My Experience with Victron

[JackConnick]

See screen shot. You can see the divot downwards where it went into float.

 

[SteveK]

Reviving an old thread...

I have a Multiplus II, with a BMV-712, 600amp Lifeline house bank. I've given up getting it to go into bulk mode and have to force Absorption by going into "Advanced/equalization/then interrupt/go to Absorption". Otherwise even if the batteries are at 58% it will quickly going Float.

Jack, you appear to have a 600 Ah LifePO4 battery bank. The images you included do not have the bank size entered or lithium checked. My immediate thought is that the charger defers to a default 400Ah bank lead bank.
I am going by what my Magnum manual says BTW.
Also you have 4 hour absorb which is for a 1300-1500 Ah bank

So it is unclear if you have correct settings entered for your battery bank to begin troubleshooting.

 

[JackConnick]

Sorry I wasn't clear: 600ah Lifeline AGM house bank. Yes 600ah is entered in the BMV settings. Magnum and Victron are sort of apples and oranges...

 

[ksanders]

See screen shot. You can see the divot downwards where it went into float.

So my only real challenge is the part I circled in your photo.

Other than that it appears that your unit is functioning as it is programmed.

You apply power, and current maxes out.

The voltage rises until it gets 14.3 volts then it holds there, reducing current.

When the absorbion to float timer expires the voltage drops to your float voltage.

Am I missing something???

 

[JackConnick]

Well, except the SOC is like -215amps. The inverter isn't seeing the actual battery voltage, just the charger voltage. I have it set to monitor the BMV.
Should I adjust the float voltage or the absorption timer?

 

[ksanders]

First calibrate your SOC, and make sure that the BMV accurately reflects the batteries you actually have.

Also set your BMV to auto go to 100% SOC after current drops below a prescribed current level. This will keep it calibrated.

Also any idea that your system shows immediately or rapidly in absorption mode doesn't matter...Except ...

The only thing Absorption mode does is reduce charge current to hold 14.30 volts. If your batteries are below this voltage then the charger will go to full output, just like in bulk mode, so again it doesn't really matter.

The Only thing that might matter is the timer that switches from absorption to float mode. If you want you could change that from 4 hours to even 8 hours. It won't hurt anything and will make sure your batteries are getting fully charged before switching to float mode

That would give you a viable workaround to the "my charger immediately goes into absorption mode" problem.

 

[JackConnick]

OK, those have been set, and the SOC was repeatedly zeroed out while on shore power for 48 hrs.
The issue is that the batteries are NOT being charged at a reasonable rate. Charging at 20 amps in float with -215 to go is not viable. When I force absorption it charges and ramps down correctly at around -120 or so. Same thing happens on shore power.

 

[ksanders]

Well, except the SOC is like -215amps. The inverter isn't seeing the actual battery voltage, just the charger voltage. I have it set to monitor the BMV.
Should I adjust the float voltage or the absorption timer?

Then just like i posted above, change the way the charger goes into float mode. This can be either current based, or time based. I would just up the time myself.

 

[dhays]

Well, except the SOC is like -215amps. The inverter isn't seeing the actual battery voltage, just the charger voltage. I have it set to monitor the BMV.
Should I adjust the float voltage or the absorption timer?

I missed what you are using as a SOC meter? When was the last time it was reset at 100%?

Last I looked (so it may be different now) Lifeline was recommending a float voltage of 13.2 - 13.4v. what do you have it set at now and what voltage is the battery currently at float?

If I recall Lifeline wants the constant voltage (absorb) stage to last until a very low tail current, somewhere around .5% of the ah capacity? You may not be able to set that with your charger so I would tend to increase the absorb timer until the tail charge gets to where you want it. However, if you have continued current draws tail current may not be a great measure to use?

Remember I am very ignorant....