Doing the math on battery charge cycles

[Naranja_CT5+]

I don?t know where I read it but they say 1 cycle is equal to 100% charging time. Meaning if you have a battery status of 50% and you charge it, that?s half of one cycle. They also implied that a battery life has approximately 800 cycle.

This is interesting because RAD says you should charge your battery every time you go for a ride. My average ride is probably going to be in the 5-10km per ride. Even if I used 10% per ride, it?s going to take multiple charging to reach one charge cycle.

It is nice to think that it?s going to be a long time to reach 800 cycles.

Of course I understand there are other variables that will prevent the batteries from getting a full 800 cycles.

[BeachWagon]

You can find a lot of good information on battery cycles.

A few things you can do for more cycles is not fully charge the battery when you don't need it. Say you only need 50% of the battery charge on a trip. Charging the battery to 80% and running it down to 30% will put less wear on the battery than charging it to 100% and then running it to 50%. If you need a full charge, ideally the less time the battery spends at 100% charge the better. So I will charge it to 100% just before I go on a long trip.

If you aren't going to ride the bicycle for a while, it is best to store it when it has a charge between 50-75%. Probably worth the effort to run it down from full charge if you know you're going to be storing it.

Hope that helps.

[mrgold35]

How many mile are you planning to ride per week, month, or year?  How many years are you planning to keep  your ebike?

I have two 2016 Rad Rovers with around 4000 miles on each with the older 11.4 Ah batteries.  I do have a spare 11.4 Ah battery I rotate in/out to spread the usage between the two ebikes (and extra spare for long rides).  I've lost a little range from 28-32 miles range new at PAS 2/3 down to 22-26 miles range after +8 years.  I also work commute if the weather is good.

I have no clue on how many cycles I have between the 3 battery packs?  I usually charge 100% if I know I need the range for a long ride of +20 miles.  Most times I just keep the same charge if my rides are shorter and charge up once I get below 20%.  I store the battery at 1/4 to 3/4 range for storage until needed.

I've lost some range; but, I still can do most of what I need to do with my riding routine.  I don't think the 800 cycle limit will be an issue unless you are planning to keep your ebike close to a decade or put +5000 miles per year for 4-6 years straight.

[Altema]

I don?t know where I read it but they say 1 cycle is equal to 100% charging time. Meaning if you have a battery status of 50% and you charge it, that?s half of one cycle. They also implied that a battery life has approximately 800 cycle.

This is interesting because RAD says you should charge your battery every time you go for a ride. My average ride is probably going to be in the 5-10km per ride. Even if I used 10% per ride, it?s going to take multiple charging to reach one charge cycle.

It is nice to think that it?s going to be a long time to reach 800 cycles.

Of course I understand there are other variables that will prevent the batteries from getting a full 800 cycles.
You are correct: 1 cycle is equal to a 100% charge cycle, and a 50% charge is equal to half a cycle. Lithium ion battery lifetime is determined by the total amount of power put through them, and for a 48v 14Ah battery, that means a total of 537,600 watt hours of energy. 24 watt hours per mile is considered typical for an average e-bike, so that translates into 22,400 miles. Avoid the obvious things like leaving it plugged into the charger overnight, and like mentioned you don't need to top it off unless you need maximum range. Sometimes I don't charge my battery for 2 or 3 trips, and I think Rad's guidance to charge every ride is to ensure a good user experience rather than enhance battery lifetime. 

[Naranja_CT5+]

Exactly my point.
Thanks Altema.

[John Rose]

The charging to 80% thing seems consistent with what Apple does with my MacBook Pro.

In macOS Big Sur or later, Optimized Battery Charging is designed to improve the lifespan of your battery and reduce the time your Mac spends fully charged. When the feature is enabled, your Mac will delay charging past 80% in certain situations. Your Mac learns your charging routine and aims to ensure that your Mac is fully charged when unplugged.

[handlebar]

The charging to 80% thing seems consistent with what Apple does with my MacBook Pro.

In macOS Big Sur or later, Optimized Battery Charging is designed to improve the lifespan of your battery and reduce the time your Mac spends fully charged. When the feature is enabled, your Mac will delay charging past 80% in certain situations. Your Mac learns your charging routine and aims to ensure that your Mac is fully charged when unplugged.

My Android phone has that feature. If it found I would normally leave it charging overnight, it might wait til morning to add the top 20%. If fully charging were itself a problem, I imagine there would be an option to charge to 80%.

Radpower batteries have 13 cells in series. Some cells are bound to self-discharge faster than others in the series. Without regular overcharging, I believe the imbalance would soon ruin a battery. At night, I check the voltage, set a timer for the estimated watt-hours needed with an extra hour for balancing. In the morning, I check the voltage, put the battery on the bike, and ride; so it doesn't sit fully charged for long.

In 11 months, I've charged my Radmission 18 times and ridden 1300 miles. I guess I rode and charged my Radrunner similarly in the 22 months before I bought the Radmission. The only reduction in range I noticed came after I let the Radrunner sit several months. Balancing fixed it.

[handlebar]

Of course I understand there are other variables that will prevent the batteries from getting a full 800 cycles.

LiFePO4 is good for 2700 to 10,000 cycles, depending on conditions. its safer because the chemistry inhibits thermal runaway. A 48 volt, 50 amp-hour one costs about $500, with 5 times the capacity of a Radmission battery for about the same price. It weighs 38 pounds, but that could keep your bike from being swept out to sea if you drive off a suspension bridge.

It could prevent theft. Unhook it and lock it under the bottom bracket like a center stand. Unable to pedal off, the amateur thief will phone a professional, who will rush to the scene only to discover that it looks like a lead-acid golf-cart battery, with about 25% of the capacity of LiFePO4. No respectable thief wants a white elephant, except of course the Pink Panther.

[JimInPT]

It could prevent theft. Unhook it and lock it under the bottom bracket like a center stand. Unable to pedal off, the amateur thief will phone a professional, who will rush to the scene only to discover that it looks like a lead-acid golf-cart battery, with about 25% of the capacity of LiFePO4. No respectable thief wants a white elephant, except of course the Pink Panther.

Always appreciate the divergent ramblings; may I ask what you're drinking to fuel that?  My gasbagging often bores even me while I'm doing it.  Like now, for instance.