12V Battery Charging

Hi everyone,

I replaced my original Denso 12V battery on my 2008 Prius (09/07 build, 11/07 purchase) in October of 2012. The original battery was reading around 12.0V in maintenance mode, and users here had suggested that I go ahead and replace it. I replaced it with an Optima Yellow Top, and it was suggested that I give the Yellow Top a full charge before installing it, because of them being sent out with significant discharge. (I never did this) After ~ 4 months of driving, I did another maintenance mode test on the Optima, and it is reading around 12.0V unloaded in maintenance mode. I recently purchased a Schumacher SC-600A battery charger, and wanted to know if it was safe to charge the 12V battery through the front terminal, at 2 amps. If absolutely necessary, I can pull out the Optima, but my preference is to not. Any help is appreciated, thanks!!

 

I see, well the charger I bought is only 2/4/6 amp, and I guess I'd prefer to err on the side of caution, and charge at 2a with the convenience of the hood access. I appreciate the response! This Prius is creeping up toward 136K miles, would you still recommend doing ATF drain and fill? That's the only major service I haven't done since the last time I asked about recommended maintenance. About to put new tires on the 2011 (41K miles), and was looking at the Defender XT from Costco. Any experience with those? I know I could go and make a new post or search for other created threads, but I have you in this thread and you have been more than helpful in the past, I figured it can't hurt to ask .

 

Shouldn't be a mileage issue, I drive the car about 65 miles a day 5x a week...I let the charger do it's business, came back to the "green" charged light, ran the test, and it was reading 12.5,12.4 unloaded, and 12.2,12.1 loaded. Bounced between 14.0/13.9 when I did brake/power. Seem normal?

 

Sorry, I didn't really specify. The battery charger that I bought has a status indicator with a small scale, 0/25/50/75/charged (green light). Once the battery is fully charged, the charger automatically switches to float mode.




In total, I think I had the battery charging for all of 3 or 4 hours, but I guess it's hard to say whether or not that's normal because this battery has been charged at least somewhat over the course of 4 months of driving since being installed. It has been on a handful of trips in the 125 mile each way category, and then two 40 minute, 33 mile commutes, 5 times a week. Approaching 136K miles total on the car, probably averaged about 27.5k miles per year for the first 4 years of ownership, and has since tapered off. I know that when we moved to NC in 2010, the car had around 65,000 miles, and we doubled that in about 2 years. Our 2011, that we bought in November of 2011 with 3 miles on it, already has 41,000 miles. I never had any indication of a failing 12V battery for 5 years on the old battery, I really just replaced it as preventative maintenance. Another member had mentioned that with my driving habits, he felt that my old battery could have survived another year or so, but I didn't want to risk it. That battery was reading 11.8 under load.

If I can squeeze 5 years out of this Optima, then in my opinion the purchase will have been worth it, even if it never reaches 12.8. My driving habits will probably prevent it from ever reaching a deep discharge, and I am careful to avoid battery draining situations - I almost always lock it in the garage to let the car remind me if I left anything on.

I do carry a small portable jump starter in the trunk for the worst case scenario in which my 12V battery dies, it should be more than enough power to run whatever pumps/relays are necessary to get the car into ready mode. The jump starter was absolutely useless for trying to jump a Range Rover, and I didn't even bother trying to jump from the Prius.

Clore CS1000 CarStart Ultra-Portable 900 Peak Amp Jump Starter with 12-Volt Power and LED Flashlight : Amazon.com : Automotive

 

Ah, I see that, and it makes perfect sense, because I was asking myself how larger clamps would ever be able to clamp to that bolt head, the clamps on the battery charger are tiny. Thanks for the heads up!