Dual battery installation question

[dhardest]

I'm considering installing a second battery, possibly using the "Add-A-Battery" kit from Blue Sea Systems. My boat is not that large but still would benefit from the second battery so I don't have to worry about running the radio all day and still starting when it comes time to head back. My question is, given the size of my boat (21'), should I locate the second battery on the other side of the boat to even out the weight, or is it recommended to keep both batteries positioned close together on the same side. Just seems like a lot of extra weight on the same side.

On a related note, does anyone have any good photos or diagrams to illustrate a good clean way to position the battery selector switch in the engine compartment and make it look well designed? Just don't want a kluge in that area. Any ideas/recommendations would be appreciated.

 

[ezmobee]

I wouldn't worry about the weight of a battery on a 21'. Shouldn't make much of a difference. Certainly not enough to make me want to deal with the expense of long heavy gauge battery cables.

 

[Silvertip]

The best advice for how to do the switch & battery install is to take some pictures of the area with the batteries and switch hung or taped in place. Now open and adult beverage, sit back and study what you see. Imagine having to run large battery cables and smaller accessory feeds. Do a good job of planning and routing cables and the installation will end up clean and professional-like.

 

[bruceb58]

The add a battery kit uses a switch that assumes you are going to have a separate house and engine load. If you don't plan on separating all the loads, don't buy the kit but buy the ACR and a 1/2/both switch separately.

I have 2 boats and have a dual battery system on both. One uses the add a battery kit and the other uses the method I mentioned earlier.

 

[alldodge]

Add a battery is best for the batteries, but have had an isolator installed for just what your doing on my Rinker since it was new. Can run the stereo and amp all day and still not effect the start battery. Don't have a Bat switch, but so far never needed it. Also installed a 2-bank charger

 

[bruceb58]

There are disadvantages to an isolater. The diode voltage drop requires you to run a remote sense line to one of the batteries. The ACR has protection so that the combiner does not combine if one battery has a failed cell. It will not combine if one battery is below a set voltage. With an isolater, if your house battery fails, the alternator will try to give all the charge to a failed battery possibly overheating and damaging the alternator.

Isolaters were the way to go before ACRs came along. Not the way to go anymore.

The Blue Sea ACR 7610 is $80 or less.

 

[dhardest]

Thanks everyone for the helpful tips. Good to hear I can put the batteries on the same side. Will keep the other side free of cables and make all the battery equipment in one area. I do like the idea of the add-a-battery kit, just need to think through where to mount all the parts. The adult beverages may help with creativity in that area .....

 

[rdds57]

I have a question do I need to put a common ground bond between my boat start battery and my 2 12v trolling motor batteries. ??

 

[airshot]

For your extra battery consider a deep cycle battery, my 22' has a deep cycle for the house battery and I can be on the water all day with everything running from radio, ship to shore, fish finder, lights etc and it will drop the deep cycle less than 10% so I can get 3-4 days of usage before recharging even though I typically charge it more often.

 

[dhardest]

OK - Good to know. Thanks. I'll definitely use a deep cycle for the house battery and a starting battery as the other one.