Are there any real advantages to a larger 12v replacement battery?

This went a little off topic talking about motorcycles with AGM batteries.

Read Post 18.

 

Put the windshield wipers on high on park or stopped at a red light, Prius will rock side to side

 

I believe you are correct. The observations of others may just be coincidental.

 

In that case it’s correct.

Understand that the resting voltage of different chemistry lead acid batteries varies and can also affect this behavior

 

The hybrid (large) battery is not part of the accessories.
The 12v battery runs the accessories.

If you turn off all the accessories than the hybrid battery with the ICE should not need to come on to charge the 12v that supports the accessories.

The reason that is true, is you never want to leave the accessories on for days or weeks and depleat the hybrid battery to zero, ever.
If the 12v takes a hit or many hits it can be changed easy and cheap compared to the hybrid.

So if you camp try it on see if the car ever starts up with everthing off. If it does turn on for any reason the larger battery will hold off the ICE more often because the little OEM battery will drain faster.

I'm not sure if you can turn everything OFF, ie dash leds, ready mode etc.
Try it and see.

To your point, lets say the 12v drops in voltage around 11 to 10.5v so now the ICE will need to start to help charge the 12v back up to a good value. The hybrid battery will not keep charging the 12v with out it being constant at 20% to 80% so the ICE kicks in to keep the hybrid at a good level.

The ICE turns on. It won't let the hybrid die. If the 12v battery does not go below the low value for the car nothing needs to runs.

my2cents.

 

Make yourself the smallest nano measurement (can't seem to paste) and look up, everything is vibrating

 

Further, the Prius engine does not need to come on to charge the 12V battery. It charges from the inverter, which is run from the traction battery. IF the traction battery gets too low THEN the engine will come on. The traction battery has 3-4 times as much energy in it as the 12V battery, so engine cycling caused by the 12V battery draining the traction battery would be minimal. Those who think a bad 12V battery causes the engine to run should ask themselves why it doesn't run very very hot. If the engine must run there must be a lot of power going into it, and it would be very hot.

Keep telling yourself "there is no alternator" (in the normal automotive sense) so without the engine running you can still have charge power for the 12V system. There are actually two, MG1 and MG2, but they generate 560V or so, three phase, which MUST go through the inverter/charger as there are no diodes in MG1 or MG2 and no regulator. The inverter/charger then converts some of that energy to 13.8 to 14V for the 12V system, to run all the computers, the lights, the radio, the A/C fan, and to charge the 12V battery. When the car is "off" the poor 12V battery must supply energy for all those 12V systems that you may request to run.

 

ALL lead acid batteries have that problem, to varying degrees depending on the type.

AND......after almost 30 "replies", the best answer is in post #2.

 

it's the 'varying degrees' that are significant. optima does not suffer nearly so much.

for those (many) here, who have left a light on, or let the car sit too long, it is a definite advantage.

 

Despite their marketing hype, Optima is just another AGM battery.
Theoretically no better or worse than any good AGM.

Alas, it seems like a LOT of people would say WORSE 'cause they seem to suffer a high "infant mortality" rate.

Because of that......and somewhat exaggerated marketing claims......I do not consider Optima to be a "good" battery.

 

yes, there are many opinions.

 

One other thing to consider is that, in an emergency, a replacement battery with the Japanese connectors (JIS) may be harder to find than one with SAE posts. Switching to a higher-capacity battery and using US-standard connectors felt like a relatively cheap insurance policy to me.