[Ovmsdev] OVMS - power drain

[Nigel Jones]

The car is lease anyway (all-in) so it won't cost me anything.. just the
hassle. Given that 10 minutes headlights only (max 1.6Ah) was enough to get
the car into a worse state than it's ever been (voltage dropped to 5V, dash
"crashed", headlights wouldn't turn off it's clear the battery is totally
gone.

It should be replaced today - I'll see if I can find out the specs of the
old (and new).

It also I think shows that the "phantom" power draw on the leaf is very
close to zero and that actually very little power is required to "start"
(boot up, drop relay etc)

it demonstrates there's a whole lot better nissan could have done with
self-monitoring IMO and for example alerting just like OVMS did (though too
late... but then had ovms been in use longer perhaps the drain would have
been slower and caught the failure at an earlier stage of battery
degredation)




On 6 June 2014 01:34, Mark Webb-Johnson <mark at webb-johnson.net> wrote:

> Nigel,
>
> Good for the prospects of the project, but not so good for your car. Is
> this a warranty fix, or just a worn-out battery?
>
> I did some googling, but can't find the specifications for the Leaf 12V
> battery. It would be helpful if you could find out (picture, whatever) the
> capacity of the battery. It would give us some idea, at 2W consumption
> worst case, how OVMS would affects things in the Leaf.
>
> Regards, Mark.
>
> On 5 Jun, 2014, at 4:12 pm, Nigel Jones <nigel at cherrybyte.me.uk> wrote:
>
> Ok I just parked at work and turned on main beam, fogs,  max blowers.
> Under load  the voltage got to the low 9s. Without load it recovered to
> about 10.x
>
> The car started,  and the 12v started charging.left  a while. Hopefully
> I'll get home but clearly the battery is the fault
> On 5 Jun 2014 08:17, "Mark Webb-Johnson" <mark at webb-johnson.net> wrote:
>
>> Nigel,
>>
>> My concern is that a 'normal' car battery should be around 1,000Wh. At
>> 2W, that is 500 hours (20 days). Even half that would be 10 days.
>>
>> The Renault Twizy seemed to last about 3 days with OVMS.
>>
>> So, either (a) the leaf has a tiny 12V battery, (b) your OVMS module is
>> consuming a lot more than 2W, or (c) Vampire bats.
>>
>> We can dramatically reduce power usage by powering down the modem (or
>> putting it in a sleep mode), but it appears that only an SMS would wake it
>> up.
>>
>> Regards, Mark.
>>
>> On 5 Jun, 2014, at 2:54 pm, Nigel Jones <nigel at cherrybyte.me.uk> wrote:
>>
>> After leaving the OVMS disconnected for a few days I decided to hook it
>> back up yesterday evening and leave overnight. Not unsurprisingly I had a
>> flat 12V this morning (<8V)
>>
>> My nissan leaf code currently running on the unit is passive only (poll0
>> indeed just returns 0) - in fact it's only the calculation of the battery
>> level that was tweaked for msg 0x5b3. I'm using the experimental config
>> with nothing else change.
>>
>> I don't have a working meter, but at 2W 2Ah should have been the max
>> overnight. I'm not sure of the expected capacity of the leaf battery but
>> I'd imagine it's 30+. The ovms was slightly warm but certainly not hot.
>>
>> Since I'm not actively polling the bus, and I no longer get this battery
>> daya when the car is "off" I'm guessing moving the EV-CAN wouldn't change
>> this behaviour? Yet we know others are using the same framework without
>> issue. But since ovms works, and the framework is common (no tight loops in
>> the leaf specific module), and the modem is common it's tricky to figure
>> out what on earth is the cause unless that 1-3 Ah is really pushing things
>> over the edge...... Hmmmmmmmmmmmm.
>>
>> I'll figure out some other test to drain the 12V at a more known rate
>> when I have a chance though it is surprisingly difficult as pretty much
>> everything switches itself off.  It is still possible the battery is very
>> bad given it needs to do so little in the leaf
>>
>> When connected the ovms seems to work normally, responds properly,
>> replies to texts on demand - just about 2 in, 3 out during that overnight
>> period
>>
>>
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-- 
----
Nigel Jones
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