Murphy’s Law with my OBD2 reader

[tom66]

Yesterday my hybrid Golf GTE flagged an error.  This car is a bastion of reliability, mostly due to the Germans -- sorry that was sarcastic.  It is throwing up a warning about the 12V battery needing service.

I checked the battery with my diagnostics dongle and it reports 12Ah usable capacity out of 44Ah total.  And the voltage drops to 11.67V without any load.  About 14.5V while charging.  (So perhaps I shouldn't be so quick to blame the Germans.  The battery is made in Spain.)

It seems to be an ordinary flooded lead acid battery so, I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur?

Car still runs and drives fine and no other obvious errors are present but I did get one occasion at a roundabout where I pushed the 'go' pedal and the car took about 2 seconds to select the gear.  I know the dual clutch gearboxes in these cars do depend on the 12V at significant current to actuate properly so I wonder if that was a sign.

I wonder if EV batteries wear a bit quicker because they don't get starter cycles like a regular car.  Certainly Tesla had a lot of problems with their earlier 12V systems.  It might just be a limitation of lead acid batteries used here and a reason more manufacturers are using LiFePO4 or Li-Ion for the 12V system.

[sokoloff]

If it's over 4 years old and measuring that low, I'd replace it without any further diagnostics.

When a gasoline car is "running" (which is ambiguous/complicated for a hybrid), the battery shouldn't have much effect on current supply for low voltage systems. With a hybrid, I can't draw as firm a conclusion, other than "well, I guess you'll find out when you replace the battery".

[PlainName]

I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur?

Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather.

[AVGresponding]

I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur?

Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather.

Presumably because it's an EV...

[tom66]

I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur?

Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather.

I think I'm agreed, it needs to be replaced.   That said, all the 12V on these cars has to do is get the contactors to actuate in the main battery pack, then the DC-DC runs everything from that for normal use.  In that sense, you can probably 'start' the car on as little as 10V across the battery... it only needs to supply about 10A (computer power, contactors, etc.) for a few seconds.

[PlainName]

I think that does indicate it is bad (5% state of charge according to a graph I found) - would others concur?

Scrap it. It will let you down when you least need to be let down. If the car is reporting it as problematic then it's really buggered and I'm surprised you haven't had to jump start your car in the recent cold weather.

Presumably because it's an EV...

Ah! I missed that bit - fixated on the normal  one this thread is about

Edit: no, the GTE is a proper car, not an EV.

[tom66]

Edit: no, the GTE is a proper car, not an EV.

It may have a 'proper engine', but it lacks a starter, alternator and a starter battery and has much more in common with an EV than an ICE.  It has a high-voltage battery (350V lithium-ion, 8.9kWh), motor-generator (80kW rated) and clutch packs which allow the electric motor to start the engine and use the engine as a generator when needed.  The 12V battery is only 44Ah and rated for 200A CCA, which would be more appropriate in a 1.0L city car if it did need to start anything.

Fun benefit of this is I know someone with a GTE in Norway, who started his car in -25C weather.  It doesn't even blink - the engine starts absolutely immediately because the electric motor can put 10kW into the crankshaft to get it up to operating speed pronto (though I hope the oil works well when it does this.)

[PlainName]

OK, so holding on to being a proper car by the tips of its finge sparkplugs. I won't ask if it has a trout pout.

Can it start from the EV battery?

[tom66]

OK, so holding on to being a proper car by the tips of its finge sparkplugs. I won't ask if it has a trout pout.

Can it start from the EV battery?

It *only* starts the engine from the EV battery.  If you mean can it drive on the EV battery, yes, it can do so for about 20-25 miles before that tiny battery is exhausted.  (Only about 60% of the battery is usable capacity.  The rest is reserved, probably for those -25C engine starts after sitting for months on end kind of scenarios.)

Edit: Actually, sometimes starting the engine is more complicated.  Since it is a parallel hybrid, the engine and motor are connected together, with a clutch separating the engine for when it is not needed (coasting, regen, pure-EV mode, etc.)  Starting the car while stopped entails having the gearbox into a virtual 'neutral' with both clutches disengaged, turning the motor to the required speed and pulling in the engine clutch then adding fuel and spark.  All happens very quickly and with very little bother.  While moving, it is a bit more challenging, because you can't stop driving the wheels (parallel hybrid = only one motor, unlike a Prius which has two, or a Volt/Ampera where the engine and wheels are often not connected at all.)  So, the electric motor adds in a small amount of torque and a precise balancing act between the clutch pulling in the engine and the electric motor adding the torque in is performed over the course of about 500ms.  This again happens very seamlessly, and besides under hard acceleration, you don't notice the engine starting and providing torque.  It happens all the time when doing lower speed driving on the engine when the computer determines which powertrain is best to use.   Once the engine is running, the motor switches to a generator (usually, just to provide enough energy to keep the hybrid battery from discharging - it runs the air con, 12V, etc.) or blends in extra torque as needed to map in little troughs on the power/efficiency map. 

