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Ok, let's try it this way.

I am tired of the assist guage lying to me. For those of you who are still blissfuly unaware, full assist on the guage does not mean the electric assistance system is actually giving you 100 percent assist. Rarely, such as at low speeds and low gears, it actually will give its all, but mostly at higher speeds, while the gauge reads max, the true assist is much lower.

Can anyone provide insight into the signaling used with the current sensor, or a better signal to read off of? If nothing else, I would at least like to know what its really doing.

If I can get a reasonably accurate signal, I would even try to track SOC, with a numeric charge indicator.
 

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Here is a something that might help you in your research.

The IMA assist is mainly based on "load" on the engine.
Hook up a vacuum gauge in the system, drive around for a while and maybe you can see the what I mean.
Don't know the electrical happenings, maybe "Mike" can help you.

HTH

Willie
 

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There's a hall effect current sensor that provides an accurate voltage in proportion to the assist / regen current; IIRC; 2mV/Amp(?)
I tapped into this a few years ago, and used a small DVM that was velcro'd to the dashboard, to precisely monitor assist and regeneration current. (The stock indicator in the Insight is misleading, particularly for regen.)

After about a year, I removed the DVM and now observe assist / regen current with lower precision but similar accuracy, on an LED bar graph (which is part of a modification kit).

Information for the above referenced hall effect current sensor is in the Insight maintenance manual schematics (which I don't have). If you don't have them either, your best resource for electrical information is "Mike" as Willie has suggested.
 

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One LED per horsepower might be nice. :D
 

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I'm using a voltmeter like nemystic mentioned. Relatively easily installed if you have the service manual schematic, difficult and dangerous without. You also need some knowledge of electronics.

The sensor has three pins: +/-12V supply and output. I used an opamp to generate a virtual ground from the split supply. This is not vehicle ground! The output signal is as nemystic says a few mV/A. I calibrated my meter using a clamp-on probe for reference. With a potentiometer I adjusted the meter reading so it is directly in Amps.
 

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I was actually able to get an accurate voltage measurement (proportional to current) using the hall effect sensor output relative to MCM logic ground. However, the virtual ground, as Armin has implemented, is preferable, particularly if you scale the signal.
If you don't have access to a clamp-on current probe, you can scale the signal voltage output to 50% and then read amps (for assist / regen) on the millivolt scale of the DVM.
As a friendly reminder, always be careful working around high voltage, as it can be deadly.

I could be wrong about this, but I believe the signal from the hall effect sensor we've tapped into does not show the low level current that is from the IMA motor/generator to the high voltage battery pack which is at an average level to maintain charge of the 12V battery by way of DC/DC converter (during the daylight hours). That's a nearly constant, but necessary drain on the ICE power, and it probably has a small impact on fuel efficiency.
The additional current that's typically required to maintain charge on the 12V battery when the headlights are on is included in the HES signal.

:idea: I suppose it's just a matter of time before LED headlights will be available . I've found the now affordable 1 Watt LED lights to be more than adequate for bicycle commuting at night.
LED headlights should improve fuel efficiency in all cars, and it would be noticeable in the Insight.

I just read that a MIMA thread will soon be re-opened on this forum. I believe that's good news for Insight nation, and I hope that everyone abides by the forum rules so it won't become necessary to shut it down again.
 

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nemystic said:
I believe the signal from the hall effect sensor we've tapped into does not show the low level current that is from the IMA motor/generator to the high voltage battery pack which is at an average level to maintain charge of the 12V battery by way of DC/DC converter (during the daylight hours).
There are two current sensors: one for motor current (between IMA motor/generator and PMU) and one for battery current (between battery and PMU). The difference between the two is the DC-DC converter current.

I tapped the battery current sensor, so I don't see the DC-DC converter current when the engine is running, but I do see it in idle-stop, when it's provided by the battery.
 

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Yes Nemystic, one Mima post MAY be reopened. The matter has been under discussion for a while by the moderating team and Benjamin. Patience.....our moderators have busy shedules so the details/rules/cautions are taking time to discuss and work out.

Now back to our regularly sheduled topic, building an accurate gauge. ;)
 

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if you wanted to build a counter to go with the real time reading as the SoC indicator is about as accurate as the assist and regen indicators.....

The efficiency of the Amps going in compared to the amps going out is around 80% for NiMH in general....

The simplest would be to include that scaling into your amp hour counter that counted in and out of the battery pack.... Maybe a calibrate every once in a while when you know the battery is at top or bottom...


Real world NiMH will actually vary in cycle efficiency depending on cell temperature, SoC , and rate of charge or discharge, and pressure, and of course internal materials ....

Since the Discharging of a NiMH battery is endothermic it will absorb some of the (I^2)R heat generated by the internal resistance and impedance of the cells.... Additionally the batteries in the pack do not get equal air flow... or equal air temperature of the air that flows over them... And the Thermal Mass of the Batteries will delay Thermal effects of charging and discharging.... so Thermal Temperature change can be useful... but will not really tell you accurately how the cycle efficiency is changing, or what energy is being lost to heat.

