Rad Power Bikes Chat > How To Information

How to maximize Battery Life

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rpwbike:
Hi all.  Have ordered a Rad Commuter Bike for myself, and a Rad Step Thru Mini for my wife.  My bike should be arriving within the week.  So I have been watching videos, trying to learn how to care for my bike and maximize the enjoyment of riding it.
Several videos I have watched mention some interesting ways to maximize battery life and range. 

Maybe some of you have had experiences that can shed some light on these tips.

 The most interesting tips I have seen regarding battery charging and extending its life (and the ones I am unsure about) are-

1) Don't charge your battery to 100%, but rather stop at 80% or so.

2) Don't charge your battery immediately after using/discharging it.  Wait an hour or so for the battery to 'rest/cool down', then charge it.

3) If you are going to store your battery for a few weeks or longer, don't store it at 100%, but rather 60%.

I welcome all constructive comments/experiences.

Other tips I have seen/read about Lithium Batteries-

Keep away from extreme temperatures.
Don't keep charging it once it reaches 100%.
Slow charging better than fast charging, as heat is minimized.
Don't allow your battery to get soaking wet or submerged in water.
Don't run the battery down to close to 0% before charging it.

RadJohn:
When you get your Rad you'll find out that charging to 60% or 80% is not as easy as it is on a Tesla because the "brick" charger that Rad supplies only terminates at 100%, so if you want to try charging to lower voltages to get some extra battery life you'll have to rig up some PITA way to read charge voltage on your own, monitor it and manually terminate at the appropriate value (or buy something like a Luna Advanced 48V Charger or a Grin Cycle Satiator).

As for some of the other points, Rad still recommends periodic balance charging their OEM batteries for up to 12 hours, even though the Battery Management Systems (BMS) built into many other modern Ebike batteries make that unnecessary  (they balance on the fly).

As for not running the battery down close 0%,  phooey, how else am I going to find out if I can get 60 miles out of my Mini (55.5 is my best so far, to one bar flashing+). It's my bike and if I want to do that three or four times a year, I will, and I'm not going to let the possibility of a few extra months battery life stand in the way of having fun.

rpwbike:
Thanks RadJohn!  Good info!  Agree with you, there will be times when I run the battery down to (close to) 0%.  That should not be a problem. 

Like you, I will be curious to see how many miles I can go before exhausting the battery.  And then I will attempt to beat that number!  LOL.

DickB:
Deep discharge does also reduce battery life. batteryuniversity.com cautions against it.

Battery charge limits can be set by monitoring either voltage or current. I've monitored both while charging to get an idea of how the Rad charger operates. Of minor concern to me is that the charger continues to supply current at a low level even after the charge light turns green.  Voltage peaks at 53.8V. Current drops to only 20 mA but doesn't shut off after several hours - this may be in order to achieve the balance charge. If not balance charging, Rad recommends disconnecting the charger as soon as possible after the green light, but that is not always convenient.  I have asked Rad via email why they don't stop charging altogether; I have not yet gotten an answer.

I'm going to build a simple circuit to plug in between charger and battery to monitor current and automatically disconnect at a desired current, and give that a try.

RadJohn:

--- Quote from: DickB on May 04, 2021, 05:58:27 PM ---Deep discharge does also reduce battery life. batteryuniversity.com cautions against it.
--- End quote ---
An occasional foray into the lower limits of what our batteries can provide isn't going to kill them because there are low voltage cutoffs in BOTH our batteries and our controllers.  When our Watt  display goes to 000, there is probably still somewhere around 39 or 40 volts left in the battery, which is ~3.00 to 3.08 volts per cell, which isn't particularly harmful if only done occasionally (<2.5 volts/cell is generally considered the lower limit to avoid more rapid/permanent damage to most Lithium Ion cell chemistries ).


--- Quote ---Battery charge limits can be set by monitoring either voltage or current.
--- End quote ---
Almost ALL modern Lithium Ion battery chargers are CC>CV, meaning that they maintain a constant current (like the 2 Amps for the Rad OEM charger) until a target voltage is reached (typically 54.6V for a 13 serial cell, 48 volt nominal Lithium Ebike battery pack), then they hold that voltage and let current decrease, until either shutting off completely at ~<50mA or providing a low trickle charge current as observed with Rad chargers (again, a sign of a BMS that is behind the times).

For those wanting to understand what to expect from their Rad batteries:

A fully charged battery will be able provide up to 750 Watts of power in Assist Level 5, as observed on the LCD Display.

As power is consumed, the maximum available Wattage shown on the LCD display will decrease, with only ~700, then ~600, then ~500, then ~400, then ~300, then ~200 , then ~100, then ~50, then ~25 maximum Watts available in Assist Level 5 as the Battery Capacity  Bar count on the LCD display drops from 5, to 4, to 3, to 2, to 1, then 1 Flashing.

Keep going and the final single bar will start flashing. Assist Level 5 will quickly become more like 2, then 1 was on a full battery, and the Wattage readout will eventually go to 000 and you're done.

If you're pushing for maximum range using pedal power and Assist Level 1, the LCD Watts display will eventually also go to 000, but when it does, increasing to Assist Level 2 will bring back ~25 or so Watts until the the LCD Displays zeroes again, but bumping up to Assist Level 3 will bring back ~25 Watts again, and so on. This makes the end a little less surprising, if not as sudden.

Time to swap in a fresh battery for the trip home...

And FWIW, I do charge to 80% most of the time, but I have another battery that is a 17.5Ah, so at 80% it's 14Ah, which is the same as the Rad OEM battery at full charge (and it balances on the fly). I also make it a point to charge fully depleted batteries as soon as I get home, as it's best to not leave them sitting around in that state.     
   

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