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KevinH1990 · 05-31-2022, 05:23 PM

My Boxster failed to start once last winter and I had to jump start it. During the last few weeks if I drove a short distance the car sounded like it was barely turning over when I restarted it. I checked my records and the battery was 7-years old.

I decided that I was risking another failure and replaced it with an Interstate AGM battery in size H7 (94R.) The H7 is larger than the battery I removed (Bosch 48-690B.) The H7/94R Interstate battery is rated at 850 CCA. Consumer Reports tested a smaller H6 Interstate AGM battery which the manufacturer rated at 760 CCA. It rated the life expectancy as 5/5, the CCA as 4/5 and the reserve capacity as 4/5. They rated an Optima H6 ($290) and an Odyssey Performance ($260) slightly higher than the Interstate.

The AGM batteries are more expensive. I paid $175 at Costco. However, the information I've been able to find indicates that they are better able to tolerate a situation in which the car is not driven for an extended period. Although I normally drive my Boxster several times per week, we had some ice and snow during the winter and I didn't drive it for about 10 days. That is when I had the starting issue. The AGM battery also has a 3-year full replacement warranty.

05-31-2022, 05:23 PM	#11
KevinH1990 Registered User Join Date: Feb 2006 Location: Virginia Posts: 1,734	My Boxster failed to start once last winter and I had to jump start it. During the last few weeks if I drove a short distance the car sounded like it was barely turning over when I restarted it. I checked my records and the battery was 7-years old. I decided that I was risking another failure and replaced it with an Interstate AGM battery in size H7 (94R.) The H7 is larger than the battery I removed (Bosch 48-690B.) The H7/94R Interstate battery is rated at 850 CCA. Consumer Reports tested a smaller H6 Interstate AGM battery which the manufacturer rated at 760 CCA. It rated the life expectancy as 5/5, the CCA as 4/5 and the reserve capacity as 4/5. They rated an Optima H6 ($290) and an Odyssey Performance ($260) slightly higher than the Interstate. The AGM batteries are more expensive. I paid $175 at Costco. However, the information I've been able to find indicates that they are better able to tolerate a situation in which the car is not driven for an extended period. Although I normally drive my Boxster several times per week, we had some ice and snow during the winter and I didn't drive it for about 10 days. That is when I had the starting issue. The AGM battery also has a 3-year full replacement warranty. __________________ 2000 Arctic Silver/Black, Hard Top, On Board Computer PNP Rear Speakers, HAES 6-Channel Amp, Avic Z140BH, Painted Bumperettes, 2004 (OEM) Top, Homelink integrated in dash with Targa switch, 997 Shifter, Carrera Gauge Cluster with silver gauge faces, heated 997 adaptive sports seats, Litronics, silver console Last edited by KevinH1990; 05-31-2022 at 05:38 PM.