Does 12v battery affect IMA battery?
 

Hi all,
I am a novice to the forum, but have been learning a lot about my 2007 HCH (bought new in July 07) the last couple of days. Amazing there is so much info out here for people needing help!

Okay, this is my first post and my first doubt... Sorry if you find it too long. How does the poor quality of 12v battery affect the performance of hybrid battery, specifically does it trigger IMA recals?

Background... during my recent oil change my regular dealer did a 43 point inspection that came up with one problem, my 12v battery was going bad. But I had no problem starting my car, even in the cold Baltimore mornings these days (near freezing temp), so I was not aware of the issue. I told the dealer I would keep an eye on it. When I checked online for HCH battery related stuff, I came across people having "IMA recals". I realized that my car has been doing similar stuff for the last several months. So today I decided to track these recals, and already I know my battery is most likely in a bad shape.

I had two recals in the morning and two in the evening, both 30 min drives (2 x 15 min with a 5 min break in between). The car sat in the parking lot for 8 hours between the morning and evening drives. My definition of recal is similar to what has been posted here... Battery level dropping to two bars within a minute or two of starting the car, remaining there for 3-4 min during which I get no assist or auto stop, then battery level shooting up to full.

Will the problem go away if I change my 12v battery? How do you suggest I proceed?

Thanks for your help. From what I have seen here so far, I am sure to spend a lot more time on these forums!

Re: Does 12v battery affect IMA battery?
 

Well, welcome to the forum though it's mostly dying given even the newest HCHII is several years old by now, and everything that anyone could face has probably been discussed. See other posts on this forum for more information on the role played by the 12V battery and the need to replace it.

In short, the car does not have an alternator, and instead uses a step-down DC-DC device to charge the 12V battery; if it's in poor condition then the 158V works over time keeping it charged anyway. This is necessary because almost all of the electronics in the car function off the 12V battery.

If you are not sure, take the car in to AutoZone or Advance Auto Parts for a 12 V battery load test. And then change it if they also report it's dying.

Re: Does 12v battery affect IMA battery?
 

Thanks. I am still going through old threads about hybrid battery failure, troubles with changing the battery, 12v battery, etc. I will try changing the 12v first (if it is indeed failing) and see if that improves car performance. I used to get 45/36 mpg, now overall average is in the low to mid-30 mpg.

A trivial (dumb/naive) question... If I buy a new 12v battery from Autozone or Advance Auto Parts, would that in anyway nullify warranty on my hybrid battery? Thanks for response.

Re: Does 12v battery affect IMA battery?
 

I don't think this will help you. I tried it when I started having trouble with my IMA battery and it was no better. I even had honda put it their OEM battery because it was cheaper than other offerings when I looked.

Re: Does 12v battery affect IMA battery?
 

Okay, I have been tracking recals these past few days. I changed my 12v on Dec. 3rd. No let up in recals. Is my hybrid battery dying? Based on the opinions of experts out there, how long would you think it may last (IMA light turns on) considering the frequency of recals and the fact that my overall mpg is down from 41-42 to 33? Thanks.

Re: Does 12v battery affect IMA battery?
 

I'm not sure the light coming on is the only criterion that Honda will use to decide the battery is dead. There are also whatever codes are read when they hookup to the engine computer (maybe).

I took anywhere from 1-2 years before I had the light come on, and it was only on for one day. The next day only the engine light came on and after that neither. It is possible Honda turned it off while we wait for the battery to be shipped, but I don't know for sure.

Re: Does 12v battery affect IMA battery?
 

Thanks, Patrick. I am planning to take the car to the dealer tomorrow. Will have them check the battery, and may be keep it overnight and check again on Saturday morning. Best.

Re: Does 12v battery affect IMA battery?
 

Your log on 12/3/12 and 12/5/12 pretty much mirrors my typical driving times, mileage, and recal frequency for the past 90k miles (2.5 years) for me on my 06 HCH2. However, I still maintain mid-40's to low-50's mpg. Your 9mpg drop and low FE is very unusual and I would get that checked out. If your battery checks out ok, you may have to alter your driving patterns like I did. Good luck.

Re: Does 12v battery affect IMA battery?
 

You might want to replace the battery on your own. Since I seldom, and randomly get regenerative breaking, I consider my car somewhat unsafe. I have to engine brake sometimes (shift down). I'm told Toyotas switch from regeneration to engine breaking on their own, which is an obviously better design since it will be more consistent.

I will definitely be asking pointed questions about this stuff when buying my next car.

Re: Does 12v battery affect IMA battery?
 

I wanted to follow up and see if you had this problem resolved? I am having a similar issue in my 08 with lots of recals (full when I start the car, down to 2 bars within 30 seconds, then not charging back up for about 5 minutes) and want to be informed so I don't get ripped off or told something inaccurate. I've got a lead foot so my mileage has never been great, but it's dropped to about 30mpg from an average of 40 in stable temperatures (thanks heat wave in December).