Jack Tyler
Active Member
Just to clarify, some battery manufacturers rate their batteries against an industry standard longevity scale. Applications in off-grid homes, golf carts and long distance sailing boats are all examples where the buyer expects the mfgr to publish rated longevity (in 'cycles') to a common standard. So e.g. a 240 amp/hr 6V storage battery will be rated in cycles based on how many times the battery can support a 20 amp load to its half-discharge point, then be recharged 100% and the draw down repeated UNTIL the battery is only capable of supplying half of its rated amp/hr capacity (or 120 amp/hrs). A good cycle rating for these applications and with premium, conventional lead acid storage batteries is ~700 cycles.
I'm a newbie re: ebikes. But from what I've read here so far, the Li-ion batteries used in ebikes these days come from multiple named and some unnamed manufacturers, and are assembled from a mix of bike mfgrs and contract mfgrs, located in multiple countries. So it's easy to understand why bike manufacturers don't (or are not able to) provide meaningful info on battery performance.
Here's a partial step towards what a 'real' answer would be for ebike battery cycles. The bike's battery assembly is actually a composite collection of many smaller batteries connected in serial/parallel fashion to provide the voltage required. E.g. the Samsung 18650 Li-ion battery we see referenced so often is 3.7V. That suggests to me that ten 18650 batteries are connected in series to provide one 36-37V bank. And the number of those banks, wired in parallel, will determine the amp/hr capacity of the bike's battery. But how long will that composite battery assembly "last"? For the Samsung Li-ion chemistry in electric scooters, here's how Samsung answers that Q: "
"The capacity of lead-acid batteries is about 50% of the initial capacity after 1.5 years of use (about 400 cycles), but that of Li-ion batteries is about 75% of the initial capacity after 3 years of use (about 800 cycles). "
That's a help...but since they don't cite the draw-down rate or level of discharge, it isn't fully informative. When I choose my ebike, I'll want to contact that Li-ion battery mfgr and try to get the whole 'cycles' standard they have been using. But another general rule WRT battery capacity is not to draw down the battery more than 50% for maximum battery life (in cycles)...which of course is why battery mfgrs choose that draw down regimen. That way their product looks as good as it can be.
Jack
I'm a newbie re: ebikes. But from what I've read here so far, the Li-ion batteries used in ebikes these days come from multiple named and some unnamed manufacturers, and are assembled from a mix of bike mfgrs and contract mfgrs, located in multiple countries. So it's easy to understand why bike manufacturers don't (or are not able to) provide meaningful info on battery performance.
Here's a partial step towards what a 'real' answer would be for ebike battery cycles. The bike's battery assembly is actually a composite collection of many smaller batteries connected in serial/parallel fashion to provide the voltage required. E.g. the Samsung 18650 Li-ion battery we see referenced so often is 3.7V. That suggests to me that ten 18650 batteries are connected in series to provide one 36-37V bank. And the number of those banks, wired in parallel, will determine the amp/hr capacity of the bike's battery. But how long will that composite battery assembly "last"? For the Samsung Li-ion chemistry in electric scooters, here's how Samsung answers that Q: "
"The capacity of lead-acid batteries is about 50% of the initial capacity after 1.5 years of use (about 400 cycles), but that of Li-ion batteries is about 75% of the initial capacity after 3 years of use (about 800 cycles). "
That's a help...but since they don't cite the draw-down rate or level of discharge, it isn't fully informative. When I choose my ebike, I'll want to contact that Li-ion battery mfgr and try to get the whole 'cycles' standard they have been using. But another general rule WRT battery capacity is not to draw down the battery more than 50% for maximum battery life (in cycles)...which of course is why battery mfgrs choose that draw down regimen. That way their product looks as good as it can be.
Jack
