[gmhand28]

I'm not getting many replys, but another question. There is a push button switch on the left side of the lower steering station that is marked "BATT. PAR." What is it.

[AMG]

On most boats, this will give you two or more batteries in parallel to start the engine. You just push during start.

[9lives]

I only use the switch when ever I found my main starting batteries drained and needed the power from either the genset or house banks to supplement. I do not believe the switch was anything other than a means of jumping the circuit to another charged source.

This is at least what I have found on 12v systems, no knowledge of its use on other voltages is implied!
Mark

[gmhand28]

Originally Posted by AMG

On most boats, this will give you two or more batteries in parallel to start the engine. You just push during start.

Thank You, I knew I'd feel stupid when I got the answer to this.

[45tf]

I always parallel batteries to start, and with each engine. Half the load on the batteries during start. Some boat manufacturers used to have that feature built-in with the circuit wired to automatically parallel to start - Trojan was one mfr that did that. The old Huckins boats had a strange and complicated battery arrangement with two sets of batteries in parallel to start.

My last two sets of main batteries have lasted six years. I have the Raritan converter always on at the dock too. Some guys don't like to do that.

My generator is on a completely separate circuit. The Raritan maintains three sets of batteries.

[artwork]

45tf,
I like your idea. I was taught 30- odd years ago that the switch was for emergencies, as others have mentioned. But recently I've done a lot of study on inverters and battery capacity. The universal school now says when a battery is drained below 50% of their rated amp capacity, their life span is negatively affected. So waiting until one battery won't start an engine has already shortened that battery's life.
Your use of the parallel every time is extending their lives. And if you let that first engine run a minute or so before hitting it with the other starting load, will begin re-charging at least one battery.

[SigSplash]

Originally Posted by artwork

45tf,
I like your idea. I was taught 30- odd years ago that the switch was for emergencies, as others have mentioned. But recently I've done a lot of study on inverters and battery capacity. The universal school now says when a battery is drained below 50% of their rated amp capacity, their life span is negatively affected. So waiting until one battery won't start an engine has already shortened that battery's life.
Your use of the parallel every time is extending their lives. And if you let that first engine run a minute or so before hitting it with the other starting load, will begin re-charging at least one battery.

Make sure you apply this rule to only Lead acid and Gel Cell Batteries. Ni-Cad, Lithium Ion, and Ni-mh like to be used all the way down before charging.

[AMG]

Originally Posted by SigSplash

Make sure you apply this rule to only Lead acid and Gel Cell Batteries. Ni-Cad, Lithium Ion, and Ni-mh like to be used all the way down before charging.

I have never seen any of those batteries in a boat. Are you sure they exist?

[SigSplash]

Originally Posted by AMG

I have never seen any of those batteries in a boat. Are you sure they exist?

Sorry, I was slightly misleading. They are rarely, if ever used on a boat. I was speaking in general terms.

[YachtForums]

Originally Posted by SigSplash

Ni-Cad, Lithium Ion, and Ni-mh like to be used all the way down before charging.

Ni-Cads and Nickel Metal Hydride batteries are prone to developing memory. If not fully depleted, their capacity can be reduced over many cycles. In contrast, lithium batteries should not be depleted. They do not exhibit the same memory problems of NiCad and Ni-Mh. But as Lars noted, I don't believe they are commercially available in marine applications, with the exception of the prerequisite onboard Black & Decker drill, or in my case... an r/c helicopter.