Because of the spiral design the lead plates do not have to be strengthened with an alloy and are 99.99% pure. This results in lower voltage drop as the battery discharges and contributes to the longer life of this battery!

The three main contributors of premature battery failure are:

1. Vibration which causes distortions in the plates and eventually shorts.
   This battery is made by sandwiching the acid filled mat and the lead together and then tightly wrapping them in a spiral. This reduces vibration by 15X as a cause of battery failure.
   
   
   
2. Repeated deep Discharges
   This Yellow Top battery has thicker lead plates to handle repeated deep discharges not huge starting currents.
   
   
   
3. Heat! Yes batteries have less output when cold but they also last longer.

If you want a battery that lasts longer. This is it! We offer free shipping on this battery via next business day for all of California and the metropolitan areas of Phoenix, Tucson, Flagstaff, Reno and Las Vegas and or Priority Mail to the rest of the 50 states Hawaii, Puerto Rico and other US territories! You should have your battery in 1 to 3 days!"

_____ is Optima red top battery YELLOW is Optima yellow top battery

soc-% state of charge ocv - open circuit voltage for deep cycle

soc ocv
100 13.18
90 13.01 The 2004-2009 Prius has a drain of approximately 12 milliamps with smart key turned off (Thanks hobbit). After two weeks the battery would still be at 95% soc and the battery good for 10,000 cycles. However, age and heat also effects batteries.
80 12.83
70 12.65
60 12.46
50 12.28
40 12.08
30 11.89
20 11.68
10 11.48
0 11.27 Look at the graph! A battery chemically configured to take deep discharges (yellow top) has 7.5x(300/40) the life compared to the red top!

Comments from customers who have used this battery in the Prius for over a year!

"The battery has performed absolutely flawlessly and is one of the best improvements you can make to a Prius . Easy to install, everything is included.

In general, I am totally sold on Optima batteries; I use them for my cars and boat, my oldest one is about 10 years old and still works.

Toyota puts so much emphasis on how the Pruis main battery lasts the life of the car; but what they don't tell you is that the accessory battery is a cheap ass lead acid that, even in a best case scenario, will be dead after 5 years. The Optima should correct this issue and bring the accessory electrical system to the level of the rest of the car.

My factory battery died when one cell failed; the car was 1 year old at the time. As you know, Prius, with all its electronics does NOT have a simple circuit to shut down the interior light! It is therefore only a matter of time until one does not shut the door all the way and the next morning the battery is completely dead. This is what happened to me twice. When I charged the factory battery for the second time it failed. The symptoms were somewhat strange as it would still run but after sitting a few days it would not.

It is good to know that with the Optima kit the chances of recovery are much better . And I don't think I'll ever have to worry about having to replace it due to age.

Regards,"

P. G., Cherry Valley, California

"I just wanted to let you know that the Optima battery in my '04 Prius has been great. We had a few sub-zero mornings last week -- the kind that in the past, with the OEM battery, had me running a long extension cord and portable charger out to where my car is parked overnight to get it started. I had been taking to turning off the keyless entry system to try and avoid a cold-morning dead battery. I found the OEM battery to be the car's achilles heel, because when it is weak, you have to resort to the physical key to get in the car, and even then you can't get the back hatch open to access the battery.

But this winter with the Optima battery in place, not an issue. No matter the temperature, the car 'boots' properly, so all other systems, including the gas engine, start up without problem. I've always been a fan of Optima batteries, and adding one to my Prius brings up the 12V traditional electrics up to a quality level commensurate with the rest of the car.

Thanks for a great kit to install the battery."

M. A., Fort Collins, Colorado

"I've had no problems since I replaced the battery. The sound system sounds great. I haven't let the battery discharge deeply (I've learned to turn off the wireless key when I'm on vacation), but I trust the yellow optima is the right battery for a deeper discharge and a good choice for this application."

J. G., Monte Sereno, California

From the manufacture:



The unique design of the SPIRALCELL TECHNOLOGY. provides many features not available in ordinary batteries. The following is a summary

SPIRALCELL TECHNOLOGY PROVIDES: More plate surface, closer plate spacing, ability to use high purity lead. RESULTING IN: Low internal resistance. This low internal resistance gives you more power in a smaller box, ability to recharge much faster and higher cleaner voltage characteristics during discharge

Immobilised plates (locked in place). RESULTING IN: Improved vibration resistance, no shedding of active paste material, lower gradual loss of power and capacity as the battery ages. This gives you a battery that lasts longer and performs better throughout its life.

• Voltage 12 (12v or 12 volts)
• Amp Hour 38
• CCA* 450 (Cold Cranking Amps)
• Shipped fully charged ready to install
• Maintenance-Free
• Valve-regulated absorbed glass mat (AGM) eliminates acid spills and terminal corrosion.
• Vent hose holes for emergencies in case the battery is heavily overcharged.
• More than 15 times the vibration resistance of an ordinary battery.
• Last up to twice as long
• Length 8.9" and 9.15" at top cover
• Width 4.5" and 4.9" at top cover
• Height 9" including posts
• Weight 28lbs
• Warranty: 3 year exchange, excludes damage due to misuse or neglect, improper charging or improper application of battery
• Free shipping to all 50 states and territories: Ships the same business day you order via UPS ground or Priority Mail! Just select the shipping method "Free to 48 states for $50 order"

Availability: Usually ships the same business day Optima D51 yellow top Battery D51-YT    Vehicle: Prius 2004-9 converted to American connectorsPrius 2010-15 converted to American connectorsAvalon HybridLexus Hybrid ES300hNissan Altima Hybrid 2007-2011Camry Hybrid 2007-2011Camry Hybrid 2012-2017other vehicle with battery temp. sensorother vehicle without battery temp. sensor