New-to-me IMA pack

[S Keith]

Originally Posted by elhigh

Okay, the longer GC didn't work. I left it on the charge for 23.5 hours. GC voltage output topped out at 180 for a while, but then dropped back down to 175-178. Output current never started to taper off. Looks like the pack's a bad 'un. I knew it was a gamble.

I have other motors to drive while the Honda is benched, so I'm going to:

Build a discharger and sock down the original pack. For future clarity, Pack 1.

The Honda is mobile with Pack 2 but the 12v light coming on is a little unnerving. I think Sweetie is happier driving a different car rather than rolling the dice. I tell her it's not much of a roll but frankly I can't blame her.

Sorry to hear it didn't work.

That's a very high peak voltage, but low temperatures can get you there. The drop is a little surprising. Were you running the fan? Are you using a Hybrid Automotive or a home-built? If it's home-built, and you're not running the fan, be very careful. Even the typical 350mA of a grid charger can cause a battery to cook if the ambient temp is high enough.

Output current doesn't generally taper unless you hit the power supply set voltage.

Just make sure you to a good solid grid charge before you deep discharge. That will ensure that the fewest number of cells will spend the least amount of time in the reversed condition.

Also consider that there are many uses for the battery sticks that don't work in a pack. For instance, I have an old battery-powered hedge trimmer that would run maybe a minute on its original pack. Soldered in a couple of leads, duct taped a couple of sticks to the handle (to keep it nicely balanced), and it's run all summer on one charge. Not that I use it that much, but there were 3 or 4 half-hour or so sessions...

Indeed. I have 20A charger/dischargers that can discharge 300W regeneratively. That means they drain the test battery into the battery that is powering them. I have 4 strapped together (2 sets in parallel, then in series) that I use as a regenerative sink for testing other batteries at 20A discharges.

[elhigh]

Went to Ace and spent $20. Picked up a couple of lampholders and incandescent bulbs.

There are no incandescent bulbs in my house except two places: the fridge and the oven. And when the bulb in the fridge dies, it'll get an LED.

I got 130v rough service bulbs to provide a bit of overhead. I hate when bulbs blow. Wired them in series as recommended.

Checked starting voltage: 154.8v

Hooked it up, fired it up. Very gratifying: they lit right up.

I saw a couple of VERY involved setups that incorporated built-in meters and automatic shutoff. I suppose if I concentrated very hard I could figure out how to do that, but what the heck, it's Sunday.

So I set a timer for 10 minutes and fired up Halo. Every ten minutes I hit PAUSE and check the voltage.

Finally, at 70 minutes I got down to 143.8v DC on the terminals.

I am pausing here while I try to figure things out. I have seen mention of minimum cell voltage of .78v, beyond which you risk reversing the polarity of cells. In my pack would mean a total voltage of 93.6 - not having disassembled the pack, I have no way of knowing whether any cell has gone below this threshold, of course, so I'm giving myself plenty of wiggle room before I do something irretrievable.

UPDATE AGAIN: it's another hour since I wrote the above and the voltage climbed back to 145. I put the discharger on it for another 10 minutes and pulled it back to 143.5. I'll see what it's relaxed back to in the morning.

[S Keith]

If you follow my suggestions, you should be fine. Your pack is broken. You're not going to make it any worse.

You WILL reverse cells. Period. The key is to do it at low current and in stages to minimize time and duration at reversed polarity. This is why I suggested 250W to 135V, then 60W to 60V. Of course, this is after a grid charge, and your starting voltage doesn't look very grid-chargy.

0.78V is the threshold at which voltage depressed cells will yield their remaining capacity. Powering through this level at low current generally restores high-current capacity.

Steve

EDIT: I've run IMA and Prius packs down to < 2V TOTAL voltage at very low current (<200mA). You're not going to hurt anything. The folks over at Insight Central are doing this routinely. Reversing 1-2A consumer grade cells will kill them. Reversing 100A industrial cells at very low current does no measurable damage.

