Phev Insight

[retepsnikrep]

Originally Posted by Mike Dabrowski 2000

It only takes .20mA to equal 1A. The hall effect holds the relationship as the real current goes up and down, tracking it exactly.

All we need to do is put a fixed resistor to chassis ground from the current output sensor wire, and the current will be passing to ground through the internal sense resistor, and our external dump resistor, effectively splitting the current so the internal sensor only sees whats left. The MIMA software may need to be changed to display the true current, and the stock assist/regen gauges will be even worse than they are now, but with MIMA, we don't look at the stock gauges anyways.
If someone wants to reverse engineer the board, you can see both sides in my photos, a schematic will help us understand how it works better.
The internal sense resistor is 100 ohms, and it is referenced to the two logic grounds on the BCM

More great work. So we are saying that at 100A then 20ma flows in this circuit with a 100ohm resistor in situ? If we put a 10ohm one in parallel to it dumping this sense current to (chassis or bcm logic ground?) won't that cause the circuit generating the current to fail? As it now has a path with much less resistance (x10) than it was designed for? Or am I missing something?

It's damn cold here again today -3C, car is frozen solid I'm off to work in about three hours.

I shall run mains charging cycle about an hour before I set off so the warm air from the charger can pre-heat the cabin a bit Need to plug in a timer to my mains socket so I can do this automatically.

I'm trying hard not to abuse my new batteries in this weather (i'm limiting myself to 25A of assist) and I need to use a bit more IC to generate enough waste heat to keep me warm. Still doing about 108mpg which is amazing in itself.

On way home last night engine only just managed to reach normal temp. I already have hot air mod and full rad block/scangauge. No recals last night on way home, nor did it fall below 3 bars soc, but I was being careful to limit assist current. It's looking more like if you can keep soc at three bars and don't allow battery voltage to sag under heavy load below the bottom reset point (yet to be determined for my car) that you may be able to have continious assist. We shall see Thanks for the all the info uhtrinity. I must have missed you real name somewhere on the site?

Just a thought in case people want to discuss ideas in real time I am on MSN Messenger for audio/video chat. Add my e-mail to your contacts if you wish.

(peter@solarvan.gotadsl.co.uk)

[Mike Dabrowski 2000]

Peter,
The self balancing nature of the circuit within the current sensor will always produce an output current of 20ma/100A to BCM ground regardless of the sense resistor value, including zero ohms. The resistance determines what the current to volts conversion will be.
Just add a 10 ohm pot in series with a 5 ohm fixed resistor, and you can tune your AH conversion to whatever you want.
10 ohms total resistance to BCM ground will change the current signal to 1/10 it's present scale factor of .02V/A to .002V/A, so the current of 100A will look like 10A to the BCM.

Here is a data sheet for a different brand with similar current loop output.
http://www.lemusa.com/docs/products/LA%20100-P%20E.pdf
Notice how RM can be zero ohms.

Because we are dealing with a known noisy environment, I would put a small 10 ohm pot in series with a 5 ohm fixed resistor right on the wires at the BCM A connector, between pins 4 (ISOC), and pin 15 (LG1), to keep the wires short. Stay away from connecting to chassis ground to minimize ground loops.

We still do not know if this will cause any codes, because of the possibility that they use the SOC current signal to cross check the MPI and phase currents, but I suspect that they did not bother, and you should be 0k. The MIMA current measurement can be bumped up to 10X to compensate by changing the value of R41 and R42 on the controller from the present 100K to 10K to change the gain of the differential amp, swo the MIMA display will still be scaled correctly, but the assist and regen guages will be off by the 10X, and will only show 10A when we are actually at 100.
Wayne could change his SOC circuit to /2,to compensate for his dual pack configuration, by adding a 100 ohm current dump resistor, and compensating the MIMA current amplifier by changing R41 and R42 to 50K instead of the stock 100K. Just tacking another 100K on top of the present resistors would be the simplest.
This should work just fine, but we will need to see how the rest of the IMA feels about the new current scale factor before we know if this solves the SOC issue.

[uhtrinity]

In my early parallel testing I did get errors if the mpi current didn't match the SOC current. I had connected the second battery between the sensors, which resulted in 50% scaling on the soc gauge. However as soon as I applied assist it would throw a code and disable the IMA sytem until the car was restarted.

This is what I had posted:

On the second attempt I connected the positive cable on the bottom terminal of the hv relay. This resulted in a fully driveable car, with one exception that I will mention below. As I expected (and hoped), by connecting to the bottom relay terminal and above the white current sensor, the mima display only showed max 50% charge and 50% assist (though both batteries were doing 100% combined). If I shut off the booster pack it would jump to 100% / 100% like normal. The stock assist / regen gauge also worked like normal going full range. So it did fool the system into thinking it was running one 5 - 6 aH battery, at least from what the mima display showed. I also didn't see any odd charging / assist behavior on the mima display that would indicate that one battery was charging into the other. Battery temps never went above their initial temperature.

Now, the one problem that I did see. If at any time I went to full assist, whether via mima mode 1 or mode 2, it would generate an IMA light after holding that assist for longer than about 15 seconds. With the booster pack off this doesn't happen. The light would also reset itself after turning the engine off then back on. A positive recal would occur over the next 30 seconds until the soc gauge was back to 18 bars. The car seemed to operate normal as long as assist was not pegged 100% for more than 15 seconds. Mode 2 (pima) also had a lot of torque, again, you just couldn't peg it for too long. Like I stated above the batteries didn't even get warm.

So if you do current scaling I think you would have to do both sensors.

[retepsnikrep]

Thanks, very interesting, I intend to build up a lot more experience with it as standard as possible before I start tweaking the current sensors. I want my Master board working as well within the next month or so.

