First, lets cut to the chase. I have a 2007 Civic with 112,000 miles on it. I was able to successfully recondition the IMA battery pack, and I havenít had a recal in over 250 miles. I was going to wait until I had 1,000 miles on the reconditioned pack, but Iíve had requests for information, so I thought I would post this now.
Reconditioning the IMA battery pack is relatively cheap (about $100 for a MRC Super Brain battery charger). The disassembly and assembly are relatively straight forward and donít take a lot of time. However, discharging and charging the individual sticks takes about two weeks if you can check on the process at breakfast, lunch, dinner and before you go to bed.
If you want to save a couple of grand, read on. Iíve tried to write down everything I learned, so you wonít have to spend as much time learning and doing as I did.
I highly recommend taking the time to recharge your IMA battery stick by stick. A grid charger might work, but given the extreme difference in how discharged my individual sticks were and how many cycles it took to get some of them back to normal, Iím not sure all of them would have gotten fully reconditioned with a grid charger.
I purchased my 2007 Honda Civic Hybrid new. I have been getting upper 40ís most of the year, and lower 40ís in the winter. In 2010, at 58,000 miles, the Honda dealer did the software update. Gas mileage was a little worse after the software update, but not a lot.
At the end of 2011, I was starting to get recals a couple of times a month. At the beginning of 2012, just before my warranty expired, I took it in to the Honda dealer. They said that since it hadnít thrown a code, there was nothing wrong with it. American Honda was similarly unhelpful, saying recals are normal.
The recals kept getting more frequent. By September of 2012, they were happening about once a week. I had the 12v battery replaced at 107,000 miles. That helped temporarily. In December of 2012, at 110,000 miles, the recals were happening daily, and my gas mileage had dropped to the upper 30ís. I noticed that the battery pack fan was sometime running when I stopped the car. Later in December, at 111,000 miles, I was getting recals every time I drove the car. By the end of December, at 112,000 miles, they were happening several times per trip and the IMA starter was no longer starting the engine. At that point, I decided if I was going to salvage the IMA battery pack, Iíd better do something right away. At no time did I get a Check Engine or IMA light.
I was lucky enough to be able to take my car off the road for a couple of weeks, so I decided to recondition each stick individually, rather than use a grid charger to try to recondition the whole battery pack in one shot. It appears that ideally the discharge/charge cycles should be applied cell by cell. Since that isnít practical, the best option is to do it stick by stick. (The sticks are welded together in pairs, but if you pop off the plastic caps and put one of the leads on the welded tab, you can charge each of the sticks individually. Since you are only charging 6 cells at a time, it should reduce the chance of reversing any cells.) If there were a problem with one or more of the sticks in the battery pack, I would have to do this anyway, so it would save me having to spend $100 or so to build a grid charger and then possibly spend another $100 to buy a battery conditioner. The trade off is that doing it stick by stick takes a lot longer.
I bought a MRC Super Brain 989 for $90 at www.ronlund.com ($100 Ė 10% for being a new customer. If your order is over $100, shipping is free, so I bought a pair of alligator clips to get the free shipping.)
Removing the Battery Pack
It doesnít take much to remove the battery pack. It took less than an hour, having never done it before. Since weíre talking about enough voltage to kill you, I strongly suggest you have a shop manual on hand to do this. If you donít have one, you can get a 3 day subscription to the same information your Honda dealer has for $10 at https://techinfo.honda.com/Rjanisis/logon.asp?Region=US. To remove the battery pack, you:
∑ Remove the ground wire from the 12v battery (Honda recommends also removing the positive wire)
∑ Remove the 10mm bolt between the seat cushion and the seat back (right behind the passenger seat belt buckle)
∑ Pull up hard on the front of the seat cushion near each door to pop the plastic locks on each side of the seat cushion. There are supposed to be 2 clips holding the back of the seat cushion, but mine didnít have any
∑ Take the seat cushion out and store it somewhere
∑ Remove the head rests and store them somewhere
∑ Remove the 3 10mm bolts holding the seat back
∑ Use 2 twist ties to keep the middle seat belt out of the way
∑ Pull straight up on the seat back to unhook it from the clips behind each head rest
∑ Remove the 2 10mm bolts holding the battery switch cover on
∑ Turn off the battery switch
∑ WAIT AT LEAST 5 MINUTES TO LET EVERYTHING DISCHARGE
∑ Remove the 9 T-30 Torx bolts holding the IMA cover on
∑ Remove the 10 mm bolt above the battery switch
∑ Carefully pry off the IMA cover being careful not to bend it
∑ Put a volt meter on the positive and negative orange cables. Honda says it should be less than 30v. Mine was 0. If it is more than that, DONíT GO ANY FARTHER UNTIL YOU FIND OUT WHAT IS WRONG!
