Is the 12V light on? If it's on, you're not getting 12V charging, so you'll need to recharge regularly.

How long was the 12V disconnected?

 

The red battery dashboard icon is lit. I took the battery out of the car to charge it with the new charger Friday night. Before that, it sat in my car without being charged since I had the car towed home on Wednesday.
ps: If I end up needing a new 12 volt battery, which brand would you recommend for my HCH3, oem, AC Delco, Duralast, Everstart?

 

Anything is better than a battery that's sat less-than-fully-charged or run flat multiple times. Most batteries are made by Johnson Controls in Mexico, so it really doesn't matter. My last Honda battery was an Everstart from Walmart. Still going after at least a few years.

 

The Everstart has the best cost-warranty combo I have found so far. The reviews aren't great, though. Does the build date of the battery matter?
Also, the battery charger I bought has a repair function. What does that do?
Thanks again for all your help!

 

I bought an Everstart and took a 25 mile ride. The interior lights and acceleration are better but not normal. Brake, battery and cel dash lights are still on. It appears that the IMA battery is low and contributing practically not at all.

 

Quality of batteries made in Mexico is random.

Repair functions on chargers vary. Some use a high frequency pulse to allegedly break up sulfation. Others hold a battery at elevated voltage and low current to break up sulfation as well. The latter has a proven track record and is commonly done on lead-acid batteries used for solar power systems.

If you rev the engine and hold 2k rpm, so the lights return to normal? My guess is that you're still not charging the 12V, and it's under continuous drain. You should be charging between drives.

One or more of the "P" codes from the last round of diagnostics are all codes that may disable IMA function and 12V charging.

This has been going on long enough that I've forgotten what you've done. Now is a good time to go back through the fuse boxes checking for blown fuses. Inspect under the hood looking for broken/chewed wires.

 

You're right. I charge the brand new 12v battery in the evening, and when I check it in the am, the voltage has decreased just sitting there overnight. I'll check the fuses under the hood again.

 

Some of that may be normal. Flooded 12V batteries need to be charged at ~14.4V for a few hours, but they will settle to 12.7 or so.

 

Something is different tonight. The IMA dash light isn't lit, and when I rev to 2k in park, it appears the IMA is being charged.

 

CEL is still on. IMA off is a good sign.

Possibility: Flattened 12V and subsequent low 12V + bad connection caused multiple "permanent" codes that stubbornly wouldn't clear EXCEPT by the car itself or a pro tool.

Continued driving with a good 12V and connection may permit the car to complete drive cycles and eliminate error codes.