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Old 11-27-2017, 10:55 AM
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Default Chevy Volt Battery Questions

What are the pros & cons of using a portion of battery from a Chevy Volt electric car on smaller electric vehicles?

They seem like a good option

...A 48V 47AH section

...would only need a 9 1/2"L x 9 1/2" H x 10"W area

...would only weigh ~45 lbs. (~1/2 the weight of 48V 35AH SLA's)

...they seem to becoming quite plentiful

...I can even find them locally

...& there are some on eBay.

...in the ~$300.00 range


https://www.ebay.com/itm/2013-Chevy-...EAAOSw5VtZ3DXv

It seems a safer/simpler solution than (trying to) building a Lithium battery pack

Most of the professional built "new" 48V 50AH battery packs I have seen cost 2 - 4 times that.

I know a BMS would be necessary

...but, I haven't seen available with a BMS attached/included

Is there a plug-n-play BMS available for this?
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Old 11-28-2017, 10:44 PM
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Silence falls upon the crowd




Well here is some info I dug up:

Chevy Volt Battery pack are made up of:

...288 LG Chemistry pouch cells (3P96S)(3 parallel, 96 in series) (each cell has 3 pouches)

...(7) - 12 cell chunks (42V - 49V)

...(2) - 6 cell chunks (21V - 24.5V)

...Cell capacity: 45AH

...Pack Voltage: 370V

...Pack Energy: 16 kWh

...Discharge power: >125 kW

...Chemistry: Lithium Maganese Oxide (LiMg204)

** ( NOT liPo4 so more risk of fire)


Here is more info from: http://www.schultzengineering.us/delta-11-12.htm

CAUTION!!!!: Lithium Batteries are extremely dangerous and should not be operated without a BMS to ensure they operate within safe limits for cell voltage, current and temperature. DO NOT under any circumstances attempt to operate a Lithium Based Battery system without an automatic battery control system. Cell voltages must be strictly preserved or the battery system can self-destruct in ways that cause extreme danger to persons and property.

CAUTION!!!!: Battery Systems contain hazardous voltages and can hurt or kill you without warning. If you have not had specific training in battery and electrical/electronic systems, DO NOT attempt to disassemble or repurpose Electric Vehicle batteries. Experiments gone wrong can cause you damage and cause needless legislation and bad publicity for Electric Vehicles and the renewable energy industry. So, if you are cheap and don't want to spend a lot of money to get a safe, well designed battery system, go to school and get training in how to work on these systems before you start working on this type of project (or just wait a few years, because the price of battery systems is coming down very quickly).

While a Chevy Volt Battery can be cut into pieces and re-used, the ideal re-use would be to use the entire pack assembly as it came out of the vehicle with it's BMS and awesome thermal control system intact and functioning. Ideally, LG Chem and GM will eventually share information so that we can make an aftermarket wiring harness that will allow this pack to be mounted vertically on a wall in someone's garage to provide stationary energy storage for residential applications aka "The Chevy Volt PowerWall"

I DO NOT RECOMMEND cutting a pack into pieces!!! It is VERY dangerous to yourself and to the battery. There is a phenomenal amount of energy stored in each cell. If you accidently short one of these cells really bad things can happen instantly (vaporized metals to breath, molten metal to burn you and the battery, battery fires, arc flashes that can damage your eyes, etc.). And, there is the very easy chance of just ruining the battery by cutting a cell pouch open.

I also DO NOT RECOMMEND running a Lithium pack without a BMS or automatic shut down circuits for over or undervoltage condtions.

I recommend keeping the modules together in their factory build configuration and attempting to use the heating/cooling features of the module design.

I recommend keeping the bottom mounting features intact.



Here is more info:

http://www.gaccmidwest.org/fileadmin...panel_Volt.pdf


...& more:

https://docs.google.com/file/d/0BwHv...MxOUwzdmM/edit
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  #3  
Old 11-30-2017, 04:26 PM
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zzzzzzzzzzzzzzzzzzzzzzzzzz ribbit zzzzzzzzzzzzzzzzzzzzzzzzzzzz

Still lookin' & doin research

I sent an Email to the guy that has some Volt battery sections for sale.

