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delaswim

Add a battery: Update 3/11/19

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Winter is driving me nuts and all I think about is getting the boat on the water.  I've got a 2003 Sunesta 243, that's only got 1 battery.  I'm going to add a battery and have looked into getting the Blue Seas Systems Add A Battery.  That set up uses a switch and an ACR.  After reading up, it looks like I need a fuse on each positive terminals of both batteries to run a battery cable to the ACR. 

My boat runs a 5.0 Mercruiser, and utilizes 2 awg wire from the engine to the battery.

I'm wondering how big of fuse do I need?  I thought 100 amp, but now I'm not sure.  Thinking that might be too much.

 

 

terminal fuse.jpg

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2 minutes ago, delaswim said:

it looks like I need a fuse on each positive terminals of both batteries to run a battery cable to the ACR. 

Not in all cases. 

3 minutes ago, delaswim said:

I'm wondering how big of fuse do I need? 

This will be dependent upon the size cable you chose to use and its length. 

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After reading up in my trusty Mercruiser manuals, I found the amp produced by the 5.0 alternator.  Looks like it produces 72 amps when cold, and 65 when hot.  I didn't know amperage varied based on temp.  

Does this mean a 75 amp fuse will be sufficient for the cable running between the positive terminal and the ACR?

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I just love this topic!!

Personally, I would not use that system for many reasons. I would install a basic dual battery setup.  As in   https://www.boatingmag.com/how-to-install-marine-dual-battery-system#page-5

Than install a battery combine which is a 3 wire install.   https://www.bluesea.com/products/7601/m-Series__Automatic_Charging_Relay_-_12_24V_DC_65A

Both installs are simple to do and give you more control.

 

Reasons not to use the add a battery kit. But in the right application as in windless, amps are fine. Not for starting.

1. You can not start your engine on ether battery alone.

2. If your #1 battery is dead, you must combine them. the poor or dead battery could suck the life out of the good battery.

3. Starting the engine on the 2nd battery alone, is a test that it can be done when the need comes. 

 

But thats me........... 

 

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NEVER use a older battery WITH A NEW battery.  Why ? Great question. Especially if the system is GOING TO PARALLEL them during charging. 

Old battery needs higher final voltage to reach maximum charge.

New battery WILL REACH maximum charge at a LOWER VOLTAGE

Some battery is going to get COOKED. The newer one.

Each battery should ALWAYS BE CHARGED SEPERATLY.  No way around this fact...……….. Why batteries die faster with goof ball hi tech chargers

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I've heard the same about adding a second battery and keeping it isolated and not charged in parallel.  I'm wondering if anyone has used the add a battery kit and had issues?  Seems like a company like Blue Seas would put in the R&D to figure out how to make this work.

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R & D is useless if they are not qualified.  Auto makers are still causing massive RECALLS. 

CHEAP  CHEAP...………. Too bad customer.  Slick pictures can sell anything. Add in the  "  Tell them what they want to hear.  " .

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   I had too much coffee this morning.

SOOO

Way back in time they had a simple relay that could only pick 1 battery at a time.  It was so simple to prevent over charging.  Even a Geico Caveman could trouble shoot it.      :clapsmiley:

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This is too simple.  On my SeaRay that I use to have I had two batteries, one was a starting battery and one a deep cycle battery used as the "House" Battery.  I did have them in parallel but connected to a switch that had battery 1, battery 2 and both.  I used my battery 1 as my starter and if my starting battery didn't have enough juice to start the boat, I put it on "both".  I only used battery two when I was at the dock or anchored with the boat off.  This made sure battery 1 was always charged and ready to start the boat.

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Forget I used the term in-parallel cause the batteries were not connected together.  The  Perko switch when turned to both provided power from battery two to start the boat.

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14 hours ago, delaswim said:

Winter is driving me nuts and all I think about is getting the boat on the water.  I've got a 2003 Sunesta 243, that's only got 1 battery.  I'm going to add a battery and have looked into getting the Blue Seas Systems Add A Battery.  That set up uses a switch and an ACR.  After reading up, it looks like I need a fuse on each positive terminals of both batteries to run a battery cable to the ACR. 

My boat runs a 5.0 Mercruiser, and utilizes 2 awg wire from the engine to the battery.

