The real Specialized charging thread.

[Utah Rider]

I've noticed over three years now that when well meaning people post advice about charging Li-ion batteries that they always say don't charge to 100% and don't run until they are dead. Did it ever occur to anyone that maybe Specialized made these battery packs dummy proof? In other words, just because the charger shuts off and the battery app says that it is at 100% doesn't mean that it is really at 100%. When I ride my Levo I often ride until the battery shuts off. A quick voltage check shows 32-33 volts on a supposed dead battery. My gut feeling is that these battery packs are dummy proof and typical Li-ion guidelines are fubar.

I have several three year old battery packs that operate at half original capacity. They were always charged to full. They set outside in my hot truck all summer with my bike and I ride all winter. Although it would be nice if they lasted longer I have serious doubts that any specific charging technique would have made them last longer. Just my thoughts. Feel free to correct my stinking thinking. Cheers

 

[wepn]

I've noticed over three years now that when well meaning people post advice about charging Li-ion batteries that they always say don't charge to 100% and don't run until they are dead. Did it ever occur to anyone that maybe Specialized made these battery packs dummy proof? In other words, just because the charger shuts off and the battery app says that it is at 100% doesn't mean that it is really at 100%. When I ride my Levo I often ride until the battery shuts off. A quick voltage check shows 32-33 volts on a supposed dead battery. My gut feeling is that these battery packs are dummy proof and typical Li-ion guidelines are fubar.

I have several three year old battery packs that operate at half original capacity. They were always charged to full. They set outside in my hot truck all summer with my bike and I ride all winter. Although it would be nice if they lasted longer I have serious doubts that any specific charging technique would have made them last longer. Just my thoughts. Feel free to correct my stinking thinking. Cheers

Simply put, there is no doubt, high SOC and temperature promote calendar ageing.

As for buffers in Spesh packs, I think you're right, there appears to be a low end buffer but little high end buffer.

No packs are dummy proof, at least as far as maximising expected lifespan. Not saying it isn't possible but would add substantial weight to accomodate large buffers and thermal protection.

This paper reveals quite a lot I think.

Calendar Aging of Lithium-Ion Batteries

tl;dr

Interesting that an oversized anode is the solution.

Also not sure which 18650's are used which would identify the chemistry which has a very substantial impact.

Battery chemistry FINALLY explained

Our experimental study of three different types of commercial lithium-ion cells has demonstrated that calendar aging does not increase steadily with the SoC. Instead, plateau regions, covering SoC intervals of more than 20%–30% of the cell capacity, have been observed in which the capacity fade is largely constant. In-depth analyses by DVA confirmed that the capacity fade is mainly caused by a shift in the electrode balancing and not by a degradation of the electrode materials.

Furthermore, our study revealed a strong dependency of calendar aging on the graphite electrode. Lower anode potentials were identified as the main driver of capacity fade during storage periods. In the high SoC regime where the graphite anode is lithiated more than 50%, the low anode potential accelerates the loss of cyclable lithium, causing the shift in the electrode balancing. The comparison of different types of lithium-ion cells demonstrated that the more the graphite anode is oversized, the higher the storage SoC can be without reaching the SoC regime of highest capacity fade.

The degradation due to the low anode potential can be attributed to electrolyte reduction and SEI growth. Signs of aging mechanisms induced by high cell voltage, such as electrolyte oxidation or transition-metal dissolution were observed only in few cases: A substantially accelerated capacity fade occurred for the NMC cells at 100% SoC. For the NCA cells, a storage SoC above 90% caused slightly increased battery aging. The aging behavior of the LFP cells correlates entirely with the anode potential. Moreover, no effects due to anode thickness or charge-discharge history on calendar aging were observed.

Overall, the effects from low graphite potential were predominant in our calendar aging study. To maximize battery life, lithium-ion cells should not be stored at high SoC corresponding to low anode potential. For long-term storage, the graphite anode should be lithiated less than 50%. To determine the respective SoC range of the full-cell, DVA provides the relevant characterization of the electrode balancing without opening the cells to insert a reference electrode or the need for post-mortem analyses.

