# LiPo charger shows a cell count or balance error: check the lead and the setting

> Fix charger errors on a LiPo pack: set the cell count to match, plug the balance lead in fully and never charge a puffed or damaged pack.

Canonical: https://roboticsengineering.in/fix/lipo-charger-balance-lead-error-cell-count/ | Published: 2026-11-03 | Updated: 2026-11-04

**Set the charger to the same cell count as the pack, and plug in the balance lead fully.** Never charge a swollen pack.

## What the message means

The charger measures each cell through the balance lead. If the lead is loose or the count is wrong it stops with an error to protect the pack.

## Fix it in this order

1. Read the cell count on the pack label and set the charger to that exact number.
2. Push the balance plug in fully and check its orientation.
3. Measure each cell voltage. A cell far below the others needs care or replacing.
4. Do not charge a pack that is swollen, hot, dented or deeply discharged.
5. Charge in a fire-safe container, in sight, on a non-flammable surface.
6. Use the charge current the pack maker allows.

## Why it happens

A charger checks each cell of the pack through the balance lead. If the cell count you set does not match the pack, or a contact on the lead is loose, the readings do not add up and the charger stops with an error rather than risk overcharging a cell.

A single cell that has fallen far below the others is a different problem from a loose plug, and a swollen pack should not be charged at all. Treat a damaged pack as scrap and dispose of it by the rules for lithium batteries in your area.

## If you see this, do this

| You see | Do this |
| --- | --- |
| Cell count error | Setting or lead. |
| Pack swollen | Do not charge. Dispose of it safely. |

## Related

[LiPo safety and charging](https://roboticsengineering.in/lipo-battery-safety-charging-robots/), [BMS cut-off](https://roboticsengineering.in/fix/bms-protection-board-cuts-off-under-load/).

Last reviewed: November 2026. These are the usual causes and the order that finds them fastest. Test on your own board; clones and cables differ.

## Why this happens

A multi-cell LiPo pack has one balance wire for each junction between cells. A 3S pack has four wires, since the number of wires is the cell count plus one. The charger reads the voltage between neighbouring wires to see each cell, and it checks the count against the number you set. If a wire is loose, or the setting is different from the pack, the readings do not add up and the charger stops with an error.

A single cell reading is also checked. A cell far from the others, or one that has fallen very low, is treated as a fault. Makers usually advise against charging cells that have dropped below a minimum voltage, and the pack label or the maker’s sheet gives it. A swollen pack is a damaged pack and should not be charged.

## How to confirm the cause

- Read the cell count printed on the pack. A 3S pack is 11.1 V nominal and 12.6 V when full at 4.2 V per cell.
- Set the charger to the same count and the LiPo mode. Check that the mode is not for another chemistry.
- Measure between the balance connector pins with a multimeter. Each step between neighbouring pins should be a sensible cell voltage.
- Look for a pin with a gap or a loose crimp. A reading of 0 V between two pins means that cell wire is broken.
- Check the pack for swelling, heat or dents before you charge.

## Worked example

An example of a good check on a 3S pack, measured from the first pin to each of the others. Each cell is the difference between neighbouring readings. A 1C charge current for a 2200 mAh pack is 2.2 A, but charge at the rate the maker allows.

```
pin 1 to pin 2 = 4.15 V   (cell 1)
pin 1 to pin 3 = 8.33 V   (cell 2 = 8.33 - 4.15 = 4.18 V)
pin 1 to pin 4 = 12.49 V  (cell 3 = 12.49 - 8.33 = 4.16 V)

total 12.49 V = 3 cells, all within 0.03 V of each other

A pack that reads normally in total but shows 0 V between two pins
has a broken balance wire.
```

## Common mistakes

- Setting 4S on a 3S pack because the pack looks the same.
- Using a charger mode for NiMH or LiFe.
- Charging through the main lead alone, without the balance lead.
- Ignoring a swollen pack because the charger starts.
- Leaving a charging pack unattended on a flammable surface.

## If this did not fix it

- The balance connector itself, which may be worn or bent.
- A cell that is far below the others, which needs a careful, slow recovery if it is allowed at all.
- Charger settings such as the maximum charge current or cutoff, if they were changed.