Dual Battery Setup with Blue Sea 7650 Add a Battery

gapple12

gapple12

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I'm planning on adding a second battery to my Monterey 190. We like to anchor to swim a lot and listen to music. I'm always worried that I will drain the battery and get stranded, plus I'm installing amps for the stereo. I have found a lot of people are using the Blue Sea 7650 Add a Battery to be able to switch from house battery or start battery. I'm wondering if I need a bigger alternator to charge both batteries or is the included charging relay going to handle this for me on the add a battery setup ? If I listen to the stereo for say a few hours and drain the house battery, do I switch to both battery setting on the blue sea switch and that will get me started to charge the house battery back up ? I'm just a little confused on how this set up works. In cars I have added bigger alternators to handle the larger sound systems and an extra battery. Thanks in advance !!!

Blue Sea 7650 Add a Battery:
Add-A-Battery Kit - 120A - Blue Sea Systems
 
bruceb58

bruceb58

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

Just have your stereo run off the house battery. Once you start your engine off your start battery, the ACR will charge the house battery.

I wouldn't bother with a bigger alternator.

By the way, listening to a stereo for a couple hours will not drain your battery much. Even if it would draw 10A, a 60Ah battery will only be down to 1/3rd of its capacity.
 
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agallant80

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

You could always just spend $100 on a jump pack and bring it with you. I did that for years.
 
dingbat

dingbat

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

agallant80 said:
You could always just spend $100 on a jump pack and bring it with you. I did that for years.
Click to expand...
gave up on jump packs long ago. My ACR setup is more reliable
 
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Auger01

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

If you are installing ampS, as in more than one amp, then you might consider adding more than one house battery.

As far as how to operate the add a battery, it is easy, just turn the switch to the ON position at the dock and turn it OFF when you return. It manages the charging automatically.
 
gapple12

gapple12

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

Auger01 said:
If you are installing ampS, as in more than one amp, then you might consider adding more than one house battery.

As far as how to operate the add a battery, it is easy, just turn the switch to the ON position at the dock and turn it OFF when you return. It manages the charging automatically.
Click to expand...

Nice, I like things working automatically !!! Especially after Ive had a few cold drinks ;)


Im adding one 1000 Watt amplifier for a small sub-woofer under the dash, nothing to major. Im also adding the best battery I can find which I'm leaning towards a Optimum Marine deep cycle battery.
 
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Gator1996

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

If you have the add a battery, the only reason to use the switch while the boat is in use is if your starting battery was dead and you could combine your house and starting battery to get the boat started. Other than that, as mentioned above, its either on or off.

Not sure what your set up is but I just installed an add a battery system and went with the 65 amp-mini version. It was a good bit cheaper and provides the same function. I have a 55 amp alternator. The add a battery works just as described. In fact it was the ACR that led me to find that my voltage regulator had gone bad. If the alternator is charging over 16 volts, the ACR automatically breaks the connection to the second battery to avoid damage.

As a side note, the cables, fuses and other supplies were a considerable additional cost that you should definitely plan for. Not sure if you already have two batteries or not, if so, I imagine that you may already have some that on hand. If you need a referral for a source on cables, let me know. I got custom made cables done for less than it would have cost me to make my own.

Good luck
 
bruceb58

bruceb58

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

I am sorry, I posted the auto one by mistake. The one you posted is the correct one.

There are often sale codes you can find online to get the battery cheaper. I actually have 2 of the ones you put the link in for. If I remember correctly, they were around $220 on sale.
 
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gapple12

gapple12

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

OK, I still haven't bought this setup yet, but I came across a cheaper version called the Blue Sea 7649 Mini Add-A-Battery system. Says 65 amps on it. I'm curious if this would work for my application or not with a house battery and motor battery connected ? I'm looking to find the difference in the 7650 add a battery to the 7649 add a battery.
 
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gapple12

gapple12

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

bruceb58 said:
The 7649 Kit has a switch that isn't rated for as much current. I am using it for an outboard but I wouldn't use it for an I/O engine.
Click to expand...

Thanks, I'm thinking this kit is for smaller motor and electric applications, not enough for mine.
 
bruceb58

bruceb58

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

I am using mine for a 90HP Mercury outboard. I just bought it and am waiting for delivery.

http://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A
Blue Sea Systems smaller, more compact version of the popular Add-A-Battery kit to its product offering was primarily designed for outboard powered boats with alternator output of 65A or less.
Click to expand...

That being said, the ratings of the contacts are 350 vs 300 so not that much less.

For my application, I actually liked the way the mini switch mounted in a bulkhead, otherwise I would have gone with the bigger one. The price difference is around $30-$40 so not much difference there.
 
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Splat

Splat

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

I use the m-acr (7601) in my truck. Been very happy with it, been installed for a little over a year.

It isolates my main battery from my aux battery that runs all my ham radio equipment and light gear.
 
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Gator1996

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

I mentioned earlier in the thread that I had installed the mini version. I contacted Blue Seas and asked for a recommendation and they said the mini version would suffice for my purposes. I have a 55 amp alternator. As far as the difference in current, I am sure that bruce would be in the know and I am not. Grand scheme the $30 is not a make or break but it is $$ I can use for something else. If I can offer any assistance in a non technical capacity, let me know. Good luck.
 
bruceb58

bruceb58

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

The ACR is not the issue if your charge current is less than 65A. It's more the switch specs.

If the I/O engine was a 4 cylinder or even maybe a 6, I could see using the mini version. I think the OP has a V8. I would be going with the switch with the higher rated contacts.
 
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Gator1996

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

bruce I am curious to know. What would be the worst case scenario in terms of the rating of the contacts? Your professional opinion; what do you think could happen that concerns you?

My conversation with the Blue Seas rep never touched on this.
 
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bruceb58

bruceb58

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Re: Dual Battery Setup with Blue Sea 7650 Add a Battery

That you would draw so much current that you would burn the contacts or have a voltage drop across them under high current draw. Probably not a super likely scenario but probably not worth it considering the cost difference.
 
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