E-Bike Battery Guide

FlatSix911

Well-Known Member
Region
USA
City
Silicon Valley
Wooh Nice article! You can also check this article "How Long Do eBike Batteries Last?".
Learn some efficient ways in taking care of your electric bikes' battery.

Thanks for sharing.

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Lightning P38

Active Member

Electrical experts.....question for you.

I like the graphic.

I looked at the web site. They say you should plug your charger into the battery before plugging into the wall socket, because if you plug into the battery after the wall, your battery will get a shock from the live connection. Won’t the battery get the same amount of juice either way? Or are they trying to say there could be a spark and that means you could damage the tips of the plug going into the battery?

They may have the right idea, but not the best description of why.
 

Lightning P38

Active Member

I happen to have a 10 Ah LiOn battery that is 36 volts, so I like this graphic. I wonder if the assumption is you are running pas 5 for the 18 miles. In reality I run at pas 3 out of 5 on average, which would be 60% of the maximum draw of power. For example, on a 14 mile ride my battery will drop about 2 volts. My route is a rail trail, so 2% grade up on first half, and 2% decline on second half.

So if I can get 15 miles for every 2 volts dropped, and I start out at 42 volts and end with 36 volts, I should be able to go 45 miles in theory, and still be at a 50% soc, or 36 volts.

Does that sound right?
 

bob armani

Well-Known Member
Electrical experts.....question for you.

I like the graphic.

I looked at the web site. They say you should plug your charger into the battery before plugging into the wall socket, because if you plug into the battery after the wall, your battery will get a shock from the live connection. Won’t the battery get the same amount of juice either way? Or are they trying to say there could be a spark and that means you could damage the tips of the plug going into the battery?

They may have the right idea, but not the best description of why.
More points to ponder for battery SOH. I would think the BMS has some protection in place for this action.
 
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Ravi Kempaiah

Well-Known Member
Region
Canada
City
Halifax
Why did Apple introduce battery optimization feature in their iOS 13 update?

You can read more about this on their webpage: https://support.apple.com/en-us/HT210512

Apple noticed that most people plugged in their phone overnight and the battery was losing capacity rapidly after a year of constant usage. So, in 2019, Apple introduced this new battery optimization feature along with their iOS 13 .update

The machine learning algorithms at Apple servers know that you plug it in at night let's say 11pm and wake up by 6.30am (an approx routine for most people). So, the battery plugged in for about 7.5 hours. With the new iOS13 update, your phone will charge to 80% when you plug it in at 11.30pm and wait until 5am for the last 20%. From 5am, it will start charging from 80% to 100%.
By the time you wake up, it is at 100% but it has spent much less time at 100% charge. Time spent at 100% charge is bad for battery health.

In my opinion, it is one of the well thought out but under-rated feature of iOS 13 update.


Some press articles are attached below:

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FlatSix911

Well-Known Member
Region
USA
City
Silicon Valley
Why did Apple introduce battery optimization feature in their iOS 13 update?

You can read more about this on their webpage: https://support.apple.com/en-us/HT210512

Apple noticed that most people plugged in their phone overnight and the battery was losing capacity rapidly after a year of constant usage. So, in 2019, Apple introduced this new battery optimization feature along with their iOS 13 .update

The machine learning algorithms at Apple servers know that you plug it in at night let's say 11pm and wake up by 6.30am (an approx routine for most people). So, the battery plugged in for about 7.5 hours. With the new iOS13 update, your phone will charge to 80% when you plug it in at 11.30pm and wait until 5am for the last 20%. From 5am, it will start charging from 80% to 100%.
By the time you wake up, it is at 100% but it has spent much less time at 100% charge. Time spent at 100% charge is bad for battery health.

In my opinion, it is one of the well thought out but under-rated feature of iOS 13 update.


Some press articles are attached below:

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This is definitely a significant improvement in the battery charging algorithm... I wish they would now release an update to charge to 80% (or user-defined) and stop.
 

