---
title: "LiPo vs LiFePO4"
question: "How does a LiFePO4 cell differ from a LiPo?"
url: "https://nearfieldnotes.com/videos/lipo-vs-life/"
site: "Near Field Notes"
video: "https://nearfieldnotes.com/media/lipo-vs-life/full.mp4"
duration: "3:04"
date: "2026-11-06"
note: "https://nearfieldnotes.com/notes/lipo-vs-life/"
---

# LiPo vs LiFePO4 (video)

How does a LiFePO4 cell differ from a LiPo?

3:04, with sound. [Read Note 18](https://nearfieldnotes.com/notes/lipo-vs-life/) for the full answer, with figures, conditions and sources.

## Transcript

Both cells are half full. Both meters are off by 10 mV.

The LiPo still reads 50%, give or take 3. The LiFe could be anywhere from 42 to 71.

LiPo and LiFe are both lithium-ion, with graphite on one side.

The other side is cobalt oxide in a LiPo, and iron phosphate in the cell named after it.

That sets the voltage. A LiPo is full at 4.2 V a cell, a LiFe at 3.6.

A LiPo's voltage climbs the whole way up. A LiFe sits near 3.3 V from 20 to 80%.

In my sim, that's 3.6 mV per % on the LiPo. 0.6 on the LiFe.

Both charge the same way. Constant current, then constant voltage.

The LiPo spends half an hour holding 4.2 V. The LiFe stays flat, then climbs its last 0.1 V in 27 seconds.

So the setting matters. A LiPo on the LiFe setting stops at 3.6 V. About 6% full. Annoying, not dangerous.

A LiFe on the LiPo setting gets pushed past full, toward 4.2 V.

A full LiPo cathode still holds half its lithium. A full LiFe cathode holds none, so overcharge heat starts right away.

Balancing is harder too. One cell in this 4S LiFe pack is 5% smaller.

For 42 minutes, it stays within 17 mV of the others. Its 5% barely shows.

Then, in 3 minutes, it runs away.

The charger stops at 14.4 V. Three cells sit at 3.33. The small one takes the rest: 4.42 V.

The same cell in a LiPo pack ends at 4.24 V. That's why every LiFe pack needs a BMS that watches each cell.

Back to the gauge. If the voltage can't tell you, count the charge instead. Every amp in, every amp out.

But a sensor that's 1 mA off drifts about 30% a month.

And a LiFe rests 15 to 40 mV higher after charging than after discharging.

So TI's fuel gauge ignores the voltage from 34 to 93%.

The one reading a LiFe gives away is full. Every full charge resets the count.

Cold hits both the same way, because both have graphite.

Charge graphite too fast in the cold, and lithium plates onto it as metal instead of soaking in.

In my sim, a 1C charge at 0 °C pulls the graphite below lithium for 31 minutes. At half the current, it stays just above.

So both datasheets say no charging below 0 °C. Heated LiFe batteries warm themselves up first.

Heat is where LiFe wins. A hot cobalt cathode releases oxygen and feeds its own fire.

Heated until they failed, a cobalt cell hit 853 °C. The LiFe cell peaked at 404, with a fifth of the gas.

Store a LiPo at 3.8 V a cell, and a LiFe at 30 to 50%. Shipped by air, both go at 30% or less.

A LiPo packs more energy per gram. A LiFe lasts thousands of cycles and fails calmer.

But a LiFe needs a BMS on every cell, and a gauge that counts.

---

Source: https://nearfieldnotes.com/videos/lipo-vs-life/