Li-ion Battery Life

[Fat Girl]

Battery Life

The eZee NiMh battery is more suitable for steep hills as it doesn't cut out under excess load, and it would do your journeys ok. The battery is £190, but unfortunately you'd have to have an NiMh charger as well. The set of NiMh battery and charger costs £250.
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Flecc
I am riding the ezee forte with a Li-ion battery, which strains in the amber range for about 2.5 miles of hill climbing twice a day. From what you say about battery life and hill climbing, I can expect to replace it in a few months... have i understood you right there? Can I use a NiMh battery on this model? This week, it hit the red zone for the first time up a hill, is this a bad sign? Certainly the motor strains, despite my pedalling contribution and 2 rests on- route to the summit.

 

[flecc]

No,that's not a problem Mil, it's the way in which the meter works.

It detects whats in the battery by measuring the voltage, and that's fine while the bike is standing still with the throttle shut. However, when the motor is running and draining some current the voltage drops a bit.

When going uphill and the motor is working harder, the voltage drops more, so the meter reflects that with a drop in the lights. As the battery ages and gradually loses capacity, you'll see more occasions of the lights dropping to red.

As far as possible it's best to keep out of the red by a mixture of a bit less throttle and a bit more pedal effort.

What counts most though is what the lights say after you stop. If the meter is back on green, the drop to amber or red was just due to the motor drain, not the battery charge low.

Eventually a situation arises when it goes to red so quickly on climbs due to age and capacity loss, the voltage drops to a point where the safety cut-out operates. By switching off and on again, you can restart then, but you'll need to pedal harder to avoid it cutting out immediately again. The battery is finally useless when the cutting out prevents sensible use.

How long you get from the battery depends on the usage. They can take around 500 charges, so if used every day five days a week, it could last a couple of years. Obviously the many users who don't commute on them and use them for shopping trips and the like can get longer.

All eZee models can use the NiMh battery, but it's necessary to use the NiMh charger with them. They also take about 500 charges so won't necessarily last much longer, but they never cut out, just slogging on as long as they have some current to give.

The disadvantage is that NiMh have to be quite fully discharged from time to time as I've described in the NiMh articles about Charging and Discharging NiMh batteries.
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[skoolrun]

Poor capacity

I had my LI ion battery checked by 50cycles this week as I had a feeling that it had a reduced capacity but as I charge it after each run, about 8 miles, I could not be sure. I was advised that the capacity was now down to 6.3 Ah which was a bit of a shock or not . The battery was new in April this year however, as I am the second owner I do not know its specific history prior to my ownership. I was told that it had been charged about 20 times and that the bike had covered about 700 miles which I thought was a bit optimistic at the time. I must now seriously question these figures as I have only added about 200 miles on my ownership. I would hate to think that this the normal state of a well treated battery after just over 6 months. Note the just over 6 months as it was really good news when I was advised batteries only have a 6 month warranty!! In fairness to 50cycles they did assist on the price of a replacement and said they would take it up with the manufacturer’s, but it still hurts. Ah well I guess I now have a spare battery or is it 6/10ths of a spare Even bleaker I was unable to get a NiMh as a replacement as these now appear to be as rare a hens teeth.

 

[flecc]

The cold weather will have made things much worse, the Li-ion I'd been using satisfactorily in one of mine suddenly started cutting out with the onset of the cold weather. Unfortunately lithium batteries age whether used or not, so your's might still have had it when warmer weather returns next Spring.

Ironically cold storage at between 20% and 40% charge can slow that ageing right down, at zero degrees it's only 2% loss each year, so if you put the battery into a shed or similar in a cold corner and away from any warming by winter sunshine, that might preserve some use in next years warmer weather. If you have access to a very large fridge that doesn't go below freezing, in there it will hardly age.
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[helHH]

storage temperature

Hope this is the right thread, as the last post was a long time ago... Is this still the main thread for Li-Ion batteries?

I just got my folding Izip and in the manual, it says room temperature is best, and NOT to store the battery below 50F / 10C and never to let them go below 32F / 0C.

But Flecc says cold is best...?

Any insights?

Thanks!

Hel

 

[flecc]

For batteries in use, room temperature is indeed fine.

It's for long term storage when not being used that cold is better, the amount to which remaining life is lost reduces as temperature drops to zero degrees. However, they must never be allowed to drop below that and freeze.

