Optima Battery

On the Prius (2015 and earlier) that 12 volt battery is not exposed to engine heat is toward the bottom of the car (2001 to 2009) so except for states like Arizona the battery should last a long time. The Toyota battery which is does not appear to be a deep discharge battery last 7 years or longer for many owners. However, when you discharge a battery you have to charge it. Just driving it is not always enough especially for a 30 to 45 minute drive. The Optimum battery in my Prius was 10 years old and I discharged it severely by charging up 7 hybrid battery modules. I then drove it about 45 minutes. A week later it died. If I had charged it right away it might have lasted a lot longer. This was a battery that had been deeply discharged at least three times, and had many many lights left on incidents and was ten years old. So how long a battery last has a lot to do with how it was used it and not giving up on a battery that appears to be bad that really only needs a good charging.

On the Prius the 12 volt battery never cranks the engine. This is good and bad for the battery.The battery is subjected to far fewer discharge cycles and that extends the life. Also, a marginal battery can be used for years because engine does not have to crank the engine. But a marginal battery gives out when you leave the car parked longer than usual or in cold weather.

However if the car is not used a lot; because the 12 volt battery never cranks the engine, the battery can be in a discharged state for a long time and you might not notice it. (Discharged lead acid batteries tend to get sulfur crystals on the plates from the sulfuric acid, charging tends to reverse this, de-sulfating charges more so. This is why leaving a lead acid battery in a discharged state is not a good idea.)

Also, as far as the Optima batteries not being made as well any more I am not sure where that comes from I started selling them in 2007 and I am not getting a lot of repeat business. Yes I get some but not that much. I have sold thousands of Optima batteries over the years. It really is a good design. Because of the design, the lead is almost pure and it is the difference between the lead and the lead oxide that creates the energy. The alloys used to strengthen the lead add weight but not electrical capacity. The yellow top Optima (the only kind they make in the Prius size) is also a deep discharge battery and good for many more discharge cycles,. The competitors that I know of are not.

As far as when to replace a battery. I have data here: Optima DS46B24R Optima battery direct fit replacement for Prius 2004 to 2015 , Prius v & Plug-in Prius with Instructions

 

The reason the Optima has a high CCA is the pure lead. Optima (Johnson Controls) states 99.9% lead. Because of the pure lead the voltage drop under load is less. You get this and deep discharge capability. It is the difference between a lead plate and a lead oxide plate that causes the electrical flow. Alloys add strength but lessen the electrical flow. The battery is composed of a sandwich of a lead oxide plate a mat soaked in sulfuric acid and lead plate. This is tightly wrapped and stuffed in a cylinder. Cylinders have amazing strength. You probably have directly observed this! Because of the strength the alloys are not needed.