Blog - Chargers and charging

Automated guided vehicle

04.Jun 2014

How to make AGV (automated guided vehicle) with automatic charging of LiFePO4 cells?

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We must design battery pack with protection (BMS, SBM) and charger.

Battery pack

The operating voltage of the AGV is 24V. To obtain a nominal voltage of 24V we will need 8 cells. We recommend using at least 40Ah capacity due to the reserve - WB-LYP40AHA LiFeYPO4 (3.2V/40Ah)

Please check our LFP Cell Model Calculator to decide which cell you need to buy:

See information here.

Before first use charge the cells, please view link below:

Initial charging information.

You can use Charger 3.6V/18A for LiFePO4 cells

For connecting the cells together it is recommended to use terminal connectors and plastic cover of terminal connector for battery cells. Color red for the "plus" terminal and black for the "minus" terminal.

The cells have to be connected to series, please see attached battery pack schema.

Simple Battery Management Board (SBM)

The battery pack must contain some kind of cell protection, we recommended:

Simple Battery Management Board 8 cells (24V/60A)

The easiest way to protect a lithium battery pack. The SBM board manages a pack of cells and disconnects the load under any unfavorable circumstances: cell over voltage, cell under voltage.

We also recommend to use a monitoring circuit for visual inspection of cells - information display. Please see here.

Charger

We have choosen 2 pcs 20A chargers so the current will be 40A. Please see attached schema of their connection.

2,2Ah will be charged in 3,3 minutes.

In order to charge with higher current we could add another chargers. Please note that the maximum charging /discharging current is limited by SBM board (60A). In case higher charging / discharging current are supposed then we would need to use a contactor triggered by SBM board (please check the detailed scheme: http://www.ev-power.eu/docs/SBM-Installation-DC-Contactor.pdf)