12V Battery Replacement Detailed
 

Well, I had a real adventure/education Friday (the 13th). I was stopped in a traffic jam in the middle of the city and car did not autostop. I turned it off to wait and in a few minutes when I went to start up, it did not start. Instead the IP flashed at a high rate continuously and there was a chattering sound like a relay coming from under the dash.
The noise, lights, and panic was very confusing...what is wrong? I noticed the SG said 9.5 volts, so I put it in park and got out to see it the terminals were tight. Nothing wrong. When I got back in the car, same light show. I was on a hill and in the middle of a jam, so I figured I could roll backwards and get out of traffic. Then I discovered that with the dead battery, I could not get it out of Park. Big trouble.
After 10 minutes of doing nothing, the battery built up enough charge to allow me to get it out of Park. I thanked The Lord. I rolled back off the road and got a jump from a guy and drove home no trouble.
(Continued)

Re: 12V Battery Replacement Detailed
 

The Honda replacement battery #151R is puny and costs $159. I instead bought an Interstate Megatron II #MT-51R for $95. OEM is 335 cca, Interstate is 500 cca.
THe case size is bigger, but it will fit in the HCH space fine, but the plastic tray has to go.
See the pictures attached to get an idea of how much bigger it is, and how it fits. I highly recommend this bigger battery.
I also submit this tale as a warning that if your 12v battery is 4 or 5 years old, you better get a new one asap. There was no warning at all that it was weak. And remember, do not put your HCH in Park if the battery is weak or dead, it can strand you helplessly.
GL

Re: 12V Battery Replacement Detailed
 

Hey John:
Thanks for your thread. Interesting! Is that Interstate 2" longer and the same width? H

Re: 12V Battery Replacement Detailed
 

Yes, thanks for the heads up and the photo of the new battery in situ. Glad no one was hurt....

Just an observation: if there was no warning at all prior to this adventure, is there a possibility that the DC/DC converter may have some sort of fault that is not making itself apparent?

Re: 12V Battery Replacement Detailed
 

I don't think there is anything wrong, other than the battery was just old, 07 OEM, and it charged up fine on the way home. It just wouldn't hold the charge.
Yes, the 51R is about 2" longer than the OEM, and the same width and height. I weighed the 151 at 21 lbs, and the 51 at 28 lbs.

It appears that the compartment will hold the 51R because that's what the non-hybrid Civic uses. Perhaps we could buy the tray, etc for a regular Civic and bolt in the bigger battery just like a normal Civic has. I haven't seen one to notice.

GL

Re: 12V Battery Replacement Detailed
 

I have a 06HCH2 and I maintain my 12v with a 2amp electronic battery charger. I watch the 12V on my scangauge for signs of weakness. Never gets below 12.5 V. H

Re: 12V Battery Replacement Detailed
 

The12v battery in this car behaves differently. Under typical conditions it uses very little power to do its job so it can deteriorate down to nothing and still start the car.


It can be hanging by a thread and give no indication.

A starting battery in regular will offer a clue, like slower cranking.

Re: 12V Battery Replacement Detailed
 

The 12V only starts the car when it is very cold or the pack is depleted for some reason. My HCH2 06 model has never started via the 12v starter. H

Re: 12V Battery Replacement Detailed
 

Yeah, that's what bugged me the most. Knowing that I had some 160 volts in the back seat and just because the ecu didn't see 12v, it wouldn't let me use them to start the car.
All the 12v battery does is power up the ECU and allow it to control the car's functions. When the 12v goes out, you lose everything, including the ability to get the car out of Park.
Honda should have provided a 12v tap off of the IMA battery for emergencies.

GL

Re: 12V Battery Replacement Detailed
 

Check that.......

Re: 12V Battery Replacement Detailed
 

I know the 12v powers the radio, fan, windows, etc, but the most important thing it does it power the brain that controls all these things. Lose it and you will see how helpless you are.
GL

Re: 12V Battery Replacement Detailed
 

Thanks GordonLightfoot! You saved me $70 on my battery today!

The best price I could find on a 51r today was Costco. $64.99 plus tax.

Re: 12V Battery Replacement Detailed
 

There is a shift interlock release switch on the center console, up and to the right of the shifter. There probably is a tiny cover you have to wedge off first (my 07 never had a cover, bought it used). Just stick your key (or really any long object that fits in there) and it will mechanically allow the shifter out of Park. As a safety feature, for situations like you described, I'm pretty sure all automatic transmission cars are req'd to have manual override for interlock.

Also, as long as your IMA SOC is decent, the computer just needs a tiny bit of power to send the "Start" command to the system. The IMA pack should always have plenty of power to get the engine running (so long as the SOC isn't so low that it wants to do a 12V start).

