Is my lithium battery damaged? As the technology becomes more popular it is a question being asked more frequently around Climatebiz.
Indeed, their price is going down and their durability, increasing. Additionally, their association with a Battery Management System (BMS) means they are more safe and reliable than ever before.
However, battery faults can and do happen.
If your battery is not performing as well as it did when you first bought it, you might wonder: is my lithium battery damaged?
There are 5 warning signs that your lithium battery is damaged:
- The capacity is reduced
- The voltage is low
- The self-discharge rate is high
- The battery is overheating
- The battery is bloated
In this article, we will answer the most asked questions about damaged lithium batteries, and how to properly take care of your battery to extend its life duration.
How can you damage a lithium battery?
Indeed, the newest LiFePO4 batteries are certified to last 10 years or 5’000 cycles, and some manufacturers are offering warranties of 5 years.
LTO batteries are even more durable with up to 30’000 cycles (80% capacity retention) and 25 years.
Moreover, they both include a BMS (battery management system) that regulates the charge/discharge steps, equalizes and protects the battery cells by monitoring the temperature and voltage.
The BMS can cut off each battery cell when it detects values above the fixed limits.
Despite their durability and the protection offered by the BMS, several factors could damage your lithium battery:
Environmental external factors
- Heat: temperatures higher than 140°F
- Cold: for LiFePO4 batteries below -4°F
- Water/air humidity
- Physical damage (shock)
- Over charging above 16.5V for a 12V battery
- Over discharging below 10V for a 12V battery
- Manufacturing defects
- Low-quality components
What happens if your lithium battery is damaged?
If your lithium battery is damaged multiple events could happen, they are categorized in function of their risks:
The lower risk events are related to the degradation of the battery performances:
- low voltage,
- low current and in the end a lower capacity.
These events are not a threat to the user but should be monitored.
The higher risk events are as follow:
- fire or explosion of your battery
- leakage of the electrolyte (toxic and flammable)
Indeed, Lithium when in contact with water (even air humidity) is extremely reactive and could catch fire. Overheating, overcharging, and shocks also promote thermal reactions inside the lithium battery.
What are the warning signs that my lithium battery is damaged?
There are multiple warning signs that could tell if your lithium battery is damaged.
Some of them are quite alarming, others would only be the sign of normal degradation over time.
The least alarming warning signs are related to the battery performances, and should not be a concern for your safety:
- The voltage is low
- The battery capacity is reduced
- The self-discharge rate is high
The most alarming warning signs are related to the physical appearance of your lithium battery and are definitely a threat for your safety:
- Overheating battery
- Swollen battery
- The battery has an unusual smell
- The battery is discolored
If you detect one of the most alarming signs, we strongly advise you to immediately disconnect the lithium battery and store it in a very well vented area, far from other batteries and potential ignition sources.
Can you repair a damaged lithium battery?
First of all, let’s have a quick look at the major components of a lithium battery.
The latest lithium batteries consist of:
- Battery casing, usually ABS (Acrylonitrile Butadiene Styrene) plastic
- Prismatic Lithium battery cells
- Battery management system (BMS),
- Connectors (bus bars, wires…)
All these components can be bought separately, in specialized battery stores and also on Amazon. Therefore, as illustrated in one of our recent articles, it opens the possibility to DIY a lithium battery and to repair your damaged lithium battery.
Repairing your lithium battery is possible but you should be extremely cautious and follow the safety rules.
- First of all, if you detect one of the most alarming warning signs previously mentioned, your lithium battery cannot be repaired and should be handled with maximum care. We advise you to bring it to a battery store. They will take your battery to a recycling center.
- If you only detect the least alarming warning signs, you could be able to fix your lithium battery either at home or with the help of a battery specialist.
- The battery specialist will evaluate the degradation state of all your lithium battery components and more specifically your BMS and the prismatic lithium battery cells.
- They will measure the voltage and capacity of each prismatic cells by applying a power load and a charging current. If one or more cells are underperforming, they could be replaced.
- Then, they will test the BMS, as most of the time, lithium battery failures are due to a defective BMS. The BMS response to a power load and a charging current will be evaluated as well as its capacity to equalize multiple battery cells.
Can you reset a lithium battery?
If your lithium battery is stored for a long time or if it was over discharged, the BMS might put it asleep.
First of all, if the battery voltage falls below 6V for a 12V battery and 12V for a 24V lithium battery, then do not attempt to reset it. Indeed, at lower voltage, chemical reactions occur inside the battery cells that could lead to internal short circuits.
