# What is the voltage of a fully charged battery pack?

I bought a 24v lion battery pack (It is not this one but almost: 24v) and I wanted to know the SoC of my battery. Since I think there are 6 batteries in series, is the full charged voltage 4.2 x 6 = 25.2v? And then the discharged voltage, let's say 3 x 6 = 18 for a 4.2v full charged cell and 3v for a discharged cell? I'm not sure. I mean, I know there is all kinds of batteries but I'm not sure about the math

Also, do lion batteries need a balance charger like lipo chargers? My battery pack came with a round clable, like a laptop charger. It seems it has a circuit inside but i don't know. Thanks for replying

– DSI
Commented Jun 21, 2020 at 2:25

Lithium-Ion batteries should be balanced charged like their LiPo counterparts. Although a commercial Lithium-Ion battery pack might be balanced prior purchase and can be charged/discharged using a single connector, the individual cells' voltage can become misaligned over time and damage can be caused if they aren't balanced.

You should consult the datasheet/manufacturer and ensure there is some type BMS circuit built in.

Or you could open it up and check for yourself... (at your own risk!)

Unless you have data on the cells, you don't know.

The voltage of a charged Lithium Ion cell is a soft number. First, because different technologies of cell can have different "correct" maximum charge level, and second, because you can always charge a cell higher than the rated value. Unless you really overcharge, you shorten the life of the cell but you don't kill it with that charge.

In fact, if you're designing a piece of equipment and discussing batteries with a cell manufacturer, they may well recommend that you don't even charge the cell up to their full data sheet value -- because LiIon cells don't like being "fully" charged for a long period of time.

So without knowing the intent of the manufacturer of the equipment that the pack is going into, you don't know what "fully charged" is.

If you bought the pack bare (i.e., if you're an RC hobbyist), then without knowing the rated full-charge voltage of the cells used, you don't know what "fully charged" is.

Such is life with Lithium-ion batteries.