Re: 12V Battery Replacement Detailed
 

I also just installed the same Interstate Battery 4/4/2012. HOnda wanted 136.00. I went to Firestone Auto Complete. Their web site has a coupon for interstate batteries for 79.99 installed. Make sure before the rign you up that the coupon state "installed." I did advice the auto tech that they have to take the plastic tray out. For some reason I didn't have to set up my radio again with the OEM code. Thanks.

Re: 12V Battery Replacement Detailed
 

On the note of the use of the 12V battery..

I noticed that when I haven't started my HCH2 for a while (3+days), then it will "crank" to start like a normal car does. If the IMA has some charge and it hasn't been sitting too long, it will start without cranking. Is this the IMA battery starting the car?

Re: 12V Battery Replacement Detailed
 

Do you guys know that DIY 12v battery replacement with interstate or any other battery void my IMA battery pack warranty?

Also, I went to Firestone to ask them to replace the battery, two store told me to take it to the dealership.

Is there any detailed instruction on how to do this?

Thanks

Re: 12V Battery Replacement Detailed
 

What am i missing? It's a battery. I've replaced mine once and disconnected it several times and killed it dead a few time. So many times I've memorized my radio code.

I've been running a $39 lawn mower battery for over a year. With no problems.

Re: 12V Battery Replacement Detailed
 

A battery that is going out can still show 12+ VDC, you should have your battery load tested to find out it's true condition. In California we have Autozone and Kragen / Oreilly stores that will test your battery for free. One quick note:Even a battery with a dead cell may show that it is ok on a volt meter!

Re: 12V Battery Replacement Detailed
 

+1 to this old thread. I didnt realize I had such a dead 12 volt battery until it died in the winter at Ikea parking lot! Basically, yes you have 160V IMA battery that wont work if the 12v is dead and it doesnt take much. Replace your 12v at least every 5 years, more if you are in hot climates.
I replaced it as recommended with the Costco brand 51r that is designed for non-hybrid Civic and it worked great. My IMA battery started to reach end of life and even required the 12v to start the car a few times towards the end and had no issues. I have a 2A/4A smart charger to maintain the 12V every few months. Especially in winter when its cold at night its good to top it off as short trips with heat, defrost, rear defrost, lights etc, all tax the 12V more than normal.

Hope this helps someone with a 2006-2011 Civic Hybrid.

Re: 12V Battery Replacement Detailed
 

I've never noticed this thread, but I've blabbered about the need to maintain the 12V in a healthy state in other threads on GH.

I vigorously repeat the recommendation for upgrading to a 51R from the puny 151R.

Here in AZ, we're lucky to get batteries to last more than 2-3 years.

Re: 12V Battery Replacement Detailed
 

Yes, thanks S.
I have read posts here in the past when I first had issues with my 12v battery and only recently joined to actually read more. Your posts are very detailed and thorough. We are lucky that we only get killer heat for a couple weeks or months here, but cold really sucks for mileage on hybrids too.

I wish I had started grid charging my IMA battery back in 2012 or sooner on my 2008. Luckily, I was able to get a warranty "replacement" as the extension just barely covered me at 150,000 KM (92k miles I guess), in Canada.
Back then I was afraid of voiding the warranty or artificially extending my battery life, only to fail at say 160k :)
Now we know better, that we should have had maintenance (like everything else on our cars) for the IMA all the way along.

Any suggestions on testing the 12v battery health? I think Im at exactly 3 years, now but maybe its only 2 and dont ever want to get stuck again for a $69 battery which is cheap compared to a tow truck to boost at -25 C
-J

Re: 12V Battery Replacement Detailed
 

The only way to truly confirm 12V health is to take it to an auto parts store and have them load test it.

Assuming it's been parked and idle for about 12hr, if you check it under the hood before starting it in the morning, it should be above 12.5V.

Re: 12V Battery Replacement Detailed
 

Thank you! I will find my volt meter and see if I get above 12.5V tomorrow AM.
My kids (or me) leave the interior light on or we left the trunk open and the trunk light was on all night :) I just have to plugin the maintenance charger to make sure its topped up before I test again.

Re: 12V Battery Replacement Detailed
 

Discharging to completion take its tolls on 12V batteries. One that's only a few months old can handle it a few times. Get 1-2 years on a battery and a long slow deep discharge can kill it beyond the point of reliability.

Re: 12V Battery Replacement Detailed
 

What did you do about the lower battery tray and the upper battery cover? The puny ones that come with HCH2 won't fit the larger battery. Did you decide to run without a tray and cover?

It would seem to me that the tray and cover would lessen the heat from the engine. It's a smaller engine in there than the gas civic, but there's still heat from in there.

Re: 12V Battery Replacement Detailed
 

I chucked 'em.

Re: 12V Battery Replacement Detailed
 

I purchased the Optima Yellow Top, and my mechanic said that it was the wrong battery. Where can I buy the #MT-51R?

Re: 12V Battery Replacement Detailed
 

Did a quick search and found this;
https://www.summitracing.com/parts/isb-mt-51r

https://www.interstatebatteries.com/products/mt-51r