 

[Utah Rider]

Thanks for posting that info. I'll look it over. A while back I cracked open my Spesh battery pack for a 480wh. There are 40 batteries. Each battery is 3.7 volts. From what I can see they put four batteries together as a cell and then there are 10 cells. I was trying to figure out how they come up with 42 volts. If we can figure this out then we can see what the total voltage capacity is. Here is a print out from a 3yr old battery pack. One cell is much lower than the other cells and the pack will not charge over 87%. The graph on the print out looks to me like maybe a cell is capable of 5 volts? Wouldn't that mean the battery pack would be capable of 50 volts? I have no idea. I was just bored and some times when I am riding I think of weird things.

 

[wepn]

I was trying to figure out how they come up with 42 volts. If we can figure this out then we can see what the total voltage capacity is.

Seems likely to be maximum cell voltage 4.2V x 10 cells in series.

Also it would be extremely helpful for everyone to have that degree of cell level diagnostics available. Individual cell voltages can give you a very good idea of what's going on with the pack.

 

[Utah Rider]

That makes sense but when I look up the part number it says each battery is only capable of 3.7 volts. Maybe I don't know how to read that spec correctly.

 

[wepn]

That makes sense but when I look up the part number it says each battery is only capable of 3.7 volts. Maybe I don't know how to read that spec correctly.

View attachment 25026

I think that's nominal voltage..

 

[Utah Rider]

Ahhhhh…..

 

[MattyB]

Yes, 3.7 is the nominal cell voltage; fully charged is 4.2V. Whilst it is undoubtedly true all the commercially available ebike packs have very safe low voltage cutoffs, there is no way they are cutting the “fully charged” voltage level significantly to improve cell life - that would also reduce range, requiring them to fit a bigger, heavier pack to keep up with competitors with less conservative charging regimens. I suspect “fully charged” is at around the 4.15V/cell level for the vast majority of manufacturers. Shouldn’t be too tricky to check with a voltmeter...

 

[Utah Rider]

That chart I posted shows that at 87% charge one of the cells is at 4139 mv. I wonder if those cells are actually overcharging and that is why the charger shuts down. I would have get a print out of a good battery and see what it says. Maybe next time I'm at the LBS I'll try it.

 

[wepn]

Maybe next time I'm at the LBS I'll try it.

Hopefully Spesh can put cell voltage diagnostics in Mission Control.

 

[ImSundee]

Alot of places actually have 18650s ect going to 4.25V or 4.3V perfectly fine, I have ran 22650 in a 6s6p pack at 4.3 for over a year with no issues.

I actually have a cell tester for checking cell capacity and health properly, and that takes cells from 3.2 to 4.25v

 

[Utah Rider]

Hopefully Spesh can put cell voltage diagnostics in Mission Control.

Each battery is spot welded in four places on each side and the carrier looks like it would have to be broken in order to get a battery out of there. Doesn't look very serviceable to me.

 

[MattyB]

That chart I posted shows that at 87% charge one of the cells is at 4139 mv. I wonder if those cells are actually overcharging and that is why the charger shuts down. I would have get a print out of a good battery and see what it says. Maybe next time I'm at the LBS I'll try it.

No, the BMS will not let a cell overcharge beyond it’s preset level as that could be extremely dangerous. It’s far more likely you have one or more cells that have failed through natural ageing/use/abuse and the charge circuit is sensing that and shutting down the charge. Without looking at the internal wiring or wiring diagram we can’t know exactly how the BMS in the Spec pack is monitoring cell voltages, but it is either checking the voltage of each individual cell or each “bundle” of parallel cells (4 cells per bundle in the case of this pack), not just the total (series) voltage.

 

[ImSundee]

Each battery is spot welded in four places on each side and the carrier looks like it would have to be broken in order to get a battery out of there. Doesn't look very serviceable to me.

It looks like the plastic sides might pop off, but until we see that who knows, taking a cell out that only has spot welds is easy, but you'd need a spot welder to replace it wiht after.

 

[Utah Rider]

It looks like the plastic sides might pop off, but until we see that who knows, taking a cell out that only has spot welds is easy, but you'd need a spot welder to replace it wiht after.

