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Discussion Starter #1
Got a weird one for you, but I think it makes sense :)

I've had my 06 Insight since February (love it!!), and have averaged about 58 mpg. Not too bad.

That being said...I think the car has been trying to charge a failing battery this entire time. I would notice 4 green charge bars maybe 80% of the time while driving, and the orange battery meter would shoot up and down frequently.

Here's where it gets interesting........

The inevitable finally happened....IMA light came on this week.

Since then, the car doesn't try to charge, nor give me assist at all. That part makes sense.

BUT, because those 4 green charge bars aren't constantly trying to charge the battery, my fuel economy has shot up to 90-100mpg!! (See the photo! I just took a 15.9 mile drive, and got 90.7mpg!!)

Here's my really curious question, and I'd love to get your thoughts :)

If I'm getting 90.7mpg with the IMA light on, why in the world would I ever spend a ton of money to fix this??

Please let me know if I'm missing something obvious, but if this car runs this efficiently without hybrid assist, I'm sort of wondering what the point of the heavy battery is altogether?

Thanks!! :)
 

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Learner
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A failing battery pack causing a decrease in fuel economy is something that has been well documented here over the years.

So why would you want to fix the IMA light?

If you do nothing, your 12V will stop charging at some point once the HV battery pack gets bad enough, potentially leaving you stranded.

If you were to actually "fix" your IMA battery (grid charge, new pack, lithium ect.) You could reasonably expect to see similar to better fuel economy without the attendant negatives such as weak acceleration and no regenerative braking.
 

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Discussion Starter #4
Thanks for the replies and ideas!

I might go the route of removing the battery completely. I will research this option. I can deal with the weak acceleration - I typically accelerate very slowly on purpose to help with fuel economy.

And, with the battery weighing about 65 pounds, and the car weighing 1900 pounds - I'm wondering if a 3.4% weight reduction might help just a pinch.

At this point, I'm just not seeing the return on a $2000 investment in a new battery when I'm still getting 90+ mpg :) That being said, if I'm forced to get another battery to keep the car on the road, I will buy another...or just keep reconditioning it :)

If you have any other thoughts or guidance, that would be great! In exchange, I'll post my progress, successes, headaches :)

Thanks!
 

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15 miles doesn't really tell you anything. See what you get for a whole tank first. It won't be 90 MPG, probably more like 60. My car with no IMA got around 65 on a road trip, and I'm a pretty good hypermiler. I hate driving that car with no power.

Sam
 

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Keep the ima battery installed, but bypassed

The ima battery might come back if it is bypassed and not being used. The ima battery might later be used for a core charge if you want to get another one.
I would keep the battery in the car, but bypass the battery.
Unfortunately, I cannot help you with bypassing it.
 

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There are several different ways to bypass a battery. One is just disconnecting the computers - you'll have a CEL but the car should drive fine. Another is an Arduino-based bypass which turns off the CEL. If you're handy with a soldering iron and know how to upload code to an arduino via USB you can whip one up in as little as half an hour.

With the battery disabled, 75% of what's in the back is no longer used. You can choose to keep the very robust but ultimately quite large factory DC-DC converter, or switch it out for a much smaller unit, though they don't tend to handle hot climates as well.

Be aware that with the battery bypassed, you will no longer have auto-stop or regenerative braking, both of which have real-world fuel economy benefits.

 

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Please let me know if I'm missing something obvious, but if this car runs this efficiently without hybrid assist, I'm sort of wondering what the point of the heavy battery is altogether?

Thanks!! :)
I don't see that anyone answered this bit. Sorry if I missed it.

Go for a drive in town with frequent stop lights and idling. You will see "the point of the heavy battery". Your in-town driving will likely drop into the 30s.

I think you have it partially figured out. Yes, the car was trying to charge the battery frequently robbing you of about 1 hp of ICE power. When cruising at conservative highway speeds in a light aerodynamic 1.0L, you are going to get very good mileage with a low power requirement. That 1hp represents a very significant portion of the power required to push you down the road on flat ground at 65mph. Remove that intermittent 1 hp demand, and you should see a notable bump in mileage.

