Can the automotive 12V battery charger be used for LiFePO4?

Some chargers can be used, some cannot. There are two things that need to be considered:

1) Full charge voltage. The LiFePO4 batteries need to be charged at least to 14.6V. However, some automotive 12V battery chargers charge only to 13.8V or even less. This is not sufficient. Only chargers with higher charge voltage may be used. Note: some chargers support higher voltage by manual selection of something like „a boost mode“.

2) Trickle charge not supported. The LiFePO4 batteries will be damaged when left on charge with the trickle mode charging. Most automotive 12V battery chargers have the trickle mode as a default setting. With LiFePO4 batteries, the charging must be stopped and the charger needs to be disconnected after the charge cycle is finished. If the charger unit disconnects (stops) after reaching the full charge, it may be used with LiFePO4. It is a must to avoid the trickling charge mode.