- On the other hand, most of the BMS will cut off the battery if the voltage falls below 8.8V (12V battery) and 17.6V (24V lithium battery).
Be sure to respect the polarity when connecting your lithium battery to the charger. Reverse polarity (+ plugged with -) could cause irreversible damages to your lithium battery.
What voltage should a lithium battery be?
As previously mentioned, lithium batteries are made of the association of multiple prismatic lithium battery cells connected in series. Therefore, the voltage of a lithium battery is the sum of the voltage of each lithium battery cell.
The nominal voltage of a prismatic LiFePO4 battery cell is 3.2V: equivalent of 12.8V for a 12V lithium battery pack.
- The lowest voltage is 2.5V: 10V for a 12V lithium battery, and the highest voltage 14.6V.
The figures below represent the battery voltage in function of its capacity (all voltages are measured at zero load)
When charging, the appropriate voltage should be applied as summarized in the chart below for 12V and 24V LiFePO4 batteries
|Charging parameters||12V LiFePO4 battery||24V LiFePO4 battery|
|Absorption voltage||14.2V to 14.6V||28.4V to 29.2V|
|Floating voltage||13.4V to 13.8V||26.8V to 27.6V|
Do lithium batteries get damaged if not used?
Lithium batteries have rather low self-discharged rates, usually 2 to 3% per month. Therefore, you can store them safely for a prolonged period of time. However, you should follow the proper protocol.
The risk of not using your lithium battery for months is overdischarge, leading to permanent performances degradation. There are actually two ways of properly storing your lithium battery:
- Some manufacturers recommend a 100% state of charge before storage
- Other recommends 40% state of charge
In both cases, disconnect the battery cables, by doing so you will be sure that no load is applied.
In addition, be sure to store them in a cool place (70°F is ideal).
5 Ways to look after your lithium battery
Usually, lithium batteries for solar systems or for solar generators are connected to a solar charge controller and to an inverter that converts DC power into AC. With the most advanced devices, you can even tune the charging and discharging voltage of your lithium battery.
Let’s now have a look at our 5 best advices to increase your lithium battery life.
1 Avoid temperatures below 32°F (0°C) and above 95°F (35°C)
Lithium batteries are electrochemical systems, they store electricity as a chemical. Therefore, their performances are affected by the ambient temperature. Operating your battery below 32°F(0°C) could cause metal deposition at the negative electrode, thus leading to short circuit. Above 95°F(35°C), other parasite reactions are promoted leading to further degradation.
2 Do not charge it to 100%
This sounds quite unnatural, but indeed, a high state of charge reduces your lithium battery life. Several experimental studies have shown that only charging your battery to 90% provides 2 to 5 times longer life duration compared to fully charged batteries. To do so, you have to reduce the float voltage by 0.1 V to 0.3 V compared to the indication of the manufacturer.
3 Do not discharge it to 0%
On the other hand, your lithium battery should not be completely drained. Deep discharge promotes metal deposition, leading to short circuits that could irremediably damage your lithium battery. Usually manufacturers recommend 80% depth of discharge to extend your battery life. 70% depth of discharge could even double your battery life. To adjust the depth of discharge you need to modify the cut off voltage of your BMS or your inverter.
- 24V battery, 80% DOD, Cut-off voltage=24V (with load)
- 12V battery, 80% DOD, Cut-off voltage=12V (with load)
4 Use partial-discharge cycles
Partial discharge cycles happen when less than 50% of the battery capacity is discharged before charging. This will considerably extend your battery life. You could perform thousands of partial cycles before your battery starts to degrade.
One of the best partial-discharge cycles is from 75% to 25% capacity. The benefits of the partial discharge should be balanced by the lower available capacity (50%).
5 Do not charge/discharge them too fast
Even though lithium batteries are fit for quick charge with solar panels, high currents generate stress in the battery chemistry. The same happens with high discharging currents. Therefore, we recommend to limit continuous charge and discharge current to a maximum of 0.8C (80% of the battery capacity in 1 hour). For example, a 50Ah battery should be charged/discharged with max. current of 0.8*50= 40 Amps.
We need durable solar batteries.
After a century of market domination, lead-acid batteries are now outdated. Indeed, their life duration is only 3 years.
Lithium batteries, like LiFePO4, are much more durable and versatile. But still, their internal chemistry is influenced by multiple factors such as temperature and charging/discharging parameters.
The good news is coming from a new lithium battery technology: LTO, slowly reaching the market of solar energy storage. LTO batteries are extremely robust against fast charging/discharging currents, tolerant to low/high temperatures and durable with up to 30’000 cycles: a battery for life.