D
duivendyk
Guest
Paralleling dissimilar batteries of significantly different capacities is a bad idea,and does not accomplish all that much either,they ought to have at least approximately equal capacities
Monitoring the output voltage of such a parallel combination does not tell you all that much about the current division between them.Looking at the voltage changes (under load !)that is A, B, A+B gives some info.The individual current monitoring using small resistors in series with the batt. tells you a lot more.
The homogenizing scheme of a 12V SLA + 12V NMH (or Nicads) in series and two of these in parallel with the crossover switch to turn them into two separate 24 V SLA/24V NMH batteries has a lot going for it,by sidestepping the crossfeeding& loadsharing problem.
Nicad batteries have a memory effect,if not completely discharged before recharging their capacity tends to decrease.
Low speed hill climbing is the pits for these kind of motors,high torque at low speed means poor eff..But total power available (rider+ motor) will limit motor speed.A lot depends on how steep the incline is.
I have derived a useful expression relating the power P (in Watts) to climb a hill to the weight (W in kg), the incline I (in %) and the speed S (in km/hr).Here goes:
P= 0.027xWxIxS Watt.For instance W= 130kg ,I= 4% and S= 10 km/hr ,P=140 Watt
This does not include the power needed to overcome the rolling&aerodynamic drag,prob. another 25-30W?
Monitoring the output voltage of such a parallel combination does not tell you all that much about the current division between them.Looking at the voltage changes (under load !)that is A, B, A+B gives some info.The individual current monitoring using small resistors in series with the batt. tells you a lot more.
The homogenizing scheme of a 12V SLA + 12V NMH (or Nicads) in series and two of these in parallel with the crossover switch to turn them into two separate 24 V SLA/24V NMH batteries has a lot going for it,by sidestepping the crossfeeding& loadsharing problem.
Nicad batteries have a memory effect,if not completely discharged before recharging their capacity tends to decrease.
Low speed hill climbing is the pits for these kind of motors,high torque at low speed means poor eff..But total power available (rider+ motor) will limit motor speed.A lot depends on how steep the incline is.
I have derived a useful expression relating the power P (in Watts) to climb a hill to the weight (W in kg), the incline I (in %) and the speed S (in km/hr).Here goes:
P= 0.027xWxIxS Watt.For instance W= 130kg ,I= 4% and S= 10 km/hr ,P=140 Watt
This does not include the power needed to overcome the rolling&aerodynamic drag,prob. another 25-30W?
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