[james_s]

It may have a 'proper engine', but it lacks a starter, alternator and a starter battery and has much more in common with an EV than an ICE.  It has a high-voltage battery (350V lithium-ion, 8.9kWh), motor-generator (80kW rated) and clutch packs which allow the electric motor to start the engine and use the engine as a generator when needed.  The 12V battery is only 44Ah and rated for 200A CCA, which would be more appropriate in a 1.0L city car if it did need to start anything.

Fun benefit of this is I know someone with a GTE in Norway, who started his car in -25C weather.  It doesn't even blink - the engine starts absolutely immediately because the electric motor can put 10kW into the crankshaft to get it up to operating speed pronto (though I hope the oil works well when it does this.)

It's a hybrid, this is a distinctly separate category from either conventional or EV. It has pretty much all of the components of both, about the only thing missing is the separate starter motor and alternator since it uses a motor-generator for that. The "plug in" aspect just means it has a charger tacked on that allows charging the traction battery from the grid. Overall I would argue that a hybrid is closer to a conventional ICE vehicle than to a BEV, although it is a spectrum. The electric propulsion is only active at parking lot speeds, once you reach a certain speed the ICE fires up and it drives much like a conventional car.

[tom66]

It's a hybrid, this is a distinctly separate category from either conventional or EV. It has pretty much all of the components of both, about the only thing missing is the separate starter motor and alternator since it uses a motor-generator for that. The "plug in" aspect just means it has a charger tacked on that allows charging the tranction battery from the grid. Overall I would argue that a hybrid is closer to a conventional ICE vehicle than to a BEV, although it is a spectrum. The electric propulsion is only active at parking lot speeds, once you reach a certain speed the ICE fires up and it drives much like a conventional car.

Just going to have to disagree here, because it can drive for 20 or more miles on electricity alone, and if you keep your driving within that range, you can 'never' use the petrol. 

So it's like a short range EV coupled to a petrol range extender that drives the wheels directly.  The actual hybrid function of it is limited to regen braking and a small amount of map optimisation (unlike something like a Prius which can run the engine at a nearly completely independent speed to the wheels, with its e-CVT design.)  The EV powertrain is very similar to the 1st generation e-Golf, the motor is different as it sits in the gearbox but is broadly a similar output power, and the battery pack uses cells from the e-Golf with additional cooling due to the higher C rates.   The biggest difference between the PHEV and the EV besides the obvious engine is that the electric motor drives a 6-speed auto gearbox, just like the engine, which makes it one of the few electric cars that shifts gears (it does this even in electric mode.)

Anyway, whilst the car is technically interesting, I'm more interested in whether my 12V battery is dead.

[TomKatt]

If it's over 4 years old and measuring that low, I'd replace it without any further diagnostics.

When a gasoline car is "running" (which is ambiguous/complicated for a hybrid), the battery shouldn't have much effect on current supply for low voltage systems.

The average life of modern car batteries is 3-5 years.  Modern batteries tend to be smaller for weight savings and also modern charging systems are a lot more complicated than they used to be - most modern cars use "intelligent" charging to limit charging under engine load situations (fuel economy again).  While it used to be a car would run without a battery once started, I'm not so sure that is the case for every design these days.  My 2009 CRV had a current sensor at the main junction box that monitored current consumption and would limit charging unless voltage was extremely low.

Point being - if the battery is over 4 years old and you're having trouble, it's wise to simply replace it.

As for OBD2 issues, the P0341 on Honda indicates trouble with the VTC variable timing control.  Though the code suggestion the sensor, more often the sensor is fine but is reporting trouble caused by either a stretched timing chain or some component of the VTEC system.  You mention low oil - that can be a killer to timing chains that causes them to stretch just enough to effect the timing.  It could also be why you feel the car is "sluggish".  Unfortunately, this can be a complicated diagnoses and you have to go through all the variables (timing chain, VTEC oil pressure valve etc) and eliminate them one at a time until you identify the culprit.

edit - if you get bored and want to watch some interesting auto repair diagnoses videos, check out Ivan at Pine Hollow Auto Diagnoses...  While not "how to" videos, watching him go through troubleshooting steps is very educational, and he does a lot with OBD and oscopes.  I'm pretty impressed by the Pico USB scope he uses.

https://www.youtube.com/c/PineHollowAutoDiagnostics