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I wanted to share the list of symptoms of a bad IMA battery for future reference:

1) re-cals - this is when your charge indicator drops from any level (even full) down to 2 bars, you get the green recharge bars for a while, then eventually it jumps to full again. if you get more than 1 or 2 of these re-cal events per week, its a sign the battery may be having issues. (mine got to the point of 3 or more per day on my commute).

2) power loss - with a bad battery you will feel the loss of power every time the random re-cal occurs, and also because the battery capacity is lower and runs down faster. You will not have assist when you most need it!

3) the backup -starter- is starting the vehicle instead of the quiet IMA motor. When my battery was bad and I let the car sit for 2 days, I would always hear the backup starter upon starting it.

Now that I removed the old battery I was able to compare the voltage characteristics to my newer battery:

Old battery - after charging to 169 volts, after 4 days of sitting, voltage dropped to 155 volts (14 volts lost!)

New battery - after charging to 169 volts, after 4 days of sitting, voltage dropped to 167 volts. (2 volts lost)

This explains why the traditional starter was used after my vehicle sat over the weekend - a bad battery may have a drain issue.

The biggest bummer here is that I -never- had an IMA light or engine light. There was no indication of a problem. It points to a quality problem at Honda because if I can figure out that the battery is bad with a voltmeter, and their software cannot, then this is a major fail. Even though my battery was past the 80k miles warranty, i believe 95k miles is pre-mature failure and the software should have at least detected the bad battery.

...The biggest bummer here is that I -never- had an IMA light or engine light. There was no indication of a problem. It points to a quality problem at Honda because if I can figure out that the battery is bad with a voltmeter, and their software cannot, then this is a major fail....

I think you're too kind.

In my opinion Honda does not have a quality problem; they have a credibility problem. There's been a lot of muttering that part of the software update was to make the IMA light near impossible to trigger.

The 3rd gen Civic Hybrid might be a superlative performer, but until corporate Honda starts performing a little better, and does it consistantly, I'm not interested.

BTW, can you post some links or guidance on how you go about charging the IMA battery? Also, I'm thinking if it came to that for the one still in our family, it might be worthwhile to go with a ReInvolt re-manufactured battery.

I almost got away with only 3 recals today (drove only 11 miles today). Unfortunately right before I got home I got a 4th.

When my Insight battery was starting to fail, I would reset it before each commute. I put a wing nut on the negative terminal bolt. It took only a few seconds to pull it off. I would leave it off for about 3 minutes and then put it on. I could make my 48 mile commute without any recalls.

Mines doing about3 recals a day too.

did 3 recals in the 5 miles on the way home today...getting worse.

"Old battery - after charging to 169 volts, after 4 days of sitting, voltage dropped to 155 volts (14 volts lost!)"

a few of your cells in the pack failed, easily found with a voltmeter..replacing them might bring the pack up for a few more miles. Not for you of course since you got a new battery :) , see if you can sell the old pack, I bet its got some life in it yet..

Dont get electrocuted, high DC voltage is lethal.. anything over 40v is enough to force some current trough dry skin.

Usually old nimh cells fail by internally shorting out to zero volts, dendrite growth crystals punch right thru the separator film and short out the plates. Sometimes you can burn the growths out with a very short high current pulse, but they always come back. If you keep an older cell charged it will self burn these growths the moment they appear, up to a point.

A lot of times I'll start a posting, then realize I'm rambling on, beating dead horses, then just back out. Just did that. Anyway, Honda has some climbing to do, to get out of the Hybrid hole, that they've dug.

I'm curious, MSantos: are you still on a waiting list to pick up a 2012, in Canada? Any updates?

Herm - I've revived the old battery by cycling it and grid charging it to 100% a few times. Now it behaves like the new battery (on the bench). The voltage drain is now much slower! However, it has maybe 2AH of capacity, compared to the 5.5AH spec of a new battery. I believe the cycling may have 'fixed' the imbalaced cells and some of the chemistry issues. I worked at GE with 380V (canadian lighting voltages) so I am very careful. Everything I am doing is with the battery enclosed, and all my connections are made with the Breaker turned off and with gloves.

...However, it has maybe 2AH of capacity, compared to the 5.5AH spec of a new battery....

