Keeping the 12V Battery Alive

I would buy a battery tender if you will be doing this often. It's a small charger designed to monitor and maintain the battery during longer periods when the car is not in operation.

Here are some examples: Amazon.com: battery tender - Battery Chargers / Jump Starters, Battery Chargers & Portable Power: Automotive

 

The Prius engine does not need to run to charge the battery "it has no alternator in the normal meaning". All the car needs is to be made ready and left in park, this will charge the 12 volt battery.
If the car is normally parked outside a solar charger will keep the battery happy. Failing that a battery tender left on for the duration will work well.
Another option is to disconnect the 12 volt battery at the negative terminal, but this has the disadvantage of loosing radio presets and auto window settings "no big deal".

John (Britprius)

 

I left my car in the garage for a month with no ill effect.

 

To keep the Prius battery alive while traveling for weeks with a Solar Power Battery Charger that I bought for around $27 on Amazon.com. The brand I got is Wagan Tech. Best thing I ever did. I usually go away for around 6 weeks at a time and had to ask friends to turn on the car and drive it around. Not anymore! My car is in a garage with dim light and it still works. I didn't get this answer from Toyota. They never helped me when I first tried to find a solution. It was the guy from the Triple A who told me what to do as he charged my dead battery. He said everyone with a Prius had this problem.

 

Get the Solar Power Battery Charger by Wagan Tech.

 

I have 4 Priis and I don't have this problem.

 

Is 2 weeks a common length of time? If it is I may need to get a charger. Figgy is this the one you are referring to:

 

If your father knows to put the car into ready mode by pressing on the brake peddle before pressing the power button, the big hybrid battery will charge the 12 volt without the gas engine needing to be on.... it is always charged by the hybrid battery to the inverter at the front, then back to the 12 volt using a dc to dc inverter circuit.

If you had not said that it 'dried' up already once during a two week period of non use, I'd say don't worry about it as 2 weeks is nothing if the battery is in good condition and properly charged.

My car is an early 2010, and I recently replaced my 12 volt battery because it is 5 years old and the capacity was degraded. Never needed a boost in those 5 years, but I can't be bothered with that kind of stuff happening when it is likely going to be most inconvenient.

Here I live in a moderate almost Mediterranean climate on the Pacific West Coast.... could be your battery lives in hotter conditions than mine, and maybe you don't have the solar roof running a cooling fan all the time when the sun is high to keep heat down for the batteries.... some 2012 people have had to change out already. Get it load tested and see if a tender or replacement is in order.

Have a safe trip,

Roland

 

I use a walwart with clipleads and leave it plugged in 24/7. I tested several walwart's until I found one that would maintain the battery at 13.2 volts. The car is 2.5 years old and only has 1500 miles on it so you can kinda figure how much it sits powered off

Mike

 

Sooooo... about every half mile you drive, you post a message on PriusChat?

 

Since I bought my Kia Soul I have not been into the Prius thing so much as before. I did renew the license on my Prius the other week so I can drive it now She's a little dusty in the garage so a bath is in order first

Mike

 

I have left my 2013 for a month with no problems. One time, I was gone for 6 weeks and I hooked a batteryminder to the battery connection in the fuse box and that worked out just fine. I guess everyone knows about the battery connector inside the fuse box under the hood. It's a lot more convenient to use than having to gain access to the battery at the rear of the car.

 

Hi - quick question: So...just got a Prius 2014 and was wondering what to do when I leave for extended periods of time to keep the 12V Battery charged. As per your post, it sounds the Solar charger from Wagan will do the trick. However in a different post on this board it says that the cigarette lighter which the Wagan plugs in is NOT active when the car is turned off. Hence the charging wouldn't work. You say above that it's working for you......so....is the cigarette lighter on when the car is turned off and the Solar charger with the regular cigarette lighter plug works to trickle charge the battery, or does it not work (or need modifications.)
thanks much for clarifying!

 

The manual only says the outlets can be used when the power switch is set to Acc or On and not to use the outlets too long when the hybrid system is Off. Seems somewhat contradictory. FWIW, I just took my Garmin out and plugged it into an outlet, it didn't turn on. I hit the Power switch and the Garmin turned on. I hit the switch again twice to turn it off and the Garmin dimmed, meaning it was now on battery power.

 

True, I've used the front. But if I am not able to be around the car and come home late at night. The car is always outside. The ctek charger has included a little 12 inch cable with which you can leave it attached to the 12 volt terminals in the back. The cable has a plug with cover that extends up onto the cargo floor, so you can just lay the charger on the floor with it attached to the cable. My hatch will close over the extension cord which is plugged into an outlet inside the garage. Of course the garage door closes over the cord too. So everything is secure and the charger is automatic. It does some cycling magic as part of the process where it is claimed it recovers the battery from sulphation.

Roland

 

That means not to use them for too long when you're not in READY; i.e. the hybrid system (HV battery and ICE) are off. In ACC and IG-ON, the hybrid system is still off, and you're running only from the 12V battery. If it gets low, you might not be able to start the car. On the other hand, if you're in READY, the HV battery will keep the 12V battery charged, and the ICE will keep the HV battery charged. You're on your own for filling the gas tank once every few days, though.

 

Thank you, it makes sense now. I'm quickly learning I can't always assume terms mean the same thing as they would in manuals for traditional cars.

 

Based on this reply, you could use the Wagan battery charger with the cigarette lighter plug for trickle charging the battery while gone for a while? Can anybody confirm that they have successfully done that?