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BAT Volts drops, reason ?

Posted: Sun Jun 30, 2013 5:49 am
by alollini
It happened while i was data logging, so i can see it on a graph.

I understand the battery normal voltage is 13.6 V to 14V

I see it dropping to 12.2 V @ 6900 rpm then it stays low for one minute of open driving / WOT at various rpm.

During that minute, here is what i had :
1- a "limiter like" feeling around 6800 - 7000 rpm.
2- an orange error, and message on the dash with a picture of a battery "check system" on the whole minute.

and then it returned back to normal.

i don't see an error code.

Re: BAT Volts drops, reason ?

Posted: Mon Jul 01, 2013 9:39 am
by Spunkster
Do you have the calibration and any datalogs showing this voltage drop?

Re: BAT Volts drops, reason ?

Posted: Mon Jul 01, 2013 9:49 am
by alollini
yes i have those.

I read the manuals all week-end and came to a conclusion.

the I.P.U. stops working @ 6200 rpm.

above that the car is on battery (like a normal car with alternator removed ie : a F1 )

the dashboard don't like that.

if the over rev is short ( from 1st to 2nd for example) then it doesn't register.

if it is longer (pushing 2nd) then it red light battery and gives a "check battery system" in orange on the dash.

this cut off the hybrid system for 20 - 30 seconds.

then everything goes back to normal, and NO DTC code is stored.

i would like to explain to my IPU that it is ok to go higher rev. too bad.

i know IMA motor is tested up to 11 k rpm.
and with my camshaft and better valve springs, everything should run fine up to 7400 rpm (and it actually does)

Re: BAT Volts drops, reason ?

Posted: Mon Jul 01, 2013 9:52 am
by alollini
i'll post the log when i'm online with my pc.

Re: BAT Volts drops, reason ?

Posted: Mon Jul 01, 2013 10:55 pm
by alollini
this datalog shows a lot of up and down in the voltage.

maybe that is not only at high rpm, but longer lasting acceleration.

on this specific data i got the red light only once (the light did not came on for each drop in voltage)

Re: BAT Volts drops, reason ?

Posted: Tue Jul 02, 2013 9:15 am
by Hondata
The battery voltage is normal for the CRZ (& 2012 Civic).

The vehicle will run between 12 & 14V depending on battery charge state, temperature, electrical load & engine speed. The reasoning is to save fuel by using less alternator load.

For tuning on the 2012 Civic we normally find that switching on the headlights makes the alternator run 14V, but I have not tried this with the CRZ.

Re: BAT Volts drops, reason ?

Posted: Tue Jul 02, 2013 10:13 am
by alollini
So you don't understand why i have the red light and "check battery" with no IMA assist or charge for 30 seconds ?

I did another datalog with staying below 6000 rpm and the voltage is variable too but within the limits.

I did not had the red battery light problem this time.

to trigger the red light, I just have to go above 6800, one or 2 seconds are enough.

Re: BAT Volts drops, reason ?

Posted: Mon Jul 08, 2013 5:00 am
by alollini
I think i have something new :

Japan 2010 CR-Z has redline at 6800.
EU and USA models redline at 6500 in all gears except 1st wich redlines at 6250.

EU model stops IMA assist/regen at 6200 rpm.

Maybe when the car goes above 6800 it is understood as as OVER-REV by some part ( maybe IPU )

staying away from 6800 I managed to drive without any problem for hours.


I triggered the problem again and noticed a few things, while red light "check bat" is on :
1- limier is temporarily set to 6200.
2- IMA assist/regen is temporarily OFF.

everything goes back to normal after 20 or 25 seconds.

Re: BAT Volts drops, reason ?

Posted: Mon Jul 08, 2013 4:35 pm
by Spunkster
Does it continue to do this if you return the ECU to stock?

Re: BAT Volts drops, reason ?

Posted: Tue Jul 09, 2013 2:35 am
by alollini
If the ecu is stock and i datalog, i see the volts fluctuate, but never any arror.
While the car auto stop at street lights, sometimes is shows 14V, and sometimes it shows 12.5 V.
Tpedal fully depressed seem to always register below 12.7 V, while every other situations register above 13.6 V

However in stock state there is no way i can go above the limiter wich is set @ 6500 rpm,
and 6250 in 1st gear.

(as stated above by Hondata the Volts dropping to 12,5 V from time to time seem to be a normal behavior of those car models)

Have you ever encountered electrical issues directly linked to higher revs ?

Re: BAT Volts drops, reason ?

Posted: Tue Jul 09, 2013 11:06 am
by Spunkster
We have not actually seen anyone reving beyond the stock rev limit.

Re: BAT Volts drops, reason ?

Posted: Wed Jul 10, 2013 1:32 am
by alollini
Ok, I'll make a try with headlights on, see how the voltage goes.

Re: BAT Volts drops, reason ?

Posted: Thu Jul 11, 2013 4:19 am
by alollini
Headlights on seem to make the BAT voltage 13,6 - 14 V without falling.

I did not have the road to rev up to test yet.

Re: BAT Volts drops, reason ?

Posted: Thu Jul 11, 2013 10:41 am
by alollini
Yes!

with headlights on = no problem.

I tested above 7000 rpm , and I had no light on the dashboard and the BAT volts graph is stable !

Re: BAT Volts drops, reason ?

Posted: Sun Jul 14, 2013 11:54 am
by alollini
No.

Problem is still there and with headlights on.
I now think it is not related to the battery but rather to the hybrid system, maybe higher revs upset it.

I have a big datalog, this time when the red light came on it stayed on for several minutes. During this time the hybrid system was asleep (no assist/regen). => i can upload it if you want.

I read the manual and it is strange, because IF the IMA system were upset, it would show an IMA warning message, NOT a battery message.

I lowered the rev limiter for now. 7400 =>7300, first step I will continue to lower it until problem disappear.

The car runs very smoothly otherwise.