Method to control multiple parallel battery packs

A method of operating a machine battery system having multiple battery packs connectable to a load bus, wherein a battery pack includes a plurality of battery strings, wherein each battery string includes a battery module having at least one battery cell, the method comprising:

• selecting a subset of the plurality of battery strings of a battery pack of the multiple battery packs;
• coupling the selected subset of the plurality of battery strings of the battery pack with the load bus;
• and
• coupling, after coupling the selected subset with the load bus, the remaining ones of the plurality of battery strings of the battery pack with the load bus,
• wherein the multiple battery packs are brought online for discharging, including:
• determining an offline voltage of each of the multiple battery packs;
• bringing a first battery pack with a highest offline pack voltage online, including a pack controller circuit of the first battery pack bringing one or more individual battery strings of the first battery pack online;
• bringing a next battery pack with a next highest offline pack voltage online when the next highest offline pack voltage is within a discharge threshold voltage of a load voltage, including the pack controller circuit bringing one or more individual battery strings of the next battery pack online;
• waiting to bring the next battery pack online, when the next highest offline pack voltage is less than a discharge threshold voltage of the load voltage, until the next highest offline pack voltage is within the discharge threshold voltage;
• and
• continuing to bring subsequent battery packs online in order of highest offline pack voltage.

A non-transitory computer-readable storage medium including instructions that, when performed by a hardware processor of a battery pack having a plurality of battery strings, cause the battery pack to perform operations comprising:

• selecting a subset of a plurality of battery strings of a battery pack of the multiple battery packs;
• coupling the selected subset of the plurality of battery strings of the battery pack with a load bus;
• and
• coupling, after coupling the selected subset with the load bus, the remaining ones of the plurality of battery strings of the battery pack with the load bus,
• wherein the multiple battery packs are brought online for discharging, including:
• receiving a command to bring the battery pack online in a discharge state;
• bringing the plurality of battery strings of the battery pack online individually and connecting the battery pack to a load when the battery pack has a highest offline voltage and the other battery packs are unconnected to the load;
• bringing the plurality of battery strings of the battery pack online individually and connecting the battery pack to the load when the battery pack has the highest offline voltage of offline battery packs, and the offline voltage is within a threshold of a load voltage;
• and
• waiting to connect the battery pack to the load when the battery pack has the highest offline voltage of offline battery packs, and the offline voltage of the battery pack is less than the threshold of the load voltage.