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Will my Honda Civic 2003 Hybrid run with a dead IMA Battery?

I have a 2003 Civic Hybrid Manual Transmission. The IMA Battery light has been on for 6 months. I have 185,000 miles and still going. Will the car still run if the IMA Battery is completely dead?

Hey, anybody interested in rebuilding these IMA batteries? The cost of the 120 Ni-Mh cells is under $900. Anybody ever take an IMA battery apart to see what is in there?

That’s a very good question. I think it will come up a lot in the near future because a lot of IMA batteries are nearing the end of their life span. I wish I could give you a definitive answer (I’m sure others will soon) but from what I’ve been able to find out…I’ll have to say no. I don’t think the vehicle has a regular alternator to charge the 12VDC battery so that will leave the little engine without a way to start. Your dash would be lit up like a Christmas tree anyway and your mileage would really suffer even if you could run on the little gas engine. I may be totally wrong here because I can’t get anyone with a Civic Hybrid to loan me one long enough to do the proper experimentation.

Where are you located?

What type of experimenting do you want to do?

I am surprised there is no alternator to charge the regular 12 Volt battery. If it is charged from the IMA charging circuit there would need to be a step down circuit in there somewhere because the IMA is 144 Volts. The IMA has to produce more than 144 Volts to charge the IMA Battery. So something charges the 12 V battery. I do not have access to a shop manual and I cannot pull one down off the network. When I get it, we are all going to make out on this!

I was just being facetious (tongue-in-cheek) about the experimentation. It would be nice to know how a Civic Hybrid, or any Hybrid for that matter, would run if the IMA battery was dead. The way that the Hybrid charges the battery is unique to DC electric motors. A DC motor is just a generator that runs backward.

The hybrid uses a special electric motor that can also operate as a generator. Send the electric motor electricity, and it will produce power; rotate it using external forces, and it will produce electricity. Using the car’s momentum to spin this motor, therefore, creates electricity, which is sent back to the battery pack. That’s called regenerative braking. In other words: a Hybrid simply does not need an alternator. Voltage control for charging from what I can determine is handled by a control box under the back seat.

" The IMA Battery light has been on for 6 months. I have 185,000 miles and still going. Will the car still run if the IMA Battery is completely dead?"

Didn’t you just answer your own question?? How a hybrid responds to a dead battery would depend on how the engineers set up the cars electronic controls. The cars operation would certainly be compromised, but it might still limp around…Junk cars are junk cars…Just because they have a badge on the fender that says “hybrid” doesn’t change that…Cars don’t wear out one part at a time. The entire car wears out as a complete unit…

Hmmm, well may be I did. But I will have to verify if my thinking is correct.

I am now on a mission to find a copy of the shop manual for my 2003 Civic Hybrid. Hopefully that will have the answer. I will post what I find.

Thanks for your feedback.

Your Civic may run with a bad IMA battery but you’ll likely be getting far worse mileage than normal as the generator trying to fully charge the battery will put a parasitic drag on the engine.

Your Civic battery can likely be rebuilt, check for more information (no affiliation).

Your IMA battery consists of 20 sticks of 6 batteries each, linked together for a total of 120 batteries. The batteries in each stick are welded together and as such are not easily replaced individually; purchasing the correct size NiMH batteries and just slapping them in there will not work.

Normally you will find that a few of the sticks have a bad cell and are not acting properly, giving you the IMA light and associated codes. Rebuilding of the battery pack involves cycling the individual sticks then determining which are bad and replacing as necessary.

The Hybrid battery repair guy has developed a computer board which can be inserted in place of your IMA battery to allow you to run the car without it, I believe it’s necessary for the charging of the 12v battery.

Thanks this is helpful. Who is the “Hybrid Battery repair guy”? Is this a generic term?

Are the sticks made up of the NiMh 1.2V 6000mA C cells?

I was referring to the link in my original post:

I believe the individual cells are 1.2v but don’t know about the amperage, I have a 2000 Insight and I think my battery is similar but not identical to yours.

Other good links are; it is mostly for the Insight but there is a section for the Civic Hybrid.; Mike knows more about the Insight than I could ever hope to know. He’s built his own welder so that he can remove/replace the individual cells in the battery.

There’s a ton of information on those 3 sites; although I’m not having issues with my IMA pack at the moment I’m considering removing it and balancing the packs just to try to keep it healthy, it doesn’t seem all that difficult.

Thanks. I checked out the link and they are D-cells but specially welded together so that the contacts do not burn up with the charging currents that can be as high as 100A.

I actually called the number as well. There is no alternator and if I have a ***49 error code it is a sudden death possibly. So I think I am going to get the replacement. With shipping it should cost around $1750.

Thanks for the very helpful information.