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Old 12-07-2009, 06:11 PM   #106 (permalink)
Engineering first
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Join Date: Mar 2009
Location: Huntsville, AL
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14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
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Originally Posted by Daox View Post
. . .

I also figured it would be a good idea to monitor my 12V battery since they are known to go bad after ~4 years and its now winter, so capacity will be decreased. I turned on the scangauge before turning the car on to see that the 12V was at 12.1V! Looks like that is going to need to be replaced. Thankfully, owners of the Prius usually notice a mileage increase after replacing the 12V. So, at least there is something to look forward to.
The OEM battery has a "DO NOT REMOVE" sticker and under that is a plastic cover for the six, filler holes. I got another year from my OEM 12 V battery by adding a little distilled water to cover the tops of the plates and then reassembled. But you are about due.

I replaced my OEM battery last January with an Odyssey PC925. A little expensive but I wanted a battery with 10 years of life. The tricky part is the 'metric' posts on the OEM battery.

In my case, I made two short jumpers, heavy gauge wire, and bolted them to the bolts on the ground and battery B+ assembly. I'll post photos if you're interested.

FYI, I didn't see any change in MPG after replacing the 12 VDC battery. However, there is a lot of information showing replacement of the traction battery gives a solid mileage boost for 3-4 months.

Bob Wilson
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)

Last edited by bwilson4web; 12-08-2009 at 07:24 AM..
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