question: what should it be? 13.1 to 13.5V? Something else?

my Ctek is claiming the AGM is "orange" status but I'm getting this voltage... and i'm wondering if the Ctek is wrong or if there's a charging issue.

thanks!

12,8 - 12,9V

This is for the most of the time. Sometimes it can be lower, as the alternator is not keeping the voltage at highest. Sometimes it can drop to 12,5 and only then the alternator will give a full job.

Edited 6 August, 20256 Aug by linni

37 minutes ago, brettikivi said:

question: what should it be? 13.1 to 13.5V? Something else?

Because of the Battery Management System there is no one answer to that.

Just after starting the BMS will tell the alternator to produce typically 14-14.5V to top up the battery after starting, if you turn off the engine soon after starting the rest voltage could be over 14V.

But when driving once the battery has been topped up the alternator could only be producing 12-12.5V, so again after turning off the rest voltage could be as low as 12V.

Alternator can produce anywhere from 12ish to 14,8V (personal experience).

But AGM is considered to be completely charged at 12,8V

'At Rest' voltage measurement is only accurate if care is taken to ensure all control modules have fully shut down and entered sleep mode - this can take longer than 10 to 20 mins after all doors are closed and vehicle is locked.

42 minutes ago, Warrior193 said:

'At Rest' voltage measurement is only accurate if care is taken to ensure all control modules have fully shut down and entered sleep mode - this can take longer than 10 to 20 mins after all doors are closed and vehicle is locked.

Correct. I have aftermarket Webasto installed. I had problems with rechanged battery about half a year ago (solved), so I tend to monitor the situation from time to time. Webasto app shows charging voltage as well as the resting voltage. Usually I have 12,8 in the mornings.

12,8V is considered to be 100% of the charge level for AGM.

Edited 6 August, 20256 Aug by linni

ok, thanks, that makes sense. The car hasn't moved but doors have been open - battery measures 12,8 across its terminals with no apparent load. Ctek still says not full, though, which i find strange.

Anyway, it's been on charge for several hours this week and I'm happy to take it out on Friday.