Lithium battery life

[Grelinette]

Hello everybody

I think this page on batteries will interest some of you.

The company Ozo-Vehicles-Electrics which provided me with some of the materials for the hybrid horse-drawn car project has just informed me that it had just published a page of advice and comments on its site concerning Lithium batteries , with in particular some very interesting remarks on the parameters which influence their lifespan and concerning the role of the participants in the chain: manufacturer, assembler, distributor, user.

It's here : http://www.ozo-vehiculeselectriques.com ... lectriques

Good reading

[Grelinette]

These explanations seem to me interesting and important enough to publish them.

Lifespan of a Lithium battery for electric bike:

This depends on the methods used by the following actors:
The manufacturer, assembler, distributor and user.

Role of the manufacturer: The lifespan of a battery depends first of all on the quality of the cells which compose it. The purer the electrolyte in the cell, the better the life of your battery. This is why we choose Samsung cells because the large manufacturers can guarantee maximum purity of the electrolyte.
Many Chinese cell manufacturers do not use the methods to design 100% "pure" cells. As a result, the more polluted the electrolyte, the worse the life of your battery. It is not uncommon to see batteries of Chinese origin having lost 50% of their capacity after only 6 months.

Role of the assembler: The batteries consist of several cells assembled in series and / or parallel and a BMS. The assembler must absolutely respect certain methods, the most important of which is to build a battery only with cells from the same production series and having equivalent internal resistance. Although essential, these points are generally not respected by the assemblers because it requires flawless logistics, time and tools. If the cells of your pack do not have the same internal resistance, it will create over time an imbalance which will cause a significant decrease in autonomy and performance. The choice of BMS is also very important. The first price batteries have a BMS which simply monitors the maximum and minimum voltages while we use BMS on our batteries which monitor the temperature of the cells and which have a balancing stage guaranteeing perfect maintenance of the homogeneity of your battery. A BMS equipped with a standby mode will prevent the battery from being discharged during prolonged storage.

Role of the distributor: Another criterion is the storage time and the storage method used by the distributor. Before being sold to you, a battery could very well have been stored for more than a year by the seller (which is often the case in electric cycle shops) and it could also have been produced a year before this seller receives it, which means that you buy a battery that is already two years old. This is a very common case.

Another important point is the way the seller has stored their batteries. Have these simply been put in a corner while waiting for the future buyer? have they been stored under the storage voltage recommended by the manufacturer? Were they loaded on time? these are some important points that will matter about the life of your battery.

At OZO we have set up logistics to resolve all these points and guarantee you maximum performance for your batteries. To avoid keeping the batteries in stock for too long, we launch manufacturing every quarter, which means that all the batteries we sell were manufactured maximum 4 months before the sale. The flip side is that we occasionally run out of stock.

User role: You too have a role to play in maintaining your battery performance over the long term. To do this, simply follow the instructions for use and storage that will be provided with your OZO battery.

Estimated lifespan if all the above conditions have been met beforehand: The lifespan of Lithium batteries is given in "number of cycles"; a cycle being a discharge and a charge.
For the Samsung cells that we use in our battery packs, Samsung announces a drop of only 10% in capacity after 300 cycles and 30% after 700 cycles (under 1C). Note that the time factor also comes into play and that these data are valid for daily use and not for 300 cycles carried out over 5 years. With hindsight we estimate that the exchange of the battery should be considered after 2,5 to three years. This does not mean that after three years your battery will no longer work at all, but it will have lost a good part of its performance.
Another factor that influences the life of your battery is the rate of discharge under which you use it. For example for Samsung 22P cells, the loss of capacity after 300 cycles is 10% under 1C (under 10A continuous for a 10Ah battery) and 20% under 3C (under 30A continuous for a 10Ah battery).

Our advice: As you can see, many parameters influence the life of your battery. Given the price of a Lithium battery and the number of unscrupulous sellers on the internet, we advise you to check the points mentioned above before your purchase and not to be tempted by a low price because a poor quality battery which will have been bought 30% less than a good quality battery but whose performance will start to drop after the first months of use can ultimately cost you 2 to 3 times more expensive than a large brand battery. It is also important to know if the seller is able to provide after-sales service for the products he sells, which is unfortunately not the case all the time.

At OZO we strive to offer you quality batteries and respect all phases of battery life, from manufacturing to recycling through assembly and storage. We also have all the tools necessary to provide after-sales service on your Lithium batteries if necessary: ​​Discharge bench, Charging bench, Balancing bench, Storage station…

source: http://www.ozo-vehiculeselectriques.com

[I Citro]

This information should be nuanced and clarified a little.

The name Lithium encompasses a multitude of technologies with very different performances depending on the materials of the electrodes, their nature, their structure ...

The article you are quoting applies to Samsung brand LiPo (Lithium Polymer) batteries.
These batteries are characterized by a good weight / power / volume ratio.
Their management is however delicate and their longevity is correct.

Lithium Manganese, Lithium Iron Phosphate batteries, etc. exist for VAE kits (excluding lead batteries and Nickel Metal Hydride).
Some of these batteries even advertise up to 2000 or 3000 charge cycles, and calendar longevities of the order of 8 years ...

It is estimated that there are only a handful of "powder" manufacturers.
Samsung in fact, I believe part, and the mastery by a single operator of all the stages of transformation from the raw material to the finished product is a guarantee of quality ...

Lithium is a hydrophilic material which must therefore be isolated from the ambient air from which it "pumps the water molecules" (manufacture in a controlled atmosphere).
The manufacture of the "pocket" containing the electrolyte and the quality of the material of this pocket is therefore essential, as is the airtightness of the electrodes which allow the electrical connection and which "come out of the pocket".