I'm wondering how big of fuse do I need?  I thought 100 amp, but now I'm not sure.  Thinking that might be too much.

 

 

terminal fuse.jpg

I'm guessing you want to keep the second battery isolated simply because you want to use it as a house battery, but your switch panel is not configured for more than one battery, is that correct? 

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The Add-A-Battery Kit has been around for about 10 years.  Despite my efforts to find negative reviews of the product, I can't.  I think I'm going to go this route unless someone with the system convinces me otherwise.

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3 minutes ago, Hatem said:

I'm guessing you want to keep the second battery isolated simply because you want to use it as a house battery, but your switch panel is not configured for more than one battery, is that correct? 

That's right.  My boat only has 1 battery at the moment.

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7 minutes ago, delaswim said:

That's right.  My boat only has 1 battery at the moment.

That's what I figured and just wanted to be sure before making any suggestions, as these important little details tend to get overlooked and lost on some who don't pay attention to them in opening thread posts. 

Have you looked into the option of replacing the switch panel to one that will allow you to wire your additional battery in 'banks' and give you more usage and charging options?  It might be easier and also give you better usage.  That is typically how almost all dual + batteries in these size- boats are configured.  Plus it gives you the easy and ever so important option of using them in parallel in those rare but emergency situations. 

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3 hours ago, delaswim said:

Does this mean a 75 amp fuse will be sufficient for the cable running between the positive terminal and the ACR?

This is the potential load that the cable and fuse calculations are based off of. But as noted, those fusses can be done without. Two less terminations to worry about, shorter cable runs

 

1 hour ago, delaswim said:

I'm wondering if anyone has used the add a battery kit and had issues? 

Yes, ive installed dozens and no, not one issue. There is no issue with installing a new house bank, while retaining the existing "old" cranking battery. They are only in parallel through the charge relay and the alternator will not overcharge one. When the boat engine is running, 90% if the alternator's output is just keeping up with the loads. Its not like a battery charger charging static batteries. 

 

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46 minutes ago, Water Dawg 6 said:

Forget I used the term in-parallel cause the batteries were not connected together.  The  Perko switch when turned to both provided power from battery two to start the boat.

I agree on your two points!!

Keep in mind what a battery combiner does when added to a basic dual setup. No matter which battery the switch is on, both batteries will be charging when the engine is on. When the engine is not running, the batteries are not combined. Its simlpe, its easy, less complicated and gives you full control.   

With this setup, I would alternate between batteries in starting. One, to use both equally. 2nd, to know that ether battery can start my engine with out the help of the other. This will give you some indication of its condition. You CAN NOT do this with the add-a-battery kit.    

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What I don't want to do is lift the engine hatch every time I need switch between house and start batteries.  My friend who has to do that hates it.  This system is pretty straight forward:  Turn the batteries on when you leave, off when you get home.  Done.

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2 minutes ago, Was_Wylie_Tunes said:

This is the potential load that the cable and fuse calculations are based off of. But as noted, those fusses can be done without. Two less terminations to worry about, shorter cable runs

 

The fuse I pictured connects right at the terminal, so battery cable length is unchanged.  I'm happy to spend the money to ensure the system functions like the manufacture intends.  Short cuts will only cause problems.

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28 minutes ago, Hatem said:

That's what I figured and just wanted to be sure before making any suggestions, as these important little details tend to get overlooked and lost on some who don't pay attention to them in opening thread posts. 

 

Uhhmm.. He states that he only has one battery in his opening post....  Pay Attention  :haha-7383:

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8 minutes ago, delaswim said:

What I don't want to do is lift the engine hatch every time I need switch between house and start batteries.  My friend who has to do that hates it.  This system is pretty straight forward:  Turn the batteries on when you leave, off when you get home.  Done.

Than your switch is in the wrong place. Which ever way you go, I would move it. 

But the same holds true with the dual system. Turn it on to which ever battery you would like to use. Then turn it off when done. 

 

Now your using the term "house". Remember too in this setup, you can connect to the 2nd battery anything. It will be charging if the engine is running and that load will not effect the #1 battery. 

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So with an isolator switch when In in position 1 (I assume starting battery) will it also charge the House battery? 

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