Smart Lithium very low voltage recovery questions

DIY
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1

Greetings all.

I have an all-Victron electrical system in my van configured with:

  1. 2 x 12V Smart Lithium 200Ah connected in parallel
  2. Lynx Smart BMS
  3. Smart Battery Protect connected to ATD output of Lynx
  4. MultiPlus 2000
  5. Cerbo GX

I recently had my van serviced and although the technician shut off the main battery switch, the batteries dropped below their ATD voltage. At the point the battery protect relay must have disconnected. However, there appears to be some parasitic drain in the system because when I went to pick up the van the voltage on the lithiums was down to 5.6V.

I disconnected the battery cabling and connected a power supply to the terminals of the first battery, set for constant current charging at 0.1A. Over the course of a few hours the battery rose to 10V, with a variation between the cells of only 0.06V. I will now do the same to the second battery.

So far, so good. However, in looking ahead to the next steps in section 6.1.5 (“Battery very low terminal voltage”) of the battery manual, I am wondering how best to proceed:

The manual says to increase the charge current to 20A (0.1C) at 13.8V. Can I do this using the MultiPlus and Lynx that are currently in place? The MultiPlus’s bulk charging voltage is 14.2V, but I should be able to adjust this — and the max charge current — using Victron Connect. If I do so, will the BMS in the Lynx properly manage disconnecting the charger as need for cell balancing? The Lynx manual says that its charge profile is not configurable, so I’m not clear on whether it will somehow interfere with the charging/balancing process. (I assume I also need to reconfigure the Lynx’s bank capacity setting since I will only be charging one battery at a time.)

Thanks in advance for your advice.

2

Yes, you can change the charging current inside the Multi on the charger tab in VictronConnect or VEConfigure. Connect your batteries as normal, once you have “revived” them, and charge away.

3

Thanks, @OGPS .

I realized after updating the GX firmware that I could set the parameters I needed (voltage and current limits) using DVCC.

It looks like the first battery fully charged and I am now working on the second.

The only odd thing I found is that steps 11 and 12 in the instructions seemed to be reversed. They suggest that the voltage increase from 13.8 to 14.2 volts will take a long time. In my case, the increase from 13.1 to 13.8 volts (with DVCC set to 13.8V maximum) took most of the day, but when I upped the charging voltage to 14.2V and the charge current to 0.5C (per step 11), the batteries climbed to the absorption voltage very quickly (i.e., within a minute) before dropping down to the float.

I’m not sure if this means anything about the state of the batteries post-deep discharge, but the first battery has been disconnected for a few hours and is sitting at 13.45V with cell imbalance of only 0.01V.