Th ereason behind what Izip are saying is that warmth is best for output and performance when in use, a cold battery delivers low current. In general between 20 and 30 degrees is best for current output.

So this confusion which often crops up is between in use and storage, the two completely different. For example I only use my laptop on battery a couple of times a year, so the rest of the time it's lithium battery is in the fridge. That's why it's still working perfectly at five years old. If I used the laptop on battery regularly, it's battery would never go into the fridge.

You can read more about lithium battery life and temperature effect on this webpage:

Battery University
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[helHH]

Aaah, thanks Flecc, that makes sense.

 

[Robin Frame]

Battery life and range

I have a new Panasonic battery for my Gazelle Easy Glider. It's a warranty replacement for the original battery which has "lost a cell". After charging it, the snow came and I didn't get a chance to test it till today. The last LED was flashing after 5.67 miles.

Any ideas what I'm doing wrong? The batteries are kept in what is essentially a pantry, probably around 12 to 15 degrees, never hot, never cold. Do I need to follow the advice of chilling them right down?

Apart from the batteries the Easy Glider is a total delight. We bought a second one in August. Its battery now seems to have lost a cell too.

 

[flecc]

Definitely don't chill the batteries right down Robin. The important thing is to condition them when new, and whenever a problem crops up, repeat the conditioning to restore the battery to full health.

Conditioning is fully charging, then using the battery until the last LED starts the fast second stage flashing. When the battery is new and first used, this should be done twice.

You can read about that in full on my Panasonic website here:

Running in the battery

For any problems you have crop up on your Gazelle power unit and battery in future, you can always refer to the index on my Panasonic site here, using the New Type Unit heading:

Panasonic Unit Advice Index Page
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[Robin Frame]

Thanks, Flecc,


I'll read it all and then have a bash at running in the battery! Instructions from Gazelle were a bit minimal. I charged the battery up again yesterday afternoon, and it seemed to take about as long as usual.

Robin

 

[john]

Conditioning of new Nickel based batteries is needed to balance the cells. For new batteries with a BMS, like most Lithium based, this shouldn't be necessary, the only purpose being to reset the fuel gauge.

 

[alex_h]

Though there's about a decade of experience with small Li-ion cells, there's very little knowledge of the large capacity multi-cell batteries that we use. The first of them are reaching a year old now, and as previously predicted from laboratory testing, many reaching that are showing around 33% capacity loss, just over 35% in one case I know of. In theory in the worst conditions, the loss could reach 66% in a year.

The worst conditions are using the entire charge every time to empty, and both using and storing the battery between uses in high temperature conditions. The best conditions therefore are using the battery for a short distance each use and immediately recharging, together with operating in cool conditions with cool battery storage between uses.

The percentage capacity loss in each year is of the capacity at the start of each year, not the original capacity, so the actual loss reduces over time. Here's a chart showing what 33% annual loss means for a 10 Ah Li-ion battery with range losses as well. Pick the column starting closest to your range when new:

Year - - - Capacity - - - Range 1 - - - Range 2 - - - Range 3

1 - - - - - 10.0 Ah - - - - 30 miles - - - 20 miles - - - 15 miles
2 - - - - - -6.7 Ah. - - - - 20.1 - - - - - 13.4. - - - - 10
3 - - - - - -4.5 Ah. - - - - 13.5. - - - - - 9.0 - - - - - 6.7
4 - - - - - -3.0 Ah - - - - - 9.0. - - - - - 6.0 - - - - - 4.5
5 - - - - - -2.0 Ah - - - - - 6.0. - - - - - 4.0 - - - - - 3

The range can restrict someone's effective battery life, a commuter doing 15 miles each way/charge could barely reach year 3 if starting with a 30 mile range and couldn't complete year 2 if starting with a shorter range, these already born out in practice in some cases.

An overriding factor is the number of charges the battery can take. The concensus is about 500 charges, some claiming 800, so obviously that could limit the length of life. Regardless of the range they achieve, if the bike is used daily for 300 days of the year, the life could again be limited to less than two years before the battery was unfit for further use due to the number of charge cycles.

Another limiting factor is the terrain. In very hilly country with a rider not making sufficient contribution, overload cut-outs can be experienced on bikes using powerful motors, and this gets worse as capacity reduces, therefore limiting the life to the point where the cut-out frequency becomes intolerable.

Additionally, lithium cells start losing life from the moment of manufacture, whether used or not.

