Connecting Multiple Batteries for Increased Voltage or Increased Amp Hours  

Question:

Helpful Expert Reply:

To connect batteries for more amp hours you would normally connect batteries in parallel so the capacity is increased but the voltage is not increased. This is how we recommend adding amp hours to a 12V trailer system.

To increase voltage but not capacity, you would wire the batteries in series. This is how you would get the 36V from your three 18V batteries, but the amp hours would not increase.

The issue with using 18V batteries if this is a trailer application is nothing runs off 18V or 36V on a traditional trailer. Everything runs off 12V or in rare cases 24V.

So with your system you can either get 36V without increase amp hours or you can get 18V with increased amp hours, but you need to make sure your system can handle those voltages.

For either application, I recommend using the Deka Stackable Battery Cable - 2/0 Gauge - Red - 13" Long # DW01485 and Deka Stackable Battery Cable - 2/0 Gauge - Black - 13" Long # DW04316.

expert reply by: Jason S

1

click to enlarge

Rick

6/5/2020

Thanks For reply much appreciated. I know it’s only 12 volts on a vehicle or RV however it’s the same principle. However f I have 4 x 12v batteries with different amp hours 2x12v 4amp hours & 2x12v 2 2amp hours. Can I wire them all in parallel to increase amp hours?

Jason S.

6/5/2020

Happy to help. With four 12v batteries you can wire them all together in parallel and it will not increase the output but it will increase the amp hours. The difference in amp hours per battery will not be an issue and them connected together will increase the amp hours. Just make sure all the positive terminals are chained together and leading to your power as well as all the negative terminals chained together and connected to ground.