∑ Remove the negative orange cable from the battery pack. Honda says to tape it up
∑ Remove the positive orange cable from the battery pack. Again, Honda says to tape it up
∑ Remove the 4 12mm bolts which attach the battery pack to the frame
∑ Unfold the 2 metal carrying handles and remove the battery pack
Disassembling the Battery Pack
Disassembling the battery pack isnít much harder and only took about 10 minutes. However, I suggest you take lots of pictures, so you know where everything goes when itís time to put it back together.
∑ BE CAREFUL! YOU ARE GOING TO BE WORKING WITH THE BOLTS THAT CONNECT THE 15 VOLT STICKS TOGETHER TO MAKE 158 VOLTS!
∑ WEAR RUBBER GLOVES UNDER YOUR WORK GLOVES TO REDUCE THE RISK OF SHOCK
∑ ONLY USE ONE HAND TO DO ANYTHING WITH THE BATTERY PACK. YOU ARE MUCH MORE LIKELY TO GET KILLED IF YOUR LEFT HAND IS TOUCHING THE NEGATIVE TERMINAL AND YOUR RIGHT HAND IS TOUCHING THE POSTIIVE TERMINAL
∑ HAVE A FRIEND READY TO MOVE YOU (WITH A STICK, NOT HIS ARM) IF YOU DO GET ELECTROCUTED
∑ TAPE UP YOUR 3/8 RATCHET, 3Ē EXTENSION AND 10mm SOCKET SO IF THEY WONíT SHORT OUT THE BATTERY PACK IF YOU DROP THEM
∑ USE RUBBER HANDLED NEEDLE NOSE PLIERS TO REMOVE THE BOLTS AFTER THEY ARE COMPLETELY LOOSE
∑ Set the battery pack down so the electronics are facing up
∑ Unscrew and remove the 2 10mm blue bolts in the middle of the pack
∑ CAREFULLY pop the 2 plugs and unscrew and remove the 2 10mm blue bolts under them.
∑ Congratulations, youíve just cut the voltage going through the pack in half.
∑ Remove the 4 10 mm bolts on around the edge, which just attach the outer cap.
∑ CAREFULLY remove the outer cap. DO NOT STICK ANYTHING IN BETWEEN THE OUTER AND INNER CAPS TO PRY THEM APART. THE INNER CAP IS FULL OF CONNECTORS BETWEEN THE BATTERY STICKS, AND YOU DONíT WANT TO TOUCH THEM.
∑ CAREFULLY remove the 4 spacers. THESE ARE CONNECTED DIRECTLY TO THE STICKS, SO YOU WANT TO GET THEM OUT FIRST, IN CASE YOU ACCIDENTLY DROP YOUR SOCKET WRENCH.
∑ Unscrew and remove the 18 10mm bolts in the middle of the pack
∑ Congratulations, youíve now gotten the voltage down to about 15 volts, which is pretty safe
∑ Remove the 4 10mm bolts around the edge, which just attach the inner cap
∑ CAREFULLY remove the inner cap. DO NOT STICK ANYTHING IN BETWEEN THE INNER CAP AND THE STICKS TO PRY THEM APART. IF YOU CONNECT THE ENDS OF THE STICKS TOGETHER, YOUíLL SEE SPARKS FLY!