It has been observed that batteries (I am thinking of LiFePo4, in particular), which had very high performance during tests and rapidly (between 1 and 3 years) lost their capacity due to "porosity" of the casing .

Energy storage will be the major challenge of this century; batteries, capacitors, hybrid battery / capacitor or other systems to discover have not finished shaking up the current situation.

Every week, several scientific announcements present extraordinary discoveries ... I am in the process of equipping my electric car with Lithium batteries (LiFePo) bought in China at less than 300 € per kWh (excluding BMS) but whose patents ( Franco-American) date from the 80s ...

I make no prognosis, I strive with the help of a prominent member of this forum, to manage them as best as possible to make them last as long as possible.

[chatelot16]

read what is said about the life of the batteries is interesting, but what is even better is to do something to increase this life

I knew that lithium is destroyed by water, but had not thought that the tightness of the battery could limit the lifespan

it could be interesting to make a double envelope around the battery pack and fill this envelope with a perfectly dehydrated gas: it would be particularly interesting for the lipos whose envelope is only a plastic film

the lipos are flexible and tend to disintegrate in the event of vibration ... it seems that their volume changes slightly between charging and discharging: we cannot therefore block them in a rigid case: I think of wedging them between inflated cushion: and if this system is also inflated with neutral gas it will also protect against humidity

[Grelinette]

What I took away from important in this article is that when buying a battery or a material using a battery, it is important to inquire about the date of manufacture of the drums.

For example, for the purchase of a pedelec whose duration of use and performance are directly linked to the battery, it seems advisable to see if a manufacturing date appears on the battery.

[Remundo]

Read on Nature engine ...

The Mercedes "Range Extender" ... break down the usual safeguards to guarantee the longevity of Lithium packs ... which do not support overloads and deep discharges, remember ... must coocoon the Lithium...

it doesn't cost the builder a lot ... on the contrary, $ 600 to re-configure the calculo ... so flexible.

By cons it could be expensive for the owner ... And a pack to repair, one!

Unworthy of "Merco". Really disappointing. Better not to offer anything than to release such an aberration. Because the class B deserves a Rex option and especially not to play with its batteries ...

[Gaston]

Unworthy of "Merco". Really disappointing. Better not to offer anything than to release such an aberration. Because the class B deserves a Rex option and especially not to play with its batteries ...

I think that a button allowing in the event of "dry out" to drag on for a few more kilometers (enough to get home or reach a charging socket) could be a good idea in all EVs.
It would not be a question of blowing up all the safeties, but exceptionally of keeping a little less margin (for example authorizing the discharge up to 10% if it is normally blocked at 15%) to avoid troubleshooting.


By cons put it as a paid option

[Remundo]

What you say already exists ...

Renault calls it "turtle mode", which is planned and imposed as soon as the calculator feels that the pack is weak.

Likewise, our old PSA Nicad VEs have the eco indicator light that comes on, followed by an impressive clamping.

This clamping is so strong that you can not decently stay on a highway or a device, and that you trot at 20 km / h as soon as there is a coast with the fear of being buffered by the back ... you put the warnings and you pray
1) no accidents happen
2) you end up arriving at Holy Grail : AC220V socket

Be careful, on Lithium, the battery that "hits the bottom", you must not come and solicit it a little more ... even if the other batteries still have a little in "the belly" ... it damages it (limits her capacity), the next time, she's the one who hits the bottom again, vicious circle ..... especially if you "unleash" electronic security.

All of this is sharp. Lithium is really "art" to manage and you have to be careful ...

[chatelot16]

you can discharge the NiCd batteries to zero without damaging them: the power becomes very low but it does not damage them

with lithium is much more serious, and given the price of the batteries, it is better to call a convenience store and tow the car ... it will be cheaper than risking replacing the batteries ...

an explanation of an additional cost in case of voluntary exceeding of the threshold? when the normal threshold has been exceeded there is a safety problem: lithium ion can explode ... it is therefore possible to need a more complicated control after having exceeded the threshold

the types of battery allowing full discharge have a big advantage: you can use the total capacity without keeping a safety margin: just like a petrol tank that can be emptied to the last drop

I only see 2 types of batteries with this quality: NiCd and Nickel Zinc

[I Citro]

Likewise, our old PSA Nicad VEs have the eco indicator light that comes on, followed by an impressive clamping.

This clamping is so strong that you can not decently stay on a highway or a device, and that you trot at 20 km / h as soon as there is a coast with the fear of being buffered by the back ... you put the warnings and you pray

What you describe corresponds to a vehicle of which several elements are faulty and which, logically should go through the workshop box ...

On a pack in good condition, the clamping is in 2 stages:
1- The vehicle limits the speed to 70 km / h and the power limit warning light comes on (warning light in the econoscope window)
2- The voltage and amperage become too low to allow the vehicle to travel at 70kmh, it will therefore travel at the maximum speed that the batteries allow until the voltage drops below the cutoff threshold programmed in the electronic computer

The first PSA vehicles were configured with 2 voltage thresholds, the first lighting the power limitation indicator, the second the charge request indicator. Then the setting lights the 2 simultaneous lights.

On vehicles with batteries in good condition, it is not uncommon to drive with the gauge below 0% (-2% in abutment) for sometimes ten kilometers without lighting up witnesses.

Since I replaced my Nickel Cadmium batteries with Lithium Iron Phosphate, and despite a 110Ah setting of my pack against the original 95Ah, I drive easily 30km after the gauge has dropped below 0% and of course I no longer light my witnesses because the voltage of the pack is always higher than the parameters of the calculator, but that does not put me safe from destroying my elements if I go below their safety voltage, hence the importance of a properly integrated quality BMS.