I have a 2004 4Runner V8 I need to sell, it’s been sitting for a year. I go to start it, battery dead. Buy a new battery starts, couple weeks later, drained.
I have a charger from harbor freight, which has worked in the past, but it won’t recognize this battery.
I saw some dudes online that said if you connect a good battery to the bad battery, then you can “trick” the charger into charging the bad one (at least enough until the charger will recognize the low battery).
—-is this dangerous? Can I ruin the good battery I’m connecting to it? I don’t really want to buy another battery as I’m just trying to get rid of this 4Runner.

Any advice would be appreciated.
Thanks

Sorry, just realized phone had me in the wrong thread. Ugh!

There are parasitic drains on car batteries; radios, ECUs, etc. If you let them sit the battery will eventually run down. In addition, I read here that the JBL radio amplifier also has a problem running down a battery.

If you don't have experience with batteries then you really shouldn't mess with them. Car batteries can be very dangerous. If you've had the battery for only a few weeks and it's dead you should return it to the store and get another one. Start the car daily for a while and check the voltage, both running and stopped, daily to monitor for any drains. When charged up it should read 12.7 volts DC. Take the car to Advance Auto or other parts store and ask them to test the alternator, battery, etc. They usually do that type of work at no charge.

The battery you should have in there should be lead-acid. This could be a standard lead-acid or it could be an AGM battery. You shouldn't have a LiFePo4 battery; Lithion Ion. That's the type that you were describing in your post. If they get drained low enough you have to put another battery in parallel with them to raise the voltage. (Positive to positive, negative to negative)