[Ovmsdev] Prolonging traction battery life feature

Sun Feb 18 22:52:33 HKT 2018

Robert,

The difference is in maintaining a single cell vs an entire pack. With a single cell, we don’t need to worry about balancing. With thousands of individual cells in a pack, we do.

Regarding Nissan Leaf support, looking at vehicle_nissanleaf.c, I see:

The usual SOC, range, charge status, etc, displays
Remote charge control
Remote climate control

For the climate and charge control, here are the notes (from the vehicle module):

// Wake up the car & send Climate Control or Remote Charge message to VCU,
// replaces Nissan's CARWINGS and TCU module, see
// http://www.mynissanleaf.com/viewtopic.php?f=44&t=4131&hilit=open+CAN+discussion&start=416
//
// On Generation 1 Cars, TCU pin 11's "EV system activation request signal" is
// driven to 12V to wake up the VCU. This function drives RC3 high to
// activate the "EV system activation request signal". Without a circuit
// connecting RC3 to the activation signal wire, remote climate control will
// only work during charging and for obvious reasons remote charging won't
// work at all.
//
// On Generation 2 Cars, a CAN bus message is sent to wake up the VCU. This
// function sends that message even to Generation 1 cars which doesn't seem to
// cause any problems.

Regards, Mark.

> On 16 Feb 2018, at 7:13 PM, Robert Sharpe <robert.sharpe at evergreen-consulting.co.uk> wrote:
> 
> Hi Tom,
> 
> Thanks for your reply.
> 
> Just to clarify, all I am trying to do is to reproduce what manufacturers do all the time to prolong battery life when they supply Lithium batteries at 50% soc.  If this charge scenario doesn't improve their life then nothing wasted.  If it does then it could prolong its life by around 50% and save thousands of pounds on battery replacement.
> 
> 
> 
> Before I think about about how to use OVMS to implement this, can someone summarise what current Nissan Leaf feature support is provided (which can then be used to update the vehicle support list <https://www.openvehicles.com/vehiclesupport>)
> 
> 
> Regards,
> Rob
> 
> --- On Fri, 16 Feb 2018 03:19:59 +0000 Tom Saxton <tom at idleloop.com> wrote ---- 
> Hi Robert,
> 
>  
> I believe most of what you want is already built into OVMS through the Advanced Charge Control feature, at least for vehicles that have implemented a charge time predictor.
> 
>  
> In OVMS v2 this was configured via text message. For example this command:
> 
>  
> ACC PARAMS CHARGEBY 07:00 STOPSOC 60
> 
>  
> tells OVMS that when plugged in at the current location, it should delay charging until charging to 60% state-of-charge will be achieved around 7:00 am.
> 
>  
> As far as I know, there isn’t currently a notion of a minimum SOC that should be achieved ASAP upon plug in. I’m not sure that’s a big deal unless you regularly plug in with SOC below 10%. For example, the Tesla Roadster has a storage mode that holds charge at around 25% for long term storage.
> 
>  
> There is a possible downside with using OVMS to limit the state of charge. Some electric vehicles, perhaps most, perform a pack leveling operation at the end of charging. If OVMS is used to stop charging early, that pack leveling will not happen.
> 
>  
>      Tom
> 
>  
> From: <ovmsdev-bounces at lists.teslaclub.hk <mailto:ovmsdev-bounces at lists.teslaclub.hk>> on behalf of Robert Sharpe <robert.sharpe at evergreen-consulting.co.uk <mailto:robert.sharpe at evergreen-consulting.co.uk>>
> Reply-To: OVMS Developers <ovmsdev at lists.teslaclub.hk <mailto:ovmsdev at lists.teslaclub.hk>>
> Date: Thursday, February 15, 2018 at 9:13 AM
> To: OVMS Developers <ovmsdev at lists.teslaclub.hk <mailto:ovmsdev at lists.teslaclub.hk>>
> Subject: [Ovmsdev] Prolonging traction battery life feature
> 
>  
> Hi All, <>
>  
> I have an idea that will help prolong the life of EV batteries and maximise vehicle resale value.
> 
>  
> In summary it involves implementing intelligent charging that keeps the battery at 50% (the best soc for long term storage) for as long a possible and minimises depth of charge and discharge.  For example
> 
> ·         as soon as you get to a charge point (eg home or work), the OVMS will detect if it is below 50% and charge it until 50% is achieved
> 
> ·         the OVMS will be told the minimum required soc and when this should be achieved
> 
> ·         it will then wait until the last moment to start charging to achieving the required min soc
> 
> ·         a later version could receive a notification from your Google calendar with required mileage via IFTT, etc
> 
> Unfortunately, I don't have the coding skills to implement it but would be happy to do all the non-coding stuff like requirements, design, documentation, testing, etc.
> 
>  
> If this sounds interesting and you would like to find out more please feel free to get back to me for a chat.
> 
>  
> Regards,
> Robert Sharpe (Managing Director)
> 07711 252971
> Skype: arsharpe
> 
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