∑ Pull out the 6 fasteners holding the stryofoam on the battery pack
∑ Remove the 3 pieces of stryofoam under them
∑ Unscrew the 8 10mm bolts holding the frame of the battery pack together. BE CAREFUL. AT THIS POINT THE WHOLE BATTERY PACK CAN FALL APART, AND YOU DONíT WANT TO DROP ANY OF THOSE STICKS.
∑ Mark each of the sticks so you know where they were originally. (I used A1 for the top left stick and A6 for the top right stick, B1 to B5 for the next layer, etc.)
∑ Remove the sticks from the pack. (This makes it a lot easier to charge them.) Take lots of pictures. They donít simply alternate Orange, Green, Orange, etc. AND you want to know where the temperature sensors and sensor wires go
∑ Pull off the plastic caps on the bottom of each pair of sticks to expose the welded metal tabs connecting the sticks together
Discharging and Charging Each Stick
Before I started discharging and charging my battery pack, I spent some time discharging and recharging NiMh batteries with my Super Brain. If you try to discharge them too fast, they reach their minimum voltage without discharging very far, and the discharge process ends too soon. I found that a discharge of more than 20% of the rated mAh resulted in the discharge process ending too soon. For charging, using the rated mAh of the battery worked well. Doing it this slowly adds to the cycle time, but my goal was to maximize the chance that I would save the battery, not to get the car back on the road as soon as possible.
I started the process with my car ready to do a recal. Since I suspected the sticks should be out of balance at that point, I did a single discharge and recharge of each stick. I did this in my garage in Michigan in the winter, so battery temperature was not an issue. However, even charging the sticks only at their rated capacity in 40 degree temperatures had the fan running pretty fast on my Super Brain, so I would be very hesitant to try to charge the sticks much faster.
In order to reach from one end of the stick to the other, you are going to have to make some longer wires to attach to the Super Brain. Two set screws hold the wires into the plug. Unscrew them, and screw in your longer 18 gauge wires. I soldered an alligator on the end of each wire, so it would be easy to connect to the sticks in my battery pack and tinned the other end so it would not break off when screwed down in the plug.
Be careful hooking the sticks up to the charger. For orange sticks, the positive side is the screw terminal, and for green sticks the screw terminal is the negative side. The good news is that the Super Brain will beep and give you an error message if you hook up the wires the wrong way. The bad news is that if you touch the screw terminals of the orange stick and the green stick together, you are going to see sparks fly!
I set my Super Brain as follows:
5500 mAh (5.5 Ah)
Charge Amp 5.50 (100% of capacity)
Discharge Amp 1.00 (20% of capacity)
Cut off Peak mV 5
Cut off V 1.00
Cut off 140 F
Trickle Amp 0.00
I recorded the data for each cell in the spreadsheet. The numbers I was most interested in were the difference between mAh remaining in each stick and the average of all 22 sticks (Column C). The standard deviation (a statistical measurement of how much variance there is between the sticks) was 1303 mAh. Approximately 2/3 of the sticks should be plus or minus 1 standard deviation, which means the spread (2606 mAh) was almost half the capacity of a stick!
As expected, there was a huge variation from stick to stick, with the lowest being less than 1% charged and the highest more than 75% charged. Moreover, 8 of the 22 sticks were less than 10% charged. No wonder my poor little Civic was constantly trying to recal to get things right!
The other interesting thing I found was that all of the sticks which were the most discharged were in the middle of the battery pack.
Surprisingly, most of the sticks were able to take a full charge (6180 mAh) on the first try. The only ones that didnít were very discharged to begin with. Therefore, it was actually quicker to use my slow discharge and charge settings and only cycle each stick once than to use higher discharge and charge settings some people have suggested and cycle all of the sticks multiple times.
