I have a Victron Lithium 12.8V 200ah Smart battery in my camper van. This battery powers lights, fridge, water pump and outlets. I purchased the van prebuilt and have been learning more about the system. The battery is charged by a Victron Orion and Solar MPPT. Solid system however there is no BMS included (not great I realize).
Why Victron doesn’t include an integrated BMS in a ‘Smart Battery’ is beyond me but that’s beside the point. So, this battery has been discharged to a low voltage probably about 4-5 times in it’s life. The lowest it’s gone is low to mid 9V say probably 9.2V at it’s lowest.
When this has happened the battery has simply been recharged with the engine running and the Orion doing its thing. Victron Connect app shows that cell voltage is balanced and the battery appears to operating normally, albeit perhaps with a little less capacity than it previously had. Visibly the battery has no signs of distress, no battery case swelling, no corrosion on the terminals.
After reading more into this topic, these levels of discharge can cause battery damage that could potentially create unsafe operating conditions. So, my question is, is there a way to tell if this battery has been damaged to the point that it is unsafe?
It is not possible to tell if the battery is OK or not with any certainty. If the discharges have been no lower than 9.2V with balanced cells and recharge happened quickly you may be OK. However, deeply discharging a lithium battery may involve for example 3 cells at 2.6V and one at 1.4V, 3 cells may be OK but the fourth is damaged.
Why do Victron sell batteries without a BMS, because they use an external BMS which is better for larger systems. They do sell a range of batteries with a built in BMS for your type of install.
I suggest you look into the Small BMS (not the NG version) and a Battery Protect to shut down loads and the chargers. That will then give you a safe install.
Lithium batteries (LiFePO4) which normally operate around 3.3V per cell are safe to discharge to 2.5V per cell, though this does (slightly) reduce the battery life. Discharge below 2.5V per cell is not recommended, but it is safe to recharge from this (2 - 2.5V) voltage. Cells discharged below 2V should not be recharged.
Over discharge normally results in rapid deterioration of the cell, more so than overcharging.
Thank you for your response. The Victron Connect app does appear to show all cells functionally normally and are balanced. I will monitor the voltages to see if one cell is deteriorating quicker than the others.
In terms of this system, do you have a reccomendation for an external BMS product? I am thinking the Victron Ve.Bus BMS V2.
Thank you for your response. I did not consider overcharging would be an issue here as well. That has likely happened in addition to the over discharge.
The VE Bus BMS V2 is only suitable if you have a Victron VE Bus Inverter such as a Multiplus. As you do not list this, just an Orion and a SmartSolar the most suitable is the Victron Small BMS. This will shutdown the chargers using their remote ports. You will also need a Battery Protect to shut down the loads on over discharge. A SmartShunt would be useful for monitoring SOC but not absolutely necessary.
Ok gotcha thanks for the information! The amount gadgets needed for this simple system is wild to me. I think I’m just going to sell my Victron battery and get a different one with all these goodies built in. Thanks!