Ok, so I've done some basic research, but it all comes up either inconclusive or just not detailed enough.
While I'm not a complete idiot, I'm not very versed in vehicle electronics.

I'd ask on the Rav4 website, but the people there are a bit...useless.

We've had our '03 Rav4 since 2012, relatively problem free. However, for the past year or so, it's had a parasitic battery drain. If it sits longer than 3 days or so, it won't start. Not even the telltale clicking. Just completely nothing. It had a new-ish battery still under warranty when this started, so we had it replaced, but the issue remains.

Basic backstory:

It has a remanned AutoZone alternator that I installed about 3 years ago. Alternator still works fine. I haven't measured the output, but when regularly driven, the battery will stay charged just fine, so it's clearly putting out enough to at least charge it when used.

I originally thought it was a cheap aftermarket radio that I had installed, but I did not splice any wires; I used a Toyota wire adapter. I've since put the stock head unit back in, and the issue remains. I now have the aftermarket radio in my 4Runner, problem free.

It has a 'rebuilt' ECM from an eBay seller that fixed the chronic 2nd Gen Rav4 transmission slipping issue. I installed this ECM about 2 years ago, and the power drain started 1 year ago.

It has an aftermarket alarm system (I think). It came from the used car lot with it, so I'm not sure. If this is the issue, it was problem free for years before then. I doubt a wiring issue if so.



I'd like to fix the main issue, obviously, but at this point I'd be OK with using one of those 12v Solar Chargers like this:
https://www.harborfreight.com/15-wat...ger-68692.html
Only problem with THIS is that the 12v/cig adapters aren't live when the key is turned off.

So 2 questions. Either or.

1. Can someone walk me through tracing this power draw? State it simply, please. Don't assume anything.

2. Is there a 'hack' to make the 12v adapters live (like this on the 4Runner: Toyota 4Runner Highlander Electrical Modifications Constant 12v Power). The Rav4 doesn't seem to have a Power Outlet relay in its fuse panels.

Tracing it down is pretty easy...
but first, even though I know you mentioned it... make sure the battery is healthy, and the charging system is good. At least make sure you are getting charge voltages when the car is running. (13.8-14.4v)... resting voltages should be in the (12.5-12.75v range).

Just get a DMM and put it in line (series) with the cars battery so you can measure current...

While hooked up like this be careful not to turn the key or start the engine otherwise ur gona blow the DMM fuse. Better the DMM, the better the readings. You want something with a sensitive low amp range. Start with the higher amp side, and depending on what you see, move over the the milliamps range for better resolution.

Also get some clamps and hold down the door open sensors so the car thinks the doors are closed and the lights are off.

After getting there, and its hooked up, identify that you do have some parasitic drain, and then start pulling fuses one at a time until you isolate the issue.

You are looking for a drop in current when you pull a fuse... Then fix the issue...

If you have aftermarket junk in the car... make sure you can also isolate those or test them as well.

Also... as to your solutions... which are not solutions... how do you even know 1.5 watts is even going to do it if you dont even know how much parasitic drain you have.

If you had 3 watts of drain and get a 1.5 watt charger, now instead of dying in 3 days it will take 6...

All good advice, but why not just close the doors?

Because often times there are fuses inside the cab as well, either on the passenger or driver side depending on the vehical...

I don't know about you but I prefer not to have to contort myself in order to work efficiently with things at knee and level level, plus I like to see what I am doing.

I'd put a top post battery disconnect terminal on it in the meantime, at least until you can figure out what is draining it.

If you park in garage or driveway a battery tender would be a better idea... at least that way you are not killing power to the ECU, radio, and whatever other systems in that car that benefit from persistent power to memory...

But for the time it takes to install that little do-dad... you could be pulling fuses and locating the problem. If its non-critical pull the fuse and leave it disconnected.

But its a valid suggestion depending on the situation...

Are there any aftermarket parts on it? I would start there first. I had the same problem on my 2008 RAV4 and it ended being a bad relay for Cadillac Horns I had installed years before. It wasn't until I pulled the relay that the problem went away.

Umm, he would be measuring current, in Amps (well hopefully, in milli-Amps) .

Not really sure what the purpose of that quote was... but isn't that like exactly what I ended up saying?

Two vehicles of mine I tested the fuse box after many hours of sensor and ecm/ecu tests.

Basically on my honda I ended up testing the fuse box with the fuses pulled out. I then probed the battery (+) to the fuse holder and found that both sides of the fuse holder (shows voltage) grounds out.
I then turned ignition switch on and probed the fuse holder hot (+) side to the chassis (-) and it also show voltage.

So petty much the fuses are both hot and grounded.

No, you were talking in terms of watts, which he can't measure with a meter.

Take this as you will. Test all the relays. Take each relay and then with a multimeter (ohm) probe the ground pin of the relay and probe the other pins with the second probe. The ground pin should only show ohms on one pin. If it shows ohms on either the power side or load side then the relay is bad.

No I wasn't... I was talking in current... ill even quote myself... you should read posts completely before making comments that add nothing to the thread.

Plus, I was making those comments in relation his solar "fix", and watts is actually the right way of expressing power... just in case you did not know...

Anyone with any background in electrical would know how to deduct current from watts... ohms law.

Current x Volts = Watts

So in my example 3 watt drain would have actually given a nominal measurement of 0.25 amps in current.

And just for shits and giggles... I do have a meter that can measure in watts, even though that has nothing to do with what I was saying... All it does it take two measurements at the same time and multiply them together to get you watts, the true measure of power.