First Battery Use: Drain It Entirely?

[tomjasz]

No memory, but, I always charge to 100% for the first half dozen charges. Then go to 80 or 90% levels, with full charges every 20 or so. I’ve some old batteries with great performance. Heat is the devil!

 

[tomjasz]

So all this means I should never charge to 100% if I really care about battery longevity?
Most of e-bike owners probably don’t have a charger showing %. By reading the 5 leds on my battery I can probably tell I’ve reached 80% but during the time the 5th led is flashing I don’t really know when I’m close to 100%.
Settling for just over 80% would save me a lot of charging time though as the last 20 seems to take unproportionally long time

Get a multimeter! Those 15cent displays are awful. Many fellas use a plug in timer to charge at lower than 100%.

 

[Gator]

So all this means I should never charge to 100% if I really care about battery longevity?
Most of e-bike owners probably don’t have a charger showing %. By reading the 5 leds on my battery I can probably tell I’ve reached 80% but during the time the 5th led is flashing I don’t really know when I’m close to 100%.
Settling for just over 80% would save me a lot of charging time though as the last 20 seems to take unproportionally long time

I use the timer on my phone and I can estimate charge time. I get pretty close to my target of 90%. Something you might try.

 

[Oldbkr]

Get a multimeter! Those 15cent displays are awful. Many fellas use a plug in timer to charge at lower than 100%.

Good advice... I just checked my 48v battery and it was 53.8 volts. I purposely took a short ride last night to shave some voltage off. Question is ... do I go for the 80% of 48 volts or 80 % of what the charger will bring it up to ~54v ? Please help this confused old man. Thanks

 

[Chris Hammond]

Good advice... I just checked my 48v battery and it was 53.8 volts. I purposely took a short ride last night to shave some voltage off. Question is ... do I go for the 80% of 48 volts or 80 % of what the charger will bring it up to ~54v ? Please help this confused old man. Thanks

Here's a chart that shows ~ charging voltage for a given percent.

 

[Oldbkr]

Here's a chart that shows ~ charging voltage for a given percent.

Thanks for the chart....I forgot about the "fuzzy" math of electricity. Printed and posted. Thanks again?

 

[MetroDuck]

My understanding is that much of this has to do with slowing down the process of 'plating" on the anode/cathode. This will eventually reduce the capacity of the battery. According to people who know, this happens as much as twice as fast at the 100% state than at the 90% state. The build up is based on the time at 100% charge. So, what you don't want to do is charge 100% and let it set for a week at a time.

Because of this I only charge fully when I know I'm going to ride the same or next day and take it from 54 volts down to 53 volts or so. It really helps if your display shows the battery voltage but if not I just ride 4-5 miles which is 10% of my battery range. Surprisingly it also corresponds to about a 10% drop in the usable voltage.

So, as best as I can tell charge to 100% to your hearts desire, just don't leave the battery in that state any longer than possible.

The other thing worth mentioning is that if you only partially charge you should do a full charge once a month or so. The reason is that the last half of the charging period is where the charger balances out the charge on the cells. If one cell is lower than the others it can affect the cutoff point of the battery pack prematurely. If one cell is lower than the rest it in a sense becomes the weakest link. So I'm told. I have an degree in Electronic Technology from long ago and without further reading this last part seems a little suspect to me. But the thoughts on charging to 100% make sense to me. I don't have a firm opinion on "conditioning" the battery by running it down initially. I did discharge mine to around 20% the first three times because I'm pretty sure it wasn't going to hurt anything. But I am firm believer in the harm of leaving your battery at 100% for even a couple of days as the plating is cumulative over time.

 

[MetroDuck]

Here's a chart that shows ~ charging voltage for a given percent.

From what I have read it is 90% of the usable voltage. I have this written down but not accessible at the moment. But I have found a very good correlation on my bike. I know the range is generally 50 miles and so when I ride for 5 miles it surprisingly correlated with the proper battery level.

 

[irishnutter]

I tend to do much of what has been said in previous posts, i.e., rarely let the battery get below 20%, alternate charging between 80-100%, never fully charging and then let the battery sit for days/weeks at full charge. On the latter, if I'm on a cycle where I charged to 100% and for some reason I cannot get out to ride the next day as planned, I actually turn on the lights to just run the battery down a bit.

