This may be a long shot but I thought it was worth asking. I have a 2004 civic hybrid with a constant velocity transmission. I have replaced the battery pack twice now and the second one has been doing some strange things. I have tried to rehabilitate some of the sticks but only succeeded in popping a couple of them. No big deal, I know how to replace them. The pack I have in there has been reprogrammed with the updated software. I know this because the last battery pack I purchased used had not been so I had to swap out the sticks from one case to the other. The system worked pretty good for maybe two years but the car sits for months at a time. Sometimes the IMA system would stop working properly and I would have to turn the ignition off and back on to get it to operate properly. Recently the system stopped working completely but the car ran fine until it got down to idle speed, then the battery light would come on. I replaced the battery and checked all the fuses I could see in the main box. I believe my next step is to take it to the dealer and see if they can tell me what the status of the batteries are.

I a completely bad stick or two can do this then no problem I can deal with that. The system does put out 14 volts above idle. Any ideas?

Something is wrong with the alternator or whatever it's hybrid equivalent is.

I'm not too familiar with the hybrids but I believe the IMA battery charges the 12V battery. Faulty IMA battery or maybe faulty IMA motor which I assume also charges the IMA battery.

When you say the 'battery light', you mean the red battery symbol on the dashboard?

And you also have on the orange 'IMA' light, and the orange 'check engine' light right, because your back battery cells are bad? (These bulbs may have been removed - they should come on briefly while starting)



If so, then your problem is this:

* The 'alternator' on this car is a 150 volt to 14 volt power converter behind the back right seat. If it's not functioning, the battery light comes on.

* It will stop functioning if it's input voltage goes below ~100 volts. This *should* never happen.

* Normally during car operation, the input is connected to the battery pack via a big relay which is connected to the battery pack.

* The battery pack can be charged by the motor inverter whenever the engine is running. However, that only happens if the rear ECU commands that charging be done (and the green 'charge' bars appear on the dash).

* The battery pack is also charged whenever the pack voltage is below about engine rpm*0.032. This happens whether software commands it or not - it's a function of the way the electronics work that it cannot *not* happen.



So... I would guess your issue is:

* One of your battery cells/sticks is bad, causing your battery to have a high internal resistance, which means that any load on it causes the terminal voltage to drop rapidly below 100v and the 'alternator' stops working. This won't happen at high RPM because the power will be supplied from the motor instead.

Other possible issues:

* Bad cable connection on any of the high voltage cables.

* Bad connection within the battery pack.

* Main breaker behind back seat is off

* Bad relay that opens when it shouldn't.

* ECU software which is refusing to charge for some reason.


To diagnose, I would attach a multimeter across the battery terminals while the car is running (beware, high voltage DC is very dangerous - more dangerous than mains AC - you should attach the wires with the main breaker off, then switch it on and not go near it while testing).

If you see the battery voltage wildly swinging from 100v to 170v while driving, then you have the issue described. If the battery voltage is fairly stable around 150v then it isn't the problem.

If you have the problem, disassemble the battery and test each stick or set of sticks for internal resistance. Each stick/cell should have a short circuit current of *150 amps*!! If it's down at 30 amps the car will still function. If it's down at 10 amps, you'll see the issue you are describing. It only takes one bad stick to cause that. Using a battery tester that has an internal resistance test mode is probably easier than measuring short circuit current directly - in which case you're looking for an internal resistance of 10mOhms ideally, 50 mOhms worst case, and 150mOhms and it won't work.

This was a huge help CivicGuy, thanks. I got deep into a video on Youtube from Advanced Level Auto where the guy explains everything about this system in great detail which was a big help but just when I thought he was going to get close to helping me with my issue he found a loose connection to the battery under the hood and that fixed everything. You cannot know how disappointing I was that it was something so simple LOL.

The video at least gave me a deeper understanding of how the system works which helps me to understand you explanation. I also previously tried to restore my sticks on an old pack. It had been replaced years ago and had worked fine for at least 150k miles. I found a used pack and tried using it but found out about the reprogramming that was done on most new packs. As a result I pulled all the sticks out of the new used pack and installed them in my old case. It worked with various levels of success for a couple of years. Sometimes the IMA light would go out and things were fine but this car sits at my trucking terminal waiting for me to come pick it up every couple of months and drive it home. It gets driven very little. So the pack it I remember was working well enough and when ever I needed to get the car inspected I would unhook the battery for a few minutes and then hook it back up and the check engine light would go off and it would pass inspection. Last year the rocker panels were so bad that it would not pass inspection so I patched them up in a very ugly way thinking the car was finally on its last legs. Well this summer it was working fine and the air conditioning system needed charged so there went another $450 for just the recharge (that was ridiculous).
So I am willing to dig in myself since these dam cars are selling for $3-4K if they work right.

When I last replaced the IMA pack I found a site on line and even spoke with the poster about restoring the sticks if possible. I had everyone out and labeled and started testing each one. I picked up a

SkyRC B6AC V2 50W 6 Cell (6S) AC/DC LiPo Battery Charger (Imax)(sorry for the font change)

The process involved discharging each stick fully with a carbon pile load tester and then recharging them with the Imax charger. I think we were putting a 1/2 amp charge on each stick for maybe 10 min or until charged. This was from the guys experience. While we were on the phone and I had one stick on the charger I heard a bang from down in the basement. Yes one of the cells popped. I think I had one other stick pop before I lost interest in the project. So I have sticks and I suspect some are still good and I understand how to check the ones that are in the pack now.

Just to be clear you recommend pulling the pack and checking each stick to see if one or more are clearly bad. This would be a very simple fix. I see the other recommendation or possibilities which appears easy enough to check along the way but ,my money is on one of the sticks being completely dead. As far as when to replace the sticks all together what are your thoughts on that. I check the cost of each stick and I looks like maybe around $100 each. That will add up to worth more than the care pretty quick. Up till now I have only seen shops offer to rebuild the entire pack and that seem to be for obvious reasons but I am thinking in this case I should start with the left overs that I already have and get the car working well enough to sell.

well, does not matter how much the car cost you, really... The parts you are buying are new, so you are being charged for new parts...

you can always go to a scrapyard and get as many used cells as you can, but chances are not good that the battery cells will be good...

Humm not sure where this came from or what I am being encouraged to think or do. Maybe a typo.

I had a hip replacement last Monday so a lot of my on line posts this week have some mistakes. So I don't even remember making.

wow, yeah, it takes a month to rehab from that hip replacement - been there, done it - (to get to a condition that you can somehow move around, I mean)

My response was for this portion (Yes, I read your response )

Yep, I recommend taking every stick out and measuring them - specifically for internal resistance.

Wether you will find 1 bad one, or that they are all equally bad, is hard to know before doing it...

Crawling into that back seat and pulling the battery pack will be a good test of just how much rehabilitation I may or may not need. I found the video on Youtube ( ) for reconditioning the batteries. The guy has a bit of a scary method of reviving a dead stick. I might try it. It will give me an excuse to buy a big battery charger. I also noticed the charge rate was 5 amps. We will have to see how that works out. I try and keep this thread updated for anyone else who might need this information. Ironically, the guy suggests not buying one of these cars because they had issues. I posted 3 years ago about that. youtube and forums are the best. How did we get anything done before.

well, the bone side is OK, but the cut muscles... Never knew how much the butt holds your body up before... Speed recovery! remember that your legs will not move out until the muscles do mend together again