What Brand of Battery do you like ? (Auxiliary)

You use slightly longer bolts than what it comes with and slightly larger washers than each of the terminals and think club sandwich with washers being the bread, terminals being the meat and the bolt being the toothpick that hold the sandwich together.

Also this battery is a tiny bit taller than OEM so you have to slightly modify/remove either the base the battery sits on or the cover that goes on top:

 

That info is further down on that page...

It says: 9.00" x 5.40" x 8.43" (LxWxH)

 

Keep in mind that the OEM battery has a 7-year prorated warranty, plus free towing in the event of a battery failure. And few of the aftermarket batteries have a connection for the Prius's vent tube.

 

lead acid batteries off gas. if not outside the car, than inside

 

The off-gas is hydrogen.

 

AGM batteries normally recombine the hydrogen and oxygen. Significant off-gassing happens only if something has gone badly wrong, for example a cell shorted internally and others being grossly overcharged as a result.

 

But the OEM battery does have the vent that connects to the vent tube, so that any gases generated are conducted away from the passenger area.

 

So does my $65 non-OEM AGM battery after I added that capability, which wasn't difficult. It's 7½ years old now, and still performing its duties.

 

Curious how did you do that, drilled a hole?

 

Yes, among other steps.
1) Remove the flat plastic cover plates over the cell vent caps;
2) Survey and mark where best to drill a hole in a cover plate that would allow a tube inserted through the hole access to gas under the plate, without damaging battery case or cell vent caps;
3) Drill the hole;
4)Replace covers, and tape their edges to secure them in place and to prevent gases escaping at edges;
5) Insert snug-fitting plastic tube down through aforementioned hole in cover;
6) Connect outer end of that tube to OEM vent tubing (including the 90° thing from the original battery);
7) Tie tubing in place.

I also added spacers to make the battery match the original space and bracket.

 

Optima

 

3rd gen Prius hold-down bracket is a poor design, completely intolerant of the slightest height variation. I changed a battery on a matrix a few weeks back: same story. Luckily I had a washer in my change pocket, made it just work. Could have used a couple more.

Wish they’d adopt the more conventional threaded rod and nut, with hook at the bottom.

 

I have read that the quality of Optima batteries is not what it used to be. And I think they are more expensive than the OEM with their 7-yr (pro-rated) warranties.

 

I did something similar to yours on a Harbor Freight 35 AH AGM battery. I thought the battery should have some built-in vent on its cover, and I should seal that vent. What puzzles me is I could not find it. Just wonder if you saw a built-in vent in its cover?

 

That's the same battery, except the label. It does not come with a provision to connect a vent hose. If the cells vent gas (which should normally never occur with an AGM battery), they apparently intend it to escape through notches at the ends of the cover plate (besides which the edges probably aren't perfectly sealed, although they're a snug fit). I sealed those spots, along with the rest of the cover plate perimeter, with tape, in order to direct any gas out through my added vent tube.

 

Where do I buy an OEM battery? Dealer?