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Thread: 1980 Kawasaki 440 LTD 8kW conversion-Workin' toward the conclusion

              
   
   
  1. #11
    Member Functional Artist's Avatar
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    Thanks guys,
    Here is some good info that I found it helped me understand batteries (it's mainly for newbies not the old timers)

    Lithium-ion battery

    A lithium-ion battery or Li-ion battery (abbreviated as LIB) is a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell. Chemistry, performance, cost and safety characteristics vary across LIB types.

    Terminology

    Battery vs. cell
    International industry standards differentiate between a "cell" and a "battery". A "cell" is a basic electrochemical unit that contains the electrodes, separator, and electrolyte. A "battery" or "battery pack" is a collection of cells or cell assemblies which are ready for use, as it contains an appropriate housing, electrical interconnections, and possibly electronics to control and protect the cells from failure. ("Failure" in this case is used in the engineering sense and may include thermal runaway, fire, and explosion as well as more benign events such as loss of charge capacity.) In this regard, the simplest "battery" is a single cell.

    For example, battery electric vehicles, may have a battery system of 400V, made of many individual cells. The term "module" is often used, where a battery pack is made of modules, and modules are composed of individual cells.

    Anode, cathode, electrode

    In electrochemistry, the anode is the electrode where oxidation is taking place in the battery, i.e. electrons get free and flow out of the battery (technical current flowing into it). However, this happens on opposite electrodes during charge vs. discharge. The less ambiguous terms are positive (cathode on discharge) and negative (anode on discharge). This is the positive-negative polarity which is displayed on a volt meter. For rechargeable cells, the term "cathode" designates the positive electrode in the discharge cycle, even when the associated electrochemical reactions change their places when charging and discharging, respectively. For lithium-ion cells the positive electrode ("cathode") is the lithium based one.

    The three primary functional components of a lithium-ion battery are the positive and negative electrodes and electrolyte. Generally, the negative electrode of a conventional lithium-ion cell is made from carbon. The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. The electrochemical roles of the electrodes reverse between anode and cathode, depending on the direction of current flow through the cell.

    Depending on materials choices, the voltage, energy density, life, and safety of a lithium-ion battery can change dramatically.

    Shapes

    Li-ion cells (as distinct from entire batteries) are available in various shapes, which can generally be divided into four groups:
    Small cylindrical (solid body without terminals, such as those used in laptop batteries)
    Large cylindrical (solid body with large threaded terminals)
    Pouch (soft, flat body, such as those used in cell phones; also referred to as li-ion polymer or lithium polymer batteries)
    Prismatic (semi-hard plastic case with large threaded terminals, such as vehicles' traction packs)

    Charge and discharge

    During discharge, lithium ions (Li+) carry the current within the battery from the negative to the positive electrode, through the non-aqueous electrolyte and separator diaphragm.

    During charging, an external electrical power source (the charging circuit) applies an over-voltage (a higher voltage than the battery produces, of the same polarity), forcing a charging current to flow within the battery from the positive to the negative electrode, i.e. in the reverse direction of a discharge current under normal conditions. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation.

    The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different.

    A single Li-ion cell is charged in two stages:
    1.Constant current (CC)
    2.Constant Voltage (CV)

    A Li-ion battery (a set of Li-ion cells in series) is charged in three stages:
    1.Constant current
    2.Balance (not required once a battery is balanced)
    3.Constant Voltage

    During the constant current phase, the charger applies a constant current to the battery at a steadily increasing voltage, until the voltage limit per cell is reached.

    During the balance phase, the charger reduces the charging current (or cycles the charging on and off to reduce the average current) while the state of charge of individual cells is brought to the same level by a balancing circuit, until the battery is balanced. Some fast chargers skip this stage. Some chargers accomplish the balance by charging each cell independently.

    During the constant voltage phase, the charger applies a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines towards 0, until the current is below a set threshold of about 3% of initial constant charge current.

    Periodic topping charge about once per 500 hours. Top charging is recommended to be initiated when voltage goes below 4.05 V/cell.

    Failure to follow current and voltage limitations can result in an explosion.

    Performance

    Because lithium-ion batteries can have a variety of positive and negative electrode materials, the energy density and voltage vary accordingly.

    Batteries with a lithium iron phosphate positive and graphite negative electrodes have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide positives with graphite negatives have a 3.7 V nominal voltage with a 4.2 V maximum while charging. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less.

    Uses

    Li-ion batteries provide lightweight, high energy density power sources for a variety of devices. To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective and more efficient than connecting a single large battery. Such devices include:

    Electric vehicles: including electric cars, hybrid vehicles, electric bicycles, personal transporters and advanced electric wheelchairs. Also radio-controlled models, model aircraft, aircraft, and the Mars Curiosity rover.

