Hi 2shae and Welcome
Take it at face value. The car is trying to warn you about the state of the battery. Get it checked by a battery supply shop or garage or check it yourself with a meter. How low does the voltage drop when cranking?
It's more likely that the car is being conservative in it's warning than that there is some fault.

 

Yeah, i know it is trying to notificate me. Uhmm yes i checked with voltmeter. When this error appears, battery voltage is 12v or 12.1V. When cranking it drops around 10.2- 10.5V.
How do you mean conservative?

 

Conservative in this case means that the car is being a little bit pessimistic.
It's telling you that your battery is dying before you need to book the funeral.
5 minutes listening to the radio....when a modern car is unlocked all sorts of electronics wake up and start drawing power, it is frightening how quickly a decent battery will drain once everything is awake.
And to be honest, if the crank voltage is dropping to as low as 10.2v, I'm surprised it is cranking at all.

 

Ok...thank you for that answers. How much should cranking voltage be?

 

I'd normally expect anything much below 11v to give problems.
But a lot depends on engine, starter, temperature, ie, it isn't a straight line graph.
In your case, get a battery load test done, I would be surprised if it showed good health and with winter on us, it will not get better.

 

Me? ................. I'd say the vehicle possibly has a "stop-start" or "eco" feature and the BMS while counting Coulombs (its job) has determined that the battery no longer is accepting charge at an acceptable rate ...............

Yes it will most likely still start the engine but you will also find the "stop-start" (if fitted) activating less frequently if at all

See

Check stop and start message | Independent Renault Forums

.................... and if you want to see ito pics the battery behaviour

Worth buying latest OBD2 for old Kangoo to monitor voltage level? * Sorted * | Independent Renault Forums

 

LVr car does not have start stop system.

 

ok - does this apply?

Disable energy saving mode on Renault Megane 3? (asacannes.com)

 

Maybe..now i have charged battery over night and voltmeter now shows 12.45V. If i crank it drops on around 10.5. I think my battery is dying. I have Fiamm battery which have online serial checkup...when i insert serial number from battery i can see date production. But dont know what does that mean. It says: Year: 5
Week: 49
Year 5? 2005 year is impossible as car is 2009 year.

 

If your battery is only showing 12.45V after being on charge all night then that indicates its not charging as it should. It should be 12.6V or slightly above.
Your cranking voltage of 10.5V is about average.
Like LvR said. The green indicator light on a battery only shows that that cell is healthy. There are 6 cells each 2.1V sounds like 1 or maybe more cells aren't holding a charge.

 

2015?

 

I dont know...i tought about that too. If this is right, then battery is produced on 2015 (year 5) and november 30 (week 49). But not sure. It also does have that "window" indicator which indicates condition of battery. It is green..so that means it is ok. Hhuumm..who knows.

 

But not sure. It also does have that "window" indicator which indicates condition of battery. It is green..so that means it is ok. Hhuumm..who knows.

That green indicator sits on exactly 1 cell out of 6 and can therefore only tell you something about that particular cell"s condition - if the chemistry in the water is correct and the indicator is green then THAT particular cell of the battery is probably still ok - absolutely nothing else to be said about any other cell on the battery based on the green indicator .................. I hate these things