How do you charge a battery on a Prius?

Q: I know the Prius recharges itself, but my battery never gets a full charge. Someone said that if you could charge it independently of the car, you can get even more mileage. Since it's a 300v battery, it can't be charged with an ordinary battery charger, so how can I do it? PLEASE, if you don't know, don't answer.

A: The displayed charge on the HYBRID battery (seen on the Energy Monitor) rarely ever reaches "full" or "empty" but prefers to stay at a happy medium. The display only shows you the useable area of charge on the hybrid battery, displayed "empty" is about 40% and displayed "full" is about 80%. Actual charge levels of a NHW20 Prius can be seen at: http://www.privatenrg.com/#Full_SOC The two bottom pink bars are about 40-47.5% battery charge. The most common middle four blue bars are about 45-66.5% battery charge. The two top green bars are about 64-81% battery charge. Quoting from a June 22, 2004 Toyota press release: http://pressroom.toyota.com/Releases/View?id=TYT2004062345528 The Prius battery (and the battery-power management system) has been designed to maximize battery life. In part this is done by keeping the battery at an optimum charge level - never fully draining it and never fully recharging it. As a result, the Prius battery leads a pretty easy life. We have lab data showing the equivalent of 180,000 miles with no deterioration and expect it to last the life of the vehicle. .... To quote from Toyota: http://www.toyota.com/html/hybridsynergyview/2006/fall/battery.html Q: Do they [the hybrid batteries] ever run out of power? GS: No. A computer makes sure the batteries never discharge completely. They never fill completely, either. " So yes, it is normal to not see the battery display on the Energy Screen reach green/full very often. (Even when it does read "full" - like after coasting down a long hill/mountain - the battery still isn't charged to full, to prolong the battery life.) It is also not common to see a low/pink battery icon either - usually a long uphill climb or heavy AC use (since the NHW20's AC is electrically-powered off of the hybrid battery, and is not a conventional belt-driven off the engine AC (like on the Classic Prius)). There is no reason to be concerned at all to see the battery level at either extreme. The car takes care of itself, and you don't have to do anything special. (Turn off the display, or just stay on the more useful Consumption Monitor.) If the hybrid battery is too low on charge, the Prius will just turn on the gasoline engine to recharge it if necessary. If the hybrid battery is too high on charge, it'll bleed off as much energy as needed by running on electric only or occasionally by spinning the gasoline engine with the electric motor (similar to B mode). I'll note that the older Classic NHW11 Prius does not have any color changes on its battery icon on the Energy monitor... Normally just sits on 3/4, occasionally on 1/2, rarely to either 1/4 or "full." On an aside, there is no 300v battery in the Prius. The Japanese-only NHW10 was the highest at 288v, the Classic NHW11 was at 273.6v, and the current NHW20 is at 201.6 (stepped up to 500v for the hybrid system). There is still a traditional 12v accessory battery used to boot the computers and power the usual electronics (like lights, radio, fan, etc.), but it is physically smaller than in a traditional car because it is not needed to turn over the gasoline engine. Because of the smaller size, it is easier to run down/flatten this battery through the usual means (leave a light on overnight, or don't drive the car for 2 weeks, etc.). You can jumpstart/boost this 12v battery, or charge it using an ordinary battery charger, to get your Prius going again after such a draining episode. Just remember that the 12v battery is physically located in the trunk, or if you have a NHW20 Prius use the jump-start point under the hood (in the fuse box), as indicated in your owner's manual. There are no commercially-available plug-in hybrids on the market so far. (So you cannot plug a hybrid in, other than the same gas station pump that most other regular/conventional cars use.) The hybrid battery is recharged either through regenerative braking (kinetic energy from coasting/slowing down spins a generator to make potential energy in the battery) and/or by taking excess power from the gasoline engine (use the gasoline engine as a generator) to recharge the hybrid battery. There is no plug. No charging off the mains/local electric supply. Some hobbiests and aftermarket companies have been altering a few hybrids (Prius, Ford Escape Hybrid/Mercury Mariner Hybrid) to make them plug-in capable. Typically this requires adding additional hybrid batteries, besides the ability to charge off the mains. For more information, check out http://www.calcars.org/vehicles.html and http://www.calcars.org/howtoget.html For cost reasons, unless you are a fleet owner or other high-mileage driver it probably will not be worth the cost of the PHEV conversion for you. (Conversion pricing is high due to startup costs and low volumes, besides the pricing of the needed additional battery packs.) To note, converting to a PHEV (plug-in hybrid electric vehicle) does not reduce the vehicle's range. It gives the owner the option to recharge the (newly added larger) hybrid battery pack at night (cheap electricity and off-peak electric load which would otherwise be lost). The vehicle would run for a certain distance (longer than stock) on the stored electric power alone, and when the battery pack is depleted to a certain point the vehicle reverts back to its original hybrid self and runs on a combination of the gasoline engine (which will also recharge the battery) and the electric motor. A PHEV would add a greater all-electric range to the existing hybrid, besides the ability (but not the requirement!) to plug it into an electric source. (Electric power is cheaper than gasoline, and can be from cleaner sources (hydro, wind, biomass, geothermal, etc.), and is usually domestically-sourced.) Toyota is working on creating a PHEV Prius, and has some test vehicles on the road. Supposedly for the 2010 US model year, and only for fleet customers at first (so not general retail). http://pressroom.toyota.com/Releases/View?id=TYT2008011405523 http://pressroom.toyota.com/Releases/View?id=TYT2007072552930 http://www.toyota.co.jp/en/news/07/0725.html video: http://www.toyota.co.jp/en/tech/environment/phv/conference/index.html Also, on http://www.toyota.com/prius-hybrid/demos.html , check out the Prius FAQs. "9. Do I need to plug Prius in? Never. Prius automatically recharges its batteries using regenerative braking, or by running the onboard generator. The driver never needs to worry about recharging the battery. 11. Can Prius be jump-started? Yes. Should you need it, Prius can be jump-started with any standard 12-volt DC power source, and it actually requires less power than a conventional car. Simply connect the cable clamps to access points under the hood (which are connected to the auxiliary battery near the cargo area) and energize the computer. Then press the Start button to turn the car on. Please see your Owner's Manual for further instructions. 16. What is the warranty for Prius? ....Hybrid-Related Component Coverage: Hybrid-related components, including the HV battery, battery control module, hybrid control module and inverter with converter, are covered for 8 years/100,000 miles. The HV battery may have longer coverage under emissions warranty. Refer to applicable Owner's Warranty Information booklet for details. 24. Does Toyota support the modification of my Prius to be a plug-in Hybrid and run on electric mode only with a switch? Any such alterations, modifications or tampering with the vehicle voids the warranty and is likely to be counterproductive for air quality and Prius' durability and safety. "

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