Voltage on NiMH tells you nothing other than top and bottom 10 to 20 % SoC..... so it won't be helpful.

We could use the Thermal Evaluation paper the government did on the Insight's battery pack and use their internal resistance numbers they got at various cell temperatures... combine that with the thermal temperature coefficient strips on each subpack to know the subpacks average ball park temperature ... combine that with a small computer chip that will adjust the (I^2)R losses as the current changes in and out of the pack... as the resistance changes in and out of the pack with temperature.... as a more accurate Amp hour counter.....

ultimate amp our counter would also include ambient temperature , air flow rate , atmospheric pressure , individual cell temperatures, memory to do comparisons for change in temperature and change in voltage of a change in time....

just thoughts.....
 

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Congratulations Ian, I believe you have discovered who really killed the electric car!

I gather what you are explaining is that when a few cells get out of spec the computer gets surprised and throws a fit, otherwise known as a recal. Whereas, when everything is in spec it does a reasonably good job of estimating the remaining charge. 8)

I hope that battery management for the new lithium cells doesn't require quite so much alchemy.
 

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b1shmu63 said:
I hope that battery management for the new lithium cells doesn't require quite so much alchemy.
Actually Li batteries new and old all require much tighter comtols as they do not tollerate any over charging or discharging....

where NiMH will tollerate over charging and discharging... like the old Lead Acid batteries over charging and over dischargeing will shorten battery life and not be good for the batteries... but they will tollerate it just not like it.... where Li will not tolerate it... old ones burst into flames , new ones either just fail or some still burst into flames.

Li Batteries are nicer in the way that they after a few hours of rest can use the the Li cells voltage to determine SoC.... where a NiMH cell the voltage rest or no will only tell you when you are at the top or bottom 10 to 20 % range.

Also Li based batteries have a shelf life issue and just spoil / go bad... that NiMH does not really suffer from in any significant way.

Also Li based batteries tend to use more environmentally nasty chemicals in the cells and in the construction of the cells....

NiMH batteries also piggy back technology development with the Metal Hydride storage people trying to squeeze more hydrogen into a storage container....
 

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james said:
All of which helps explain why I really wish I could replace the batteries with a high-speed flywheel...
there is no magic answer...

Fly wheels just trade one problem for another....

The containment device in case of failure for a fly wheel almost always makes them way too heavy... all the great numbers you see for fly wheel energy per pound numbers re always talking about the fly wheel itself and ignoring the issue that if a fly wheel fails you have all at energy released in a fraction of a second and not as electricity or some volitile fuel , but as a explosion with shrapnel.

The other issue with Fly wheels is they while the fly wheel itself is very energy efficient... the mechanism you use to put power unto a fly whel ... ie spin it up... and the mechanism you use to take energy out of a fly wheel are not so effecient....

most fly wheels end up with cycle efficiencies nearly the same as a NiMH cell, coming in lower than Capacitors and lower than Li cells.

Fly wheels energy is based on the speed of the rotating mass... so your system of putting energy in and takeing energy out has to be very efficient at a wide range of speeds.... and in either direction... electirc motors are thier most efficient when they are set up for a specific dirrection and speed.

fly wheels have to have a perfect seal and no air can ever get inside the fly wheel chamber... or the fly wheel will at best fail... at worst catch on fire and explode.

Fly wheels add interia to the vehicle as the fly wheel stores more energy....

old physics experiment about the spiing bycycle tire on a bar stool example.... if the car tries to turn with a full charged spinnning at full speed fly wheel, some of the energy of the fly wheel will resist sertain directions of turning , change.

Fly wheels to hold significant amounts of power also must be build to exacting very close design tollerances... Li batteries are less complex and easier and cheaper to make than a high energy density fly wheel.

no magic answer ... any energy source or technology you use, will have its problems... they all do... it is just a question of which problems you are more able to deal with etc...
 

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Fly wheels just trade one problem for another....
True enough, but with luck you get to where you have a set of problems that you can either solve, or live with.

The containment device in case of failure for a fly wheel almost always makes them way too heavy...
They can be designed to fail without shrapnel (they disintegrate into tiny pieces instead of big chunks), while a good engineer would integrate a containment structure into the car frame.

Fly wheels add interia to the vehicle as the fly wheel stores more energy....
Rotational inertia, though.

...if the car tries to turn with a full charged spinnning at full speed fly wheel, some of the energy of the fly wheel will resist sertain directions of turning , change.
Which could actually be a benefit: if the spin axis is vertical, it resists rollovers.

Li batteries are less complex and easier and cheaper to make than a high energy density fly wheel.
Then why can't we buy reasonably-sized ones at a reasonable price? Look at the batteries in the Insight: effing D cells, fer gawdsakes. And the Tesla is taking a similar approach for its batteries.
 

