2 battery setup with switch

[Trevor Shipman]

Wondering if anyone can help me with a diagram. I looked through and couldn't find one. Right now I have 2 batteries. 1 deep cycle (that I have 2 amps connected to and the stereo) then a cranking battery which is strictly hooked up to the engines. I purchased a perko switch (3 prong) and j would like to install so that both batteries can charge while underway. Any help would be great! Thanks!!

 

[Bill D]

Here is a very good diagram and explanation from Mel @txav8r

Blue Seas Add a battery kit Questions

 

[cozilla]

The 3 prong set up should be Batt 1, Batt 2, and Common. The switch should have 3 selections Batt 1, Combine, and Batt 2. Which ever battery the the switch is switched to will be the battery that is in use and is charging. To charge both batteries while underway the switch would have to be switched to Combine.

 

[txav8r]

Using a combine battery switch setting is an emergency procedure and shouldn't be how you charge both batteries. It won't charge any faster by doing this. You have a stator magneto charging system, like a motorcycle, and it can only put out about 28amps. That runs your electrical system and "maintains" the charge on the batteries. If you discharge your battery much at all, it WILL NOT recharge the battery, unless you go for a very long cruise at cruise power settings...like 4 or 5 hours. So the very act of trying to charge two banks is just a waist of time. The reason for an ACR, automatic charge relay, is to allow a charge to the second battery bank when it is depleted. If you have two batteries, and a 1,2,off, combine switch, just let the engine charge back the battery you have just been using. Use one today, use two tomorrow. If you don't want to do that, get an appropriate switch and ACR to allow them to combine with protections. Just food for thought.

 

[KXCam22]

I have direct experience with how little it charges. Starting the day with an almost dead battery and keeping the boat running ALL day lead to no significant increase in battery voltage. We were surfing and not steady cruising but the amount the battery charged was minimal. Not what I expected but then you have 2 small motorcycle sized mags trying to charge a monster size 27DC battery. Plan on a using a charger at home. Cam.