Handling Guide

Charging LiFePO4 Correctly And What Ruins A Pack

Charge voltages, the 0 degrees rule, why an equalisation stage trips the BMS, and how to store a pack that will sit idle.

Almost every field failure we see traces back to charging rather than to the pack. Four rules cover most of it.

Rule One: Use A LiFePO4 Profile

A lead-acid charger with a fixed equalisation stage will push the pack above the BMS threshold and trip it. Some chargers have a lithium setting; some do not. Tell us the charger model with your enquiry and we will confirm before the pack ships rather than after it stops working.

Rule Two: Never Charge Below Freezing Without Heating

Discharging a LiFePO4 pack in the cold is fine. Charging it below 0 degrees Celsius plates metallic lithium on the anode and permanently removes capacity. This is why heating is an option on several of our packs and why it should be specified for cold-climate vehicles and unheated cabinets.

Rule Three: Respect The Charge Current

Our packs accept 0.5C to 1C, which is what makes a one to two hour recharge possible. That is a ceiling, not a target - and in a vehicle it means a DC-DC charger between the alternator and the pack, because a lithium battery will draw everything an alternator can produce and overheat it.

Rule Four: Store At Partial Charge

A pack going into storage for months should sit around half charge rather than full or empty, somewhere that does not freeze. LiFePO4 self-discharges slowly, so a pack stored correctly will still be usable the following season.

Common charging mistakes and what they cost
Mistake	What happens	Fix
Lead-acid charger with equalisation	BMS trips, pack appears dead	Charger with a LiFePO4 profile
Charging below 0 degrees Celsius	Permanent capacity loss	Heating option, or wait for the pack to warm
Alternator connected directly	Alternator overheats, pack charge uncontrolled	DC-DC charger sized for the alternator
Stored fully discharged	Cells drift, pack may not wake	Store around half charge
Mixing old and new packs in parallel	Circulating current between packs	Match model and state of charge before connecting

Bluetooth monitoring on the deep cycle range shows exactly what the charger is doing. Ten minutes with the app at commissioning prevents most of the problems on this page.

FAQ

Questions On This Guide

What voltage should my charger end at?

It depends on pack voltage and the BMS thresholds for the model. We provide the charge parameters with the specification sheet - use those rather than a generic lithium figure.

Can I leave the charger connected permanently?

With a proper LiFePO4 profile that stops rather than floats indefinitely at a high voltage, yes. Check the charger's behaviour at the end of charge, because that is where the differences show.

Is fast charging bad for the pack?

Within the published 0.5C to 1C acceptance, no. Beyond it, heat becomes the limiting factor and cycle life suffers.

How do I wake a pack that has gone flat?

Contact us with the model before trying anything. Some BMS units need a specific procedure, and the wrong approach on a deeply discharged pack can make it worse.