1 cell is composed of 3 separate cells, each held together by a plastic mold that contains 2 cells in series of 3 in parallel. Each cell is LiFePo4 and has 50Ah. The characteristics of a LiFePo4 cell are:
Min - 2.5V
Nom - 3.2V
Max - 3.65V
Per cell. The internal resistance of healthy cells connected 3x in parallel ranges from 0.40mΩ to 0.65mΩ. Each cell individually should have from 1 to 2mΩ. Above 2mΩ I would consider the cell damaged/old.
The dimensions of the cell are width 200mm x height 150mm (excluding battery terminals) + 20mm battery terminals x thickness 29mm, the connecting screws are a bit atypical M11 (I will check again)
The battery has its own BMS system from E-Pow. This battery uses the type YT02-24 and the corresponding software is called EV05-AA in version V1.2.02 and V1.3.03 (A photo of this SW was already added by user Vavrkok in other threads).
This BMS Knows:
Left connector
-3x CAN-BUS, 1 galvanically isolated (2 are used (one for communication from VMS and the other is Diagnostic))
-8x NTC-20k temperature sensor (6 are used (4 pcs for measuring cells 4, 12,16 and 22. The other two are used to monitor the heating pads under the cells, Right and Left sides separately))
-5x Contactor / Relay output (4 are used (Main contactor on B- in the battery, Heating contactor in the battery, Pre-charging relay in FuseBox, Contactor B+ in FuseBox))
-2x Analog low voltage input (1 is used for Monitoring PP (Pilot Pin) in the vehicle charging connector)
-3x Input power from auxiliary 12V battery (2 are used (they are connected to one common branch and when the Key is turned off, no power is supplied to them. Except for the key (or VMS) This branch can also be powered by a module that is used to start charging a 12V battery))
Right connector
-Separate +/- input for total battery voltage
-Input for measuring 24 cells, each separately (total 26 wires)
-Input from current shunt for measuring current on B+ branch
On the outside of the battery there is also a 26-pin Service / Balance connector which is used to check the cells and balance them with an external balancer (The maximum current drawn or supplied through this connector must not exceed 5A per cell and I would call even this current excessive considering the cross-section of the bottom wires used in the battery).
The battery also contains 2 heating pads, one under the right and the other under the left battery compartment. These pads have their own temperature sensors on both the L and R sides. They are controlled by one common contactor secured by one fuse and controlled by the BMS itself. They are turned on when the charger is connected to the car and the cell temperature is below -1°C. When the cells warm up above -1°C, the BMS only then turns on the negative contactor in the battery and starts charging the battery to prevent damage to LiFePo4 below -1°C, which would lead to permanent damage. The battery DOES NOT mind being discharged at temperatures below freezing, it only bothers when charging it.
Exactly halfway between the battery cells C.12 and C.13 there is a central (Emergency/Crash) fuse 400A from the Bussmann brand
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