Upgrading to 24v from 12v system

[John Dismang]

I have a 26' cruiser that currently operates on 1 cranking battery and 1 house battery. There is a battery switch to it but when I turn on some of the lights or bilge, the gauges will dim and you can tell it is pulling alot of power. I want to upgrade to a 24v system and I need some help figuring out what I need. Does anyone have a diagram or can tell me the parts I will need to do this?

 

[bruceb58]

Re: Upgrading to 24v from 12v system

You need to figure out where your voltage drop is. Then you will be fine. You may need to upgrade the size of the wire to your main fuse block if it isn't just a highly resistive connection somewhere.

 

[Silvertip]

Re: Upgrading to 24v from 12v system

I don't think you really mean you want to switch to a 24 volt system as that would require all of the current 12 volt items on your boat would need to be replaced with 24 volt items. what you really mean (I think) is that you want to add another battery. That battery gets added in "parallel" with the existing house battery. That system remains at 12 volts but the electrical capacity is doubled. So lets verify that's really want you want to accomplish.

What position is the battery switch set to when you notice the dimming?

Is the house battery fully charged and in good condition? Had it load tested lately?

How many cabin lights are we talking about?

On that size boat a second house battery would certainly be a benefit. But lets make sure the switch is being used properly and that the current system is up to par before changing things.

 

[John Dismang]

Re: Upgrading to 24v from 12v system

Yes you are right. I just want to add a second battery. I just purchased the boat not long ago and I'm learning as I go. I typically keep the switch on "both" batteries and lights dim when I turn on the bilge switch typically or the nav lights. Batteries are new deep cycle batteries so I believe they are ok.

 

[Silvertip]

Re: Upgrading to 24v from 12v system

Leaving the switch on BOTH means the starting battery and the house battery are both powering everything on the boat. This position would typically be used when the engine is running so that both batteries are charging. When you dock or anchor for an extended period you would want to switch to BAT 2 (house battery only) so that the start battery (BAT 1) does not get drawn down. Whatever position the switch is in means that is the battery/batteries that power everything and are being charged.

Dimming lights with two batteries in parallel (switch set to BOTH) means you either have some loose or corroded connections or there are more lights in the system than you have power for. What you need to do is set the switch to BAT 2. Using a voltmeter, measure the voltage at the BAT 2 terminals (the actual posts). Then turn on the lights and measure it again. If there is a significant drop you either have a bad battery, it is not fully charged. Then move the COM terminal on the switch and repeat the tests. With the lights off the voltage should be the same as when measured at the battery. With them on if you see a drop, that says there is an issue with the switch or the connections to it. In other words, follow the current until you find the spot where the drop occurs.

It would be a waste of money to buy another battery if the system has some wiring issues.