personally I'd say 2 fuses on the powre feed is overkill (so long as the relay is rated for more than the fuse and cable is rated for as per my instructions).

Also, something tha diagram misses is a fused ignition source... make sure to fuse it Smile

Pop Addict · Criminal Joined: 25 Jun 2010 Posts: 79

You guys are a world of help here.

Now you got me thinking about fuses. Sorry for the dumb questions, but I'm a rookie with hooking up electronics. So with my switch and isolator combo that I'm about to start wiring up, do I ONLY need to fuse the power wire from batt 1 to the ACR and the power wire from batt 2 to the ACR? And what types of fuses? The chart on the link below says it's based on my alternator "charging amps"...but I'm not sure what my alternator rating is (I have an inboard if that matters). What about all the ground wires? Do I need to fuse those too? And I don't need to fuse the switch, do I?

http://bluesea.com/files/resources/application_briefs/app_brief_selecting_fuse.pdf

I've read in the bluesea briefs that I want to use 1/0 AWG wire for the ACR, and 4/0 AWG wire for the switch. Here's the setup I'm trying to use: http://bluesea.com/files/resources/sales_sheets/6833.pdf

Brit Rider · Posted: Apr 27, 2011 9:15 am Post subject:

Thats max cable size I think that you are looking at....

4 guage will be fine all round.

60Amp will be the appropriate fuse for you.

As for a relay, the one you've found look great, but I normally use something more basic like this:
http://www.rawcomponents.co.uk/100-amp-12v-relay.html

PimpinD2 · Posted: Apr 27, 2011 10:23 am Post subject:

now i am all confused.

Brit Rider · Posted: Apr 27, 2011 10:40 am Post subject:

PimpinD2, Haha, no good. Whats the problem?

Luckily, I know X1's fairly well so can guide you through if you need?

PimpinD2 · Posted: Apr 27, 2011 11:45 am Post subject:

i sent you a pm

Okie Boarder · Ladies Man Joined: 03 Mar 2008 Posts: 10056 City: Edmond

Just as an FYI, I went this route.

http://www.allbatterysalesandservice.com/browse.cfm/4,2705.html

Connection diagram...

http://www.allbatterysalesandservice.com/browse.cfm/6,2705.html

A few pictures...

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Okie, thats a nice relay right there...

browneye253 · Outlaw Joined: 07 Jul 2008 Posts: 115 City: Tulsa

Okie, did you make those cables yourself?

Okie Boarder · Ladies Man Joined: 03 Mar 2008 Posts: 10056 City: Edmond

Thanks Ryan. So far the initial test shows it's going to work well.

browneye, nope I had them custom made. Same company I used last year to make up the main battery cables.

http://shop.genuinedealz.com/

Pop Addict · Criminal Joined: 25 Jun 2010 Posts: 79

I got my new ACR and switch all hooked up, turned on the boat, and immediately blow the 80amp terminal fuse going from the switch to Batt #1 when I tried to turn over the engine. So then I tried a 100amp fuse...it blew. Then went to a 150amp and seems to work fine.

Could it be that when I crank the engine, the current is over 100 amps? Above someone said to use a 60 amp fuse, and the instructions call for around an 80 amp fuse. It seems strange I've had to go above a 100amp fuse to get it to stop blowing.

See any problems with my hookup?

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

If you have a fuse that is in-line with the starter....yeah its gonna blow at anything less than 150, i'm surprised it held at that....

Brit Rider · Posted: May 08, 2011 7:00 am Post subject:

Pop Addict,

Hook the starter up to the battery isolator switch (so it see's power when the switch is on and doens't when not), which should have no fuse between the switch and the battery as it pulls a ton of power.

Again this is all getting way over complitcated.

The fused power cable that runs to the isolating relay are literally only there to be carry charging current... they are not there to carry starting current.

The smart relays that many of you are using are more complex, expensive and not really whats required here...

ryan351w · Addict Joined: 26 Jan 2009 Posts: 532

Brit Rider, lol yup, i got mine for 8.00 from my parts dealer!