bunzeyda avatar image
bunzeyda asked

Multiplus Bulk Charge with Lifeline AGM Batteries

I've just installed 2x Multiplus 3KW/12V inverters together with the BMV-712 and cerbo GX and further installed a new set of 6x8D Lifeline AGM 12V batteries. The system is setup in the adaptive + battery safe mode with all the Lifeline recommended settings for float and absorption voltages.

My observations/questions are that:

1) for low depth of discharge the Multi's never go to absorption mode as is indicated by BMV charting. Documentation says Absorption should be 20X bulk time. If bulk is really short, say 30 secs, that would still imply 10 minutes in Absorption. But that doesn't occur. In fact, it is hard to say that "bulk" has occurred because the BMV charting suggests absorption voltage, 14.4V, is never reached. It stops at float. Is this normal?

2) is it true that the Multi's wont go to bulk mode unless the battery voltage drops to float -1.3V? For the Lifeline batteries that would be 12V which would be > 50% Depth of Discharge per the Lifeline tech manual. Therefore, over time and per Lifeline tech manual, would suggest a degradation in battery life. Is there a way to set this up that doesn't require power cycling the Multi's to get them to go to bulk and doesn't exceed the settings suggested by Lifeline (i.e. raising the float voltage)?

Multiplus-IIcerbo gxbattery chargingBMV Battery Monitorbatterylife
1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

bunzeyda avatar image bunzeyda commented ·
Anyone have any input on these questions?
0 Likes 0 ·
1 Answer
kevgermany avatar image
kevgermany answered ·

With small discharge, the multi stays in float.

Adaptive absorption calculates how long is needed. It depends on depth of discharge.

Your system seems to be working correctly.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.