brclark82

Adding a second battery

61 posts in this topic

I will be taking delivery of a '17 21 H2O sport in the next couple weeks and I have a few things I would like to do shortly afterwards.  Probably #1 on my list is adding a second battery and I've read quite a bit about the topic but wanted to get some specific info from all of you knowledgeable people.

#1 My boat will come with a battery on/off switch. Can this just be straight replaced with the blue sea battery selector switch (will it fit in same opening) and is that how I should do it?

#2 Is there a certain type of battery I should get for the second or just get the same type as the stock battery?

#3 The main reason for wanting a second battery is we spend a decent amount of time anchored and floating with the music playing. Should I always switch to battery #2 with engine off and then #1 to start and run or do I need to alternate to make sure they both stay charged (not sure if it will charge both batteries while running).

#4 Do I need a battery charger on board? I trailer the boat to/from my house every trip.

 

I know that's quite a bit of stuff but for some reason I feel like I'm reading conflicting info about a lot of it and can't quite wrap my head around it.

Thanks

 

Share this post


Link to post
Share on other sites

#2 You'll want one starting battery wired to position 1 and a deep cycle battery wired to position 2.

#3 If wired right both batteries will charge on position one and only battery 2 will charge when in position 2. No need to switch back and forth as long as you start and run on position1.

#4 Not mandatory but makes it much more convenient when charging on the trailer.

Share this post


Link to post
Share on other sites
1 minute ago, Phillbo said:

#2 You'll want one starting battery wired to position 1 and a deep cycle battery wired to position 2.

#3 If wired right both batteries will charge on position one and only battery 2 will charge when in position 2. No need to switch back and forth as long as you start and run on position1.

#4 Not mandatory but makes it much more convenient when charging on the trailer.

 

+1

Share this post


Link to post
Share on other sites

Answer to # 1 : the blue sea selector is good or you can have the dealer install a 2 battery system for you.  That way it is warranted. 

7D0DC353-B915-47EE-B4DA-34108DAD8B88_zps

Share this post


Link to post
Share on other sites

Personally I would stay away from the add a battery kit. The biggest reason for me, you can not start your engine on ether battery alone. So you will never know if the 2nd can start the engine on its own.

First off, you need to do the math. How much does your system pull or draw? How long do you want it to last? Than you can decide on the size battery or even a 3rd battery. I would go with a AGM which can act as both starting and deep cycle. Also for its size, there amp hours are better! As to the switch, just add a basic dual battery switch and one of Blue Seas arc (auto charging relay).

Than as long as the engine is running, both batteries will charge and you can control which one or both will start your engine. 

On board charger is not a bad idea, but if your going out every weekend you will do fine. If its 2 or 3 weeks, you might want to add one. 

Share this post


Link to post
Share on other sites

1) Yes, discard the original ON/OFF. Blue Sea makes a mini and standard switch. They can be surface or flush mounted. Good chance one of these will work for you, but check it out first. Need to consider the back side of that panel too.

2 & 3) Based on your Q #3, id suggest a group-29 or similar marine deep cycle battery. It will give you plenty of play time for a moderate system at a moderate level and will crank an engine if needed. You can decide which bank you wire to #1 and #2. At that point, you will typically crank and run on the cranking bank, switch over and anchor on the deep cycle house bank. Once back underway, id run on BOTH or the house bank to all it to recover. 

4) good possibility. This is going to depend on what size your house bank is in terms of Ah, how deeply you typically deplete it. The issue is that after long periods at anchor, a short 15 to 20 minute ride back to the ramp, will not recharge that house bank. 

Share this post


Link to post
Share on other sites
51 minutes ago, Iggy said:

Personally I would stay away from the add a battery kit. The biggest reason for me, you can not start your engine on ether battery alone. So you will never know if the 2nd can start the engine on its own.

First off, you need to do the math. How much does your system pull or draw? How long do you want it to last? Than you can decide on the size battery or even a 3rd battery. I would go with a AGM which can act as both starting and deep cycle. Also for its size, there amp hours are better! As to the switch, just add a basic dual battery switch and one of Blue Seas arc (auto charging relay).

Than as long as the engine is running, both batteries will charge and you can control which one or both will start your engine. 

On board charger is not a bad idea, but if your going out every weekend you will do fine. If its 2 or 3 weeks, you might want to add one. 

I like what you're saying but am still a little confused. 