Roughly 2/5, or 4/10. When I would watch our recalibration behavior, the state of charge struggle up to 4 bars, and sit there, and sit there, then suddenly bump bump bump up to full.

2Ah of capacity sounds like its ready for the dump.. is this an overall pack reading or perhaps some cells are close to new in capacity and some are dead?.. only way to tell would be to cycle each cell individually.

I worked at GE with 380V (canadian lighting voltages) so I am very careful. Everything I am doing is with the battery enclosed, and all my connections are made with the Breaker turned off and with gloves.

one hand in a pocket and standing on one foot? :)

At work we use a "rope man," a guy who holds a rope that is tied to the guy working on the electrical gear.

one hand in a pocket and standing on one foot? :)
I've always preferred rubber mats... one foot works great until you realize that only folks with a really good sense of balance can keep that up for any length of time before the leg gives out, you fall over, and suddenly you're grasping at anything nearby to keep from diving headfirst into the switchgear.

at my current job, the electricians wear a full body suit when they work in the 'switchgear' room or with 4180 Volt pump motors! they have to worry about deadly arc-flashes

back to batteries - I would rather have a 2AH battery that is balanced (and is not self discharging), than a 4AH battery that's imbalanced. In this case the 4AH battery would keep starting the 're-cal' sequence, while the 2AH would -never- re-cal. since honda's software only uses 80 to 20% of capacity, and adjusts as the battery loses capacity, you may not even notice the difference from a newer battery

unless a battery is 'babied' and never driven in hot weather, I'm guessing most will have lost half their capacity after 95k miles but who knows

Thats the problem with nimh, they generate so much heat.. then combined with hot weather is not good.

I worked at GE with 380V (canadian lighting voltages) so I am very careful. Everything I am doing is with the battery enclosed, and all my connections are made with the Breaker turned off and with gloves.

Are there test points on the car somewhere convenient for checking the high voltage?
Perhaps under the hood somewhere?

Also, the autostop controlled by the ECM has one input which is some measure of the big battery's voltage. No way that is the full 300V (or whatever), perhaps they send 1/100th of that through a precision voltage divider to the ECM? It is probably in the manual somewhere, but finding things in that manual is a bit challenging. (The entry in the index never seems to be under the name I would have used.)

Thats the problem with nimh, they generate so much heat.. then combined with hot weather is not good.
I guess that's why Ford only uses 40% - 60% SoC and uses the air conditioner to cool the battery pack if it gets too hot. I was kind of surprised when I first crawled under my Escape and saw freon lines in the back of the truck, and it doesn't have rear a/c.

I guess that's why Ford only uses 40% - 60% SoC and uses the air conditioner to cool the battery pack if it gets too hot. I was kind of surprised when I first crawled under my Escape and saw freon lines in the back of the truck, and it doesn't have rear a/c.

Do you ever hear of Ford having nimh issues?.. no, its just good engineering. Old nicads are endothermic, they get cold when they are charged.. but they are much heavier than nimh.

That was one reason I actually decided to buy a Hybrid. I talked to my brother in law who is the service manager for a local Ford dealer. He told me that he only saw one that had a bad battery, and Ford didn't believe it. Ford sent a tech from the battery factory in Japan and a translator to the dealer to test the battery before they replaced it under warranty. He told me to check the air filter for the hybrid cooling system in the back. He said if that filter was serviced on schedule then the battery should outlast the vehicle.

He said if that filter was serviced on schedule then the battery should outlast the vehicle.

That's a pretty dubious claim. All rechargeable batteries will fail after enough charge cycles, and a car that is driven regularly is going to go through a lot of charge cycles.

Which is why I purchased the 7 year bumper to bumper warranty, just in case. It seems that Ford was very protective of the long term usability of the battery when they programmed it not to charge beyond 60% SoC, and to start the engine if the SoC falls to 40%. It is my understanding that Honda and Toyota allow for more of the battery to be used, but they seem to be more prone to having battery failures as well.

Roughly 2/5, or 4/10. When I would watch our recalibration behavior, the state of charge struggle up to 4 bars, and sit there, and sit there, then suddenly bump bump bump up to full.

Mine's been doing the same thing since April, about 170 logged incidents so far.

