Yesterday while debugging new code on my matrix,

Yesterday while debugging new code on my matrix, I accidentally discharged on of the cells on my LiPo battery below manufacturer recommendations. I have a voltage meter that plugs into the balancing plug of the battery. Upon noticing my error, I immediately unplugged it and tried to charge it slowly at 1 amp, however the digitally controlled charging unit would not allow me to charge it at all. The voltage meter indicated one cell was below the desired voltage level of 3.2v

This morning, looking at a potential $60 error on my part, I tried to charge it once more. I should have taken a reading but I just threw it on the charger at 1 amp again. Walla! The unit charged my battery. There are no visible bulges or swelling on the pack and every cell is holding a charge according to my balance voltage monitor.

Is this thing a ticking time bomb? What do you think?

I’ve had similar experiences with my lipo batteries. I have one 4S 6000mAh battery that puffed about 4mm on the sides after I discharged it down to 3.05v but it continues to work like a champ.

You can expect some puffiness in lipos in general. Most of the time they puff up big when over discharged, discharged to fast or charged to over 4.22v per cell.

I would watch the battery over the next few charge cycles and discard it if the puffiness grows, it starts leaking or if the battery won’t balance charge to within 0.1v per cell

Keep it stored away from any flammable materials (including other LiPos). I’ve seen LiPo safe bags and I have also seen people use concrete cinder blocks and ammo cans.

And $60 seems a bit high for a LiPo. Check out the batteries at and you could save money. disclosure: i shop at HobbyKing. I don’t work for them or make money off sending people to their site.

It’s possible once it cooled off and regenerated a bit, that it was enough for the charger to sense and charge it. Chances are it’s fine, but I would certainly be aware of it wherever you use it.

I’ve discharged a Li-Ion down to 1.8v and was able to charge it right back up using the charger it came with. But then, their chemistry is slightly different.

There is damage done to the battery, it only can fully charge to 11.8v…oops

There’s your answer then. :slight_smile:

After I almost killed my battery I bought a couple of these and I use them when I fly or race. These plug into the balance port and give you an audiable alarm and flashing light if the battery goes low. Worth the $6 + shipping.

@Michael_Sharnet Those look great and cheap, however I am more interested now in turning my arduino into one of

With a 3S battery I would think you could use three analog pins to read voltage from each cell. A pin for the buzzer and if you want to go all in add a flashing led. I don’t know enough to get an LCD to display voltage, but I have seen it done.

You can also charge it shortly as a regular battery to increase the voltage and then try to charge it as lipo works most of the time

@elad_o That sounds intimidating. I discharged the battery down to 11.2v then charged it at 1amp, now the charger stopped at 12.3v, looks like the battery is “regenerating” for lack of better term. No swelling or overheating is occurring, still keeping an eye on it.