BTW... The concept of X Volts per cell goes out the window below 1V/cell. When you go <1V per cell, you can more accurately describe it as "Pack Voltage = # of cells that haven't reversed".

[elhigh]

Okay, that's very different from what I had anticipated. I thought when I saw the 2v description...

Okay, that was a headslap moment. I just realized that if it meant 2V per cell, the pack voltage would be above 200. I can be monumentally stupid sometimes. D'oh!

All right, back to the store for smaller bulbs. This evening (hopefully, Son #1 has a super-late class on Mondays, we carpool, and I get home completely ragged out) I'll pull Pack 2 from the car so I can remove the GC preparatory to beginning the recharge.

[S Keith]

Originally Posted by elhigh

Okay, that's very different from what I had anticipated. I thought when I saw the 2v description...

Okay, that was a headslap moment. I just realized that if it meant 2V per cell, the pack voltage would be above 200. I can be monumentally stupid sometimes. D'oh!

All right, back to the store for smaller bulbs. This evening (hopefully, Son #1 has a super-late class on Mondays, we carpool, and I get home completely ragged out) I'll pull Pack 2 from the car so I can remove the GC preparatory to beginning the recharge.

Don't sweat it. The concept of taking a 144V pack to 2V is hard to wrap your head around if you haven't been exposed to the concept and practice in the Insight community. It's particularly concerning when

Any progress?

Thanks,

Steve

[elhigh]

I wired up two 100w bulbs in series to load Pack 1. The car is benched while I discharge the pack, even though I could probably run it safely on Pack 2. It makes my gut clench a little every time I see the 12v light come on, so I'm doing without my sweet sweet economy goodness for the time being.

In other news I'm using Torque to chase my Forester into the 27.x MPG range, which is crazy great for that thing.

I will stop by a store this evening and pick up a couple of larger wattage bulbs. I may die of old age and/or boredom waiting for the 100's to get the job done. I pull it down to 143.x and in the morning it's at 144.x again, and I can only do a couple of hours of draining per evening, and the voltage rebound between drains is mocking me.

I was going to have Son #2 screw in the smaller bulbs and just let it be going while I'm at work, but he appears to have left for class already, so that's an opportunity lost.

If I'm still at this on Thanksgiving Day, I'll be able to give it a lot more time and attention while helping in the kitchen. The rig is set up on the kitchen floor (though if I'm still at it on Thanksgiving I'll move it to the sitting room).

[S Keith]

Originally Posted by elhigh

I wired up two 100w bulbs in series to load Pack 1. The car is benched while I discharge the pack, even though I could probably run it safely on Pack 2. It makes my gut clench a little every time I see the 12v light come on, so I'm doing without my sweet sweet economy goodness for the time being.

In other news I'm using Torque to chase my Forester into the 27.x MPG range, which is crazy great for that thing.

I will stop by a store this evening and pick up a couple of larger wattage bulbs. I may die of old age and/or boredom waiting for the 100's to get the job done. I pull it down to 143.x and in the morning it's at 144.x again, and I can only do a couple of hours of draining per evening, and the voltage rebound between drains is mocking me.

I was going to have Son #2 screw in the smaller bulbs and just let it be going while I'm at work, but he appears to have left for class already, so that's an opportunity lost.

If I'm still at this on Thanksgiving Day, I'll be able to give it a lot more time and attention while helping in the kitchen. The rig is set up on the kitchen floor (though if I'm still at it on Thanksgiving I'll move it to the sitting room).

That's the downside to dual bulbs in series. They keep bulbs from popping, but 2X 100W are like a single 50W. Since you're already at nominal and not terribly higher than 120V, you're mostly out of the bulb popping danger zone. You could switch to a single 100W, which would be like 2X 200W down to 135V. Then switch to 60W to 120V, then dual 60W to 60V.

Don't fret the voltage bounce. It's not an indication of lost progress. It's the robust NiMH chemistry getting back to the nominal 1.2V/cell after the load is removed. Voltage bounce peels away pretty quickly once you resume discharging, and it adds a minimal amount of total time to the overall discharge. Note that when you switch bulbs to lighter loads, you will see a notable voltage bounce even after the load is applied.

