Phev Insight

[retepsnikrep]

Originally Posted by jtbball

How much thought has been put into cutting the stock BMS from the system all together?

The simple answer is a lot.

There are quite a few threads on here covering the BCM and MCM and the IMA drive. Have a read of those threads as well. Removing the BCM is not a trivial matter although it may be getting nearer to being possible as we continue to build our understanding of how it all works.

The MCM and BCM exchange a lot of data not all of which is fully understood. So at this stage it's better just to simply fake inputs to the BCM which keep it happy and manipulate it's data stream (The parts we do understand to get it to do what we want) A seperate standalone BMS can look after the lithium cells. Peter

[retepsnikrep]

Amazingly it's over three years now since my first attempt at a phev insight rolled out of my garage on a cold winter morning in Jan 2009.

It's still working fine and i'm off on a longish trip in it on wednesday to do the HCH1 data gathering across the other side of the UK.

I'm intending to do some OBDIIC&C measurements of capacity on the journey in both directions to establish the capacity of the weakest out of my 50 cells now. When I get back with the pack exhausted I shall then use my new electronic load to discharge the remaining capacity from the highest/best cell to see what the difference is between best and worst.

As a seat of the pants figure I would say useable capacity of the pack is around 30ah be intersting to see if i'm anywhere near when checked.

I haven't touched my BMS etc or BCM interceptor fooler in the car for nearly two years, it just works. With some newer cells now and the extra knowledge we have gained it's only a matter of time before someone else takes the plunge. Current mileage is 133265

[retepsnikrep]

Back from my trip I averaged a little over 31ah (minus regen) each way before weakest cell was exhausted. I regened about 4.5ah on both trips. Not bad for 3 year old abused Lifepo4.

Down around 25% from initial 40ah capacity.

[Cobb]

You lost 25% capacity in 3 years of abuse? Any idea of how many cycles and their DOD?


Sent from my Autoguide iPod touch app

[bobmutch]

@retepsnikrep
>>>With some newer cells now and the extra knowledge we have gained it's only a matter of time before someone else takes the plunge.

How much money do I need to take the plunge?

[TheForce]

With my Hymotion pack in my Prius I seen about a 13% decrease in capacity over 3 years. Mostly running it down to about 80-90%. Its also a different setup using A123 cylinder cells and a maximum current draw of about 30-35A and no regen.

I wont know how the capacity would have played out longer than 3 years since I had it replaced under warranty. The good side is I get to compare my new refurbished pack against my original.

[retepsnikrep]

Average DOD prob around 50% but quite a few have been to over 95% like last two days for instance on long trips or testing. Cycles no idea.

How much cash do you need to do an install $4000-7000 off top of my head.

[TheForce]

The Hymotion pack I think is still $10k.

[nasphere]

Originally Posted by retepsnikrep

The simple answer is a lot.

There are quite a few threads on here covering the BCM and MCM and the IMA drive. Have a read of those threads as well. Removing the BCM is not a trivial matter although it may be getting nearer to being possible as we continue to build our understanding of how it all works.

The MCM and BCM exchange a lot of data not all of which is fully understood. So at this stage it's better just to simply fake inputs to the BCM which keep it happy and manipulate it's data stream (The parts we do understand to get it to do what we want) A seperate standalone BMS can look after the lithium cells. Peter

To tag onto this,

IMO the BCM can be totally removed. The MDM spits out an analog 0-5v value for current and another for voltage. If we use that analog signal to fake values on the BCM data stream, and use our own custom BMS SOC values, we might get better use of the system while removing more unneeded stuff like the nickel BCM in a lithium environment.