Charging state changes

[AJMike]

I noticed today that the Victron dc-dc charger was in Absorbtion state, charging the Lithium batteries very slowly, in spite of the fact that the batteries were only at about 80% SOC. I don’t know why it was not in Bulk charge state.

What determines the proper charge state? Battery voltage? SOC? Something else? As far as I know the charger setting are correct for BB batteries. Absorbtion voltage = 14.6, Float voltage = 13.6. Don’t know the proper setting for Bulk Time Limit. And don’t know if that is important.

 

[DavidEM]

Measure the voltage. If the DC to DC charger is in absorption mode and you have set it at 14.6 volts and it is charging slowly and the voltage is significantly below 14.6, then there is almost certainly something wrong with the Victron unit.

But if the voltage is about 14.6 then how do you know the batteries are at 80% SOC. Maybe they are closer to 100% and the charging rate has dropped off as it should.

David

 

[AJMike]

Measure the voltage. If the DC to DC charger is in absorption mode and you have set it at 14.6 volts and it is charging slowly and the voltage is significantly below 14.6, then there is almost certainly something wrong with the Victron unit.

But if the voltage is about 14.6 then how do you know the batteries are at 80% SOC. Maybe they are closer to 100% and the charging rate has dropped off as it should.

David

As for the SOC figure, that comes from the Victron battery monitor.

As for checking the battery voltage, does that require me to disconnect from the solar input? And/or letting the battery get to rest state?

 

[DavidEM]

As for the SOC figure, that comes from the Victron battery monitor.

SOC could be off due to the battery capacity you inputted being off from actual. Also not sure if Victron does this but many do- it resets the capacity value once charging amperage drops to some low value, ie a couple of amps.

As for checking the battery voltage, does that require me to disconnect from the solar input? And/or letting the battery get to rest state?

My knowledge of this issue comes from lead acid but maybe LFP's work the same. So measure the battery voltage while charging and then disconnect solar input and wait an hour to check again. If the charging current was low, it won't change much.

David

 

[AJMike]

I got this all worked out and it turned out that somehow (and I still don’t know how) the settings on the Victron 12/12/30 charger got set back to its default values. When I saw what had happened I set them back for BB Lithium and now everything is working properly.

I have no idea how the Victron app got its settings so messed up but I will have to keep an eye on that in the future.

Thanks for your help.

 

[Winterbagoal]

Has the Victron app (assume it's on your phone?) auto-updated recently?

 

[AJMike]

Interesting question. I don’t know but will check.

 

[imnprsd]

AJMike: I presume you have shore power and are using your RV?

If this is the case, then your Victron charger has already fully charged your house batteries, and now you are using your converter to power just the lights and other 12V systems in your RV. Likewise, the Victron charger is replenishing your power draw (times charger efficiency).

So I was wondering if you can take a 3 or 4 or 5 day power "snap shot" and let us know how many amp-hours your Victron charger pumps into your house batteries?

This will give you/us an average power consumption/day for just your 12V system... and I would be curious to know what that amp usage is?

I did this last summer when I was staying in my RV and I was surprised to find out that I was using ~91 AH/Day. (See attached picture.)

I would also describe my energy use as "high"... meaning I used 2 fluorescent lights on in the kitchen and TV-room all day and part of the night; and in the evening I would use the 12V vanity bulbs (not led) and my shower lights and my bedroom light normally.

It's just me in the RV too, but since I had shore power I was not thinking "green" like I would be if I was boondocking. I was also in my RV when it was warm so I was not using the Suburban heater fan.

So if you do post a 3-5 day "snapshot" of your Victron charger, please tell us what loads you used (in general terms) or just let us know if you think your power consumption was "light" or "average" or "high?"

 

[AJMike]

AJMike: I presume you have shore power and are using your RV?

No. We almost always either dry camp or boondocks so we rarely have shore power.

 

[AJMike]

Well, it has happened again so now I am beginning to wonder what is going on with the Victron app on the iPhone. Driving back from Yuma I noticed that the Victron app showed that the Lithium batteries were at about 80% SOC and in Float mode. Float mode???

When I set up the options for the Victron DC-DC charger I created a Battle Born preset with the values BB gave me for their batteries but thought I might change one of the minor values from Automatic to manual, changed my mind and set it back and resaved the preset. As it turned out the app did not over-write the existing preset but created a second preset with the same name and the exact same values. I tried to delete the second preset but could not find any way to do that and, as it turned out, I am glad that I could not delete the second preset.

When I noticed that the charge state was Float I opened the preset selection and selected the other Battle Born preset and, when I did so, the change state changed from Float to Bulk. Again, both presets are identical but the change state changed from Float to Bulk just by selecting the second preset. Apparently the charger had somehow gotten its settings mixed up and the change of preset values must have reset the charger to the correct values. Don't know how, don't know why, but that is what I saw.