erollii

My C300h Hybrid seems to work fine but the hybrid part seems to work mostly when accelerating when the car starts mostly of the time starts with engine and on traffics when not moving the car dosnt stop to save fuel, but otherwise all others work fine.
I searched and seems that the Auxiliary Battery is the main cause for this issue, I wanted to know how hard can such thing to replace my self and is the location same as a c300? or its on a different as I cant find anywhere anything that says soo.
And maybe just charging it coud that fix it or needs replacment at all?

stockbmw

Your car probably have different system. I would look into why the hybrid system isn't kicking in more, perhaps due to lack of charging. Is the car sitting in the garage more? To charge the hybrid battery, the car probably runs it's engine more. Is there was to charge the hybrid battery with external charger?

erollii

The hybrid battery is 60-80% charge mostly of the time I doubt thats it, no its not a plug in to use a external charger, I tried turning off AC and navi and stop and start the car and sometimes it goes up to 18km/h with hybrid but thats it on stop it dosnt start anymore with it.

stockbmw

What does 12v car battery reads? And how old is it?

On regular w205, eco start/stop isn't functional when the battery is under 80% and you already know about the aux capacitor.

So I am thinking similar principal applies to the hybrid, because yours is usually at 60-80%, eco start stop not kicking in.

Do you remember what the hybrid battery level was usually at when the car was brand new?

UKEngineered

I take it you’re in “C” comfort or “E” eco, as the independent hybrid drive doesn’t work in “S” or “S+”.

In my preferred “C”, it starts and runs up to about 15mph (on light throttle) before the diesel engine starts or cuts in. The exception is ambient temperature extremes when either high A/C or heat in the cabin is required. Otherwise, pressing the start button, you get the green “ready” light and off you go, on electric motor.

erollii

The charge is 60-80% stays but I doub thats teh case as the main use of hybrid battery is to start/stop with it not just for acceleration idk what the 12v car battery reads

erollii

Yes in both C and E same case

stockbmw

I would start with cheapest repair first. Diagnostic fee, new 12v battery, aux capacitor (doubt your car would have this because it has hybrid battery). Look into charging system like the alternator and DC converter/charger for hybrid battery. I would think that won't be cheap replacing the hybrid battery or it's charging system. I didn't include starter because you never mentioned you had problem starting up in the morning.