Since most of the sticks appeared to be fully charged during the initial cycle and doing a full discharge/charge cycle shortens the life of the battery, I decided to get all of the sticks fully charged. Therefore, for the second and subsequent cycles, I only cycled the sticks which didnít take a full charge.
Based on my experience, I suggest that as soon as you find a stick that doesnít take the full charge, you keep cycling that stick, increasing the Cut off Peak mV by 1 mV for each subsequent cycle until the stick is fully charged. Also, based on my experience, I would cycle any stick that is discharged to less than 20% of capacity (1100 mAh) again, as these gave me trouble in subsequent cycles. If it took a full charge the first time, there is no need to increase the Cut off Peak mV above 5. However, my worst sticks were much better after a second cycle.
I understand another possible reason for recals is that one or more sticks donít hold their charge, causing the voltage to be lower than when the car was last run. I waited about a week (which is about how long it took me to get through the initial cycle) to see how much charge each stick had lost (Column BC). (Donít forget to change the Cut off Peak mV back to 5 before running the discharge test.)
The other thing I was looking for was whether any sticks were losing substantially more of their charge than the rest (Column BD). Not only was the average mAh substantially higher than in the initial cycle (4573 vs 1711), but the standard deviation was less than half as big (627 vs 1303), meaning there was a lot less difference between the sticks. Both of those should be good things.
After about a week, most of my sticks had lost about 1/3 of their charge (discharged down to about 4500 mAh), and almost all of them charged back up to a full 6180 mAh. I cycled the ones that didnít take a full charge and the ones that were discharged below average again. Doing that resulted in all of my sticks being at least 70% charged after sitting for about a week.
Top off the Charge
Since the sticks will have been sitting around uncharged for varying amounts of time while I did the Discharge Test, I topped them all off one more time before assembling the battery pack. I set the Super Brain for Charge only, increased the number of sticks to 12 (I charged each pair of sticks together) and set the Cut off Peak mV back to 7 to make sure they took a full charge. It took less than 10 minutes per pair of sticks, so the whole process only takes a couple of hours.
Reassembling and Installing the Battery Pack
Since almost all of the sticks which had initially been the most discharged were in the middle of the battery pack, I moved those sticks to the outside of the pack, and moved the sticks which initially had been the least discharged to the center of the pack. I put the best ones where the worst ones were and vice versa. It takes a bit of planning. Donít forget to move the temperature sensors to the new sticks, so the temperature sensors are in the same place in the battery pack. I wonít be able to tell if this has any effect until the next time I recharge the pack, which hopefully wonít be for quite awhile!
One possible reason for the most discharged sticks being in the middle of the battery pack is that they get the hottest. Honda uses a baffle design to get air to flow from the top of the battery pack to the bottom of the pack. When needed, a fan sucks the air out from behind the rear seat, circulates it through the battery pack, then past the IMA electronics and it exhausts in the trunk. Perhaps it doesnít cool the battery as well as it should, so I mounted 3 12 v computer fans to the bottom of the battery pack to make sure lots of air was flowing around all the sticks.
I used silicon seal to attach the fans to the battery pack. Make sure you mount the fans so they are SUCKING air out of the battery pack, NOT PUSHING air into it. (Usually, that means the decal on the fan should be facing away from the battery pack.) Otherwise, your new fans are going to be fighting the factory fan when it turns on. Also, make sure the fans are over the openings in the baffles, otherwise they wonít do any good! Finally, make sure you donít put any silicon seal inside the fan housing. Check that the fans spin freely after the silicon seal has dried.
Wire all 3 fans up in parallel (connect all the red wires together and all the black wires together). I inserted a plug in connector so that the battery pack could be easily removed in the future simply by unplugging one more connector. I suggest using a big enough connector so it canít accidently touch any of the bolts on the battery pack when it is fully assembled.
For power, I ran a fused 22 gauge wire under the rear carpet to the connection for the rear accessory socket which is just ahead of the gear shift. This results in the fans running whenever the key is on. Doing that uses 0.5 amps, but I felt the certainty of knowing the fans were running whenever they might be needed made up for the extremely small power draw. Make sure you use a 1 amp in line fuse as close to the connector as possible. The accessory socket is protected by a 15 amp fuse, which means that if there is a short, you could melt the insulation off the wires going to your fans before that fuse blows!
