LiPo batteries are so essential for RCs and regularly used by many. But sometimes we face a problem while charging them which can be very frustrating. It just won’t charge! But that is not the end for the battery. We can revive it!
But what exactly should be done when a LiPo battery won’t charge?
This happens because of over-discharging the battery. To safely charge it again, you’ll have to charge it as a NiCd battery. Once the charge per cell reaches a certain level, you’ll have to balance to charge it. This time as a LiPo battery.
It might sound hard and confusing, but it’s not! If you’re ready to spare a minute, let’s jump into the details-
Reason Why A LiPo Battery Won’t Charge
LiPo batteries may face many problems. For example, swelling up because of overcharging is a common issue. And it also has easy fixes, such as depuffing a swollen LiPo. The charging problem of LiPo batteries also has a very basic cause behind it. Not to mention an easy solution too!
When a LiPo battery won’t charge, the balance charger is not being able to connect to it. Some chargers simply tell you that it’s not chargeable. Whereas, some give you a better answer: low voltage error. That is exactly what’s wrong with the battery.
When the LiPo battery goes below a certain voltage, it goes flat and won’t charge. In fact, charging a LiPo battery that’s low in voltage is dangerous. That’s why, when you charge it using a balance charger, it won’t charge given the risk.
To sum it up, your LiPo battery is not charging because it is dangerously over-discharged. To prevent that, you need to keep note of the discharge rate of LiPo batteries. Now that we know the cause, let’s look at the solution.
Process of Charging A Flat LiPo Battery
The primary reason it won’t charge is that the balance charger deems it to be dangerous. But how does it know that? It’s because we set the charger to LiPo battery charging. And the charger sensed the low voltage of it when connected. We simply have to trick the charger into thinking the LiPo battery is not a LiPo battery. Here’s how-
Step 1: Charge as A NiCd Battery
For this step, you’ll need a balance charger that allows Nickel-Cadium battery charging. On that note, take a look at these that we recommend-
First, you need to disconnect the balance charging cord used in balance charging a LiPo. Then, you’ll have to go to the settings and set it to NiCd battery. But that’s not the end of it.
Remember that charging a LiPo battery that’s low on voltage is not very safe. So, we’ll set the charge to the lowest possible, 0.1 amperes.
Once you have the settings right, start charging your battery. Keep a close eye on it until it reaches 3.3 volts per cell.
There are differences between 3S and 4S LiPo in terms of total charge output. And, since you’re using the NiCd setting, you won’t be able to tell the charge per cell. So you’ll have to charge until the following:
- For 2S LiPo, charge until 6.4-6.6V
- For 3S LiPo, charge until 9.6-9.9V
- For 4S LiPo, charge until 12.8V
Once the battery is charged up to that, stop charging immediately.
Step 2: Balance Charge as A LiPo Battery
Now that we have made up for the over-discharge, we can charge it as a LiPo battery. Make sure to put your balance lid back on for this.
Go to the settings and choose LiPo battery, then choose balance charge. Here too, we will decrease the charge to around 1.3A or less. Once you’ve done that, start charging your battery. Once it’s fully charged, you’re done!
Important Points to Remember
Remember to check if all the cells have the same amount of charge when balance charging. Sometimes, a particular cell might fail due to discharging. You can expect a little bit of desynchronization of charge among the cells, around 0.1-0.2A.
Don’t use a revived flat LiPo for high-power consuming utilities. You can use them for things that don’t use too much power.
Tips for Charging LiPo Battery Safely
Here are some tips that will help you with charging LiPo batteries and prevent mishaps-
- Don’t over-discharge a LiPo battery. Each cell should not go under 3.2-3.3V.
- Don’t charge a LiPo battery with flammable objects around. Charge on concrete or non-flammable surfaces.
- Don’t keep a LiPo battery unattended while charging.
- Don’t store Lipo batteries in heated places. Also, don’t charge under direct sunlight.
- Try to charge a LiPo battery while keeping it in an anti-flame box or container.
Keep these in mind. This way you can prevent your LiPo battery from exploding when charging.
Question: How long does it take to charge a flat LiPo battery?
Answer: If it’s a 3S battery, the NiCd charging should take around 10-15 minutes. But it changes depending on how discharged it was. The Balance charging phase should take around 70-80 minutes.
Question: How long is it okay to keep a LiPo discharged before charging again?
Answer: Every hour adds to the damage dealt with the LiPo battery if it’s been over-discharged. You should charge it as soon as possible. Don’t charge it if it has been a few days or weeks.
Question: Will the battery be back to normal after recharging?
Answer: Once over-discharged, the battery will never be the same as before. After you charge it up again it might be a bit swollen. But that is to be expected since it was flat before.
We hope this article cleared you up on what to do if a LiPo battery won’t charge. Be extremely careful while reviving a dead LiPo battery. Don’t stay too close to it, but don’t leave it unattended.
Until next time, have a great time!