Alternator. ?

No alternator. It has a high voltage ie 200-250dc to ~14 v dc converter. If you have an oem amp hour battery and a prius with sks(keyless entry) the battery will drop too low to start around 3 weeks.

There's an under dash button to disable sks to limit passive battery usage. If you press this button you'll have to unlock it with the remote or physical key.

Showing 8 bars, which i recall is basically in the green zone, is not necessarily a sign of your hybrid battery being in great condition. Every time your prius hits 1 bar it recalculates overall capacity. Doing a lifespan estimate with dr. Prius is the smart way to get an idea of hybrid battery health.

54mpg is great but that number really reflects speed and throttle usage. Seems like you're probably driving 60mph on the freeway and only doing longer distance trips. Even with a brand new hybrid battery, if you only drive 10 minute distances the gas mileage will be below 40 due to emissions system warm up cycle.

The gas mileage at flat freeway speeds is really based on aerodynamics, not battery health. Not saying your hybrid battery is weak but without hill climbs involved it's just guessing.

 

There is no alternator. The car has a DC-DC converter to recharge the 12v battery.

Check voltage while the car is in READY mode.

 

Our generation 2's electronics will say all kinds of things on the MFD 44 to 51 miles to the gallon. I don't believe any of that nonsense until I get to the flashing pip the last gas square add another 20 mi to that and then I stop at Sheetz and fill up with blue fuel and every time I do this just in this way I don't fill up the car any other way traveling in town none of it this is the same way all the time forever in the history of my life before the gas pips flashed in old Corollas I'd run it down to e add 20 mi stop and fill up same methodology. When I'm filling up the Prius after this has happened I'm generally adding 8.9 to 10.1 gallons of fuel almost like clockwork every time I stop It is very boring it never changes ever. And then I can calculate my actual driving on the gas that I just ran out.

 

Prius has a long history of 12volt batteries that lose their charge because the 12volt doesn't start the engine, only turns computers on, so the amount of amps the car sends to recharge the 12v is very low. A cheap trickle charger can work, but if you forget to use it and battery drains down it'll take days to recharge the battery fully.

So your best bet is a smart charger for 12volt that goes up to at least 10amps. You can find them for $30 to $50 online. The smart part means it will use all 10amps when the battery needs it, but once fully charged it will turn into a trickle charger.

 

Same here I don't have any 12 volt problems I just make sure I get good 12 volts when I buy them Good name brand all that sort of thing I've also run some cheap universal batteries. They all seem to work fine if they're good as in made well We seem to have a lot of problems with batteries right now.

 

Usually, people who say, "First 2.5 yrs with this car from 72k - 112k there was never a 12-volt battery problem", change their driving habits as time goes on and are not driving the car for long enough anymore. Sometimes we forget to qualify the advice because to us it is common knowledge and we forget it is not so common to everyone.

If you are now driving multiple runs for less than 20 minutes each, then the battery will not get a chance to charge up fully so it will run down quickly.

 

I switched to using a wheelchair agm years ago and have absolutely no complaints. There's a write up on this forum. Not only does it decrease battery replacement cost but also increases overall capacity. It's very useful if you're leaving your vehicle parked, using auxillary stuff like a 12v fridge or power inverter.

Worth checkin out. I paid around $90 for my battery 3 years ago and even when left alone for a month(driving camry instead) the prius fired right up.

 

Totally agree... @brittprius on here over a dozen years ago posted and I argued on his behalf ever since on the thread that this was the most intelligent approach for 12v for Prius. So many no-nothings attacked us for being unsafe and unwise, yet my first wheelchair AGM lasted almost 10 years and am already 4 years into my next one.

This is the battery I recommend to people for Prius: 12 Volt (12V) 55 Amp (55Ah) VRLA AGM Sealed Lead Acid Battery 55 AMPS HIGH CAP | eBay

 

I remember when those things were like $45 seriously probably about 10 years ago when you first started buying them right? These are like the UB universal batteries used an alarm systems and elevators inside of those 12 volt fire lights and all that kind of stuff

 

First one I bought was in Oregon in 2012 and It was like $88 and no sales tax. As BritPrius explained, the mobility batteries, which are also used as a personal desktop computer's backup power supply, as well as the other issues you mentioned are so abundant that the prices are way lower than what all the auto parts stores charge because a Prius battery is "different" and thus earns an extra $150 charge on top of standard price for no particular reason other than profit/they can get away with it.

 

Sorry, but that is his posting style, he isn't going to change.

 

Either a bad battery which is easily load checked where you bought it or you have an excessive parasitic draw far in excess of 30ma. Also easily checked with a $7 Harbor Freight meter.

Other than lights (see below) the usual suspects are aftermarket accessories like radios, navigation, alarms or obd2 devices.

Measure once to avoid fixing it twice.

He said he does not trust gen2s mpg calcs and simply waits to low fuel light, drives up to twenty miles more and fills it up.

True. Had gen2s and a gen3 since 2008 and well over 400k miles and never needed a trickle charger. However not latching the hatch through second stage or leaving a map light on will discharge the 12v overnight.

 

Well then why does the 1.5L motor for a Prius that I have in front of me about to install into my 2009 Prius have an alternator attached to it?

 

History is about to be made! Do you have enough posts to add a pic?

 

Also, I didn't realize how much different a PHEV works compared to the none, the cars in themselves even have higher volts than the non PHEV. That's why I always thought of mine as a generator on wheels. I noticed after the first 85ah 12v some change in the number of times ICE turns on, after adding second 85ah ICE turned on significantly less. Particularly over night in Ready mode. A fully charged HV battery together 6-8 hours was the max time between or before ICE turned on running fridge and a/c plus everything else. I know the upgraded cells now will get me 12 hours but the goal is 50kwh and 24 hours of usage from the HV system.

I haven't don't overnight since new upgraded cells and just found the battery I hope gets me to ~50kwh...I just still think they have been leaving clues all these years. There is something in here that's an ecu swap from another toyota vehicle that's gonna unlock this all.. you know, the new Gen 5 Prius and Rav4 share the same CVT...

 

If it is a factory alternator the engine is not a Prius Atkinson cycle version. Most likely a conventional Corolla, Scion or Yaris engine.

 

Lawdy. Yeah okay what's driving that alternator? So the thin little water pump belt is going around in alternator too or there's a second belt from the water pump on the said crankshaft pulley so there has to be another set of grooves to turn this alternator which is on what side of the engine maybe you have a Yaris engine or something who knows who's even worried about it when you get this into your Prius which it will fit in both up You're going to have some hysterical running problems balance problems that sort of thing I would imagine but this is the project I wanted to see somebody do You might need to lose the alternator but I guess you could maybe keep it I'm not sure what you'll do with it in the same size frame I think you can get 200 amp units that might be used for something but I have no clue.

 

Maybe the alternator was only there at 12:10 AM. By 12:25 it was all about PHEV differences and extra batteries.