I get it... In any given project, I can guarantee that I will have an accident of some sort. In this case, I connected the energized grid charger to the live pack. Everybody says that's a no-no. I agree, but I only got a little spark.

Additionally, I hooked the UN-powered grid charger to a live pack once. Absolutely no indication of a problem. I flipped the switch off, energized the charger and flipped the switch back on... charged as usual. I checked the charger, and it was still putting out 360mA @ 190V.

Glad to hear of your results. Everything I have read says you got lucky. You may have had the good fortune of having relatively balanced cells at the time of the discharge. With 10 recals per day, I wasn't taking any chances with my pack.

It's only day two and a little over 100 miles, but I haven't had a recal, and the pack has performed very well even with A/C. I've never dipped below 4 bars, and it seems very happy between 5-7 with boost in almost every case.

AZ summers here are really hard on NiMH. Interior air duct temps have been measured up to 140°F, but I expect the battery compartment doesn't get that hot. I'll probably do a preventative series of grid charge/discharge cycles in April to get the pack to optimal before we get into the heat of summer.

I'll be doing a write up of my stick-level refurb on Ross' old pack. I hope to get it as good as possible and use it as a replacement while I do a stick-level refurb on my pack. Some weekend, I'll optimize the sticks between the two packs to make a "best" and "worst" between the two packs. Hopefully, those two will last me the life of the car. At 132K mi, I'm well on my way to "driving the wheels off it."

Thanks,

Steve

 

Just in case someone reads this, here's a little follow-up. I'm now getting 1 recal per trip after the car has sat for more than a few hours. It happens within the first few minutes and goes very quickly. When not in a recal, the IMA system performs great with lots of boost. My mpg has gone way up. w/o A/C and very gentle driving, I can see north of 50. "Normal" driving (pretending it's not a hybrid), and I'm in the low to mid 40's up from the mid 30's. Still very happy with the results, but I'm sure my days are numbered.

I started my refurb of rossfree's old pack. It is going very well, and it looks very promising. Paired sticks are showing >5.3Ah, and they appear to hold charge very consistently. 20 hours after a "soaked" grid charge, all paired sticks were between 16.57 and 16.59V. I am awaiting more hardware (chargers) to get more momentum going.

I've also fabricated "trickle dischargers" to gently pull the sticks down to .78V/cell after a 5.5A discharge to 1V/cell. It's a 4.7V zener diode and an 18 Ohm resistor drawing the sticks down at a rate of about 260mA. Once the stick voltage drops below 4.7V, the zener diode clamps down and acts like a regular diode mounted backwards stopping the flow.

Steve

 

Keith on the battery that has 1 recal on startup - what is the final voltage that it reached on full charge?

In my experience, a good battery only reaches 180V or so. A worse battery would be 183V, and I've seen one at 188V

However, this final number only seems to matter if its the final charge. (before a full cycle, even a bad battery may stop charging at like 178V)

 

EDIT: attached pic of trickle dischargers

188.6V after 18 hour, 20 minute charge @190V (charger unloaded Voltage). Settled to 176.7V after 9 hours. Based on the results of Ross' old pack (one day I will think of it as mine!), I'm not convinced I hit 100% SoC on my pack

I dialed my charger up to 193V based on references indicating a 1.45-1.50V peak at full charge during charge. The original insight grid charger was to be set at 177V unloaded for a 120 cell pack (1.475V/cel).

Here's a datapoint for you that might make you change your mind. I grid charged Ross' original pack for 20 hours, 47 minutes at 193V. It peaked at 192.2 and started to retreat. I disconnected the charger and checked temps with my IR thermometer. They ranged from 108°F on the bottom and 127°F on the top of the pack as it sat on the table. I setup a box fan blowing through the pack. I could feel heat coming out the other side, so I was getting at least a little pass-through.

After 1 hour and 23 minutes of cooling, I reconnected the charger for nearly 3 hours until the pack showed 192.2V. The airflow was sufficient to the point that I couldn't detect any heat, and the cells I could hit with the IR were only a few degrees above ambient. I disconnected and let it settle for nearly 20 hours and measured the paired stick voltages I reported in my previous post. I believe I found the point at which surplus charge was being shed as heat.

As I mentioned previously, the four pairs analyzed from that pack thus far show 5.3-5.4Ah capacity under a 5.5A load. Based on the results of my 500W discharge time against the new pack's 5.3-5.4Ah capacity, I would estimate the installed pack has a 3.5Ah capacity.

I think the peak voltage of the pack during charge has nothing to do with the quality or state of the cells. I think it's determined by chemistry. I would suspect that the "settled" voltage may play more of a role, but I don't have any data to confirm. It is my understanding that cells with higher impedance will have higher voltage, but I believe this is applicable not to the charging voltage but to the "settled" voltage after charge is removed.

Based on this reference starting voltage of a freshly charged cell in good condition is about 1.4V. That would put the pack at 184.8V or 16.8V for a paired stick. Mine were 16.58V or 1.38V/cell at disassembly 20 hours after charge was removed.

 

So here's a question for you guys that appear to be in the know -

I just bought my wife an '09 Civic Hybrid a couple of days ago. Contrary to my normal practice of doing research, I bought this one sans doing any real research (since I've never had issues with Honda or Toyota or heard of any horror stories). Of course after buying it, I find out about the whole CEL/IMA light issues, battery packs, etc. Well lo and behold, after her driving it for two days, she calls and says the CEL/IMA light has come on. The car only has a little over 58K miles on it. Today she drove it and said the IMA light went out, but the CEL is still on. It sounds like the normal 12v battery having issues can cause the CEL on these cars if I understand it correctly right? I'm assuming it's got the original factory battery and that puts it a bit over 5 years old and we're in Texas, so the heat is also a factor. From what I can also tell, we should be covered under the 8yr/80K mile warranty for the battery pack (I called and talked to a Honda service manager who confirmed this before I bought it), so I'm not *overly* concerned about it at this point.

I need to get a code checker anyway, so I have no idea what error codes it's putting out.

Thoughts?

 

IMA light came on. Push for a new pack under warranty. Push hard. Push until you get it replaced under warranty. Provided the pack isn't about to completely grenade, the CEL will likely go out soon as well as it's one of the OBD codes that trips the IMA light.

Seriously. Get the battery replaced under warranty. Now.

For the last 1.5 years, my pack has had multiple recals per day, but the IMA light never came on. IMA function was minimal and mileage suffered. From a functional perspective, it should have been replaced. Warranty replacement isn't even considered until the IMA light comes on. You hit that milestone. Aggressively pursue replacement.

BTW... did I happen to mention you should get it replaced under warranty?

Steve

 

That is the plan, but she said the IMA light went out today. We will see what Honda says this afternoon.

 

IMA light gets logged along with the CEL code. As long as you don't clear the codes, there's a record. If the pack has deteriorated to the point that it will throw the CEL code/IMA, they should replace it even if the IMA/CEL lights go out.

Steve

 

OK, that's good to know. I drove by my local Honda dealer on the way home to talk to them about it and they made it sound like it shouldn't be an issue. They said to drop the car off this afternoon and I should have it back by tomorrow, so we'll see what happens. I talked to one of their techs after talking to the service advisor and he confirmed the 8yr/80K miles and said it shouldn't be an issue. He wasn't sure about the extension to 9yr/96K that I had heard about, but again, he said it probably won't be an issue. I'll post back with what happens.

 

Sounds like you're off to a good start. The 9yr/96K mi applies to you due to the settlement in the states.