    Anode

    Charging at greater than 4.2 V can initiate Li+ plating on the anode, producing irreversible capacity loss. The randomness of the metallic lithium embedded in the anode during intercalation results in dendrites formation. Over time the dendrites can accumulate and pierce the separator, causing a short circuit leading to heat, fire or explosion. This process is referred to as thermal runaway.

    Discharging beyond 2 V can also result in capacity loss. The (copper) anode current collector can dissolve into the electrolyte. When charged, copper ions can reduce on the anode as metallic copper. Over time, copper dendrites can form and cause a short in the same manner as lithium.

    Multicell devices

    Li-ion batteries require a battery management system to prevent operation outside each cell's safe operating area (max-charge, min-charge, safe temperature range) and to balance cells to eliminate state of charge mismatches. This significantly improves battery efficiency and increases capacity. As the number of cells and load currents increase, the potential for mismatch increases. The two kinds of mismatch are state-of-charge (SOC) and capacity/energy ("C/E"). Though SOC is more common, each problem limits pack charge capacity (mAh) to that of the weakest cell.

    Safety

    If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to leakage, explosion or fire. To reduce these risks, many lithium-ion cells (and battery packs) contain fail-safe circuitry that disconnects the battery when its voltage is outside the safe range of 3–4.2 V per cell or when overcharged or discharged. Lithium battery packs, whether constructed by a vendor or the end-user, without effective battery management circuits are susceptible to these issues. Poorly designed or implemented battery management circuits also may cause problems; it is difficult to be certain that any particular battery management circuitry is properly implemented. Lithium-ion cells are susceptible to damage outside the allowed voltage range that is typically within (2.5 to 3.65) V for most LFP cells. Exceeding this voltage range, even by small voltages (millivolts) results in premature aging of the cells and, furthermore, results in safety risks due to the reactive components in the cells. When stored for long periods the small current draw of the protection circuitry may drain the battery below its shutoff voltage; normal chargers may then be useless since the BMS may retain a record of this battery (or charger) 'failure'. Many types of lithium-ion cells cannot be charged safely below 0 C.

  2. #12
    Member Functional Artist's Avatar
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    Then, to properly match a lithium battery pack to an application you have to keep a few different variables in mind.

    Most electronic speed controllers & motors are designed to work within the "safe usable range" of Lead Acid batteries (usually in multiples of 12V)

    The safe usable range for most 12V lead acid batteries is ~10V - ~13.3V

    ...for 24V it's ~20V - 26.6V
    ...for 36V it's ~30V - 39.9V
    ...for 49V it's ~40V - 53.2V
    ...for 60V it's ~50V - 66.5V

    The "safe usable range" of most speed controllers is;

    ...for 24V low voltage cut-off is ~20.5V & the high voltage cut-off is ~27V
    ...for 36V low voltage cut-off is ~31.5V & the high voltage cut-off is ~40V
    ...for 48V low voltage cut-off is ~42.5V & the high voltage cut-off is ~54V
    ...for 60V low voltage cut-off is ~53.5V & the high voltage cut-off is ~66V

    As you can see, the "safe usable ranges" align nicely

    Now comes the tricky part

    There are (2) different lithium chemistries in use

    The most common or well known is Lithium ion Phosphorus (LiFePo4) which has a nominal voltage of 3.2V (low voltage cut-off 2.8V - high voltage cut-off 3.7V)

    So, the "safe voltage use range" would be for:

    6S (6 cells in series) 16.8V - 22.2V
    7S (7 cells in series) 19.6V - 25.9V
    8S (8 cells in series) 22.4V - 29.6V
    10S (10 cells in series) 28V - 37V
    12S (12 cells in series) 33.6V - 44.8V
    13S (13 cells in series) 36.4V - 48.1V
    16S (16 cells in series) 44.8V - 59.2V

    The other is Lithium Manganese Oxide (LiMg204) which has a nominal voltage of 3.7V (low voltage cut-off 3.2V - high voltage cut-off 4.2V)
    (This the kind of chemistry the Chevy Volt battery pack uses)

    So, their "safe voltage range" would be for:

    6S (6 cells in series) 19.2V - 25.2V
    7S (7 cells in series) 22.4V - 29.4V
    8S (8 cells in series) 25.6V - 33.6V
    10S (10 cells in series) 32V - 42V
    12S (12 cells in series) 38.4V - 50.4V
    13S (13 cells in series) 41.6V - 54.6V
    16S (16 cells in series) 51.2V - 67.2V

    As you can see Lithium batteries are NOT a drop in replacement for lead acid batteries

