2015 Land Cruiser

Battery appears dead. So I hook up my charger positive to positive, negative to ground.

Plug in the charger.

Hearing a distinct buzzing/clicking noise. That normal?

Do I need to disconnect the battery then?

Nope. Battery can stay connected to vehicle. Just ensure battery charger is off until cables are connected. You're thinking of jumping off of a battery installed on another vehicle. Negative to ground on dead battery/vehicle ensures a safe connection. Has more to do with not being able to turn "off" the connection from the working battery. When you make contact with the terminal it's a live connection. Not the same as a battery charger.

Buzzing from the vehicle or the charger?

That could be the solenoid for the starter trying to engage but not having enough current from the battery to function fully yet.

A really dead battery may have trouble taking a charge.

Is your ignition stuck in start?

xMusashix said:

---

2015 Land Cruiser

Battery appears dead. So I hook up my charger positive to positive, negative to ground.

Plug in the charger.

Hearing a distinct buzzing/clicking noise. That normal?

---

Most newer computerized chargers won't charge a completely dead battery. I have one that clicks/makes electrical hums that happens. You might see if the charger has an override mode. I have a Schumacher that does.

If the charger doesn't, the only other way I've been able to get completely dead batteries to take a charge is to hook them up with jumper cables to a good battery and then connect the charger in parallel. That shows enough voltage to get the charger to work.

Turns out the car was trying to start.

damn keyless ignition...

My suggestion is to pull the negative terminal and charge it.