As a new owner, you probably haven't figured out that the hybrid system does essentially nothing for you at highway cruise. It's simply a very efficient ICE car at that point. It can help with mild elevation changes, but not by much.

The Hybrid system is essentially nothing more than a kinetic energy recovery and release system. It converts your forward energy into battery chemical energy, provides a means of powering the car while stopped thus saving on gas with no idle and then releasing the stored energy during acceleration - a brutally inefficient phase of driving.
 

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H. I. 06:

In addition to the hybridautomotive bypass (pack switch off and 2 front plugs on the bcm pulled), if you pull the four plugs in front of the mcm (ingnore the MIMA plugs in my 1st pic), your IMA light will remain off. You will still have the cel lit up.

For pack removal bypass, you can cannibalize your junction board for some wiring. If you want to keep your old pack intact for future use or experimentation, you can buy the parts shown on the bags in the 2nd pic.

Wire it up for the dc / dc to keep your 12v charged. Your IMA light will be out, but your cel will still be lit. Be sure to use some hefty electrical tape / or insulation. My red tape is rated for 600 v.

To get the cel to be out also, you'll need to explore the use of an ardrino device.

Some areas will not pass a vehicle inspection with trouble lights on.

I drove my silver bypassed for a couple years and still got decent mpg.
 

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Have you done a deep discharge and grid charge yet?

No?

Then do NOT remove the battery. Get a grid charger.
 

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Discussion Starter #13
Hi ADDvanced,

That's a really good question. I did a grid charge, but just a week after, the IMA light came on. That being said, I did not do a deep discharge. Do you think one of those light-bulb dischargers might do the trick? Maybe the one offered by Hybridautomotive?

Or, do you think a stick-level discharge/charge with the 12V HiTec-style NiMH chargers might do the trick?

Thanks!
 

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Hi ADDvanced,

That's a really good question. I did a grid charge, but just a week after, the IMA light came on. That being said, I did not do a deep discharge. Do you think one of those light-bulb dischargers might do the trick? Maybe the one offered by Hybridautomotive?

Or, do you think a stick-level discharge/charge with the 12V HiTec-style NiMH chargers might do the trick?

Thanks!
You don't necessarily need a special discharger from HybridAutomotive, the discharger is really just two wires to always-live spots on the battery, with a light bulb at the end of them. Keep an eye on it with a meter and pull it off when it reaches the advised voltage. There are lots of different ideas on the best process.

If you already have a charger, just take off the cover and splice a NEMA outlet to where the wires first come into the charger, and then plug a lamp into it. That's your discharger.
 

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You don't necessarily need a special discharger from HybridAutomotive, the discharger is really just two wires to always-live spots on the battery, with a light bulb at the end of them. Keep an eye on it with a meter and pull it off when it reaches the advised voltage. There are lots of different ideas on the best process.

If you already have a charger, just take off the cover and splice a NEMA outlet to where the wires first come into the charger, and then plug a lamp into it. That's your discharger.
That's what I did. I spliced in an extension cord. Make sure you turn off the battery before doing this! My discharger is a piece of scrap wood, the other half (male end) of the extension cord, and a $1.50 porcelain light bulb fixture that has a built in outlet. The built in outlet is nice because you can jam the leads from your multi meter into the outlet to measure the voltage while discharging.
 

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That's what I did. I spliced in an extension cord. Make sure you turn off the battery before doing this! My discharger is a piece of scrap wood, the other half (male end) of the extension cord, and a $1.50 porcelain light bulb fixture that has a built in outlet. The built in outlet is nice because you can jam the leads from your multi meter into the outlet to measure the voltage while discharging.
Any possibility of getting either of you to gents to elaborate, preferably with a photo, of where, exactly, these: "just two wires to always-live spots on the battery" points are on the battery, that you refer to, are located?

I purchased one of those cheap ebay chargers several months back, and have used twice now to sucessfully charge up and top off my pack, but I would love to construct this "poor man's discharger" setup, so I can begin doing the occasional deep discharge cylces on it, too.