TomD

Well-Known Member
I skimmed through this thread for thoughts on how low is advisable to discharge but didn't see anything. I've heard that you don't want to drain a battery much below 20%, particularly under load. Thoughts? Is it bad to drain the battery close to 0%, or is it more that you just want to charge (or discharge) it as soon as possible if it gets out of the 20-80% storage range?
 

FlatSix911

Well-Known Member
Region
USA
City
Silicon Valley
I skimmed through this thread for thoughts on how low is advisable to discharge but didn't see anything. I've heard that you don't want to drain a battery much below 20%, particularly under load.

Thoughts? Is it bad to drain the battery close to 0%, or is it more that you just want to charge (or discharge) it as soon as possible if it gets out of the 20-80% storage range?

Yes, it is bad to discharge the battery to 0% especially if you let it remain at zero... recharge from empty ASAP.

Here is a handy charging guide, thanks to Ravi... 20-80% will provide the maximum lifespan (3X of 0 -100%). 😉

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TomD

Well-Known Member
Thanks, but let me rephrase. Is letting a battery drop to zero on a ride and immediately charging it any worse than charging a battery to 100% and immediately using it? Or stated differently, is time spent below 20% any worse than time spent above 80%? My impression was taxing a battery below 20%, (especially under load) was a worse thing, but it seems it might not be so bad in a pinch as long as you charge it immediately.
 

Ravi Kempaiah

Well-Known Member
Region
Canada
City
Halifax
is time spent below 20% any worse than time

Time spent at state of charge (SOC) less than 20% is not an issue at all.
You can leave the battery at 15% for a couple of days without any issues. I would not leave them at 0% for days on end. 15% charge, no problem for a day or two.
On the contrary, time spent at 100% SOC oxidizes the electrolyte a bit more aggressively.
The chart from the University of Michigan captures the very essence of battery care succinctly and clearly. Following that will yield pretty great results (5+ years).

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(Advanced) Tech Talk..

Now, one of the reasons to have a larger battery pack is that you will not be able to empty it quickly.
Discharging a fully-charged battery to <20% in an hour, that is a high discharge rate and that will impact the cycle life lot more than keeping a battery at 10% or 90%.

Scenario 1:

I have a 500 Whr battery and I start at 100% and I ride aggressively and deplete the battery to 10% by the end of 1hr.

Scenario 2:

I have a 1000Whr (500+500 combination), start my ride at 100% SOC, ride aggressively for an hour (just like Scenario 1) but by the end of hour 1, I still have 60% capacity left. Because I am not drawing one battery all the way down. This significantly enhances the life cycle.
 

TomD

Well-Known Member
Thanks, how about scenario 3. Let's say I have a 750wh battery and charge it to 100% for a long ride. I ride it for 4 hours and on the way home it's getting low (25%) and I still have a big hill to climb. One thing for sure, I'm not going to push my bike home, battery be dammed, but how bad is it for my battery to use up a good portion of that last 25% in 30 minutes?
 

Ravi Kempaiah

Well-Known Member
Region
Canada
City
Halifax
but how bad is it for my battery to use up a good portion of that last 25% in 30 minutes?

Not an issue. You can draw it down to single digits safely.
There is already a low voltage cutoff built into most batteries.
Once you draw them down to single digits let's say 5%, it is good to charge it back up to 30 or 40%

This feels like micro-managing and it is true. But, if you are a high mileage rider (6000+ miles a year), you will certainly see benefits.
 

tomjasz

Well-Known Member
Heat is the biggest enemy. As cells go they are rated in spec sheets. I NEVER go to
Discharge Cut-off Voltage, EVER. But qualifying with data is near impossible for the average rider.

For example 35E.
Discharge Cut-off Voltage is for 14s is 37.1V.
Discharge Cut-off Voltage is for 13s is 34.5V.

I use 40V and 38V. I plan my rides or carry a spare 3p battery pack rather than beat on my primary packs.