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james said:
True enough, but with luck you get to where you have a set of problems that you can either solve, or live with.
true enough... and depending on what problems you want to tackle different people go different routes.


james said:
They can be designed to fail without shrapnel (they disintegrate into tiny pieces instead of big chunks), while a good engineer would integrate a containment structure into the car frame.
True , true... but, the same amount of energy is still released in the explosion .... also, if the fly wheel is designed to disintegrate into tiny pieces that will cause trade offs in the materials used to make it which means trade offs in energy storage ability and how quickly you can charge it up and discharge it....

Just like the safer Li Batteries that if over charged or punctured just get hot or stop working but do not burst into flame and other nasty stuff... they do not hold as much energy per pound as the less safe Li Batteries do because of the changes made in materials... they also tend to cost more as well.

james said:
Rotational inertia, though.

Which could actually be a benefit: if the spin axis is vertical, it resists rollovers.
Again True, True..... It is just one more issue you trade off with a fly wheel / have to consider with the use of the fly wheel... NiMH and Li Batteries have their own issues, but you do not have to have them tops side up in the car, orientation matters very little.... a Fly wheel in a car for energy storage in order to avoid having the rotational inertia be a problem would have to have the fly wheel aligned properly in the car.

james said:
Then why can't we buy reasonably-sized ones at a reasonable price? Look at the batteries in the Insight: effing D cells, fer gawdsakes. And the Tesla is taking a similar approach for its batteries.
Because while fly wheels are more expensive and less mass produced than Li and Ultra Capacitors.... Li and Ultra Capacitors are more expensive and less mass produced than NiMH which is more expensive and less mass produced than Lead Acid.... the order is something like...

Nuclear
FlyWheels
Fuel Cells
Ultra Capacitors
Li
NiMH
NiCd
Lead Acid

That plus some of the issues with different methods / technologies are harder or more expensive to deal with....

The combination of:
Cost to engineer & produce , Energy per Unit Volume , Energy per Unit Weight , Energy per unit Time, consumer acceptance , Environmental operating conditions , Safety Systems during use and failure, durability , maintenance , Legal issues , etc....etc....

some technologies are better at some things and worse at others... they crunch it all and NiMH 6.5 Ah Panasonic High Current "D" cells for EV's came out as the "best" solution for Honda Insight... When Toyota With Slightly different priorities crunched the same numbers at about the same time they went with NiMH as well but not the "D" Cells.
 

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One small point: A "battery" is a set of cells. Whether the battery is made up of big cells or small cells is purely an engineering decision. There's no fundamental advantage of a big cell over a battery of small cells--and some advantages.

For example, if you want a 12 volt lead-acid battery you put 6 cells in series. If you want a 144 volt NiMH battery you put 120 cells in series. A single 1.2 volt cell that provided the same energy as the Insight battery would have a connector about the size of your arm.
 

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It would seem that flywheels might be better suited for heavy trucks or otherwise train locomotives (that travel over mountain passes) than light aluminum passenger cars like the Insight.

Hydraulic energy storage, either by bladder/compressed air, or otherwise by bladder/spring, probably would be more effective in a light truck or heavy passenger vehicle than a flywheel.

Because of the various limitations of currently available battery technologies, it would seem as though there's no panacea for energy storage at this time.

Hopefully, R&D will continue for both improved energy storage and "alternative" renewable/sustainable energy sources, as these are both preferable to the liquid fossil fueled internal combustion engine that has become the world standard for transportation.
 

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One small point: A "battery" is a set of cells. Whether the battery is made up of big cells or small cells is purely an engineering decision. There's no fundamental advantage of a big cell over a battery of small cells--and some advantages.
There certainly are a couple of disadvantages to smaller cells. First, the smaller the cell, the more of its weight is taken up with the packaging, instead of active material. Second is what I'm seeing (I think) with mine now: the battery is only as strong as its weakest cell.
 

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Dougie said:
There's no fundamental advantage of a big cell over a battery of small cells--and some advantages.
Interesting????? That goes against everything I have ever read about battery pack design... and engineering in general....

If each small cell can only put out 1 amp and you need 20 amps you need 20 cells to get that 1 amp which mean 19 more places for something to go wrong than with 1 cell that can handel the 20 amps.

As stated you also suck up more space in the packageing of each individual cell in a smaller battery cell for a given battery pack.

And you also suck up more space and weight in connecting wires to connect all the smaller cells than a single large cell...

Also as far as efficency goes... a single 1.2V cell cranking out the same power as in watts as the whole 144V battery pack of the insight at 100 amps means 14,400 kW for one 1.2V cell that would mean 12,000 Amps... the extra weight needed to carry that kind of current would be a serious disadvantage of a single low voltage cell... power losses due to Resistance are = Current * Current * Resistance.... so the more current you pass the more you lose... higher voltage is always a better way to get less loss and have the same power output.

just my 2 bits.
 
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