Bad 12V battery??

[greenrider]

At the beginning of the last winter, the 12 volt battery in the HCH II was unfortunately completely drained by a done light that was left on. After charging it up again, the indicator has consistently shown a good battery and there have been no obvious issues with it. I've had a drop in mpg to the low 40s consistently, and the IMA battery is having increased fluctuations, with crashes even in cool weather when half to almost fully charged (no codes yet).
Could a dying 12 volt battery be putting a load on the DC-DC and the IMA battery, causing the lower charge state and lower mileage? Or is my IMA battery going at only 41K?

[msantos]

Hi Mike

Your diagnosis of the 12V battery as the cause is dead on. I've literally lost count of the number of cases similar to yours and in each one of them the replacement of the 12V battery was the solution.

MSantos

[greenrider]

Manuel, you just made my day Thank goodness I won't have to battle it out for a new IMA battery.

Now, if I remember correctly, the HCH has a specific battery that really can't be purchased in the aftermarket, correct?

Is there any place cheaper than the dealer to replace it?

Mike

[msantos]

Hi Mike;

This is a touchy area and others will certainly have a different opinion.

I in the other hand, prefer getting a direct replacement either from the local dealer or an online Honda dealer/retailer if at all possible.

The primary reason I would do so is because the OEM 12V battery has very unique load characteristics and plays such an important role in the overall energy equilibrium of the car that a slight difference in the specs will make itself noticed. Maybe not noticed by many people, but I will tell you that some of us would notice it anyway.

With this said, you can get third party replacements elsewhere. Autozone, walmart, pepboys and the rest provide "direct equivalents" that appear to do the job well and come with good warranties at least as far as the battery is concerned.
And depending on how well you are tuned into it, your mileage and results may or may not not fall under the same garantee.


Cheers;

MSantos

[Mendel Leisk]

Mike, our '06's 12 volt battery had a couple of close calls, once due to the 2 map lights being left on overnight, and another time with the headlights left on for about one hour. In both cases I was able to restore the battery with a charger I have, and the indicator window shows the battery as ok.

Anyway, I'm thinking the 12 volt battery may or may not be the source of your problems. I would go through the dealership, and ask them to verify it's condition first.

I just happened to do a maintenance on our daughter and son-in-law's 12 volt battery last night. It's a non-hybrid vehicle that's been back east up to now, maybe 4 years old. They're not sure if it's the original battery. Corrosion on all the fasteners, coupled with the white stuff around the battery terminals made it very tough to extract from the car.

The positive terminal lead in particular was very difficult to work loose, and I wished I'd had the proper battery cable puller. I managed to pop it loose gently, though.

Our car is maybe 1 year younger, but the 12 volt battery looks as-new. Maybe in part due to west coast environment, but could it also be due to reduced load, since the IMA battery typically does the engine start-up?

[psyshack]

Just take the batt in to a local parts house and have them check it. If you have a dead cell you found the problem....

[armadaman]

Just replaced my 12V in my 2000 Insight this past Saturday as the electric windows were moving slowly and the voltage on scangauge was reading a lower than normal value.Had the battery checked and it had a dead cell.Replaced and one of the first things I noticed is the car ran better.Wasn't assisting as much.Now the HV battery is staying topped off longer and my MPG is better.

[greenrider]

I put in on a trickle charger after leaving it in the garage for 5 days while away. It took a few hours to charge back up. I think I'll bite the bullet and make a trip to the dealer for a batt check.

[hunter44102]

If you have a Harbor Freight nearby, you can get their 50A or 100A battery tester. It basically puts the 100A load on the battery while measuring the voltage, and it should stay in the green region if its good. (should not drop too much voltage).

They are like $20

[Mendel Leisk]

Verbatum from the HCHII Service Manual:

(I'll skip the first few steps, which basically say to check the case for cracks, and the status window colors)

4. Apply a 300 amp load for 15 seconds to remove the surface charge.

5. Wait 15 seconds, then apply a test load of 280 amps for 15 seconds.

6. Record battery voltage.

* If voltage is above 9.6 volts, the battery is OK.

* If voltage is below 9.6 volts, go to step 7.

7. Charge the battery on High (40 amps) until the test indicator window shows the battery is charged, plus an additional 30 minutes. If the battery charge is very low, it may be necessary to bypass the charger's polarity protection circuitry.

* If the test indicatory window indicates the battery is charged within three hours, the battery is OK.

* If the test indicator window indicates the battery is not charged within three hours, replace the battery.