I seem to recall that the plastic cage is glued together with pillars in the middle sections. I think the integrity and rigidity of the set up would be compromised if it had to be broken or cut to get to the batteries. Might not sound like a big deal but just imagine if you were 20 miles from the car and the battery stopped working from vibration. I found a place in the U.S. that says they can rebuild them but do to the age of the whole pack I am thinking maybe it's not worth the risk. Maybe they could replace and upgrade all 40 batteries but I am not sure it would be cost effective. Especially since the electronics have been bouncing around for over three years.

 

[ImSundee]

I seem to recall that the plastic cage is glued together with pillars in the middle sections. I think the integrity and rigidity of the set up would be compromised if it had to be broken or cut to get to the batteries. Might not sound like a big deal but just imagine if you were 20 miles from the car and the battery stopped working from vibration. I found a place in the U.S. that says they can rebuild them but do to the age of the whole pack I am thinking maybe it's not worth the risk. Maybe they could replace and upgrade all 40 batteries but I am not sure it would be cost effective. Especially since the electronics have been bouncing around for over three years.

Na the plastic is usually just there as a holder, with the cells spot welded they become very strong together so much so that the plastic is just there to make it look good.

Cells are about £4-5 each for the decent ones (probably better than stock), so for £160 to £200 a battery it makes sense to me, but you do need the knowledge and a spot welder to do this. My bigger question is if you can get the BMS to reset and forget about the battery it had in it before.

 

[Utah Rider]

No, the BMS will not let a cell overcharge beyond it’s preset level as that could be extremely dangerous. It’s far more likely you have one or more cells that have failed through natural ageing/use/abuse and the charge circuit is sensing that and shutting down the charge. Without looking at the internal wiring or wiring diagram we can’t know exactly how the BMS in the Spec pack is monitoring cell voltages, but it is either checking the voltage of each individual cell or each “bundle” of parallel cells (4 cells per bundle in the case of this pack), not just the total (series) voltage.

What I am saying is that 87% charge is the maximum that the battery will allow before the charger shuts off. I was just theorizing that maybe it was stopping the charge cycle because some cells were at the upper cut off.

 

[Jeff H]

My OCD half gives me a headache worrying about all this battery management crap but my other half says fook it, the sooner it dies the sooner I get a bigger 700 wh.

 

[Rusty]

When I ride my Levo I often ride until the battery shuts off. A quick voltage check shows 32-33 volts on a supposed dead battery. My gut feeling is that these battery packs are dummy proof and typical Li-ion guidelines are fubar.

Voltage is not battery capacity.

 

[Rusty]

There are 40 batteries. Each battery is 3.7 volts. From what I can see they put four batteries together as a cell and then there are 10 cells. I was trying to figure out how they come up with 42 volts. If we can figure this out then we can see what the total voltage capacity is.

They are 'wired' with a mix of Series & Parallel. Can't remember all of my training but if all one you would get high voltage and low capacity and the other high capacity with low voltage. To power the motor and get a a balance of power & torque you need both.

 

[ImSundee]

My OCD half gives me a headache worrying about all this battery management crap but my other half says fook it, the sooner it dies the sooner I get a bigger 700 wh.

TBH these batterys are very resistant to damage, there are 2 main rules.

Dont leave for long times at 0% or 100% - always 60-80%
Try not to leave them out in the cold or in extreme heats when not in use.

Otherwise they will last for a long time.

Also try to minimise on charges, think before you go out if you really need to top it off or if whats in it will be enough.

 

[wepn]

Each battery is spot welded in four places on each side and the carrier looks like it would have to be broken in order to get a battery out of there. Doesn't look very serviceable to me.

I agree it seems as though it isn't serviceable not only because of the design & fragility of the holder assembly but also reportedly due to the bms self destruction on unsynchronised cell removal.

Either way, cell level diagnostics could save some unnecessary haulage to your dealer just to find out it's not fried and the result of something else unrelated to the battery. Also an indication of cell balance even when there's no issue.

 

[MattyB]

What I am saying is that 87% charge is the maximum that the battery will allow before the charger shuts off. I was just theorizing that maybe it was stopping the charge cycle because some cells were at the upper cut off.

I get that, but I don't think it is the reason. The BMS is a balance charger - it can control the charge given to each set of parallel cells, so if one reaches 4.2V it will leave that at a trickle charge whilst waiting for the other (lower voltage) cells to reach the same level. However, if it sees a cells or bundle of cells at (say) 4V but not charging as expected it will shut down the WHOLE charge because that cell is more likely to fail catastrophically causing a fire. Simply put it's the cells that won't take a charge that are the ones to worry about.

