Easy to add in a relay to turn on spare battery with key switch?

[thehill]

I run my USB charger/underbodylights/stereo/etc off of a 12v battery, but it has an LED voltage indicator plus devices always connected to it that drain a little power even when completely off.

Would it be easy to add in a 12v relay for the 12v battery, and splice into one of the wires that's only powered (6v?) when the key is turned to on instead of off?

Can a relay be used as a cut off between the 12v battery and the fuse panel or would a manual battery switch be better, especially since the line from the battery to the fuse panel is 10ga?

[Seaquell]

I think a relay would be a great idea.
I had to use a relay on my light bar because it could handle more amperage than the switch could.
So you would just be using your ignition as the switch for the relay.

I don't know what voltage your ignition is , so just get a relay that activities with whatever volts you need and get a big enough one to handle the load plus some.

[Sergio]

This is what You need to power the fuse box from the key switch:


Relay Wiring:

http://www.buggiesgonewild.com/attac...ux_battery.jpg

36v Relay:

https://www.digikey.com/product-deta...-01-ND/1427730

48v Relay:

https://www.digikey.com/product-deta...413-ND/1427732

1N4007 diode:

https://www.digikey.com/product-deta...7DICT-ND/76454

[thehill]

Originally Posted by Sergio

This is what You need to power the fuse box from the key switch:


Relay Wiring:

http://www.buggiesgonewild.com/attac...ux_battery.jpg

36v Relay:

https://www.digikey.com/product-deta...-01-ND/1427730

48v Relay:

https://www.digikey.com/product-deta...413-ND/1427732

1N4007 diode:

https://www.digikey.com/product-deta...7DICT-ND/76454

So where does the diode go?

Can I use 10GA wire from the battery, to the relay, to the fuse panel?

Which wire from the back of the ignition or inside the battery area do I tap into for the switched 36v wire that connects to the relay?

[Sergio]

The diode goes between the 2 Relay coil tabs, which are the small 3/16" tabs.

The side of the diode with a stripe connects to the same relay tab as the positive +36v switched power wire.

The Relay contacts tabs, which are the larger 1/4" tabs, can handle 30 amps, so 10ga wire is fine.

I will defer to folks that know your cart wiring for the best location to get the switched +36v for the relay coil.

[bronsonj]

Didn't the older models of F-N-R switches cut power to the key switch??? Not positive, but I thought they did.

If he has the FNR behind the knee (and if I was right about the power) then this would cut his relay for 12v whenever he changed direction. If you have a radio, that'd mean the radio shuts down each time and you'd have to turn it back on anytime you switched direction. Small price to pay, but I thought I'd mention it. If your FNR is on the dash should be no problem.

I have a buddy with a mid 90's EZGO and he wired the stereo off the key switch similar to what you want and didn't know it would do this in advance. He still has it that way as he only changes direction a handful of times in an outing.