I have some specific MIMA questions/requests now I am posting to the Mima thread. Before I moderate myself I have to remember MIMA specific discussions have to be confined at present to the sticky thread. Of course here on the PHEV thread we have a wider scope as the discussion is not about MIMA but about additional batteries and how to get the best/use/integrate them

Worked fine again on commute to work today, another positive recal on first starting car.

I noticed that as cells were full when I set off if I let it do some forced charging for a few seconds it pushed one of the cells over Max V and triggered my alarm. That's no problem you just disable the charging/regen until you have used a bit of current It also shows the over V alarm works as well

[Mike Dabrowski 2000]

Thanks for the feedback uhtrinity,
I am reluctant to try and fool the second current sensor, as I suspect that it is more directly involved with current control compared to the SOC sensor.

Your experience may point to a problem though.
If we ever get a nice warm day, I may fool with my silver insight and see what effect changing the current scale factor does to a non boosted system as an initial point of reference.

[IamIan]

Originally Posted by Mike Dabrowski 2000

This sounds like the problem we anticipated, a mismatch between the expected AH and the real AH. Bummer
The Insight pack has 2 current sensors, one in the output circuit to the power inverter, and the white one that measures the current in and out of the pack that MIMA taps.
What we do not know is how the system uses the sensor information.
If the white bipolar current sensor is used only for SOC determination, we should be able to scale the output voltage from the current sensor with a simple voltage divider, so the BCM thinks you are only using 10A a when you are actually using 100A.
On the other hand, if that current sensor information is also used to control motor current, that could cause the inverter to exceed the max and do some damage.
I suspect that this is unlikely,

I agree it is unlikely... for instance when you run your 16 Amp V-Boost when the MDM pulls 30 Amps to drive the IMA, it pulls a total of 30 Amps... not the 30 amps from the Battery + the 16 Amps from your V-Boost... even though the battery current sensor is still only showing the current coming from the battery and not the total current that the MDM is using.

unless of course I am missing something

[retepsnikrep]

More testing.

Got my voltmeter installed now. Tweaked charger V up a bit and charged to 177v this morning. Pos recal on starting. Batteries cold again though 1C. Now set Mima to 50% max manual assist. Also set up PIMA to give gradual assist starting at anything less than 130mpg with max at anything under 105mpg approx. At 125mpg I have it set to about 25A (1 Led) of assist.

I've been driving around my test loop for what seems like hours but still not flattened them Had a couple of three bar/features/bug and had to force charge for a mile to get back to 4 bars when unlimited assist became available again. If you only force charge to two or three bars it goes down again the moment you start using power, but it only has to reach four bars for a second or two and then it obviously resets something and assist then continues with soc stuck at 3 bars for ages.

Batteries warmed up a bit to about 10C now and available assist level is building, pack voltage varied from 180 under max regen to about 150 under max assist. Average at 25A assist seemed about 160v at these temps.

[retepsnikrep]

Further Info.

Mains Charge now completed 2.75kwh absorbed. I need a long trip now. Just trying to work out the capacity.

Lithium cells are pretty effcient, so lets say 100% to make calcs easier. Zivan charger is quite effcient as well about 85-90%.

Lets say my Li-Fepo4 50 x 3.2V battery pack nominal voltage is 160V x 40AH capacity = 6400w for one hour at 1C discharge. About 6.4kwh. Call it 6kwh.

What is the kwh capacity of the nImh battery? Are my calculations all off?

Charger max power is about 2700w so that means about 2.5-3hrs for a full charge allowing time for the tapering current during last phase.

That all fits in with the charge cycles so far.

I intend to reset one of my trip meters tomorrow and record mpg against kwh used now for the next 2000 miles (Trip meter limit).

Theoretical assist levels/duration available. I'll round all these down to save batteries, no point pushing them to 100% dod.

100A = 24mins (Full) (Probably lop 9 mins off and round that down to 15minutes)
50A = 48mins (50%) (Probably lop the 18 minutes off that and round that down to 30mins)
25A = 96mins (25%) This is my current choice (Probably round that down to 80-90mins) At lower drain you can get more out
10A = 240mins (10%) For a long journey. I do have a 200 mile 4hr trip I make a few times a year.

[Hybrid-Battery-Repair]

Originally Posted by JimIsbell

Problem is, its NOT zero cents per mile. Have you ever priced a 10'x20' solar panel? What about all the conversion cost and the batteries that have to be changed out, not to mention the original car used for the test bed. Then amortize that over the life of the car in miles.

I think you have to figure the panel and home battery array as infrastructure. They will outlast the car and be used on the next one, so you have:

Cost of solar array amortized over 30(?) years
Cost of home battery array amortized over the life of the batteries (will be different than the life of the batteries in the car because of different charging/discharging profiles) This is a recurring cost.

Cost of EV batteries amortized over their expected lifespan (lifespan is dependent upon the battery technology used)
Cost of EV conversion amortized over the life of the car
Cost of the car to aquire (probably cheap)

If you keep the car long enough, you'll replace the EV batteries
Eventually, you'll have to replace the house batteries
The solar array will keep pumping long after the car has been replaced with another EV.

[JimIsbell]

I have started ANOTHER thread called "Monitoring/Diagnoses/Repair of the IMA Battery" where I have moved this discussion on the sub cell problems. The moderator is supposed to move all this stuff over there later...I think thats what he said..... It started here because of the PHEV aspect of external charging but after migrating from monitoring of the battery to diagnosing the battery, and now, hopefully to repairing the battery it probably needs to move to its own thread.

[mod insert - linked to thread as shown above]