question

frankdg avatar image
frankdg asked

IP22 absorption-modus

Hi,

We did a test with my MPP100/30 and the current remains stable until the end of the absorption-time. The SoC of my 180A Lifepo4 will always reach the 100%. My 180A Lifepo4 battery is from CS batteries in Germany. This LFP is equipped with Prismatic cells. We did the same test with my IP22 set on Li-ion. Before we started the SoC was 80%. Once the IP22 was in absorption-modus the current was dropping down (what is normal). But, we discovered that de current was going even to zero for a few seconds and than it will comes again. For so far has I now is that the absorption current may never go "out"...? Also the SoC came not back to 100%. Is a SoC from 100% so important?...No....but we did a test to see of the IP22 has the same algorithm than my MPPT100/30.. Further....on the IP22 the setting for lithium is market has "Li-ion" My battery is a Lifepo4....Could that be the reason that the IP22 do not have te samen algorithm like the MPPT ?

I cannot believe that a Victron use another algorithm in his IP22 chargers than they use in the Victron MPPT's

Is a IP22 not compatible for Lifepo4 battery's ?

I will "think" no but...what is than the difference between both chargers?

To do a second test with the IP22 I will first modify (only) de "maintenance" current down to 12,8v (lower is not be possible) and I will set the tail-current to 0,8 only, to see what the IP22 will do with this settings.


battery charging
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

2 Answers
johanndo avatar image
johanndo answered ·

Would be helpful to actually provide the voltage settings for absorption and float and not referring to SOC, as the SOC is something defined by the user settings in the battery monitor for synchronization and not carved in stone. Also your SOC from your BMS has the same flaws and needs the same syncing to be somewhat trustworthy.

Your LiFePO4 cell is really 100% full only when it hits 3.65V and the charge current is less than 2% of the nominal capacity. If you set your Absorption to 14.4V you would stop charging maybe at 98% on a balanced battery (3.6V), unbalanced batteries may trigger full / over voltage protection alfeady at 13.8V if one cell runs off. It means only this cell is full, but you don't have the full capacity of your battery.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

frankdg avatar image
frankdg answered ·

Hi all,

A good friend of me has a lot of knowledge about electronics

So, he modified my text from yesterday here above.

Maybe it will more clear in what we saw during the charging-test between my MPPT100/30 and my IP22 charger

This text here below is what my friend discovered during the test

"When I charge my CS LiFePo4 battery with the Victron SmartMppt 100/30 the current drops gradually during the absorption phase until the float phase starts. The battery always reaches 100% SoC. If the same battery is charged with the IP22, the current also drops during the absorption phase, but after a while the current drops to zero and back up. And so it goes on all the time until the float phase starts. This phenomenon does not happen when loading with the Mppt ! The battery never comes to 100% SoC with the IP22 and with the same settings of the Victron Smartshunt."

Best regards

Frank & Patrick


1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

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

fred111 avatar image fred111 commented ·

Do you have the same settings on both chargers, same absorption voltage, same float/storage voltage, lifepo4 should have a fixed absorption time.

If those settings are the same then have a look at the smart shunt, set the the charged voltage about 0.1v below your absorption voltage. Taile current you can have around 4 % and charged detectiontime to something like 5 minutes and it should go to 100% after every charge cycle.

I also use a mppt and ip22, yes the ip22 dose go a little up and down with the current to maintain a fixed voltage but still works fine. Probably the mppt have som faster electronics inside.

0 Likes 0 ·