Correct way to wire accessories to aux battery?

[KiloMikeZ71]

I'm going to be installing a second battery in my 1997 K1500 so I can install a 12v receptacle in the rear bumper for my boat trailer's winch. Thanks to the info on this site, it looks like I'll be able to do that without a problem!

Now for the question: How do I power my radio and the cigarette lighter ports off of the second battery? Do I run a wire to a new fuse box of my own and connect things up there? Or should I be looking to connect the in-cab fuse box to the second battery and just have everything inside the truck run of the second battery when the engine is off and the isolator is open?

Thanks for any direction and clarification!

 

[DonYukon]

Couple of questions first
This second battery, is it going to be placed on a isolator to back up your primary battery or completely isolated? I would imagine it would at least be tied in somewhere to help with recharging as you stated with the isolator open.

Regardless of this be sure to buy a deep cycle battery for your intentions. typical batteries like the one thats in the truck is most likely a starting battery and not a deep cycle. deep cycle batteries are better suited for things like winches and heavier electrical loads . they also last longer when charging them from near empty.

Secondly why would you want to power the radio and cig lighter separately ?

 

[KiloMikeZ71]

Couple of questions first
This second battery, is it going to be placed on a isolator to back up your primary battery or completely isolated? I would imagine it would at least be tied in somewhere to help with recharging as you stated with the isolator open.

As I understand it, I'll be hooking up both batteries to the isolator so that the alternator will charge both when running. When off, the voltage will drop and the isolator will open so I can run things off the aux battery and it won't drain the starter. Hopefully I have that correct?

Regardless of this be sure to buy a deep cycle battery for your intentions. typical batteries like the one thats in the truck is most likely a starting battery and not a deep cycle. deep cycle batteries are better suited for things like winches and heavier electrical loads . they also last longer when charging them from near empty.

Right - I measured and can fit a group 24DC battery in the tray. I've used Interstate deep-cycle batteries in my boat with good results.

Secondly why would you want to power the radio and cig lighter separately ?

I guess the radio isn't critical, but I'd like to have certain accessories available to me in the cab when things are off. A charger for my hand-held HAM radio for instance... and maybe an inverter. Those plug into the cigarette lighter receptacles, so I was wondering about the procedure of getting things off the normal circuit and onto the aux battery.

 

[DonYukon]

As I understand it, I'll be hooking up both batteries to the isolator so that the alternator will charge both when running. When off, the voltage will drop and the isolator will open so I can run things off the aux battery and it won't drain the starter. Hopefully I have that correct?



Right - I measured and can fit a group 24DC battery in the tray. I've used Interstate deep-cycle batteries in my boat with good results.



I guess the radio isn't critical, but I'd like to have certain accessories available to me in the cab when things are off. A charger for my hand-held HAM radio for instance... and maybe an inverter. Those plug into the cigarette lighter receptacles, so I was wondering about the procedure of getting things off the normal circuit and onto the aux battery.

first part , Yes thats possible with one of those fancy smart isolators. not sure about the cost of those and that is smart. just make sure when you wire them together you are wiring them in parallel. that way you dont cook any circuits and you should be golden.

second part , agreed

As for the third. It is completely possible to wire in the second battery to certain functions of the vehicle while the key and ignition circuit is off. The easiest way without complicating things IMO would be to run the ham radio and Cigerette lighter off the second battery entirely. as for the radio Id imagine the best way would be to tap into the ignition wire at the radio head unit. HOWEVER. I can't think of a safe way to do this without a disruptor or isolator of its own as I'm not sure what would happen if it received both current draws at the same time if you should start the truck while the radio is already powered.

Hopefully someone with a better understanding of radio head units can chime in and correct me or validate it

 

[KiloMikeZ71]

As for the third. It is completely possible to wire in the second battery to certain functions of the vehicle while the key and ignition circuit is off. The easiest way without complicating things IMO would be to run the ham radio and Cigerette lighter off the second battery entirely.

Right... and that's what I'm ultimately after: How do I do that? Does this involve disconnecting the cigarette lighter leads from the existing fuse box and creating a new, fused run through the firewall? Or is there some way to do this "officially" using the existing wiring and fuse box in the cab and/or under the hood? I was kinda assuming there might be some official way to do this... otherwise I'm not sure why one would have an aux battery with a gas motor? Unless it is just what I'm after and it's all DIY.

 

[DonYukon]

I mean why the need to have them separate? I know you want to use them while the truck is off but with two batteries its unlikely you'll kill them. esp if you put the main cranking battery on a isolator disconnecting it and just using the deep cycle . that way you can always start the truck

 

[thegawd]

your overthinking it. keep it simple. power whatever you want off the 2nd battery, from the battery with new wire and a fuse... if you want something kind of already built go to a pro audio store that installs car stereos or online or whatever and get all the wiring, with inline fuses as long as you want. connect it to the battery and connect it to your circuit. use an appropriate fuse for what you need and your done. simple. ya your guna have to cut wires. remove wires and add wires. get a soldering iron and good rosin core electrical solder along with some double wall heat shrink tube. make these connections last forever.

if your equipment draws some high power you can still keep it simple and use relays to turn on the circuits. I can share a simple schematic if you need one but I bet Google is faster.

I like to roll my own but sometimes I just buy a premade kit, then take it somewhat apart and solder all the connections because they are usually only crimped.

Al

 

[KiloMikeZ71]

your overthinking it. keep it simple.

Overthinking it?? Isn't exploring and analyzing every single possibility part of the fun?

power whatever you want off the 2nd battery, from the battery with new wire and a new fuse. if you want something kind of already built go to a pro audio store that installs car stereos or online or whatever and get all the wiring, with inline fuses as long as you want.

I can totally run another line myself - in fact I've done this kind of thing with the RigRunner with great results. I was just curious if there was an official way, hidden away somewhere in the shop manual to do this kind of thing. I guess I'll get out some wire, heat shrink tubing and start hacking away!

 

[thegawd]

I help a buddy constantly upgrading his audio system and the last time he bought a new amp he also bought a new positive power line with a built in fuse straight from the battery to the back seat of the trunk in his car. I couldn't convince him to solder a extra chunk of wire on the end so he pulled it out, replaced it and gave it to me. it's a pretty sweet power line and intended for car audio amps drawing lots of power. I think I'm guna use it to power an air compressor.... that's why I suggested using one like that as it's already rolled and ready to go... and looks great...

 

[thegawd]

this is what I'm talking about... its 6 gauge and 8 feet long. I forgot about the sweet little ground wire he didnt need either. my buddy did not want to solder an extra chunk of wire on the end because he believed it would mess with the current flow to his amps.... and yadda yadda yada. hes prolly right but like I wouldnt think it matters.... he overthinks everything but is a perfectionist and so am I. he throws a crazy idea out there and I usually simplify it for him. lol.

I just noticed this is only a schoosch so it's probably just from walmart and cheap. but I dont see any issues with it, it looks like the quality is there.