All that looks a bit gloomy, but conversely, someone using a bike two or three times a week for short distance shopping or social trips in moderate terrain and charging after each use could use a battery for several years and be very happy indeed with it's life.

Only time will enable us to fully know what to expect with these batteries, and during that period further advances may make that knowledge unnecessary anyway. Meanwhile our best protection is the availability of the highest possible Li-ion capacity at the outset and I'm hoping to see some progress there for our existing bikes.
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Hi Flecc,

It is so interesting to see all that figures and facts. can you please tell me if that is from your own research or the figures are taken from somewhere?

 

[Robin Frame]

improved range

Hi Flecc,

I seem to be messing up where I put my posts so this may appear twice.

Followed your advice and ran the battery down to single LED flashing. What happened was to begin with the battery was normal, doing over 6 miles before it reduced to two handle bar lights and then another almost 7 miles BUT then it went straight to flashing mode missing out the single constant LED which usually gives me about a final 6 or 7 miles. (The LEDs on the battery were also reduced to one and flashing.)

It's on charge again - looks a promising way to sort the problem. Maybe a couple more goes and it will be sorted.

Robin

 

[Robin Frame]

improved range

Hi Flecc,

Some advance, also stumbling a bit with the forum putting replies in the wrong place!

Followed your advice and ran the battery down to single LED flashing. What happened was to begin with the battery was normal, doing over 6 miles before it reduced to two handle bar lights and then another almost 7 miles BUT then it went straight to flashing mode missing out the single constant LED which usually gives me about a final 6 or 7 miles. (The LEDs on the battery were also reduced to one and flashing.)

It's on charge again - looks a promising way to sort the problem. Maybe a couple more goes and it will be sorted.

Robin

 

[flecc]

Hi Robin. If you have a double post again like this, yiou can go into Edit, then select Delete, Delete this post etc and get rid of one.

I hope the battery does come good with conditioning, these Panasonic ones usually do.
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[flecc]

Hi Flecc,

It is so interesting to see all that figures and facts. can you please tell me if that is from your own research or the figures are taken from somewhere?

It's a mixture of my own research and experiences, blended with the accumulation of gathered information from many owners over time, then coupled with technical and experience information from the battery and e-bike companies.

It cannot be precise since the circumstances of each riders usage and bike model power drain vary so greatly, but it does give a rough guide as to what might reasonably be expected.
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[Robin Frame]

Battery better, controller affected.

Following Flecc's advice, I now have the battery acting like new. Well it should, it is new, if in fact a warranty replacement. The range is about 20 miles with lots of steep valleys and long hills.

But now the controller on the two year old Easy Glider acts oddly, showing a dim glow on the "eco" light when "norma"l is selected and both "normal" and "eco" glowing faintly if "boost" is selected. Trying the battery on the newer Easy Glider (we have two) does not replicate the fault. I also think I may be detecting a little "snatching" in the power delivery.

The bike still has a few days of warranty to go but no local dealer since Electric Cycles in Edinburgh gave up trying to deal with Gazelle.

Robin

 

[flecc]

That sounds like it could be a minor problem with the electronics in that older Easy Glider Robin. They were originally specified for the 8Ah batteries, later specified for the 10 Ah. It may just be something to do with some mismatching on the older unit.

The snatching is a different problem that the newer units are prone to, and there's several causes, all associated with the chain drive and idler. This page on my Panasonic site has all the details on those problems and how to sort them out. To diagnose the problem if it gets worse, try the fourth heading down:

Drive snatching
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[Robin Frame]

"older" Easy Glider

hi Flecc,

Although the Easy Glider is older, it is one of the first of the 2008 models and the handlebar controller is the up-to-date one. I trialled the 2007 model and I remember it as having a different, more limited, controller along with the smaller battery.

I'm waiting for a response from Gazelle and I'll tell the forum what they say. Gazelle have a great product but they perhaps aren't very well "geared up" for UK sales and service as yet.

Robin

 

[flecc]

Thanks Robin. You're right, for an excellent product Gazelle really haven't supported it well in the UK. I think much of the trouble is the e-bike sales boom in the Netherlands and Germany where they have been selling in large numbers, the much weaker UK market not interesting them very much at present. The quality Sparta e-bikes have similarly suffered from inadequate support.

As those markets reach saturation they may get more interested in the UK.

Another factor is the way Gazelle's interest and marketing has moved away from the Panasonic system in favour of their hub motor Innergy model.
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