The Sienna - at least the first part of the second generation - uses a BCI Group 24F size of battery. This was a very common size (both my 1984 Tercel and old Chev pickup used it) and is still common as the smallest size in RVs (my travel trailer has one), but it has become much less common recently. Costco doesn't even stock one; Optima doesn't build one. The BCI Group 35 size seems to have replaced it, and since group 35 is the same as or a bit smaller than group 24 in every dimension, some suppliers specify a group 35 for the Sienna. The problem is that the smaller battery has less capacity... and I'm not willing to sacrifice any capacity.
Does anyone have suggestions for a proper 24F replacement, or a report of what you used (if group 24F) or how it has worked?
The battery topic comes up in discussion of batteries going flat due to lights being left on, et cetera, but I don't think that is has been covered yet in this forum as a topic in itself.... but if it has, please point me to it.