question

Immediate absorption may be indicated by:

1) excessive voltage drop - poor connections, thin wire, etc. Worth checking ALL your connections for proper torque.

2) 400A @ 14.3V is going to have substantial voltage drop unless you're using massive cables. That's why you're seeing only 400A initially and why it drops quickly.

Your statement:

"Lifeline batteries are designed to take max charge up to end of absorption mode, it's bad for them not to do this." is very very false. Absorption is by definition a constant voltage charge. As they fill, current must be reduced to maintain the absorption voltage. They even indicate that charging is complete when current drops to 0.005C or 9A in your case:

https://www.batterystuff.com/files/805-lifeline_tech_manual.pdf

I trust you have absorption set to 14.3V and float set to 13.3V, and you're using temperature compensation.

Do you have the BMV properly configured to sync at 13.1V?

Snoobler, thank you for your help.

I have just been talking with the installers and they have noticed different settings within the BMWs. This has now been changed and hopefully on next full charged they will show same %,

they are looking into how to check the BMW synch at 13.1.

I didn't explain myself properly about max charge, I understand that the voltage drops until 0.5% and then drops to float. But i think that this is not monitored but done on a time basis by Victron even though the voltage drops.

Maybe the quattros are getting a little warm, they have now been charging for 20 mins and they have dropped from 412Amps to 356Amps input. The case seems constant at 35C and the other at 38C

It could be good to see if one could monitor the quattro temp and see if this changes their output

You may need to extend the absorption period to ensure the batteries are getting fully charged. If the inverters never drop to float at the appropriate time, the sync criteria are not being met.

Charging 12V at such high currents may pose a significant challenge in getting the BMV to sync properly.

If the Quattros are in absorption mode, then that means they are seeing 14.3V at their terminals in response to their charge currents. If they are below 14.3V and still in absorption, they are throttling the charge current for a different reason - possibly temperature.

Do you have a GX device in the system? Are you sharing one of the BMV voltages systemwide?

yes I have a GX and the installers are monitoring the system thru the portal.

They made some changes and the after a full charge the BMVs are reading within 1% of each other.

Success.

I will try and increase the air flow around the quattro's. one is running hotter than the other, 35C & 38C.

Once again thank you for your help, it's been a frustrating couple of months but things seem to be getting sorted.

@snoobler

With the GX, are you using one of the BMV as a shared voltage sense?

Sorry not to have answered before.

There are 3 BMVs, one for each bank and one that is labelled as master and reports on the 2 banks together.

The yard where she is now, are telling me that if I have 2 quattros charging 2 banks that are linked together to be used as one, which is how it is being used now then one quattro should be set up as a slave to the other and if not this could cause problems.

@snoobler

If the Quattros are using the BMV reported voltage, then they shouldn't have an issue with voltage drop, so that would set aside my earlier suspicion.

If they're running in parallel providing the same AC output, then they are already configured as "master/slave."

If you're using VRM, can you post the voltage/current plots reported from the "master" BMV like this:

Zoom in as you can to focus on just a single charge.

The boat is on the hard and I cannot access the VRM. I will try and get the yard to check the wifi and see if i can get the info. Otherwise it will have to wait until later in the year.

Are you by any chance in the UK on the phone?

@snoobler