2002 Honda CRV Electrical problems. Please Help.

The battery died a couple months back, we were at a stoplight and everything in the dash as well as radio shut off and coming to a stop resulted in the battery dying and shutting off the car. We took it to the shop and they replaced the battery, Napa Legend. Everything seemed fine for a while. About a week ago it was only starting after the 2nd try, it was very cold so I dismissed it. Then the other day as we were planning a big trip, car wouldn’t start. We figured the battery had froze, so we jumped it with my car and everything seemed fine. An hour into the trip and again everything in the dash/radio shut off, so we pulled into a gas station and let it run, eventually the alternator charged the battery, everything came back on, battery light shut off. We drove home instead of continuing our trip. The car was fine the whole drive back. So today we took it to the shop and he says it “might” be the alternator. They tested it though and it came back fine. Battery tested as well, just fine. So, after doing some research I found out about the electric load detector. It controls the voltage regulator inside the alternator because it uses a dual mode charging system. How would I diagnose this? I also need to check wire connections from the battery but the only way to get to anything like the starter where the positive terminal leads to is to remove the intake manifold.. such a pain. I don’t think it’s the alternator. If it was, we would’ve been stranded as the battery would not have recharged or made it the whole hour drive back. One more thing, I have a diagnostics code reader, and we got a p1166. That has to do with the oxygen sensor I guess. Would that be able to drain the battery or is this highly unrelated? Last week I didn’t have any codes show up, but if the wiring is bad it might have erased stored codes. I’m very new to fixing my own vehicles and any advice would be appreciated thanks for reading.

O2 sensor will not drain the battery. It sounds like your alternator is going out. Simplest fixes clean up all battery cables, grounds, tight etc.

If the battery light came on and it wasn't charging then the alternator is failing. They dont always fail all at once.

Just got back from O’reilleys and the guy there said it’s probably the voltage regulator inside the alternator. I’m just trying to diagnose any other possible causes as I live in Wisconsin without a garage and I’ll have to remove the radiator or intake manifold just to get to the alternator. It’s a lot of work. I noticed the wires from the negative terminal are heavily corroded as well, I’m going to try and clean those up but it’s more on the actual wires. Guy at Oreilleys said that’s not the problem as the vehicle is starting, if it was corroded enough it wouldn’t start. I feel like that makes sense but still could cause problems. I wish I could find a way to test the ELD, I bought a multimeter..

The O'Reilley's guy is right. If the negative terminal were a problem it wouldn't start. I know you are hoping to find a different issue, but the problem is the alternator.

I've seen a couple posts about guys removing passenger side mount and jacking the engine up to get to the alternator.

You guys were right, it was the alternator. I had no idea they could go out slowly and not all at once. If anyone finds this and needs to replace theirs it’s not as bad as it seems, just take out the bar that holds the door lock, a few bolts at the top and one under the car. Splash guard was easy to remove down there by popping out the buttons with a screwdriver. Then we took out the fan nearest to alternator, removed the liquid canisters and we were able to carefully remove the old alternator in the space between the manifold and radiator. Some people take out the intake manifold and I’m glad we didn’t do that. It wasn’t as hard as I thought it would be! Luckily we got all this done before the -55 degree weather and it had no problems starting up in the extreme cold.