I WOULD like to be able to start the engine from either battery alone.  You mention not getting the add a battery kit. So then I just buy a second battery and a switch and that's it?

I will be upgrading all 4 cockpit speakers to Kicker KM series speakers as well as adding a Kicker 400W 2 channel amp powering 2 8" KM Series speakers in tower enclosures. Not sure how much power this uses but I would like to be able to run for 3-4 hours and not worry about starting the boat.

Thanks

Share this post


Link to post
Share on other sites
2 hours ago, brclark82 said:

I like what you're saying but am still a little confused. 

I WOULD like to be able to start the engine from either battery alone.  You mention not getting the add a battery kit. So then I just buy a second battery and a switch and that's it?

I will be upgrading all 4 cockpit speakers to Kicker KM series speakers as well as adding a Kicker 400W 2 channel amp powering 2 8" KM Series speakers in tower enclosures. Not sure how much power this uses but I would like to be able to run for 3-4 hours and not worry about starting the boat.

Thanks

The make a dual battery switch. It has "Off"- "-#1" - "#2" "Both"  So "Off" is just that, On for #1 and on for #2. If ether battery is that low, than you use "Both" and the two batteries are now combined.

Now a wet cell battery you can bring down to 50% and a AGM to 40%  before doing any harm.  You will need to go into the user's manual to find out what it uses. BUT, lets say it used 50 amps total. Now you buy a 100 amp hour battery (100Hr), so now you have 2 hour of use. Well on paper you do, but real world you have 50 to 60% of that. So 1 hour to 1 hour and 15 minutes or so. I hate to say it, but you need to do the math and you may want a 3rd battery. You don't want the voltage to drop below 12-11.9 volts if my memory is right.

 

Share this post


Link to post
Share on other sites

Just note that having the ACR in conjunction with the 1/2/BOTH switch, does not prevent you from running both banks down while at anchor. The system is still manual and you still have to work the switch. Some will say the work around is to wire ALL your house loads battery direct to the house bank, I do not like this. 

The Kicker KMX400.2 is a good amp for a pair of the KM8. If you want to drive them to their potential, I really like the KMX400.4. its 2X wattage. 

I would consider also putting in an amp for the in-boats. This will really help their performance while under way. I would look at the KXMA800.8. It would drive the KM8 at 200W each, 4 in-boats @ 50W each and 2 spare chnls for a mild woofer @ 200W. 

Share this post


Link to post
Share on other sites
1 hour ago, Was_Wylie_Tunes said:

Just note that having the ACR in conjunction with the 1/2/BOTH switch, does not prevent you from running both banks down while at anchor. The system is still manual and you still have to work the switch. Some will say the work around is to wire ALL your house loads battery direct to the house bank, I do not like this. 

The Kicker KMX400.2 is a good amp for a pair of the KM8. If you want to drive them to their potential, I really like the KMX400.4. its 2X wattage. 

I would consider also putting in an amp for the in-boats. This will really help their performance while under way. I would look at the KXMA800.8. It would drive the KM8 at 200W each, 4 in-boats @ 50W each and 2 spare chnls for a mild woofer @ 200W. 

I was under the impression the 400.2 and 400.4 were essentially the same amp, one was 200x2 and the other was 100x4, maybe I'm wrong.

As far as the 800.8 is concerned I hadn't heard of that until you just mentioned it and it looks like it hasn't been released yet. If it is by the time I do the speaker upgrades I'll be picking that up for sure.

I think I've decided to just get a battery switch for 1,2 or 1+2 and see how it goes with 2 batteries.  Do I need to make sure the second battery I add is similar to the first or does it matter and if I decide I need a third is there something I could do didn't the install of the second to make that easier if that time comes.

Also how do I calculate how much power my setup would use? Nothing else would be drawing power except the stereo.

Share this post


Link to post
Share on other sites

The 400.2 and 400.4 are not the same, in a number of ways. In your scenario of a single pair of speakers, its a difference of 100W (2x the wattage) to each speaker but about the same retail price. In your case, the 2 channel KXM400.2 would deliver 100W rms to each 8" KM8 speaker. The 4 chnl KXM400.4 bridged into a 2 channel amp, would deliver 200W rms to each speaker. So 2 times the wattage for the same price. 

Yes, the 800.8 is new and due to drop any time now. I can check tomorrow for an updated ETA. 

Based on the equipment and how its configured, we can estimate. otherwise, we have to actually measure it with a DC amperage meter. With that said, the Kicker Class-D marine amps are very efficient compared to their watts output. 

