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We are getting delivery of a 2006 Prius in about 2 weeks. Shortly after that we will have to leave it unused for nearly 2 months. With a normal car we use a "battery minder" to keep the battery fully charged when unused for a lengthly period of time. Should we do the same thing with the Prius?
 

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Absolutely. The Prius has a smaller battery with a smaller AH capacity, since it doesn't have a traditional starter requiring hundreds of amps. If you were going to tender a conventional car, then tender this one.
 

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I have a further question about using the battery charger on the Prius.

Are the main batteries are able to send energy to the 12v battery to keep it charged? And if that is the case, is it possible for the 12v battery to send energy back to the main batteries to keep them charged too?

So if you were gone a long time could you somehow use the charger to keep the main batteries from declining too?
 

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Shelf life of the main batteries is probably well over a year and the shelf live of a standard size 12 volt would be well over several months. Our problem is with the selection of the small battery by Toyota. To me it appears there is plenty of room for a standard 12 volt car battery and that would not only save over a hundred dollars on a replacement but eliminate better than 90% of the troubles with the Prius 12 volt system.
The Civic hybrid has a standard size battery under the hood like the Civic and Camry.
 

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sub3marathonman said:
I have a further question about using the battery charger on the Prius.

Are the main batteries are able to send energy to the 12v battery to keep it charged? And if that is the case, is it possible for the 12v battery to send energy back to the main batteries to keep them charged too?

So if you were gone a long time could you somehow use the charger to keep the main batteries from declining too?
HV battery only charges the 12v battery when the Prius is in READY. When the car is not on, the HV battery is disconnected from the electrical systems for safety reasons.

The 12v battery can only send energy over to the hybrid battery if you have a NHW10 Prius (1998-2000 model year, only produced for the Japanese home market).
 

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hyperion said:
The Civic hybrid has a standard size battery under the hood like the Civic and Camry.
Yes, the Honda hybrids have a standard 12v battery, but they also have an emergency 12v starter as well. The Honda hybrids are able to still be driven like an ordinary gasoline-only car should the hybrid battery be totally depleted/unusable. (Normally, the hybrid battery is what starts the gasoline engine.)
 

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I figured that one of the reasons for the fullsized battery in the Cuvc was for the optional starter use but it also will save an owner a hundred bucks when it needs replacement and why with all the other backup systems in the prius did Toyota find a reason to customize a smaller, and much more expensive battery? There is a lot of room back there that will never be even "looked" at, and 12 volts, is 12 volts. It's become fairly obvious that the smaller size battery can to lead to a lot more problems. With the big battery those dome lights could be left on for a week.
I also wonder if a local Prius dealer keeps one of the batteries "in stock?"
Toyota isn't alone with this parts problem. My son picked up a spike in one of his tires on his 06 Civic hybrid and the dealer had to replace the OEM Dunlop with a Michelin of the same size for a week while he waits for an OEM Dunlop.
(as an after thought, I now know someone who has had a flat tire in the past twenty years!)
 

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Battery Minder

A battery minder is a good idea as long as it does not overcharge the battery. I believe that the Prius 'Glass-Matt' battery is more sensitive to overcharging. I read somewhere in Prius documentation that 12V Charging must be done with currents less than 1 or 2 Amps.

A lot of Battery Minders produce 1-2 Amps and then Float the Voltage to prevent overcharging. My parents left their Prius on such a Gadget (bought at Lowes or Home Depot) for 4 months and had no problem.
 

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Use a Float Charger to keep the Battery topped off if the car is left un-used for an extended period. It will only keep the battery at the level it is at when the float charger is connected. It will not over charge the battery.
Harbor Freight has then for a couple dollars. :D
 
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