12 V battery specifications

I've seen different numbers for the original, all around 40 ampere-hours. For a replacement, bigger is better, as far as how long it might survive an unusual challenge (leaving the car unused for weeks at a time, for one example). However, normally the capacity isn't critical, and bigger generally means heavier and more expensive. I'm using a 35 AH one.

 

Do you get more "play the radio while in ready mode" time with more than 35 ah?

 

No, because in "READY" mode you're drawing power primarily from the traction battery and engine, not from the 12-V. However, you would obviously get a little more "play the radio in 'acc' mode" time with a 40 AH than with a 35 AH. (In both cases, that's unfortunately a lot less time than the battery would be able to power the radio, if the radio were the only load on the battery.)

 

I thought the OEM battery was 45 Ah capacity?

Regardless, I'll be ordering 20 Ah LiFePO4 batteries soon to play with. I'll then replace the failing battery on my Acura with the lead-acid one from the Prius. Before I complete the replacement, I want to test the charge efficiency so I can compare between the 2.

Since the Prius uses the traction battery in Ready mode, it seems pointless to have a large capacity. If the car is going to remain parked for months at a time, then it needs to be put on a battery maintainer regardless of capacity.

I also converted all interior lights to LED so leaving one on won't drain the battery.

 

I don't think the 12V battery from any Prius will work in an Acura, because it won't be able to turn the starter motor. In a Prius, the Traction battery starts the engine, not the 12V battery.

 

I failed to mention I will pair it with a supercapacitor bank that I have already verified is sufficient to start the vehicle alone. Eventually the plan is to replace the TSX battery with a combo LiFePO4 / Supercap bank.

I'll be following what LaserSaber did here.

 

That.
Is.
Cool.

 

Since I've already derailed the thread... for those interested in what I was working on, here is my poor quality video.

Although I took good precaution to protect the battery, I later destroyed it while measuring various Prius loads by allowing the voltage to drop too low. Stupid gets expensive.