I'm using a $25 lawnmower battery for Prius 12v

Yes. Unspecified CCA is also fine, because CCA is kinda irrelevant in a Prius. Batteries designed for starting applications are likely to have shorter life than same-size, same-brand, same-quality batteries designed for deep-discharge applications, because the plates of the latter will be thicker (but less numerous). With some major brands of batteries (not including Toyota), the model supposedly intended for Prius use is physically identical to the same brand's Group 51 starting battery, except for the smaller JIS terminals.

Like those of typical recent "smart alternators," the Prius charging algorithm is specifically engineered for maximizing fuel economy, with adequate battery life, NOT for maximizing battery life.

 

People are such haters. Some people have had good luck and well I didnt. Your $200 one could last 3 years or less if you drain the battery a bunch. Im just trying to add input. Costco had a Group 51R for $109 so the check walmart for 51 since the termminals are better

Well I randomly stumbled onto this battery at walmart ($160). Its not even listed for our Car but its a perfect fit and even has the vent plug that kits the prius. I had a super hard time even finding the battery on the website to share it. Its got a 4year warranty too.

online only one out of 5 stores had this battery in stock so good luck hunting

https://www.walmart.com/ip/EverStart-Platinum-AGM-Automotive-Battery-Group-Size-S46B24R-12-Volt-410-CCA/1247321234

 

That's an interesting find at that price!