Hello,
I am interested in using a 48V 47AH section of a Chev Volt Battery (seen on eBay) for an electric motorcycle conversion. I see where it says "BMS leads available" but, what about a BMS?
Do you sell or can you recommend an appropriate BMS for this battery?
Thank you, Kevin


His response:

Hello Kevin,

Im afraid there are so many options for the bms, that I dont bother getting them.

It is all about preference. Some are plug and play, others give you more control over what happens.

It is up to you. Searching "12s BMS" on ebay will bring up many results. The question is what discharge amount would work best for you.



So, lookin' on eBay, I found this:

https://www.ebay.com/itm/44V-48V-50-...kAAOSwNSxVQfoJ

Applicable for


43V (3.6V * 12S) lithium battery & packs

44V (3.7V * 12S) lithium battery & packs

50.4V (4.2V * 12S) lithium battery & packs

Lithium battery (Li-ion)

Prismatic Lithium Polymer battery (Li-Po)



Technical Parameters:

Balanced current: 60mA (VCELL = 3.90V when)

Balanced for: 4.20 ± 0.05 V

Over-charged Protection: 4.2 ± 0.05 V

Over-charged Release: 4.05 ± 0.05 V

Over-discharged Protection: 2.9 ± 0.05 V

Over-charged delay: 5mS

Over-current Protecton: 100 A

Supports Max. Continuing Discharge Current: 100A

Max Charge Current : 40A

Static power consumption: less than 200uA

Short-circuit protection function: disconnect the load from the recovery.


Dimension: 200mm * 110mm * 20mm (L*W*T) - with Radiating Board


The main functions: Over-charged, Over-discharged protection, short circuit protection, over-current protection, with Balancing function.


Interface Definition:

The board have balancing function. So you may see a balance connector with 12 wires, below chart shows how to connect the wires onto 12 batteries to realize balancing and protection.
1.The Positive output on Battery Pack (48V + ) could connecting to charger positive pole (charger +)
2.Battery Pack (48V -) connecting with B- on board
3.Chip board P- connecting to Charger Negative Pole (charger -)
4.Chip board P- could be Negative output for charger, motor, controller
5.Battery B+ could be Positive output for charger, motor, controller

photo LOGO Connecting Chart.jpg


1, The charging port and the discharge port of the board are the same Positive port. “B-“ for negative Pole of the battery pack, “P-“ is negative pole for both discharging and charging.

2, “B-“, “P-“ welding pad are through-hole port, hole diameter of 3.5 mm; You could use solder iron to weld the wires through the hole port, Every charging port for battery are the DC needle seat forms output.

3, First connect the “B-“ to the battery pack, then re-check with the battery voltages, then connect the 12 wires onto the batteries, Do not connect in wrong ordering, or it will burn out the board.



If you made wrong connection and reverse the board that will cause smoke, please check with every wire to be sure you are doing correct connection.


check all the wires voltage with orderly, start from B- , and see if it increasing from 3.6V, like:

( wires / voltage )

1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12

3.7V - 7.4V - 11.1V - 14.8V - 18V - 22V - 24V - 29.6V - 33V - 36V - 40V - 44V

Check every voltage on the wire step by step before plug in the connector. Check every wire and see if the orderly are correct. Because if any of the wire get a wrong order, it will get burnt. Smoke shows board already get burnt for protecting the battery being damaged by wrong connection, For DIY assembling. Please make sure you are capable to do the assembling before ordering! If you dont know how to do the connection, DONT ORDER IT!


IMPORTANT!!!
The BMS only use for new and consistent high drain batteries.
Do not use for battery packs that mix with new & half-used, or mix with different brand battery cells.
Do not use for used and imbalance battery cells.
Do not use for batteries with fake capacity.
Do not touch the board by hand while it is charging / discharging.

*If you charge the battery by Lithium Balance Charger, then there's no need to use BMS.


What does this last line mean?
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Old 11-30-2017, 11:59 PM
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WAIT!!!! You had to wait for the last line to ask that????
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Old 12-01-2017, 07:24 AM
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Hmmmmmmmmmmmmm

This looks interesting

https://www.ebay.com/itm/BMS-assembl...-/112558983691

For sale is a NEW BMS assembly for Chev Volt 48vdc battery. easy to install by user. Picture above shows installation

on battery which is also available from seller, all NEW items not from a junk yard like others that sell on Ebay. BMS

assembly will monitor and balance the battery cells providing a longer life span for the installed battery not included

with BMS. Installation requires installing the orange plug into battery receptacle, connecting negative lead with eye ring

to battery negative post. A optional lead from the BMS is provided for a 48vdc negative connection to a charger

designed for lead acid, etc. The BMS will disconnect the 48vdc negative to the charger when battery is fully charged

at about 50.6vdc. A 48vdc relay should be used if the charger exceeds 15smp output, available from seller as a option.

