voltmeter and second battery install help

jstaz

Seaman
Joined
Oct 3, 2010
Messages
64
I want to install a second battery and a voltmeter to my boat. However, I don't know how. - was wondering if y'all could help me figure it out. I hear a lot of guys talking about battery switches as well. Do I need to install one or can I tie them together? I am new at all this so any help would be great.

Stats:
1994 TD Penny 170 is the boat.
1994 Tohatsu M60B 60 HP

I know I'll need a marine grade voltmeter. Any brand better than the other or they all the same?

Thank you in advance for your help guys.
Joe
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: voltmeter and second battery install help

Yes to both options. Yes you can add a switch. No you don't "need" a switch but running two batteries in parallel without one will mean the weaker of the two batteries will always draw down the stronger one until both are equal. Therefore a dual battery switch or automatic charge relay (ACR) is suggested. These two devices provide a way to protect the starting battery from being discharged. They operate a little differently however. An ACR is automatic -- no switching is required. The charging system on the engine will charge the start battery first and then switch the house battery on-line. A dual battery swtich however is a little more flexible in that it allows you to run everything from BAT 1, BAT 2, or BOTH and it also has an OFF position that shuts down the entire electrical system. If you go that route, the bilge pump in your boat should be wired directly to the house battery which should also be a large deep cycle (not a starting battery). Now then the question is "WHY" do you feel you need two batteries and how do you intend to use them. Wiring diagrams for a dual battery switch or ACR is included with the unit. There are also a bunch of diagrams and descriptions in this forum. Use the search feature using terms "Dual Battery Swtich" or "ACR"

A voltmeter has three wires. +12 volts when the key is on, ground, and a connection for an internal light.
 

rwidman

Lieutenant
Joined
May 27, 2004
Messages
1,396
Re: voltmeter and second battery install help

Some meters have lights that plug or clip into the meter housing. These have their own positive and negative wires. In this case, there would be two terminals on the meter - positive and negative.
 
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