But I'm wondering if we're all killing ourselves to do what the BMS might be doing for us. It knows the actual health of each cell and the balance across the cells. It could tell us it's charging to 100% and only charge to 95%, or tell us were at 5% while the cells are actually at 15%. And the algorithm could adapt as the cells age. I have the Bosch system which supposedly has a pretty sophisticated BMS. Sometimes I think I worry way too much about the battery.

 

[tomjasz]

BMS balances the pack, not the charger. Better battery builders use a BMS with balance functions built in. 100% will age cells faster. Period.

 

[tomjasz]

I tend to do much of what has been said in previous posts, i.e., rarely let the battery get below 20%, alternate charging between 80-100%, never fully charging and then let the battery sit for days/weeks at full charge. On the latter, if I'm on a cycle where I charged to 100% and for some reason I cannot get out to ride the next day as planned, I actually turn on the lights to just run the battery down a bit.

But I'm wondering if we're all killing ourselves to do what the BMS might be doing for us. It knows the actual health of each cell and the balance across the cells. It could tell us it's charging to 100% and only charge to 95%, or tell us were at 5% while the cells are actually at 15%. And the algorithm could adapt as the cells age. I have the Bosch system which supposedly has a pretty sophisticated BMS. Sometimes I think I worry way too much about the battery.

I’m sure Bosch fellas here can confirm the sophistication of their BMS. It makes sense it would balance but 20%-80% charges would still be valuable.

 

[tomjasz]

Bosch writes, "Bosch batteries are designed for lots of trips, miles and years of service. The intelligent, electronic Bosch battery management system (BMS) protects lithium-ion batteries from excessive temperatures, overcharging, and deep discharge. The BMS checks every cell, extending the life of the rechargeable battery. This makes the time from initial use to the need to replace a Bosch battery very long."

 

[Gustnado]

I bought a used Specialized Levo & I know the previous owner barely rode it as it only had 115 miles on it when I got it . I have no idea how the previous owner charged the battery. My Mission Control app states that the battery health is 100% but not sure how trustworthy that info is.

With that said, my main question is: How bad is it to discharge your battery down to 5 or say 3%? I have done this a few times as my rides ended up longer than anticipated. Does this really hurt the battery or the longevity of the battery? If it does, why doesn't it shut off to protect the system? Just wondering...

 

[PowerMe]

These battery issues and gotchas drive me crazy. It's already a bit of a challenge to figure out what one's accurate range is on an ebike (at least it is for me because it's variable). Then, on top of that, having to worry about the battery being charged but "not too charged." It actually makes the case for the need to have a 2nd battery, which can be an expensive proposition -or- decrease one's estimated mileage to make sure one never goes below 20%. Then, try to figure out how not to ever go above 80% when charging.

More trouble than it's worth? Just start a battery replacement fund from day #1 of ebike ownership and expect to purchase a new replacement battery in 2 years? Bite the bullet and start off with 2 batteries from the get-go and meticulously keep the battery charge in that magical 30% to 80% power range at all times, which you'd at least get the "full expected range" stated from 1 battery.

I say it's frustrating.

 

[Gator]

I agree.
I would think there would be a way to produce a programmable charger that stops at a certain % or senses when the cells are at their most stable for long-term. Seems like it should be a part of the package when a consumer purchases the bike. Maybe some smart electrical engineer will design one and carve out a place in the ebike market.

 

[Alex M]

So all this means I should never charge to 100% if I really care about battery longevity?
Most of e-bike owners probably don’t have a charger showing %. By reading the 5 leds on my battery I can probably tell I’ve reached 80% but during the time the 5th led is flashing I don’t really know when I’m close to 100%.
Settling for just over 80% would save me a lot of charging time though as the last 20 seems to take unproportionally long time

1. Yes, avoid charging it to 100%.
2. Yes, most e-bikes come with a cheap charger that goes all the way to 100%.
This charger from Luna can be set to 80% or 90%: https://lunacycle.com/batteries/chargers/luna-charger-48v-advanced-300w-ebike-charger/.
There are also expensive programmable chargers : http://www.ebikes.ca/cycle-satiator-48v-8a.html.
Or get some 110V timer.

Also, buy a decent multimeter, it's a useful tool for many purposes.

