Battery lithium 36V, 10Ah is running for 9 hours with no load on the motor (with 0.5 A draining) which gives us 4.5 Ah, and for 2 minutes with load on motor (with 17 A draining). If we consider 4.5 Ah and not 10 Ah, it should stay working 16 minutes. I changed the BMS and still have the same problem, I checked all the wires. What could be the problem?
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Batteries have internal resistance.
As more power is lost right in the batteries, you get less amp-hours at heavy load than at light load.
All batteries work like that.
For example when you buy a battery for camping van, the batteries are typically rated for some Ah capacity when they are discharged down to some level of voltage in some amount of hours.
Sometimes you get charts about capacity if it is discharged faster or slower, i.e. with more or less current, and how many charge-discharge cycles you get when letting the voltage drop more or less than the rated voltage.
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\$\begingroup\$ An important addition: the difference between the low-current capacity and the high-current capacity gets worse as the battery ages. \$\endgroup\$– fraxinusCommented Apr 29 at 6:25
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\$\begingroup\$ Thank you for your response. the original rated capacity is 8.8Ah. depending on what you say, the problem does not come from the circuit nor the BMS nor any other component ? but how could my battery internal resistance increased in 4 months while it's an original one, not some weird china ultra fire cells ? is there anything I can do to revive them ? \$\endgroup\$ Commented Apr 30 at 0:26