This same 48vdc negative lead can be used for powering a low current device that will disconnect when the battery is

depleted. This can be the 48vdc contactor on a golf cart, EV, boa,t and solar charge controller inverter. Seller can

provide support after purchase if required.


Seems simple enough but, I wonder about functionality

...& still costs ~ the same price as the battery (section)

...but, it's plug-n-play

...just need an appropriate charger


Another odd fact-

* A complete Chevy Volt battery pack (~360V * 45Ah) has the energy content of ~14kg of TNT.

Or ~58 sticks of dynamite
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Old 12-01-2017, 08:56 AM
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I'm no battery expert but looking at the power output compared to several AGM batteries as well as weight, if say it's probably well worth it. That seems to be the Achilles heel of electric karts, the sheer weight of the power pack.

Zero Motorcycles uses a small pack not sure how large and they can get about 120 mile range, the higher end has about 200 mile range on the highway. Maybe wait until a wrecked bike goes up on sale or something and buy the pack and motor?

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Old 12-02-2017, 04:53 AM
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Hi Functional Artist,

I don't know much about Volt batteries, but there is a lot of info over on Endless Sphere:

https://endless-sphere.com/forums/se...7f01b545707aba

I do know that used 2kwh ones from wreaked cars are starting to show up on eBay for about $265 +

https://www.ebay.com/sch/i.html?_fro...ttery&_sacat=0

Along with Nissan Leaf's, Prius etc.
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Old 12-02-2017, 10:48 AM
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More info

*Most peoples first mistake is charging 2kWh sections of Volt batteries to 4.2V per cell.

In the interest of long life charge only to 4.1 or 4.15V/cell.


Those batteries are so over-engineered that if they're drifting more than +/- 0.01V cell then there's something wrong.

I have read about several people that have a number of those 12s modules in service for over 2 years, and none of them has required balancing.

Discharging them too deeply, is another no-no.

Don't call a 2kWh section of a Volt battery a 48V battery, because it's not.

It's a 44V battery.

For charging it's a mistake to rely on Hobbyking chargers to run that kind of load for such long durations regularly.

Instead pick up a couple of reasonably priced 12s 6A chargers with a cutoff set at 49.5V or so, and run them in parallel. As extra protection run the chargers through a cutoff timer, and have a fan blowing on the chargers.


...or something like this

https://www.ebay.com/itm/EV-PEAK-A9-...4383.l4275.c10
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Old 12-03-2017, 02:47 PM
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Sorry for ramblin'

There is just sooo much information

So, to summarize

From my research I have found:

A 2kWh section of a Chevy Volt battery pack is

...12 cells connected in series (12S)
...each cell is a sturdy plastic frame with (3) 3.7V 17AH pouches per cell
...there are aluminum heat dissipating plates between each cell
...there are coolant channels running down each side of the pack
...there are long bolts running thru the sides of the cells to metal plates on each end, of the pack
...the bolts compress & hold the cells together as (1) unit


THE SAFE VOLTAGE USE RANGE OF THIS TYPE OF BATTERY IS (3.0V - 4.2V)
...3.0V x 12 cells = 36V
...3.3V x 12 cells = 39.6V
...3.5V x 12 cells = 42V
...3.7V x 12 cells = 44.4V
...4.0V x 12 cells = 48V
...4.2V x 12 cells = 50.4V

* Going below 3.0V will damage the battery cell
* Going over 4.2V can overheat/damage the cell & increases risk of fire

***An even safer situation but, less usable capacity would be to use a rule of ~3.3V/36V as a lowest setting & a highest setting of ~4.0V/48V
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Old 12-03-2017, 03:43 PM
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Now, looking for a BMS
...that is compatible with this battery
...& the motorcycle