Honda released another SW update that the dealer performed after the IMA battery failed for them on a test drive 11/10/11. Now, it's only worse, failing 2 or 3 times a day vs an average of 1 before.

Man you folks are scaring me with all this bad pack talk.

Man you folks are scaring me with all this bad pack talk.

It's hard to know just what to think sometimes. My pack is just about to hit its sixth birthday, and will probably be right around 100k miles when it does. I can easily tell that it has degraded, but my changed commute pattern (barely 5 miles now) and the non-LRR tires have made a far greater impact on my mpg numbers than the battery.

Yes a bad battery has less affect on mileage than you think. However a bad battery has a major affect on acceleration, especially when it is needed most.

Once the battery is replaced (or reconditioned to eliminate re-cals), the car is just so much nicer to drive. No loss of power and plenty of assist

since honda's software only uses 80 to 20% of capacity, and adjusts as the battery loses capacity, you may not even notice the difference from a newer battery


I measured my IMA battery at the terminals coming off the pack just past the relay after the infamous software update. When full, the IMA was at 189-190v. When at 2 bars SoC the IMA sat at 171-172v. Obviously far above the "nominal 158v" listed in the shop manual. Additionally, this means that the pack was essentially using 10% of it's charge, correct? I took several readings at various states of charge for several days last year in warmer weather (left the IPU cover off with the upper back seat out).

It's highly suspicious that Honda did reprogram the IMA to keep a nearly maximum charge in an attempt to balance the out-of-balance cells/sticks in the packs?

When I took the HCH II in to the dealer per Honda's direction in November due to IMA battery discharges the HDS showed no faults despite these excessively high charge levels (or excessively high per the OEM shop manual, at least). The dealer installed yet another software update at that point which has only served to increase the frequency of fluctuations in SoC.

Looking at the manual there is a way to check individual voltages in the sticks with a voltmeter via a harness connection. I'll be curious to see what they are once it's a little warmer out in the garage.

It's hard to know just what to think sometimes. My pack is just about to hit its sixth birthday, and will probably be right around 100k miles when it does. I can easily tell that it has degraded, but my changed commute pattern (barely 5 miles now) and the non-LRR tires have made a far greater impact on my mpg numbers than the battery.

I did the math and realistically with the miles driven by my wife, let alone my less than 10 mile RT commute I'm losing $8-9 a month is fuel savings even if she drives the car all month. Is it worth a new battery at this point? Probably not. In the winter I can still pull 38-39 mpgs though my wife averaged 34.8 mpg this last fill up :(.

To me, it's the principle of Honda not standing by their product. After reading the press release from Honda's Chris Martin re: the Torrance, CA small claims court case, I honestly have no hope that Honda will do anything to correct the problem unless forced to by the government or courts.

Be careful about judging based on the "nominal" voltage. The first gen is nominally a 144V pack, but if you ever get that low you are completely flat. Fully charged it tops out at 168V in the summer, 177V (100% from a charger) or so in very cold weather, and typically settles after (quickly!!) losing the top charge to 164V or so. There are 120 cells in my pack so that is 1.37V to 1.4V each (ignoring the high voltages in cold weather). You've got 132 cells in your pack and so your per cell voltage is around 1.44V at the top end, 1.3 at the bottom. Using 1.3V for my pack yields a total of 156V, which is about right for the low end, though it will drain a bit further than that if I really empty it all the way.

True, nominal voltage is in no way a hard and fast rule. Even taking variables such as ambient temperature into account, how can there be a 30+ volt increase with temps in the 40s-50s at the time? The battery did drop to 181-182v after about 30 min. Even this would be high.

If you can, try a different DMM/Voltmeter. I have 2 batteries and in normal operation the voltage should never get past 172V in a HCHII.

The range is 167V = 8 SOC bars, and 148V = 1 SOC bar

This matches both my real time measurements of both batteries, along with the graph that MSantos posted in the recal thread:
http://www.cleanmpg.com/forums/showthread.php?t=24097

NOTE: during grid charging, I get up to 185V, but thats the absolute 100% charge, which is out of the charging range of the vehicle (since they run 20% to 80%)

The voltmeter could be suspect; it uses the internal battery as a reference point so when the battery is getting low mine shows a higher display voltage. Swapping the batteries out brought the measured voltages back down to normal.