I have a 2014 Prius Plug-in. It's the 1st time I'm having a real issue with it. The car doesn't turn on and it looks like a dead battery. We bought a new battery less than 2 years ago, so it was under warranty, we bring it back to the store, they recharged and tested it, they said it was good. The car was doing fine for a few days after re-installing it. Then the same issue happened again, we bring back the battery and they gave us a new one. The car runs fine for a few days and same issue today. At this point, I don't think this is an issue with the battery, do you guys know what it could be? Bad fuse maybe? How can I troubleshoot this myself? Thanks! Edit: Just found a very similar post but with no solution provided: Prius plugin won’t start - after new 12v battery | PriusChat
Just a possibility - that your alternator is shot. What your describing happened to my wife’s benz last winter. When charged the car would start - and drive - but because the alternator wasn’t charging while driving the battery would drain. good luck - but have a shop test your alternator.
Strange, the guy at the Pepboys told us the Prius didn't have any alternator. Just confirming that from Google "Unlike normal cars, the Prius does not charge the 12 volt battery via an alternator spun by the engine. This vehicle charges its 12 volt battery from the hybrid system"
measure the battery when the car is charging, and when the car is ready. if those values are okay, then it is not the inverter (aka alternator) the other possibilities are a drain on the battery due to a short or corrosion, or you got a defective battery. (it happens) also possible the new battery was in a low state of charge. they should be charged before use as the car is not very good at it. testing for a quiescent drain with the car off is a bit complicated, and you need the normal value for your car from the service manual. instructions can be found by searching here. any aftermarket electronics on your car? are you driving every day?
the other thread you are referring to said the car was draining the 12v when plugged in. a couple measurements as mentioned above will tell you if that is the case
Pepboys had the right answer. No alternator in a Prius. That doesn't mean the DC/DC converter is good or bad, but those very rarely fail. It's super easy to just measure the voltage at the battery while the car is running to verify that it's charging. It's unlike to be the problem, but easy to eliminate. (Ignore whether the ICE is running. Again, the Prius has no alternator. Just have it in READY mode.) @bisco is sending you in the right direction. Measure the 12V battery's voltage at the battery terminals and also at the jump point in the fuse box under the hood. They should be close to the same. If the battery reads good and the jump point low, then there's a loose connection. Sometimes it's the battery terminals themselves, but the hidden one that bits a lot of people is the negative connection to the car's body near the 312V battery. Make sure it's clean and tight. If the battery voltage itself is dropping, then there's some load that's staying on while the car is off.
I'm planning on bringing the battery to a different shop to test and charge it. Just to have a different opinion (I haven't received great support at Pepboys unfortunately) And then plug my OBD scanner and see if I can find anything by myself. If not, the best option would probably to bring it to my local Toyota. I'm just worried it will cost a lot of money there but I don't think I have a choice. I'll make sure to update this topic once I have news
That is correct, no alternator. Does your ready light come on? How about other lights? For example can you turn on your headlights, interior lights or are they all dead? Does your dash show state of charge of your hybrid battery or is dash dead?
By now, I'd think you'd have a charger and be using it. If you don't have any trouble lights showing, then you won't find any trouble codes. Yes, it might cost quite a bit. And/or, they will say your battery is fine, which it probably is. You need to locate the vampire load or the loose connection. Please do. Happy hunting. Hope you get it sorted out quickly.
Does your ready light come on? No How about other lights? For example can you turn on your headlights, interior lights or are they all dead? I can turn them on. And I actually turned off 2 of them this morning. Could it be the root of the issue? They stayed on the entire weekend and we haven't used the car Does your dash show state of charge of your hybrid battery or is dash dead? all dead. By now, I'd think you'd have a charger and be using it. haha, yeah I've been thinking about getting one actually Yes, it might cost quite a bit. And/or, they will say your battery is fine, which it probably is. You need to locate the vampire load or the loose connection. I'm afraid there will be a lot of back and forth unfortunately Please do. Happy hunting. Hope you get it sorted out quickly. Thanks!
@bractar how often are you using the car, and how long are your drives? Ever had any accidental discharges, say a door left ajar overnight, or similar?
So, I brought the car to Toyota a few weeks ago. They’ve done a bunch of tests and haven’t found anything wrong. The car is working well. The issue was probably coming from the headlights that stayed on. Even if it’s still possible I got a bad replacement battery the 1st time Thanks all for your support!
