Phev Insight

[retepsnikrep]

I'll try as I get a chance to move the post's, but it may be easier if individual users pick there own posts, copy & paste them to a new post on the new thread and delete them from this one. Thanks. Moving posts for the mod is not easy I have just discovered

[Mod Insert] Please be paitent and continue the different discussion in the other thread. Peter and I will get this thing figured out in a couple of days so please no deletions or copied posts, yet. The big pond between us only allows a couple common hours a day weekdays. [Mod insert, Merge successful, linked above] [end]

[retepsnikrep]

Touchwood. Still working fine! Weather still terrible here

Voltmeter finally working properly as it was also suffering from the IMA interference cured by a 0.1uf capacitor from Li-fepo4 negative to voltmeter negative supply rail. Supply is isolated anyway. That gives me a possible solution for the master interference.

I shall be re-locating/re-installing the master in next couple of days and running it alongside analog system. I've got a few clamp on ferrites/caps/clamp diodes etc now

I will reintroduce/re-connect each function individually starting with battery temp and battery current etc until it stops working, then I'll add the filtering to the circuit responsible which I am certain is the Master data bus

I'm off on a 135 mile overnight trip on Monday 19/1/09 to see Greg in Scotland and talk BMS/EV's over beer!

I'm going to go for 135mpg (4.54L or One UK gallon) if I can.

Still tweaking pima to get better/best assist/petrol ratio.

BCM observations continued.

Just charged with 3.58 kwh after using car over last few days, soc has not fallen below the three bars at all during this time, which makes me suspect the soc only drops to zero if the detected voltage goes below the recal point as I have been careful not to stress cells.

It appears allowable ah may be higher than we thought, maybe > 10ah perhaps even unlimited as long as pack voltage does not go below the cut off point. 140-145v

I shall confirm this on my long journey hopefully, I'll try hard not to let pack V get below about 150v and see if it allows assist for entire trip

Peter

[retepsnikrep]

Reinstalled BMS Master screen in cubby hole and put Master board at the air vent behind drivers seat. I can get at it now from within car. Not wired it up fully yet, need to open up ipu compartment and fish out temp/current sensor wires.

BCM behavior

Positive recal after overnight charge.

Temp a bit better today and getting about 65% assist now.

I note max regen still cut's back after about 10-15 seconds on long hills, I was hopping it would not do that now Oh well.

[uhtrinity]

On regen, based on the mima display.

I can do 3 leds regen indefinitely, but if I push it to 4 it also cuts me off around 15 - 20 seconds. I have ever seen a battery temperature change, so I assume it is buit in BCM protection for the batteries. I usually just put mima into mode 2 and set it to charge at 3 leds and have fully charged my two packs back to full. Granted, it takes a long hill / mountain streatch of about 5 miles and under these conditions battery temps might gain 10 degrees F.

[retepsnikrep]

Balancing in progress,
bat temp 5.8C
charger set to 178v,
250ma balance load switch on at >3.60v,
about 40% of cells have reached balancing load switch on in this photo.

Pretty lights

http://www.solarvan.co.uk/bms/BalancingLight090109.jpg

http://www.solarvan.co.uk/bms/BalancingDark090109.jpg

[retepsnikrep]

More BCM fooling.

I'm quite happy at the moment with the way bcm is reacting to the new cells, but with the soc stuck at three bars most of the time I'm sure it is limiting assist and possibly autostop. (Need warmer weather to check the autostop)

I though about ten (+9 - 0 - 9-)v dc-dc converters wired in series with the tap points fed to the bcm instead of the tap points from the battery. This way bcm would see 18v at each point & pack V of 180v whatever the actual battery voltage was.

http://www.farnell.com/datasheets/67777.pdf

Would it force a continous positive recal? Would soc stay high no matter how much ah counted out? Any thoughts.

I note the 0v and 144v points also tap off to the MCM any idea why there or for what?

Anyone measured the current flowing at the voltage sense points? What size (ma/watt) dc-dc would be reqd?

[IamIan]

I don't know if I would go for 180V total... yes the pack does get that high during regen... but that is not the pack voltage just about any other time that it is not getting regen... and it is expected to dip significantly under assist... I don't think I would go above 170V... 160V might work fine ... I wonder how the BCM will react when the voltage doesn't drop under assist?

I have noticed several times when I install a fully 100% SoC Insight pack that regen was greatly limited and while not extreme the stock IMA seemed more eager to give assist than it normally is... I suspected this behavior was the BCM method of getting the pack back into the middle SoC when it detected that it was at a higher SoC.

[retepsnikrep]

Originally Posted by IamIan

I have noticed several times when I install a fully 100% SoC Insight pack that regen was greatly limited and while not extreme the stock IMA seemed more eager to give assist than it normally is... I suspected this behavior was the BCM method of getting the pack back into the middle SoC when it detected that it was at a higher SoC.

That may be what we want, force it to think it's very high soc and very eager to give assist.

The problem with going for 170v or 160v is getting the dc-dc's the 9-0-9 is a standard part. Unless you can think of another way to generate the voltages, I'm not sure about a PD resistor ladder as we don't know the current drawn. And you would still need a 170/160v supply to power it.

Further Testing

Good 60 miles trip today, freezing fog! mpg creeping up and lmpg also clicked up a notch which it never normally does in the winter

Batteries warmed up to about 15C, and now got 75% assist, which I held on some punishing hills for several minutes. No cutback or signs of fan activity from ipu compartment.

What have I learnt so far.

1) The Insight can take a lithium pack.

2) The Highpower li-fepo4 40ah cells seem able to cope with the full regen and 75A assist in the temps experienced so far

3) The BCM although a bit confused seems able to cope without throwing errors, under prolonged heavy load the soc will go below 3 bars, but with gentler discharge it appears to stay at three bars for a very long time.

Advantages over nimh packs?
1) More capacity and minimal self discharge balancing issues. Could be left for several months without issues.
2) More effcient charge discharge energy usage, less wasted energy. You get out almost what you put in

Disadvantages
1) Expensive and requires BMS although that can be quite simple.
2) Requires MIMA to operate effectively.
3) Quite heavy and compromises load carrying/cargo space. (If I was doing this again I would try and squeeze it all into IPU compartment.)

Conclusion to date.

Perfomance is amazing and car can cruise with one bar of assist at 145mpg on the flat for miles, I can't wait for the weather to improve

I only need to put a couple of gallons in at a time now as mpg is so high, also means I can ofset the weight of batteries by not filling it up.

[Insightful Trekker]

Originally Posted by retepsnikrep

I only need to put a couple of gallons in at a time now as mpg is so high, also means I can ofset the weight of batteries by not filling it up.

There is a long term consequence in doing such. Water condensation. But unlike older cars most of the fuel system is polymer. Read: immume to rust. An annual treatment with some isopropyl alcohol should keep such in check.


HTH!

[Mike Dabrowski 2000]

Sounds like your system is working pretty well.

I would expect that the voltage taps do not require much current at all, since the series resistor is 160ohms, and would have been selected to not attenuate the voltage at all.
It is easy enough to just measure the voltage drop (if their is one) across one of the series resistors, and we will know the current.

There are many companies that make HV dc/dc converters. I have used this companies products for several projects.
http://www.emcohighvoltage.com/
Just put a voltage divider to replace the Insight pack, and tune the output to what you want.
It is isolated, and runs off 0-12V with the output proportional to input, so you could tune it to whatever you wanted the BCM to see. and run it from the 12V system.