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[sharagan]

I am creating a new thread as the SOC drop is actually not a battery self discharge but the motorcycle is using up the battery even when it is turned off.
European models appear to use 1% per day for 7.2 and 0.5% per day on 14.4 models.
For the European 7.2 models it comes up to roughly 30% SOC per month.
US 7.2 models appear to use up roughly 10% SOC per month...or at least Valnar's bike .
(bike not in long term storage mode - which turns on after 30 days, but the manual states to check the SOC at least once a month - this way the storage mode is useless)
 
According to the information from Zero the always on OBD2 connector in European bikes (starting with model year 2020) is responsible for the power drain even if the bike is turned off and described as normal (no issue with my bike). Result of a warranty claim I made due to the SOC drop. When comparing European 2020 FX and FXS models, which loose 30% SOC per month to an American FXS model which looses 10% SOC per month there is a 20% difference.

I personally can not understand such a power usage from an OBD2 port with nothing plugged in....so the DC DC converter comes to mind.
 
When looking at the information on the Sevcon website, the efficiency of their converters is 93% or higher. I do not have enough of an electrical engineering background to calculate if this could explain the high SOC drain or if an OBD2 port with nothing plugged should really draw so much power, but in my opinion it should not. Zero's statement is that the power drain is normal and that the OBD2 port is responsible, but I am missing an explanation behind this statement. I sent a message to Zero with my question, but does any of you maybe have any assumptions or ideas to this phenomenon?

Another consideration is the long term life expectancy of the electrical systems which are nonstop under power and working.

[TheRan]

I did the math in a different thread, 1% loss over 24 hours is 2.6W. Sounds a bit much to me.

[sharagan]

yes, it was in "Battery self discharge on Zero FXS 7.2", thanks for the calculation.
What I mean with my question here is if the efficiency of the DC DC converter can account for the excess power loss as the 2.6W over 24 hours are way too much for an OBD2 port with nothing plugged in.

[Auriga]

Welcome to the wonderful world of electrical systems and their complexity. Let's do some math! Efficiency isn't really the important metric here, but I guarantee you it's far less than 90% at almost no load. Most datasheets will have a graph of efficiency versus output load.

I'll be using this datasheet, which is probably fairly close to Zero's part.
https://wiki.neweagle.net/ProductDocumentation/EVsoftwareAndHardware/DC-DCconverters/80V_500W_DCDC_Datasheet.pdf

I'd like to draw your attention to the Zero Load Input Current, which is the current consumed by the DCDC whenever it's ON from the input, with nothing attached. That's 85mA max, as compared to 15mA if it's off and disabled.

Power = Voltage * Current = 110Vdc(this battery voltage will vary, but it's an estimate) * 85ma = 9350mW or 9.35W. If it's off, that's only 1.65W

Taking 9.35W, assuming its on all day, watt-hours per day =9.35W*24h = 224.4 Watt-hours per day.
With the DCDC off, that's 39.6 Watt-hours per day

Finally take a 7.2kW longbrick, with a nominal(actual) capacity of 6300 Watt-hours and divide by 224.4 watt-hours/day

Gives a rough total of 28 total days of life with the DCDC on and 160 days with the DCDC off.

That being said, I know that Zero has a safety interlock that disables the always on OBD port and the DCDC when the battery voltage drops  to around 20-30% SOC, extending your lifespan considerably if the rest of the system is in the microamp/very low milliamp range.

This really highlights how critical no load consumption/quiescent current is when choosing a dcdc converter for a battery powered device. On a smart device like my apple watch, the no load current is measured in microamps. I don't think you can do better in a high power DCDC though, but Zero could have chosen to use a proper low power part with better characteristics. Which probably would require another circuit board assembly/more harness changes and hurt their cost per bike.

I'm guessing EU regulations required an always on 12V to make their OBD port "compliant" and they came up with this solution.

Not sure about SOC drops, as the SOC is a black box algorithm, but you can see from the math how it would be around  6x worse battery lifetime on the EU versions.

