With my continued gas savings I bought this! (2001 Insight)

[cowmeat]

Ahhhhh . . . . . yeah, unfortunately.

I actually bought it with that beast already siliconed on there, and I have yet to figure out a better placement for it since there's about a 3 inch diameter hole hacksawed in the hood underneath it.

So unless I cover the hole with a fake cowl or add a whack-a-mole game there, I figured it's just easier to leave it.

[cowmeat]

Pics below are of the lifetime MPG the day I bought the car (which I reset later that day) and coming up on 10,000 miles of my daily commutes. It's definitely a car that's sensitive to the way it's driven!

[pgfpro]

Nice driving skills

[cowmeat]

The car is loving the cooler weather!

Well, I'm loving not having to hit that AC button anyway . . . pretty good mpg
for the first trip home on this tank

[cowmeat]

Picked up a brand new set of RE92s from a nice guy on IC today, they're destined for one of the family Insights.

Started the discharge process on Ron Burgundy just a minute ago. Once I discharge down to around 20 volts I'll leave it on the grid charger the rest of the weekend and see if it peps up the IMA battery, which is starting to recal a lot. Seems to have worked good on Turtle, hope it does as well on Ron. Wish me luck!

[Ecky]

20v is way too low! You should read this thread before proceeding:

Impact of 'deep' discharge prior to grid charge - Insight Central: Honda Insight Forum

Originally Posted by joecvt

I had two out of three Insights giving me IMA lights (P1449) on a near daily basis in November and part of December. Even with light IMA use, I would get the IMA code of death. I had to pass inspection in Janaury (check engine light on with IMA light is a problem in the state I live in) so I added a wiring method to discharge the battery with the ignition turned off.

I manually deeply discharged both cars (one at a time to see if positive results). I used a 40W / 60W light bulb and brought the voltage down to what some claim were dangerous levels (below 100v) and they think I possibly damaged some cells n doing so. Since then, I have not even had a sngle recal and hence no IMA lights or codes for more than a month. I even tried to "abuse" the batteries in both cars and so far, it has worked like a charm. I think there is really something to this SLOW deep discharge that s really worth looking into. Perhaps my approach was more careless compared to what others would have done. But considering my pack was reporting to be "toast" with IMA lights in every day driving with inspection coming up in the next month, I had to try something. So far, this technique has been quite a remarkable fix. Time will tell but so far, so good.

JoeCVT

Originally Posted by Eli

Deep discharges are the key to rejuvenating Nickel based cells. However, to do it safely, you must do it at the cell level.

When doing it at the pack level, this is the question: Is the damage sustained during cell reversal worth a balanced pack?

I guess the answer could be yes, if you don't have anything to lose?!

Originally Posted by 3-Wheeler

eq1,

I would agree with Eli, in that the only way to *safely* get to a cell voltage of 0.78 volts would be to monitor all six cells per stick, when performing a discharge, and then watch for the lowest voltage cell to start dropping out.

Maybe if your current was low enough, one could stop the process it time and still get below 0.78 volts?

I would venture a guess and say that the current draw would be way less than 10 amps.

I can see one other scenario happening:
- the level of the cells starts to drop below 0.78 volts, but the other cells are still going strong.
- how do you get all the cells in the stick to get below the 0.78 volt threshold without reversing the lowest voltage cell?
- I suppose one would have to charge up the lowest cell first, and then continue on the discharge for the entire stick?
- Oh, now it dawns on me: one could simply discharge each cell of the stick, one at a time, and get each one below the threshold.

Jim.

Originally Posted by eq1

When I was testing single cells I never saw a benefit to dwelling at a deep discharged voltage, such as 0.2V. At the cell level, I found the lowest I needed to go was about 0.4V at 0.3A. Of course it's not like I have a large random sample of cells and a database based on it... So for the pack, whatever you think you need to do to get every cell down to that level is what I recommend; you can't just take the average - 120 cells times 0.4V. Hopefully everyone knows that by now. You basically need to go to zero...

On deep discharge current, I'd choose a bulb or resistor based on the current at 140V (but within a range of about 0.5A to 2A) and how unbalanced your pack likely is. The more unbalanced, the lower within this range you'd want to be... 140V is about where you might see the first cell reversals...

[Ecky]

There's a lot of debate over on InsightCentral, but this post caught my attention. Bear in mind that this is theoretical, but I think consensus is that these deep discharges DO damage cells, but people still do them anyway because they get rid of voltage depression and can have an overall net positive.

Originally Posted by sser2

I think there are few misconceptions here re. grid charging and discharging a NiMH pack.

Looking at discharge plot, a NiMH cell is fully charged at about 1.5V. Upon discharge, the voltage quickly drops to about 1.2V and stays around there during the most of discharge. At about 0.9V, the cell is almost fully discharged. If discharge continues, voltage drops precipitously.

A NiMH CELL (but NOT battery, as you will see further) can be safely discharged to zero volt, and kept for a long time in this fully discharged state without degradation of capacity. However, if a current in the discharging direction continues through the cell after its voltage has dropped to zero, cell's polarity is reversed, and this condition damages the cell by screwing its electrolyte. This is exactly what happens when a BATTERY of dissimilar cells (e.g. old tired IMA pack) is discharged to zero. Weaker cells drop to zero faster than stronger ones, and stronger cells then push the reversing current through the weaker ones, damaging them. So, the result is further damage to those cells that are already weak.

As a rag-tag battery with zero volts on its terminals is charged, stronger cells reach their full charge much faster than those whose polarity has been reversed. So, as the weaker cells are catching up, the stronger ones are being punished by pushing current through them for a long time after they have been fully charged.

There is absolutely no point in discharging a cell below 0.9V. If the IMA battery is not discharged below 0.9x120=108V, this will pretty much guarantee that no cell in the pack is re-polarized.

The safest regimen for reconditioning an old pack is to charge it at low current (200-300 mA), and stop charging as soon as voltage reaches the plateau at 170-180 V. If there is no voltage sensor that automatically stops charging at this voltage, it is necessary to monitor charging to stop it manually. Discharging should be also monitored and stopped at the safe voltage.

To Natalya: instead of galvanizing the corpse, pull out all the sticks that you have, measure their capacity, assemble the pack with 20 best sticks, and cycle it several times using your grid charger.

[cowmeat]

Well, so far Turtle's pack seems to be rejuvenated and isn't doing any recals, it's charging and discharging fine and giving full assist and full regen. I'm not pushing it to any limits testing it, but in normal driving it's doing good so far.

I'll find out later in the week how Ron Burgundy's pack acts, hopefully it will turn out as good as Turtle's has. I'm not kidding myself, at some point in the near-ish future both cars are gonna need new packs unless we disable them, which I really don't want to do. Hopefully I'm not doing any irreparable harm, time will tell.

[cowmeat]

The IMA battery in Ron Burgundy hasn't had a recal since I deep discharged/grid charged it a couple of weeks ago, and it's giving full assist and full regen. Seems to have really worked well!

[cowmeat]

It's been over a month since I discharged & grid charged the two Insights, and neither car has had a recal since. I have been using assist a lot more than I used to, and the battery has been handling it very well. So far, so good!

I pulled off the moon discs and aired up the tires this weekend for the first time since August. When I checked them before airing them up, the lowest was at 49 psi and the highest was at 52 psi, that's not too bad considering it had been about four months since I aired them up last, and they all lost air at about the same rate.

After the holidays I'm going to swap out the tires for the new set of RE92s I recently bought.