Share this post


Link to post
Share on other sites

Well let's assume I have 4x KM654's and 2x KM84's with a KMXA800.8 running the KM84's at 200W and the KM654's at 50W. I will also have the KMLC lighting controller if that means anything.  

First, should I add a second battery before I even consider this upgrade? 

Second, is this setup going to mean I'm probably going to really need more than 2 batteries?

Share this post


Link to post
Share on other sites
1 minute ago, brclark82 said:

First, should I add a second battery before I even consider this upgrade?

yes, IMO. Im a huge fan of dual batteries in a boat. Installed a 2nd bank in by first boat bank in 95, the 2nd boat in 2001 and had dual banks on every boat since. 

 

3 minutes ago, brclark82 said:

Second, is this setup going to mean I'm probably going to really need more than 2 batteries?

No but maybe. Cant really look at it as the number of batteries, but rather the number of Ah. Same with audio amplifiers. We dont look at the number of amps, but rather the wattage needed and number of amp chnls. In an ideal world, the shallower we cycle a battery the better the battery recovers. In other words, 2 batteries cycled 50% last longer than one battery cycled 100% each trip. Even though the bank had the same Ah. To prove this point, I have 5 amps driving a woofer, 2 pair in-boat speaker and tower speaker and can run about 7 hours on an 80 Ah battery before my woofer amp starts to drop out. 

Share this post


Link to post
Share on other sites
16 hours ago, Iggy said:

 I would go with a AGM which can act as both starting and deep cycle.

Aren't there certain issues regarding charging an AGM with only the engine running and without a battery charger?  Also, shouldn't both batteries in a dual setup be of the same type?

Share this post


Link to post
Share on other sites
12 hours ago, Iggy said:

The make a dual battery switch. It has "Off"- "-#1" - "#2" "Both"  So "Off" is just that, On for #1 and on for #2. If ether battery is that low, than you use "Both" and the two batteries are now combined.

 

This is the set up I used on my first boat but it was kept in the water and not on a trailer.  When running, selector switch should be on both so all the batteries will get charged.  When you anchor, select either 1 or 2.  When you put it on the trailer, move the switch to off, no need to have power to a bilge pump or any other accessories.

Share this post


Link to post
Share on other sites

I would simply buy a HUGE   lead acid battery.   Use it ...........only ..........for the music system. Has a separate ON  OFF switch for it.  Recharge it .......easily...........at home each time.  No different battery problems.  A set a battery jumper cables would be used if needed.    Keep the systems ..... isolated.......

Done.

Share this post


Link to post
Share on other sites

Thanks for all the help everyone, but I'm about as confused as I was when I started the thread. Why are there so many different gd options for adding a second battery. I'll continue to research it and take your recommendations into consideration when doing that research. 

Right now it looks like I'm leaning towards the exact setup @Perseverance just suggested and use the same type of battery that comes with the boat.

Share this post


Link to post
Share on other sites

The batteries have to match or your going to need 2 different chargers.

 

My set up looks like this:

Off = Off but the bilge pump is hard wired to the house battery so it is still hot.

#1 = Starting battery is used to start and both batteries are charging while the engine is running.

#2 = House battery is being used and only the house battery will charge when the engine is running.

Both= Both batteries are used to start and both batteries are charging when the engine is running.

So I start and cruise in position #1 and switch to position #2 when on the hook for the night and then back to #1 to start the engine in the morning.

Share this post


Link to post
Share on other sites

It can be confusing and the reason for all the combinations and permutations for a boats' electrical supply is that everyone has different needs and wants.  To make the process a little easier, you need to determine what you want to accomplish.  As with all things boating, over time, your needs may change and you can always upgrade.  The only thing I would recommend is, if you're not comfortable/knowledgeable about electric wiring on a boat, have a professional do the install. 

Don't sweat it, relax, sit back and have a :beer-7687-1:

 

Share this post


Link to post
Share on other sites

I dunno, different strokes for different folks. 

I used the add a battery kit, and moved all accessories to 2nd battery, the starting battery is all by itself.  But when the engine is running the ACR, combines the batteries so both charge up.  It's safe, both batteries are always charged and I always know my starting battery is ready to get me home at the end of the day.  All this without yet another system on-board that I have to re-explain its purpose to the admiral each time we go out.  I just tell her turn the power on or off.