 

[MattyB]

They are 'wired' with a mix of Series & Parallel. Can't remember all of my training but if all one you would get high voltage and low capacity and the other high capacity with low voltage. To power the motor and get a a balance of power & torque you need both.

Edit - This is an example to show how to calculate pack capacity only using the info posted by the OP in this thread on pack configuration; I have not stripped down a Levo pack so cannot say if this is actually the case within one of their 700Wh packs or not.

From the OP's post above the pack in the Levo must I guess be 10S4P - 4 parallel banks of 10 cells in series for a total fully charged voltage of 42V, and a capacity of 4x the rated capacity of a single cell. To calculate the theoretical capacity of any pack in Wh simply multiply the series voltage (in tis case 42V) by the capacity of 4 cells in Ah (by the power of maths each cell in the larger Spec pack must have a capacity of ~4.16Ah/4160mah), thus giving a 700Wh battery.

 

[ImSundee]

The pack in the Levo must I guess be 10S4P - 4 parallel banks of 10 cells in series for a total fully charged voltage of 42V, and a capacity of 4x the rated capacity of a single cell. To calculate the theoretical capacity of any pack in Wh simply multiply the series voltage (in tis case 42V) by the capacity of 4 cells in Ah (by the power of maths each cell in the larger Spec pack must have a capacity of ~4.16Ah/4160mah), thus giving a 700Wh battery.

Wasn't it the 500Wh with 10s? and a 700 being 14s?

The best 18650 cells are only 3600mah.

Spesh use 3500mah cells:
Or did they change to 22170s for the 2019/2020?

 

[Doomanic]

Capacity calculation is based on nominal voltage, not peak.

 

[MattyB]

Wasn't it the 500Wh with 10s? and a 700 being 14s?

The best 18650 cells are only 3600mah.

Spesh use 3500mah cells:
Or did they change to 22170s for the 2019/2020?

Apologies, my example above was just really to show how you calculate capacity; I arbitrarily picked a 700Wh an 10S4P config based on the OPs post as I had no more info to go on than that (I don't own a Levo). Apologies, I will update my post accordingly.

PS - Apparently they use 18650s for the 500Wh and 21700s for the 700Wh, so I guess the overall pack config does not change; the increased capacity comes purely from the increased capacity in the individual cells...

YT Decoy 700WH battery - EMTB Forums

 

[RCDallas]

Edit - This is an example to show how to calculate pack capacity only using the info posted by the OP in this thread on pack configuration; I have not stripped down a Levo pack so cannot say if this is actually the case within one of their 700Wh packs or not.

From the OP's post above the pack in the Levo must I guess be 10S4P - 4 parallel banks of 10 cells in series for a total fully charged voltage of 42V, and a capacity of 4x the rated capacity of a single cell. To calculate the theoretical capacity of any pack in Wh simply multiply the series voltage (in tis case 42V) by the capacity of 4 cells in Ah (by the power of maths each cell in the larger Spec pack must have a capacity of ~4.16Ah/4160mah), thus giving a 700Wh battery.

Rated capacity is usually calculated at nominal voltage and not maximum voltage. Specialized is most likely using 2170 4800-5000 mAh cells in a 10s4p arrangement. (700whr ÷ 36vdc) ÷ 4 cells in parallel = 4,861mah which is about what a LG 2170 5000mah cell will supply at 5amps. (20amp max motor draw ÷ 4 parallel banks of 10 cells)

 

[RCDallas]

Wasn't it the 500Wh with 10s? and a 700 being 14s?

The best 18650 cells are only 3600mah.

Spesh use 3500mah cells:
Or did they change to 22170s for the 2019/2020?

I don't believe specialized is using 14s because the higher the voltage the higher rpm the motor will spin therefore you would have different power output from the motor when you changed from a 500Whr to a 700Whr battery. They are only providing higher capacity cells.

 

[ImSundee]

I don't believe specialized is using 14s because the higher the voltage the higher rpm the motor will spin therefore you would have different power output from the motor when you changed from a 500Whr to a 700Whr battery. They are only providing higher capacity cells.

yea now I read that I really wonder what I was thinking when typing that....