    You gotta analyze & match/align the numbers

  3. #13
    Senior Member Ted Dillard's Avatar
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    Quote Originally Posted by Electro Flyers View Post
    It looks like you're combining and condensing old posts from the DIY forum.
    Well, sort of. He's pulling posts from posts he's made to a handful of other forums: DIY Electric Cars, DIY Electronics - for example, his last post is a straight cut and paste from DIY Go Carts: http://www.diygokarts.com/vb/showthread.php?t=38167 The post that he started this thread with was originally on both DIY Electric Car (https://www.diyelectriccar.com/forum....php?p=1009786) and DIY Go Carts (http://www.diygokarts.com/vb/showthr...t=37062&page=6) Typically you'd want to at least link to the original post, and cross-posting verbatim from one forum to another (much less two or three) is very much frowned upon in forum-land, but you could argue he's collecting and clarifying all that into one thread here, which makes it better (I guess).

    All you have to do to find the source material is to grab chunks of the copy and paste them into the Googles. I learned that grading papers for the college classes I taught.

    So that clarifies why he's not willing to change his "style" since that would involve re-writing all that from various sources to make an actual readable thread, and the reason he's not happy about being questioned, interrupted or challenged about his designs, since they were built a few years ago and the "discussion" has already been had. In several forums I've been on it would be grounds for a spanking, but whatever, I don't really care. I'm not reading it anyway, and he shouldn't care since he's ignoring my "trolling". As I've said before, it would make a much better blog than it does a discussion thread.

    By the way, the very informative (and readable) stuff he just posted about lithium batteries was straight out of Wikipedia and Battery University, and should also have been cited. https://en.wikipedia.org/wiki/Lithium-ion_battery and https://batteryuniversity.com/learn/...of_lithium_ion
    Last edited by Ted Dillard; 1 Week Ago at 0707.
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  4. #14
    Member Functional Artist's Avatar
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    SAM_1748 (2).jpg Well, I'm going to have to assemble another Tri-Quad.

    But, I still need to monitor the balance of my "new" battery, until then so, I went ahead & assembled a "mini meter"

    I just put (2) of the digital voltage meters in a small plastic box, with a (DPST) switch & wired differently, this time.

    I'ma gonna call it a Digital Battery Pack Balance Monitor

    Here is a short video showing the meter, in action & explaining some more details.

    https://www.youtube.com/watch?v=uzwUiSl0Azg
    Attached Images Attached Images

  5. #15
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    Quote Originally Posted by Ted Dillard View Post
    Well, sort of. He's pulling posts from posts he's made to a handful of other forums: DIY Electric Cars, DIY Electronics - for example, his last post is a straight cut and paste from DIY Go Carts: http://www.diygokarts.com/vb/showthread.php?t=38167 The post that he started this thread with was originally on both DIY Electric Car (https://www.diyelectriccar.com/forum....php?p=1009786) and DIY Go Carts (http://www.diygokarts.com/vb/showthr...t=37062&page=6) Typically you'd want to at least link to the original post, and cross-posting verbatim from one forum to another (much less two or three) is very much frowned upon in forum-land, but you could argue he's collecting and clarifying all that into one thread here, which makes it better (I guess).

    All you have to do to find the source material is to grab chunks of the copy and paste them into the Googles. I learned that grading papers for the college classes I taught.

    So that clarifies why he's not willing to change his "style" since that would involve re-writing all that from various sources to make an actual readable thread, and the reason he's not happy about being questioned, interrupted or challenged about his designs, since they were built a few years ago and the "discussion" has already been had. In several forums I've been on it would be grounds for a spanking, but whatever, I don't really care. I'm not reading it anyway, and he shouldn't care since he's ignoring my "trolling". As I've said before, it would make a much better blog than it does a discussion thread.

    By the way, the very informative (and readable) stuff he just posted about lithium batteries was straight out of Wikipedia and Battery University, and should also have been cited. https://en.wikipedia.org/wiki/Lithium-ion_battery and https://batteryuniversity.com/learn/...of_lithium_ion
    I think we're just dealing with transition nerves here. So let's try to be supportive. Unless, FA, some patron is paying you for each word posted. In which case, I think we should get a cut for having to read all of this stuff. You can send my cut to the moderator because he has definitely been working overtime lately.

    Seriously, FA, brevity is often a sure sign of wisdom. Enough said.

  6. #16
    Senior Member Stevo's Avatar
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    Quote Originally Posted by Electro Flyers View Post

    Seriously, FA, brevity is often a sure sign of wisdom. Enough said.
    That's why the edit button is our friend!
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: WORX.VOR.v3.2

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