Need an engine-running-only power source. Ideally I'll tap into the inverter. Help w/ the pinout?

I'm wiring a 20A DC-DC battery charger into my backseat.

Sidenote on this, you guys will love to see the photos of my seat-delete/ platform project when it's complete. Very clean.

Anyway, most of the electronics will be where the 1/3 seat was. I've built a platform, along with a back panel and side wall so that I can mount up all my breakers, fuses, kill switch, etc. and so that it all looks nice and clean. I'm sending a 2AWG cable to the bed on a 125A breaker. I've fully (I hope) dust & waterproofed the bed, storage pockets, rails etc... the large storage pocket will be my fuse box.

THE POINT OF THIS POST...

My 20a DC-DC charger needs an ignition-on power signal so that it knows when to start doing it's thing.

Since everything's in the back seat, and I can't think of another source outside the engine bay, I thought it'd be a good idea to tap into the inverter that's located in the bottom of the center console. It's right there, so it seems like a no brainer.

I can always make a test light and start touching stuff while the truck is running... but I thought someone here might have a definitive answer on which wire I should tap into for the power signal I need.

I haven't even taken the console apart yet to look at things, but I'm assuming that there are probably 2-4 wires going into it, and 2 coming out to the bed. I would assume that the inverter gets a heavy power cable in, as well as a heavy ground. Then I'm thinking there is probably a low-voltage power and ground to tell it when the engine is running.

Does anyone have a diagram of what's going on down there, a related post, or a YouTube video? My searches are coming up pretty dry.

 

i would just use a module like this, that trips a relay to enable the dc-dc whenever the trucks charging system exceeds 13v. anything above 13v is the engine/alternator running.

$28 UCkasayfy Dual Smart Battery Isolator 12v 80amp Voltage Sensing Relay(VSR) Compatible with UTV ATV Marine RV Motorcycle, Not Fit for Lithium Batteries

https://www.amazon.com/Isolator-Sensitive-Compatible-Yacht，Not-batteries/dp/B0C2V96VL9?th=1

 

Simple design would be to put a switch on the ignition on line and jumper it to the charger using the 20amp source input. Then I would use a proper gauged cable to run from the 20amp source input to the battery as well, and add a 25amp breaker or fuse on the battery side of that cable as well. Then you can just manually turn on and off the charger. It won’t over discharge the truck battery if you get a good charger, it’ll shut itself off before the battery voltage goes too low, and some of them are even programmable for what battery voltage level you want it to shut off at.

 

Right. So what ignition on line are you talking about? That's my question. I know for sure there's going to be one at the inverter, which is about 18" from where I need it. Sure I can pull the door sills and get to the OBD2 if I need to, but I'm certain there's going to be one at the inverter.

 

Sorry, I wrote this in a hurry, you’re talking about a battery charger, not an inverter. I have a Renogy 20 amp DC to DC battery charger. Its ignition on sensor wire is jumped directly into the power input source cable that comes from my 2nd (house) battery mounted up front, and is programmable so it comes on when the house battery voltage drops below 10v. It charges a third battery I have in the back of the bed where I keep my refrigerator.

 

Okay. No answers here. Test light time I guess.

 

https://www.tacomaworld.com/threads...3rd-gen-today.399305/page-14078#post-29878451

That's what I did. All under the hood.

 

OP, does your Taco have (had) the amp in the rear seat?

 

On your quest for the inverter IGN wire, it only has juice when you select the inverter to run.

 

a bit harsh, don't you think?

also, most of the circuits within the vehicle are ignition-on, but not engine-running. you specifically asked for engine-running circuits.

 

OP is trying to do it the hard way…

 

Yah best option is to run direct off the starter to see the voltage increase from the alternator. You can run a line under the truck to the rear cab and into the seat delete. I considered the rear of the cab but came to conclusion you need to run some lines. Will be putting in the front of the bed.

 

But you don’t need that if you have a good charger - the sensor line for engine on (at least on the Renogy DC to DC charger) can be directly jumpered to its main power input to fool it that the alternator is running. One can even add a switch to the jumper to manually turn the charger on and off remotely, or as Carbie points out, they can use the line from the OEM inverter and its dashboard switch to do it if they wish.

The charger also has the ability to turn itself off if the source (“house battery”) goes too low- in my case, it’s drawing directly from my second battery under the hood so it still works while parked and never draws power from the main battery.

 

Yah Run a red arc setup and it taps the main for car input or solar whichever is greener and chargers the house battery. When the truck is off it’s not drawing from the battery. Diff setup but how mine is ran. If it works then go for it.

 

i should also add, it seems in really poor taste to connect the dc-dc setup to only an engine-running wire, specifically because it would indicate end-use is anticipating allowing the truck to be on but not running for extended periods of time, and there's no mention of any main battery voltage protection, change-over, or cutout.

that's a really good way to strand the truck somewhere for long enough to hike back to civilization, regardless of the gear being added.

if this is not the intent at all, connecting to any standard ignition-hot source via an add-a-fuse would be more than adequate for the situation, and solve a majority of the starting battery issue as well, though not entirely. if one is really going to be boondocking out far, a secondary starting/accessory battery solution would be highly recommended.

 

Yeah there are a lot of little issues with the way this charger checks for engine-on current, and my initial plan.

It would seem that the most straightforward way of tacking this as intended by the mfg would be to tap into fuse #7.

If I'm correct I just need to trace that fuse to the other side of the firewall before it branches off to anything else. I don't want to screw around with switches or more wires through the firewall, I just want it to work as intended. It knows when the voltage is above 13v, so it seems redundant and frankly stupid that renogy requires a direct connection to an engine-on circuit. But here we are.

Anyone know how to identify the wire coming through the firewall by the OBD2 from fuse 7?