[sharagan]

Hello Auriga,

thank you for the detailed breakdown and the explanation. This makes a lot more sense to me now.

Now I am considering...Would there be a possibility to turn of the "Always on" feature?
I assume the OBD2 port is physically present also in the US models, just doesn't have to comply with the EU standards and does not have to be always powered.

Not sure if it is worth it to spend time on that idea or just leave it be, when taking the longevity of the electrical systems into account, which are always on due to this...mainly the converter.

[Auriga]

They actually added a second OBD-II connector to the EU models and made that one always powered.

DCDC lifespan is probably reduced by this, but it's difficult to say by how much without a manufacturer spec/study. Everything else is unaffected. It seems like more people lose DCDCs to water ingress over time, but it's really hard to say without a large dataset.

I've heard there is a fuse that can be removed before the circuit board powering the second OBD-II port, which would disable this(I don't see it in the manual though). I think it could also be disabled by removing the 4A  DCDC fuse, which would disconnect the input to the DCDC and is in the owner's manual.

Unfortunately I'm an american dealer and thus do not have more specific instructions for you

[sharagan]

What are your thoughts on pulling the low power b+ fuse?

[staples]

This is very interesting. I actually want an always on OBD-II port, but my 2018 FXS in the US doesn't have it. I was sad when I looked at the port and it didn't even have the +12V pin.

[karlh]

Beginning in 2018 the EU required bikes to comply with the OBD-II standard, ISO 15031.  Part 3 of that standard, which describes the connector, requires that pin 16 have a "permanent positive voltage."  In other words, pin 16 should be connected directly to the battery.

[sharagan]

I found both of them, one is under the seat, the other is in front of the battery and sticks out of the side next to the side panel.

[Auriga]

I do not think low power b+ would work, it’s between the mbb and the battery, and Probably does not disable the dcdc or the obd controller

[sharagan]

much appreciated 

[Jan Wespelaar]

I wonder, as Zero has added this always active OSB2 port on the Zero's for Europe, in which way we coulded use this port to communicate with the motorcycle from distance or use it as a data collection point to drive by example a IFTTT script for the charging of the motorcycle to 80%, or monitor when the bike is charged?

I'm not a electronics or It specialist, but as we can't avoid loosing 1% of load each day, why not using this in a positive way for us as users?

I would personally be very happy to have 2 extra functions on my 2020 FXS, being:

• to be able to see the present loading of my bike by using a web app on my phone ad distance
• to be able to stop automatically the charging of my bike when I'm at work without the need to go to the garage. I haven't always the time or I forget to do so, by result I do overload my bike regulary, which would be nice to avoid

It the thinking above to simplistic? Is there some one in the forum how has more indept knowledge about this or maybe is there someone how has already worked on this.

Best regards,

Jan

[Crissa]

How about a switch so you can disable the OBD port if you're not using it?  The it still has the power all the time (potentially).

-Crissa

[UlsterZero]

I think Zero has probably added a second low power dc/dc converter just to provide the 12v pin on the European OBD socket.

I doubt they would leave the main converter enabled all the time, not least because it would mean they would need to add a relay and some additional electronics so that the lights and ABS module are active only when the bike is keyed on.  Given there is a second socket for this, it's probably a self contained unit that is just tapped into B+ and the existing lines going to the original socket, either in the factory, or maybe even in the Netherlands to ensure imported bikes comply with the EU homologation rules.

They may be using an inefficient dc/dc converter which would explain why the SOC drops so much quicker.  If it is a separate converter, it would be easy to check.  If the 12v supply is still present in the second OBD socket even when the main dc/dc converter is disconnected, there has to be an additional unit.

If anyone wants a permanent 12v feed, why not use something similar: small 3w or 10w PCB mounted dc/dc converters are available at relatively low price. Build one into a small case, fit an inline fuse just to be safe, tap into the B+ supply, and you'll have a constant 12v available for trackers or anything else you need...

Ulster Zero