View Full Version : 2nd Battery

12-27-2007, 12:15 AM
I just added a 2nd battery to my 5th wheel trailer. I noticed that I only have 1 feed that charges the batteries from my truck and from the onboard inverter. I know that I have to added jumpers from 1 battery to the other, but do I connect them positive to positive ( parallel ) or positive to negative ( series ) to keep the 12 volt. I know 1 way creates 12 volt and the other creates 24 volts, but don't remember which is which.
Thanks for the help.

12-27-2007, 01:58 AM
You will connect the batteries positive to positive and negative to negative ( Parallel ). This will keep the voltage at 12 volts, the series connection will get you 24 volts.

12-29-2007, 01:02 PM
Thanks. I will go do it now.

12-30-2007, 09:18 PM
Think I need the same on my Jon Boat :D

Parallel Connected with a 24 Volt BatteryMINDer

http://vdcelectronics.com/images/Diagrams/24V_Diagram_b.gifBatteries of the same or different type (engine starting, deep cycle, sealed, gelled, AGM, maintenance-free) can be charged at the same time in parallel
(+ to + and – to -).

When you connect the batteries in parallel, you are keeping the total voltage the same. For example, if you connect two 24 volt batteries in parallel, the total voltage of the combination is 24 volts.

When you connect multiple batteries in parallel, connect the + of the first battery to the + of the second battery. Then connect the – of the first battery to the – of the second battery. The + of the first battery and the – of the first battery connect to the BatteryMINDer if possible; otherwise, connect to the accessible battery.

See diagram.

Connect each battery to one another using 18 gauge (lamp cord type) insulated wire.
Strip at the points where you wish it to be in electrical contact with the posts of each battery, then use ring or clip connectors.

VDC Electronics, Inc. does not provide any type of wire harness to accomplish this, due to the many variations in size and terminal configuration.

Always desulphate each battery separately for 2-3 days if they are connected in parallel.

Otherwise, they will not be equally desulphated.
(Back to Index (http://vdcelectronics.com/charging_multi_batteries.htm#Index:))