Currently in 1.25 you cannot remove a car battery once it's placed inside a BaseRadio (Field Transceiver).
I found the issue and solution, just needs a tweaked inventory check -
VehicleBattery.c (which CarBattery inherits from) has some code which prevents the car battery from being interacted with once placed in a BaseRadio attachment slot:
override bool CanPutIntoHands(EntityAI player)
{
if (!super.CanPutIntoHands(parent))
{
return false;
}
if (HasEnergyManager())
{
ItemBase poweredDevice = ItemBase.Cast(GetCompEM().GetPluggedDevice());
if (poweredDevice && poweredDevice.IsInherited(MetalWire)) // This should also check "|| IsInherited(BaseRadio)
{
return true;
}
else if (poweredDevice)
{
return false;
}
}
return true;
}
override bool CanPutInCargo(EntityAI parent)
{
if (!super.CanPutInCargo(parent))
{
return false;
}
ItemBase poweredDevice = ItemBase.Cast(GetCompEM().GetPluggedDevice());
return !(poweredDevice && poweredDevice.IsInherited(MetalWire)); // also needs BaseRadio check
}