To my knowledge, the only thing they can do to check the IMA battery is check the 10 tap voltages through HDS. That tells you a little, but not a lot. Not likely they'll do it by request.

Steve

 

What does that do tell them the voltage of individual sticks of cells?

When batteries go bad is it just a few cells that are out of the charge discharge range of the others or a few cells that are damaged or is it the whole pack is worn from repeated charge/discharge cycles?

 

There is a specific code that indicates a problem with those voltages. They should be very close to one another. Generally speaking the greater the disparity between the minimum and maximum, the worse the pack condition.

those are the 10 voltages the car monitors, not the whole pack. When the first of those 10 voltages hits a peak for a given charge current, the car will terminate charging operations as it registers that tap at 80% SoC. Conversely, when the first of those 10 voltage drops to a minimum for a given discharge current, the car terminates assist as it register that tap at 20% SoC. In the vast majority of cases, it is a single tap that trips both the high and the low in a severely imbalanced pack - one that has triggered an IMA or is having frequently recalibrations.

Your question is too black and white. "Go bad" is literally that... go bad. When batteries go bad, it's a handful of cells that have excessive IR or high self-discharge making them unsuitable for use and unable to stay in any kind of balance for any significant period of time. Cells also short outright and lose all ability to hold any charge.

When packs start to show signs of deterioration like limited assist/regen and regular calibrations, it's usually from imbalance; however, this imbalance is typically caused by slight variations in IR and SD that will always act to drive those cells out of sync with the rest of the pack. This is where grid charging plays an important role.

No matter what you read, reconditioning efforts for imbalanced sticks are always temporary. It might be 1-12 months, but you'll be in it again.

NiMH suffer from voltage depression when short-cycled and over-charged. This shifts their capacity from a 1.2V potential to a 0.8V potential as the phase of the terminal materials change. The cells still have a lot of their original capacity left. They can only discharge some of at 1.2V and the rest at 0.8V. Below 1.2V, the car can't use it.

Cycling repeatedly dips into this reserve of lower voltage capacity and consumes it. When this happens, the phase is restored to the 1.2V potential. A single deep discharge of a CELL to 0V will completely wipe out that capacity and restore it to the 1.2V potential.

The above restoration of capacity can prolong the period where an imbalanced pack can still work within acceptable limits. Businesses have started and failed trying to recondition sticks. Capacity is restored and function is regained, but once out of balanced, the tendency is to go out of balance at an ever increasing rate.

Grid charging is the only preventative measure in this situation.

 

Now that's a detailed explanation! I now think I see the big picture of what you have been trying to tell me.

What's the difference if any between grid charging and the HA charger/discharger?

I'm at dealership now. Said they couldn't find any codes and the computer checked the IMA system and it was good. There was an update they applied and my 12v battery was low so had that replaced. The car just had oil change done and they said Trans fluid looked okay. They entered radio code and said GPS was missing disc that they don't stock but gave me website to order it from. Whew these are some complicated systems on board for a 2005!

I have body parts to locate so I'll drive it in meanwhile to make sure it's good before I sell it.

 

UPDATE:
IMA and MIL light came back on with same codes after car sat for 2 weeks waiting for body work. IMA light went off and I reset MIL light but came back on within a few days. I am re-researching my options lol
I don't want to spend 400 on charger then have to get another battery within a year but dont' know if I will keep car long enough to justify the 2k for battery but will have to do something soon.

 

These codes?

P2279 Intake Air System Leak
P0AC4 Hybrid Powertrain Control Mod Requested MIL
P0A7F Hybrid Battery Pack Deterioration

I have no input on the first two.

I would check the 10 voltages I mentioned in a previous post. They are on the orange plug that connects the battery to the BCM. I DO NOT HAVE THE ONE FOR THE ACCORD.

Here is the one for the HCH1:



And here's the one for the HCH2:



Neither are likely correct for the Accord, but there should be a similar pattern. You will either get 0V about 16V or some multiple of about 16V.

I would document the 10 different voltages and report back.

There is a DIY charger "plan" in my signature. The pack MUST BE PULLED FROM THE VEHICLE TO CHARGE IT as you can't run the IMA fan without a PWM controller. If you find this works for you, I recommend you invest in the HA grid charger as the convenience is well worth the price.