Charging Question: Every Time You Ride?

Noreen

Member
I have an ST1, and was wondering whether I should charge the battery every time I ride? I have been doing this, but today I only ride to the store and back - less than 8 miles. The battery is showing 3 bars and was fully charged when I started.

Thank you,
Noreen
 

J.R.

Well-Known Member
Thank you - I probably should have found that myself. Appreciate your pointing it out to me.
Hey Noreen,

Very valid question!!! Battery technology has changed many, many times in the past 15 years and when I started looking at ebikes a year or so ago, I had the same question at the top of my list. Good question, good concise answer JoePah! Info many new ebike owners will want and need to know.
 

Noreen

Member
Great tip bluecoat. Since I charge in the basement, the battery is generally at room temp before I start charging. I am not yet commuting, because I have yet to figure out how the logistics. I would like to, but that may have to wait for Spring.
 

biknut

Active Member
For lithium battery's, depth of charge is more important than the number of charges. Your battery will supposedly last longer with a lot of little charges, than fewer deep charges. The thinking is if you charge after every ride your battery will last longer , because the depth of the charges won't be as much.

It's also considered good practice to let your battery cool off before charging.

This is probably the case with LiFePo4 battery's but other chemistry's like Manganese or Cobalt may have slightly different property's.
 

JoePah

Well-Known Member
For lithium battery's, depth of charge is more important than the number of charges. Your battery will supposedly last longer with a lot of little charges, than fewer deep charges. The thinking is if you charge after every ride your battery will last longer , because the depth of the charges won't be as much.

It's also considered good practice to let your battery cool off before charging.

This is probably the case with LiFePo4 battery's but other chemistry's like Manganese or Cobalt may have slightly different property's.

I'm pulling the bullshite card that limiting the depth of discharge will improve battery life. No offense to you, since this is the current thinking and recommendation from bike shops etc.

In 2009 I bought a A2B Metro, LiMn 36v11 ah.. I ran that battery down to low voltage shutoff every single time (0%)... Lost about 10% of range per year, over 5 years. The first year was less, and it progressively degraded. Total around 700 charge cycles.

For the last year I rode a Stromer Elite.. Only ran it down to 0% twice... Most of the time I recharged when the battery state of charge was 30-70%.
After 1 year, 200 shallow charge cycles and 2000 miles, lost 20% of range.

As far as I'm concerned it makes no difference how far you run down your battery before charging.
 

Shea N Encinitas

Active Member
A buddy just bought some of those Lith-Ion cells like you see in fork lifts, gold carts, etc. I read the manual and the manufacture indicates 70% discharge will result in 3000 charge cycles VS 1000 discharging to minimum voltages. I'm clearly holding different cards. -S
 

JoePah

Well-Known Member
There's plenty of discharge graphs from battery manufacturers for depth of discharge and capacity and they all show longer battery life if you limit charging to less than 100% and discharging to greater than 0... Just not my experience!
 

Shea N Encinitas

Active Member
Yeah well human and environmental factors VS lab conditions, real world app & holographic realities are to blame. Material migrating to the anode or cathode is the gist of it. -S
 

biknut

Active Member
There's plenty of discharge graphs from battery manufacturers for depth of discharge and capacity and they all show longer battery life if you limit charging to less than 100% and discharging to greater than 0... Just not my experience!

My experience with Lithium battery's is pretty limited, so I definitely don't claim to be an expert.

I've also read that limiting maximum charge extends battery life, but wouldn't discharging to greater than zero be the same as reducing the depth of charge? In other words, don't discharge all the way down to zero?

I'm under the impression that Stromers use 18650 battery's, but I don't know for sure. Most of the 18650 I've looked at we not LifeP04, but usually Manganese, or sometimes cobalt.
 

Nebster

Member
All of the (common) lithium chemistries perform better if the SOC is kept in a safe energy band, say roughly between 20% and 90% of capacity. All (common) lithium chemistries also are happiest at in a thermal band roughly between 0C and 70-ish C.

Get too hot, and charge transfer becomes very inefficient. Get even hotter and thermal runaway happens... see: Boeing 787. (In cars with huge, expensive packs, most systems will actively cool the batteries when needed to keep them in a safe regime.)

Get too cold, get above 90% SOC, or both, and the lithium electroplates the battery anode... permanently. As more and more of the anode is plated, the total capacity of the battery falls off. Many management systems will reduce or stop charging in the cold to prevent this damage. (In cars with huge, expensive packs, most systems will actively heat the batteries to keep them above the danger zone.)

Get too far below 20% SOC, and the anode itself starts to dissolve into the electrolytic fluid, kind of the opposite of the plating described above. Those copper ions will redeposit all over the place when the battery warms, making a big mess of things, reducing capacity, and, ultimately, taking out the battery, because copper is conductive, and so the battery begins to short circuit.

So the trick is to keep the battery between freezing and hotter-than-hottub-hot, and between ~20% and ~90% of its nominal charge capacity, always. In that range the lithium reactions are very reversible and should be able to go back and forth many, many times. Each time you wander outside of those zones, irreversible degradation will occur.
 

opimax

Well-Known Member
I wonder how the percentages are determined on my somewhat closed system on my Stromer. I have a light that says done when charging, hard to stop at 90%. Also I wonder if the battery cells in a different branded battery use the same voltages for the fully charged and discharged states.

Does 1 company set smaller ranges so one automatically gets less ride time but offers more life cycle charges? This would make for actual different "90%" ...

Mark
 

bluecat

Well-Known Member
IMHO, riding a Stromer should be fun!

Since 2009, I do it on the hedonistic way. Maximum range at maximum speed. Commuting became pleasure. My battery is always charged at room temperature until 100%. The battery is used at -15ºC and at 35ºC as well. The price I had to pay was the difference between my old 360Wh an the new 522Wh battery (replacement under warranty).

I believe, If I want to drive a Porsche, I should not complain about the fuel consumption.
 

opimax

Well-Known Member
I must admit I am with Bluecat. This bike is my only money sucking hobby. I gave up stereo and home theater improvements. I will buy a battery if needed. I go out w/3 batteries, If I know the timing of my trips i will divide by 3 and use each battery equally. If I don't know the total time i don't think twice about running them out till it shuts off. I tend to go to eco for the last bar or two to make it last.

That being said i certainly want to do the best possible for the batteries. and when working w/stats in general we need to be sure we are comparing apple to apples, they can be so misleading. Does anybody know if companies are playing w/stats or using the same batteries w/different BMS to make their product look better or different?

Mark
 

Nebster

Member
I wonder how the percentages are determined on my somewhat closed system on my Stromer. I have a light that says done when charging, hard to stop at 90%. Also I wonder if the battery cells in a different branded battery use the same voltages for the fully charged and discharged states.

On a modern, high-end bike like a Stromer, it's almost for sure that when it says "100%" on the display, the real SOC is being managed to something lower than the absolute peak. It doesn't take too much backing off from crazy-full to realize a lot of benefit and get good cycle counts out of lithium.
 

bluecat

Well-Known Member
@opimax & @Nebster

I'll come back on this later; meanwhile my posting in german.

 

JoePah

Well-Known Member
Will say that the Stromer battery is about 30% lighter than the A2B Metro battery, same capacity 36v11ah... Don't think the Stromer battery will last 5 years though... not at this rate.

Doesn't matter.. Think I'll just buy a bigger one from Crazy Lenny!