Originally Posted by
whizzkid14
hi every one, been looking through the site and I must say its very good indeed
I would be great full if some one with more experience could give me some advice..
right then. I have a very basic understanding on bike battery's but im stumped on some things namely this..
I understand that on batteries volts x ah = watts im looking to purchase a 36v 800w ebike kit of ebay. now I understand that the wattage wont be 800 watts more like 20amps x 36v = 720w and then they add up the extra to make 800...
The battery iv been looking into is a 36v 10ah lithium battery.
I look forward to your replys
many thanks whizz-kid
36V 800w kit will require 1600w to output a peak 800w.
1600w / 36v = 44.4A
So a 10Ah battery would have to be ~ 5C capable
Continuous 800w output would drain battery completely in about 10-12 minutes.
Fortunately,
continuous :
15 mph cruising uses only 150w, ~80% efficiency = 187w.
36V x 10Ah / 187.5w = 1.92 hours ~28.8 miles
cruising at 15mph from a 10Ah battery.
20 mph cruising uses only 340w, ~80% efficiency = 425w.
36V x 10Ah / 425 = .84 hours ~50 minutes ~17 miles
cruising at 20mph from a 10Ah battery.
See -
Motor Output Watts for MPH
You must determine your desired distance and speed, then you can figure your required battery size.
SLA batteries only output about 50-60% usable of "rated".