GEVCU and Limiting

[Lars Rengersen]

While I am getting towards finishing my 1967 Volvo Amazon conversion I have some improvement ideas / enhancements for the GEVCU.

Unfortunately I am not able to implement this myself since I am not a skilled enough programmer and am looking to hire someone. Therefore I am reaching out to this group to

1) Check whether you think these enhancements make sense

2) See whether anyone is interested to do the development

My ideas are geared towards limiting and ideally I'd like to use some "dynamic" features with the GEVCU triggered by external (CAN) inputs:

1- In case of low state of charge of the battery I'd like to limit discharge currents.
2- In case of battery temperature below zero I'd like to disable regenerative braking
3- In case of slippery roads I'd like to be able reduce regenerative breaking
Are there any features in the GEVCU that I can use to achieve this?

I have not found any info on this in the recent GEVCU 5 and GEVCU 6 manuals.
However in the GEVCU1.1.03 documentation I found:

LIMP MODE
This input is used to force an immediate reduction in power available via speed and torque command. All speed and torque commands are scaled by the LIMPSCALE variable.

LIMPSCALE.  0-100. This configuration variable is used as a multiplier for ALL torque and speed commands to the vehicle.  The default value is 100 indicating full power Scotty.  Lower values of course reduce output power to the percentage indicated in this variable. The variable is applied ONLY when the LIMPMODE input is active.

Looks like that feature could help me in achieving feature 1. But how do I activate LIMPMODE? (preferably over CAN)
And how do I set the LIMPSCALE (preferably over CAN)?

And feature 2 and 3 can perhaps be achieved if I could dynamically set "TMAXRN" and "BMAXR". Any thoughts on how feasible it is to set these dynamically over CAN.

Thanks in advance,
Regards,
Lars

[Charles Galpin]

Hi Lars

Great to hear you are using a GEVCU on your project. I’m beginning to wonder how many are.

I only have a GEVCU 2 and 4.2 and haven’t used it in my car yet. Years ago when the project was active, I helped with the software a bit and I think these are good ideas, and worth implementing, but I am not in a position to help until I get a bit further along in my project (which I did not work on for years but have recently started back on - as you might recall I got an iBooster based on your success ). I would be lying if I said it would be anytime soon.

Anyway, just wanted to say I think the ideas are sound - Tesla does this too. Perhaps someone like Collin or Michael might chime in, but I am not aware of anyone else actively using or working on the GEVCU, and after a quick look it appears there is a separate code base for the GEVCU 6 - not 100% sure I understand why that was needed or how it affects me :)

charles

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