Put the battery pack back together, being careful to:
∑ Snap the plastic caps on the back of each stick.
∑ The black nylon spacers go second from the rear on the bottom and top. The rest of them only fit one way.
∑ Make sure the orange and green sticks are in the right places. If you change the location of the sticks, you have to make sure all the orange sticks are where the orange sticks were originally and all the green sticks were where the green sticks were originally!
∑ Move the temperature sensors to different sticks, so they are in the same place where they were originally.
∑ Route the wires from the temperature sensors out to the sides of the battery pack
∑ Route the fan wires inside the metal frame. Bolt the frame down on the side near the fans first, and then carefully attach the other side so you donít short out the wires going to the fans.
∑ Be careful not to pinch the temperature sender wires when installing the cap.
∑ The 4 long bolts attach to the baffles. I suggest you tighten these first, so nothing shifts when you start connecting the sticks together.
∑ The shorter bolts connect to the screw terminals on each stick.
∑ The 4 spacers go where the top cap is going to connect to the 2 halves of the pack (sticks A1, A3, C6 and D5). Put these in last, so if you do drop something, you donít connect these together.
∑ For the outer cap, the 4 bolts with shoulders attach to the cap. Again, Iíd install these first, so nothing shifts when you start playing with the real high voltages.
∑ Next, I installed the 2 positive bolts (A1 and D5).
∑ Finally, I installed the 2 negative bolts (A3 and C6).
∑ Connect the 3 temperature sender plugs to the outer cap and make sure the wires are neatly routed in the slots in the cap and outer cap.
∑ If you added extra cooling fans, make sure you donít break them off when you install the battery pack. They are on the bottom of the battery pack when it is installed, and if you just slide it in, they are going to break loose
∑ Before you tighten the bolts holding the battery pack in place, make sure the battery pack is pushed all the way up against the top of the mounting compartment so the there is a good seal between the air intake and the battery pack.
∑ Make sure the IMA compartment lid seals tightly so there are no air leaks, which will reduce cooling of the battery pack and the IMA electronics.
∑ Hook up the 12 volt battery and turn on the key to make sure you hear the cooling fans running.
∑ Push in the red button on the battery pack and flip the switch on.
∑ Put the seats and center console back in and youíre ready to go.
I turned on the key, and had NO battery on the indicator. Honda says to rev the engine to 3,000-4,000 rpm until you get 3 bars. I just let it idle. It started charging, and went up to a full charge within half a mile.
I havenít had a recal in 1,000 miles, and the 12 volt battery hasnít started my car since I reconditioned the IMA battery pack. I get much more frequent assists and for much longer duration. It also takes a lot more coasting to get 8 bars of charge. Gas mileage is up a bit from my winter average.
All in all, Iím happy with the result. Iíll try to remember to update this post periodically to let everyone know how many miles Iíve put on the car without a recal.
Re: Sucessfully Reconditioning an IMA Battery Pack
2007 Civic (O.P.),
Thank you so much for posting detailed instructions! And congrats! For doing what in hindsight seems like a common sense thing to do with a battery pack like this. I can't quite believe Honda does not offer such a reconditioning service under warranty or for a nominal cost. They could get a ton of good customer feedback for relatively minimal cost instead of disgruntled customers pissed at them for not helping them out. I will bet Honda does not because it is still not good for their bottomline--lame.
My 2008 HCHII is not in as bad a shape like yours appears to have been before you reconditioned the sticks in your battery pack. However, its performance is noticeably worse than even last winter, and the battery's capability to stay even at 4 bars is much lower (yes, I've replaced the 12V battery... car only has ~45k miles but is > 5 years old.) Nevertheless, if the situation gets worse, I'd be tempted to try your instructions. Thanks again!