The Kelly KDZ72550 speed controller on my motorcycle is capable of operating
...within a voltage range of 36V thru 72V
(the voltage range of a 2kWh section of Chevy Volt battery is 36V thru 50V so, it should work fine in this situation)
...& it can handle up to 550A

So, the BMS
...must be 12S
...100A discharge

This one seems adequate
https://www.ebay.com/itm/222353573658

It's 12S compatible with battery pack
...& 100A should (I don't know really) give plenty of power

* I think, I understand the balance connector wiring & other connections but, the output wires seem kinda small for 100A

...but, where does the (-) negative battery cable attach?
Attached Thumbnails
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Old 12-04-2017, 09:30 AM
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I ordered a similar BMS from China earlier this month:

https://www.ebay.com/itm/48V-16-cell...72.m2749.l2649

Once I get it, I'll let you know how I set it up.
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Old 12-04-2017, 11:15 AM
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I (think) I got this figured out

The first pic is how the bike is set up currently, with the SLA battery pack

Second pic is how it should be set up with the BMS & a lithium battery pack

...& a demonstration/explanation video

Attached Thumbnails
SAM_6955.jpg   SAM_6956.jpg  

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Old 12-05-2017, 01:56 PM
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Still thinkin' & researchin'

It's pretty clear, to use these lithium batteries SAFELY you need the protections that a BMS provides

...mainly the over-charge protection (don't want no fires)

...& also the balancing function
(if they are out of balance, some cells can charge up quicker than others then were back to the overcharging problems (again, don't want no fires)

But, I am not sure if I am comfortable with running the motor off/thru it
...is it necessary? (it seems like the only benefit would be over-discharge protection)

...& it seems like it would be a performance limiting factor (only 100A continuous discharge current)


An amp/volt meter hard wired to the battery pack
...would be a good (but, simple) addition to the bike
...& will help me monitor current & voltage levels

The "charge meter" that is on El Moto now is more like an economy gauge
...during normal riding the "meter" usually drops down to ~70%
...during hard acceleration it drops down to ~20%
...but, it doesn't really show the actual "state of charge" of the battery pack


I was thinkin'

Hypothetically (just an idea) -- (what if we split the baby?)

* Mount the BMS on a 2kWh section of a Volt battery
...pretty much as described earlier

But, only run the charger thru it

...& leaving the propulsion system connected as is


BMS specs:

The main functions: Over-charged, Over-discharged protection, short circuit protection, over-current protection, with Balancing function.


I believe this set up would provide:

...over-charged protection (while charging only)

...BUT, NO over-discharged protection (would have to be monitored & controlled by user)

...short circuit protection (while charging only)

...over-current protection (I don't think it should be an issue @48V with this size battery)

...& the balancing function would (always) be working


Sound plausible?
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Old 12-08-2017, 07:12 PM
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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 (mA·h) 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.
  #15  
Old 12-10-2017, 03:37 PM
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There's a "sticky" for ya, (see previous post)

"practically" everything you ever wanted to know about lithium batteries


Here's another one for ya


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)

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 the numbers
  #16  
Old 12-10-2017, 07:22 PM
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Using a Lithium battery to power a 24V system

(most 24V speed controller have a "usable" input voltage range from ~20.5V thru ~27V)


So, if you use the (3.2V) LiFePo batteries

In a 6S configuration, the voltage range is ~16.8V thru 22.2V

...but, the ACTUAL "usable" voltage range would really ONLY be ~20.5V thru ~22.2V (That's NOT much!)

...this is because the speed controller's under voltage limit would limit the available voltage to ~20.5V
...& the bat pack's maximum charge would limit the highest available voltage to ~22.2V


In a 7S configuration, the voltage range is ~19.6V thru ~25.9V

...but, the ACTUAL "usable" voltage range would really ONLY be ~20.5V thru 25.9V (Much better!)

...this is because the speed controller's under voltage limit would limit the available voltage to ~20.5V
...& the bat pack's maximum charge would limit the highest available voltage to ~25.9V


In a 8S configuration, the voltage range is ~22.4V thru ~29.6V

...but, the ACTUAL "usable" voltage range would be ~22.4V thru ~27V (Not bad!)

...this is because the speed controller's under voltage limit would limit the available voltage to ~20.5V
...& the speed controller's high voltage limit would limit the highest "usable" voltage to 27V



If you use the (3.7V) LiMg batteries

In a 6S configuration, the voltage range is ~19.2V thru ~25.2V

But, the ACTUAL "usable" voltage range would really ONLY be ~20.5V thru ~25.2V (Not great!)

