Battery Switch for 2 Batteries

[GaBoy]

Can you tell me the best switch to purchase. And I need some explanation on how to setup correctly for 2 batteries, one for cranking and one for other items like radio and ect.

 

[PondTunes]

Re: Battery Switch for 2 Batteries

I always recommend the blue sea systems 'add-a-battery' setup. I recently installed one on a customers boat and found it was easy to set up and works just like it claims. Here is a link to the previous post.

http://forums.iboats.com/showthread.php?t=215068

Theres also links to a couple other threads talking about this system.

Once you decide on a switch setup then you need to figure out what you're going to isolate from each other. Some people only isolate their radios/amplifiers while others isolate everything except for tilt & trim and the starting circuit.

 

[GaBoy]

Re: Battery Switch for 2 Batteries

Thanks and Do you use another device for isolation? or is it included in the device you are talkiing about?

 

[drewpster]

Re: Battery Switch for 2 Batteries

What the add-a-battery setup basically is an automatic switch. When it senses charging voltage it closes allowing that voltage to recharge both batteries. When you shut off the engine the add-a-battery will sense the resting voltage of the batteries and open up, isolating the two batteries from eachother.
Right Pond?

 

[wire2]

Re: Battery Switch for 2 Batteries

I can't tell what's in that one but I did the same function on a motorhome with a single large rectifier diode, 150A, 100 V.
It passes current one way only.
I got it from a welder repair shop, he had a big box full of used ones. $2 each.

There is 1 very minor drawback, the 2nd battery will be .7v less than the main one. I had 14v and 13.3

 

[firehog6305]

Re: Battery Switch for 2 Batteries

I perfer the perko switch's never had one give me a problem yet

 

[drewpster]

Re: Battery Switch for 2 Batteries

I think that is the appeal of the automatic switch, no voltage drop across the diode. And there is no need to remember to flip the battery switch.
I forgot mine one to many times, 40 miles up river and a dead battery. I was so upset with the mistake I bought a similar unit.
There has been allot of debate in the past over these set-ups in here. Some folks like diode isolators, some like manual switches, some like an automatic isolator. Apples and apples if you ask me. If it works for you that's great. I like the set and forget it option this system provides.

Here is my setup. It uses three individual manual switches and an automatic combiner. Many offshore boats use this type of battery management. It provides complete isolation of the batteries and allows the use of any battery, or all batteries, to power either the house circuits or the start circuit or both. The automatic switch will provide charging to all the batteries while the engine is running and isolate house and start banks when the engine is off. Seems complicated I know but its not. I do not have to touch the box at all unless I want to turn the batts off or if there is a failure of some kind. I always have a charged battery even if I run the spot light all night with the engine off. (its happened, however unintentionally)

 

[drewpster]

Re: Battery Switch for 2 Batteries

sorry, I got a little off the question, i like blue sea systems switches.:redface:

 

[PondTunes]

Re: Battery Switch for 2 Batteries

What the add-a-battery setup basically is an automatic switch. When it senses charging voltage it closes allowing that voltage to recharge both batteries. When you shut off the engine the add-a-battery will sense the resting voltage of the batteries and open up, isolating the two batteries from eachother.
Right Pond?

Yes its either on or off no switching unless you want to either totally disconnect the system or combine both banks in case of a problem. No need for anything else.

Like others have suggested there are other ways to do this, diode isolation, manual switches, automatic switches. It's really up to you and what you're doing with the setup. The customer I installed the add-a-battery system only had 1 battery the entire time he owned his boat. I installed three amplifiers on the boat and a second battery. He wanted a setup so that he didn't have to remember to throw any switches or worry about getting his battery drained. This setup is 100% transparent to him and he uses his boat just like he always did.

A diode isolation setup prevents the house or second battery from draining the starting battery. There is a slight voltage drop across the diode and there isn't any way to combine the two in the event of a bad battery. A set of jumper cables or a switch to combine them could be wired in to do just that however.

A manual switch is another approach. Each battery is connected to a 4 position switch (OFF - 1 - 2 - BOTH) You select #1 (or whatever your starting battery is) crank up and ride to wherever you're going. You could move the switch to #2 to charge only your accessory batt or use the both setting to charge both while underway. Once you get to where you are going to anchor down or drift you need to remember to switch it to battery #2 so that you still have power but don't drain #1. This setup lets you switch between batteries, combine them in the case of a failure but *YOU* have to remember to do the switching, or if you have more than one person who takes the boat out they also have to be instructed on proper use.

***IMPORTANT*** With any system it is of extreme importance that you NEVER switch the switches to OFF or otherwise disconnect the batteries from the alternator with the engine running. Doing this will destroy your charging system and you won't be a happy camper.

 

[GaBoy]

Re: Battery Switch for 2 Batteries

Drewspter, did you buy the setup you have from a company or did you create yourself?

Thanks for all the info everyone. At least you have several options. I plan to have only 2 batteries and maybe add another just for good luck. ????? One for cranking, one for extras, and one for good measure and protection. ??

 

[drewpster]

Re: Battery Switch for 2 Batteries

I built the panel using a drawing from another website.

There are battery management setups like this one made by Blue Sea and several other marine electrical suppliers. They look a little too 'modern' for my boat. I wanted to keep the older look of my panel to suit the boats age. The only change I would make to my panel is to use a different combiner. The one I have is a good unit, however it has more options than I need. I could have used the add-a-battery switch or one similar. The Xantrex combiner I have is relatively old technology, but it works well, and it will carry allot of amps. The add-a-battery switch and similar electronic charging relays are generally for charging loads only. The combiner I have will also carry starting loads.