[Ovmsdev] OVMS v2 Memory/Settings Corruption

Fri Nov 25 08:44:33 HKT 2016

The two biggest power hogs in OVMS v2 are:

The use of a LM to go from 12V -> 5V (blowing off 140%+ as much energy away as heat as we use).
Powering on the SIMCOM modem, and maintaining the GPRS connection.

The PIC itself uses negligible power, by comparison.

Changing that is hard in v2. We can put the modem to sleep, but have no way of remotely waking it up.

In OVMS v3, we’ll switch to use a switching power supply. More complex, more noisy, and a little bit more expensive; but much more efficient at bringing 12V down to the levels we need without blowing off heat.

The SIMCOM modems have a low power mode where they can maintain a GSM connection, but not GPRS/3G, to drastically reduce power requirements. In that mode they can be woken up by a SMS. If we use Hologram.IO SIMs, where the incoming SMS is free, we could enable a mode where the modem is put to sleep. If an App connects, the server sends a free SMS to the module to wake it up; the module then powers up and establishes GPRS. Without Hologram.IO, we could still do this - but would need some way of remotely waking up the connection. The Wifi/Bluetooth radios have similar capabilities.

The framework I’m working on for OVMS v3 includes these low power modes as a fundamental function. I’m confident that we can really bring the power requirements down and offer several different types of low-power sleep mode.

Regards, Mark.

> On 25 Nov 2016, at 5:59 AM, Julien Banchet <jaxx at jaxx.org> wrote:
> 
> Hi Michael,
> 
> And thanks,
> 
> Mine is a 2012, also got the charger replaced in time, but maybe a simply power-tweaked one at the time... I didn't know it was the charger responsible for deciding to keep the 12v charged (I know it does the charge, though I believed the decision making was done elsewhere)
> 
> I'll put it in SMS mode tomorrow and see how it goes over the weekend (though I can't monitor the 12V without IP, i'll get the low bettery alerts though ;-) )
> 
> Can't wait for V3 !
> 
> JaXX./.
> 
> 
> 
> On Thu, Nov 24, 2016 at 10:47 PM, Michael Balzer <dexter at expeedo.de <mailto:dexter at expeedo.de>> wrote:
> Hi Julien,
> 
> I was lucky to get my charger exchanged just before end of warranty, it's definitely better with the charger keeping the 12V battery up.
> 
> Tough situation when parking underground. The module may use a lot of energy if the GSM and GPS situation is bad. Switching off GPRS and GPS should save a lot of power then. I'll have a look at it.
> 
> Have you tried switching off GPRS to see how much that will help?
> 
> The EEPROM data loss is a known issue, and I'm afraid there's nothing we can do about that. It seems to be a bug in the PIC18.
> 
> Regards
> Michael
> 
> 
> 
> Am 24.11.2016 um 22:10 schrieb Julien Banchet:
>> Hi all,
>> 
>> Thanks to Michaels last message to remind me to ask a question here:
>> 
>> Since a few months, maybe a bit more because it happens only once in a while, I have noticed I wasn't receiving the SMS alerts (feature on SMSIP mode) , and sending a "Stats?" only gave me the nasty access denied answer.
>> 
>> It turns out, using the application, I noticed that the phone number was getting corrupted (afaik, it's the only setting affected)
>> 
>> Normally: "+33651886877 <tel:%2B33651886877>" it became "+336k1886877" or "+33651886Z77" etc... like a solar flare bit flip !
>> 
>> It seems it happens only upon reconnection of the ovms module the the OBD plug (Twizy) as, well, the 12V battery, though brand new, can't last a weekend (car parked underground, I suppose the GSM needs to force a bit too much)
>> 
>> So question: Has any one suffered from such an issue ?
>> 
>> And, otherwise, Michael might be able to tell:
>> Would having the feature on SMS only (without IP) consume less energy ? If so, would it possible to imagine a Hybrid mode, IP active only if vehicle on charge or keyon ?
>> 
>> Thanks,
>> 
>> JaXX,
>> PS: Despite winter, thinking of building a solar panel + thin plexi sandwich for the rooftop, just because of the 12V battery :-) Only recent twizys can charge the 12V from the traction battery when resting.
>> 
>> 
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> 
> -- 
> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
> 
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