Good luck!

Steve

[elhigh]

Happy Thanksgiving everyone!

And to our non-American friends, happy, um...November 26. Thursday.

Finally pulled the pack down to about 55v. Took FOREVER. Wrestled Pack 2 out, wrestled Pack 1 in. Hooked it all up.

Removed the pack bolts, wrestled it halfway out, hooked it all up. Looked at everything two more times. One more time for good measure. Reinstalled the pack bolts.

Plugged it in. 181v, 0mA? Whiskey Tango Foxtrot?

Son #2: "Hey, I turned the switch back on." 125v, 348mA. Man, I'm fatigued. It's the little stuff that gets you and the damned IMA is ALL little stuff. And Son #2 builds computers because it's fun, he's really good at catching details.

S Keith says give it a couple of hours on the charger, then fire up the car and go for a spin. So after Thanksgiving dinner, I'll take a little cruise and see what happens.

[S Keith]

Originally Posted by elhigh

Happy Thanksgiving everyone!

And to our non-American friends, happy, um...November 26. Thursday.

Finally pulled the pack down to about 55v. Took FOREVER. Wrestled Pack 2 out, wrestled Pack 1 in. Hooked it all up.

Removed the pack bolts, wrestled it halfway out, hooked it all up. Looked at everything two more times. One more time for good measure. Reinstalled the pack bolts.

Plugged it in. 181v, 0mA? Whiskey Tango Foxtrot?

Son #2: "Hey, I turned the switch back on." 125v, 348mA. Man, I'm fatigued. It's the little stuff that gets you and the damned IMA is ALL little stuff. And Son #2 builds computers because it's fun, he's really good at catching details.

S Keith says give it a couple of hours on the charger, then fire up the car and go for a spin. So after Thanksgiving dinner, I'll take a little cruise and see what happens.

No, S Keith said to charge for two hours, start and let it idle charge for 15-20 minutes, resetting the 12V battery as needed to get there.

Spin comes after the car terminates idle charge shortly after charging.

And happy t-day to you too.

Steve

[elhigh]

S Keith keeps giving advice and I keep not following it, or not all of it. My Dad insists I'm ADHD but I think he's full of hey, squirrels!

After letting Tiptoe sit on the charger for 2 hours, Son #2 and I took it for a quick spin. LOTS of depth of charge has returned, even with such a short charge aboard. Regen and assist behaved properly.

A quick note about assist: under the old paradigm before the discharge, I had about ten seconds of full assist before the IMA would go into recal. It would recal multiple times per trip. I got a grand total of about 20 seconds of full assist (and lots of lesser assists) on this little trip and it hasn't recalled at all. So on that basis alone I would say this has been a success.

But the 12v light came on. That was worrying. And it stayed on at all speeds, which worried me even more.

I brought it home and did a few 12v resets as described, pulling the negative, waiting a couple of minutes, reconnecting and starting to let it run for a few minutes. No luck on the 12v.

In fact on the 5th 12v reset process the car was struggling, wouldn't rev above 1200 or so, and the instrument panel was flickering. Shut it down and fetched the meter to check the battery. Metered at 11.45v. It was still daylight then.

Fast forward to ten minutes ago. Read about another tinkerer wandering through the maze of Honda hybrids, he mentioned the 100a fuse on the connections side of the IMA pack. Well, I just happen to have a spare here, let's tip that pack up on its side and look at it, shove that plug out of the way...

hmm...

that plug...

I remember what a challenge it is to get that out, but do I remember what a challenge it is to put it back? Unholster the flashlight and pop the panel out of the way. NOTE: knowing myself a little too well, only the battery pack is bolted down. Every other cover is still loose.

No, as it turns out I do not remember plugging it back in, and for good reason. Plug it in.

And the car fired right up, 12v light is out. So that's one hassle less. If nothing else I have my car operating in condition similar (actually markedly improved) to before I started all this.