When it comes to working with high voltage electricity, I tend to treat it like I do deep water, affording them both a healthy amount of respect, and avoiding getting into anything that's over my head.
 

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Any possibility of getting either of you to gents to elaborate, preferably with a photo, of where, exactly, these: "just two wires to always-live spots on the battery" points are on the battery, that you refer to, are located?

I purchased one of those cheap ebay chargers several months back, and have used twice now to sucessfully charge up and top off my pack, but I would love to construct this "poor man's discharger" setup, so I can begin doing the occasional deep discharge cylces on it, too.

When it comes to working with high voltage electricity, I tend to treat it like I do deep water, affording them both a healthy amount of respect, and avoiding getting into anything that's over my head.
If you already have a grid charger attached, it's where you attach your grid charger. You can drain the battery from the same place you charge it.

I'd advise checking out the "grid charger/balancer" thread in the Modifications and Technical section of the forum. A grid charger, in its simplest form, is basically a dumb power supply (usually 350ma and in the right voltage range for the battery) connected to the + and - on the battery - they typically run around $20-40 for a nice one. A discharger in its simplest form is a resistor connected across the + and - of the battery. A light bulb is typically the resistor of choice.

As you can probably guess, the profit margin on these eBay devices is typically north of 90%.
 

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Discussion Starter #18
I really like where this thread is going, and I really appreciate all of the input and questions.

Please tell me if my understanding is close on the following:

1. It's bad to discharge a cell too far
2. If I discharge the entire pack via the light bulb method (ie draining the full battery pack at once, as a whole), won't some individual battery sticks discharge quicker than other sticks within the battery pack, and therefore discharge too far? Because of this, is the better method to discharge/recharge on a stick-by-stick level?

Note: I really don't want to discharge on a stick-by-stick level......sounds like a lot of work! :)

Thanks!
 

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That's been discussed to death. I believe that accepted practice now is that as long as you do the discharge slowly enough, taking some cells to zero or even into reversal doesn't do permanent damage. Use a high watt bulb to bring the voltage low, then a low watt bulb to very slowly bring it close to zero.

Generally a discharge is more dangerous than a charge. In a small number of cases it has rendered inoperable batteries which might have had a couple of marginal years left in them. In other cases it has restored batteries which were otherwise unusable.

Others may feel differently. Read some other opinions. I now have an Acura TSX engine under my hood so it's not something I actively have to think about anymore.
 

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I really like where this thread is going, and I really appreciate all of the input and questions.

Please tell me if my understanding is close on the following:

1. It's bad to discharge a cell too far
2. If I discharge the entire pack via the light bulb method (ie draining the full battery pack at once, as a whole), won't some individual battery sticks discharge quicker than other sticks within the battery pack, and therefore discharge too far? Because of this, is the better method to discharge/recharge on a stick-by-stick level?

Note: I really don't want to discharge on a stick-by-stick level......sounds like a lot of work! :)

Thanks!
Don't listen to me, I'm not an electrical engineer, just some guy who's kept my insight on the road.

I have absolutely FLATTENED my pack before because I forgot to check it and left it discharging overnight. I think it had less than 1 volt. There's a voltage 'bounce back', so as soon as you take the load off, it will start climbing back up. So even if you drop it to say.... (literally any number here)... 50 volts. If you unplug the lightbulb but leave your meter plugged int, you will see it go from 50, to 51, to 52, to 53, it just keeps climbing and will slow down exponentially.

I'm not taking my pack apart. It's not worth the time when doing a deep discharge on the assembled pack produces such great results. Maybe doing a stick level discharge would restore even more capacity, but if I can get 80-90% of the improvement with like 5% of hte work, sorry, I'm doing that.

I currently need to deep discharge my pack once, maybe twice a year. I grid charge generally once every 1-2 months. YMMV. I would not be worried about 'hurting' an old IMA battery, especially if it's starting to show symptoms of being old. Worst case, you wind up getting a new pack. Best case: You don't need to spend anything.
 
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