Share this post


Link to post
Share on other sites
3 hours ago, Perseverance said:

Aren't there certain issues regarding charging an AGM with only the engine running and without a battery charger?  Also, shouldn't both batteries in a dual setup be of the same type?

As to charging off the engine, no. That would meant that everyone that used one would need the alternators changed out or adjusted. No one would buy the AGMs then.  An on board charger is made to be on 24/7, so yes. They should be the same chemistry it that's what you mean.   

Share this post


Link to post
Share on other sites
15 hours ago, Was_Wylie_Tunes said:

Just note that having the ACR in conjunction with the 1/2/BOTH switch, does not prevent you from running both banks down while at anchor. The system is still manual and you still have to work the switch. Some will say the work around is to wire ALL your house loads battery direct to the house bank, I do not like this. 

The Kicker KMX400.2 is a good amp for a pair of the KM8. If you want to drive them to their potential, I really like the KMX400.4. its 2X wattage. 

I would consider also putting in an amp for the in-boats. This will really help their performance while under way. I would look at the KXMA800.8. It would drive the KM8 at 200W each, 4 in-boats @ 50W each and 2 spare chnls for a mild woofer @ 200W. 

On "does not prevent you from running both banks down while at anchor." Well it should. If the other battery is OFF, than its off. Unless, someone has connected something to it. But like anything, it needs to be wired right and all loads need to be considered.  

On "Some will say the work around is to wire ALL your house loads battery direct to the house bank, I do not like this." On bigger boat this is how they are set up. This leaves the starting battery isolated so you can start your engine. BUT, ever boat is different and it all depends on your needs too.  

Share this post


Link to post
Share on other sites
3 hours ago, Perseverance said:

This is the set up I used on my first boat but it was kept in the water and not on a trailer.  When running, selector switch should be on both so all the batteries will get charged.  When you anchor, select either 1 or 2.  When you put it on the trailer, move the switch to off, no need to have power to a bilge pump or any other accessories.

I am BAD. But you do want power to your pumps, no matter how the switch is set. If something was to happen, well you may want your pumps to work. I know I do!

If an ARC ( auto charging relay) is installed. No matter if the switch is on 1 or 2, both batteries will be charging. On my smaller boats, I would start the engine on the #1 battery and restart on #2 to get home. This too would tell me that each battery is good and can start the engine on its own. The add a battery kit can not do this. Also with this kit, if your starting battery was dead there is no way to use the 2nd battery for starting. Get out the wrenches and start moving cables.

Share this post


Link to post
Share on other sites
2 hours ago, Iggy said:

On "does not prevent you from running both banks down while at anchor." Well it should. If the other battery is OFF, than its off. Unless, someone has connected something to it. But like anything, it needs to be wired right and all loads need to be considered.  

On "Some will say the work around is to wire ALL your house loads battery direct to the house bank, I do not like this." On bigger boat this is how they are set up. This leaves the starting battery isolated so you can start your engine. BUT, ever boat is different and it all depends on your needs too.  

I agree, if the switch is off, but if the switch is off while at anchor, the boat is dead, no stereo, lights, frige, etc. If we want to use things while at anchor, the switch has to be on. if its on, theres a chance it could be on BOTH, leading to both banks being rund down. The ACR with a 1/2/BOTH switch is not ideal and advised.  

Just because big boats are wired that way, does not make it best practice. Now, I can wire ALL loads the common post of a dual bank switch and isolate the cranking battery all day long.

Having all loads wired battery direct means you need to have alternator contribution to both banks when the engine is running, or one of them is dead half way through your day. Your solution is to use an ACR. I agree, but the proper switch, the dual circuit plus switch.    

Share this post


Link to post
Share on other sites

Sorry I did not make myself clear. I meant if your on the #1 battery, than there is no way that the #2 battery will be drained. Because you were saying that "does not prevent you from running both banks down"

There is more than one way to do this. The boat in question is not setup for a house and starting to be isolated. You like your way & I like mine. Your way turns on both batteries and than combines them. So its OFF, BOTH ON, & COMBINED. The dual switch I think gives you more control. It lets you turn on ether battery or combine them. It just depends what you want to accomplish. To me, the Dual Circuit Plus makes it a switch that you could use but not the proper switch. 

For me "Just because big boats are wired that way, does not make it best practice." it does. Why, I can run the house batteries down as much is I want and I can still get home. If needed, I can use the house bank to start ether of my engines. Also charge up the starting and house banks off of ether engine.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now