 

[PaD]

These battery issues and gotchas drive me crazy. It's already a bit of a challenge to figure out what one's accurate range is on an ebike (at least it is for me because it's variable). Then, on top of that, having to worry about the battery being charged but "not too charged." It actually makes the case for the need to have a 2nd battery, which can be an expensive proposition -or- decrease one's estimated mileage to make sure one never goes below 20%. Then, try to figure out how not to ever go above 80% when charging.

More trouble than it's worth? Just start a battery replacement fund from day #1 of ebike ownership and expect to purchase a new replacement battery in 2 years? Bite the bullet and start off with 2 batteries from the get-go and meticulously keep the battery charge in that magical 30% to 80% power range at all times, which you'd at least get the "full expected range" stated from 1 battery.

I say it's frustrating.

I tried to get my Specialized Vado 4.0 with the largest battery, 604Wh, but was told that there was no option to upgrade a new bike from the 504Wh. I mean I was of course willing to pay for the upgrade. Only option is to buy a new 604Wh battery for the insignificant cost of $900.
I think that is pretty low level customer service as everybody, incl. manufacturers, know that the larger battery would make it easier to get biking range and well maintaining the battery ( like 80% charging)

 

[tomjasz]

These battery issues and gotchas drive me crazy. It's already a bit of a challenge to figure out what one's accurate range is on an ebike (at least it is for me because it's variable). Then, on top of that, having to worry about the battery being charged but "not too charged." It actually makes the case for the need to have a 2nd battery, which can be an expensive proposition -or- decrease one's estimated mileage to make sure one never goes below 20%. Then, try to figure out how not to ever go above 80% when charging.

More trouble than it's worth? Just start a battery replacement fund from day #1 of ebike ownership and expect to purchase a new replacement battery in 2 years? Bite the bullet and start off with 2 batteries from the get-go and meticulously keep the battery charge in that magical 30% to 80% power range at all times, which you'd at least get the "full expected range" stated from 1 battery.

I say it's frustrating.

Overthinking, one poorly managed but well made battery in 5th season. Sags but does just fine with PAS under 20MPH.

 

[Acey]

If you ever have a battery question, go to Battery University. Great resource. Here's their answer on extending life of Li-ion battery: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

"Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery) "

Clearly, this shows that it is more important to guard against deep discharges than full charges and it can be a double-edged sword if you focus only on the top end of the charging cycle.

A battery charges faster at the beginning and then slows to the point that it will take an hour or more just to top off the last small percentage (<10%). Our battery manufacturer recommends keeping the battery on the charger for at least an hour after the charging light goes out to get a max charge. You can buy a Satiator, which is GREAT, but don't use the fast charge unless you have a fast charge BMS.

Warning: It may cancel your warranty on your battery if you don't use the charger than came with the bike!

Most battery's BMS will have a built in safety protocol that turns the battery off before it drains completely, saving it's "life." Ours is about 8-10% to safeguard against low DOD.

Let me demystify this a bit. I was fortunate to have had my LEVA Technician Training with Ed Benjamin, (THE Ed Benjamin, sorry Ed). He's the e-bike expert's expert and our industry's go-to battery guy. In spite of having all the sophisticated chargers at his disposal, his "common sense" solution is: plugging the charger into a Christmas tree light timer and setting it to turn off after X hours, depending on how much charge it needs. If you are going on a long ride, plug it in to top off a couple hours prior to leaving. My point is, don't overthink it. Get a timer, set it and forget it. Check it later and see how close you guessed. After a few times, you'll be surprised at how consistent it is.

And since I brought up Ed, his personal mission is to get every e-bike owner to use a mirror. Since I shared his knowledge, I should promote his cause.

 

[Alex M]

There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery) "

Clearly, this shows that it is more important to guard against deep discharges than full charges and it can be a double-edged sword if you focus only on the top end of the charging cycle.

Most ebikes use instant current to "guesstimate" the remaining charge. They don't keep a track of watt-hours of spent energy. You slow down and the gauge goes up. Don't know whether calibrating it at the beginning by charging 100% and discharging to 5% (or whenever BMS will shut down) - don't know if this will have any effect on guesstimation work of an average ebike display.

Yes, you must guard it against deep discharges - like 10% remaining charge - when in use.
But, when in storage, the word is that keeping it 100% full is worse than keeping it near empty. Justin the Grin says so . Hopefully at some point technical (and not too complicated) write-ups will be published that explain this.