Came back from vacation about three weeks ago and my battery was flat. Charged it up and haven't had an obvious problem since then.

But, today, when reading my dead-ACD/AYC-pump codes with an AccessPort, we also found both of the low-voltage codes: C2100 and B210D. The second of these would instantly come back when cleared.

The car's voltage when off is about 11.5. (When running, it's 14.0 or so.)

I'm sorry to say that I did not test whether that code would instantly come back when the car is running (and the guy with the AccessPort is a distance away, so please don't ask me to try this [unless it's crucial]).

My question is whether the battery did not come back after I charged it. What voltage should I have when the car isn't running?

 

oddly enough, I have a voltmeter in my trunk for some reason, lemme go check and I'll reply via my mobile phone!

give it a second tho....it's coming back from SPACE

 

12.6

 

Thanks. The FSM says that warning don't kick in until 9 volts. This is weird.

 

Just tested out of curiosity, 12.7 here - stock Panasonic. Have someone monitor the vDrop when you turn the ignition key to the ON position and then when you fire it up. The battery could be on its way out.

 

Drops to 10.1 when cranking and then, bang, straight to 14.3 as soon as the alternator starts doing its thing.

 

Hmm, maybe it gets into the 9.9v range and causes a code? The alternator is doing its thing so only the cranking condition could cause enough of a vDrop for the ECU to be concerned. 5 years on the stock battery is not ideal but not bad at all either.

 

Just had the dealership check a B210D code for me...registered 11.7 volts when it tripped the code. SRS system is extremely sensitive when it comes to voltage regulation. Battery tested good and they wrote it off as a fluke.

My guess, if your system is dropping to that low of a voltage and only spikes back up once the vehicle is running...then your probably looking at a bad battery, having such extreme discharge prior to cranking the vehicle might suggest a bad cell...swap out the battery and within 3 cycles of the ignition (running and shutting down) the on bord diagnostics will erase the faults on its own...it will be stored in a memory bank (factory settings allow the fault code to be held under a temporary file to track vehicle health for things such as warranty claims)...but a simple CAN compatible system can overwrite and clear those temporary files.

Replace and continue to remain worry free my friend...

 

Yea sounds like the battery is on its way out you could always tale it to your nearest autoparts store i know the test batteries at no cost

 

Thanks! That's exactly the information I needed.

As to owning an Evo X ever being worry-free, your experience varies from mine.