...this is because the speed controller's under voltage limit would limit the available voltage to ~20.5V
...& the battery packs maximum charge would limit the highest available voltage to 25.4V


In a 7S configuration, the voltage range is ~22.4V thru ~29.4V

But, the ACTUAL "usable" voltage range would really ONLY be ~22.4V thru ~27V (Pretty good!)

...this is because the bat pack has a low voltage cut-off of ~22.4V

...& the speed controller's high voltage limit would limit the highest "usable" voltage to ~27V

In a 8S configuration, the voltage range is ~25.6V thru ~33.6V
(practically out of the "usable" voltage range for a 24V system)


So, it seems when trying to match Lithium batteries to a system designed for lead acid

...a) the specs don't always align well

...b) & many times your NOT able to use all of the available battery capacity

...c) but, when they do align, WATCH OUT!
  #17  
Old 12-10-2017, 07:47 PM
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We need a more up to date thread on electric motors next. Reading all this on electric karts and how some are coming back http://actevmotors.com it's sparked (pun intended) a slight interest in me for the future. I mean let's face it, small gas engines mighy be going the way of the dodo within 40 years if not sooner. Might as well stay ahead of the curve. But more info would be nice on what size electric motor as a replacement for gas engines in the 3-10hp range. How many watts and so on as replacements, and some examples of said motors.

Looking at some battery packs and kits are running about $1200-12,000 for 24v to 144 volt systems. I've seen your videos and your system looks great, I can't imagine what 72+ volts would be like. I know this is more or less on Chevy Volt battery packs, but what are some examples given that we can look at in those given cells and voltage range to look for?

Sent from my SAMSUNG-SM-G935A using Tapatalk
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Old 12-11-2017, 08:16 PM
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Check out this simple little devise

Lee Hart's Batt-Bridge Battery Balance Alarm


The Batt-Bridge is about as simple as you can get; that's why it is so inexpensive. If all you want is an 'idiot' light to say, "Stop driving, your batteries are dead," I can't imagine anything any simpler. You really don't need dozens of ICs and hundreds of components just to light a light.
The Batt-Bridge divides the pack in half, and compares the voltage of each half. It lights an LED when one of them is 1v less than the other.

If a cell dies somewhere in the pack, it typically causes a 2 volt change. So the Batt-Bridge warns you that a cell went dead. There are two LEDs, so they indicate which half-pack contains the bad cell.

R1 and R2 are chosen to draw about 10-20ma from the pack. For example, if you have a 120v pack, R1 and R2 each have about 60v across them. At 15ma, they would be R = 60v / 0.015a = 4k ohms. They need to be identical values (1% or hand picked or trimmed). And they must be power resistors; 60v x 0.015a = 0.9 watts, so use at least a 2 watt resistor.

Use an ordinary low brightness green LED. Its purpose is just to indicate that power is on, and to act as a low-voltage 2.4v "zener" diode. However, the red LEDs should be high brightness types -- the brighter the better, so you can see them even in daylight.

Here's how it works. All voltages are relative to the pack center tap. If +pack == -(-pack), then the green LED lights. The green LED's anode is at +1.2v, and its cathode is at -1.4v. The red LEDs don't light because they only have 1.2 volts across them (they need over 1.5v to light).

Now, suppose you have a dead cell in the upper half of the pack. Then +pack is 2v less than -pack. R1 and R2 form a voltage divider, so both ends of the green LED are 1v more negative; its anode is at +0.2v, and its cathode is at -2.4v. This means there is now 2.4v across the lower red LED; so it lights! Likewise, if the dead cell is in the lower half, then the upper red LED lights.

The total resistance of R1 and R2 sets the sensitivity, and the ratio of these resistors sets the desired center-tap voltage of the pack. If both LEDs light, then the resistors are too low a value; increase the resistance of both of them proportionately. Ten milliamps through the resistors is low sensitivity (over 2v difference to light an LED); 20ma is normal sensitivity; 40ma gives you high sensitivity (less than 1v difference to light an LED).

If one LED lights when the half-pack voltages are correct, then adjust the value of one of the resistors. This is also how you deal with packs with an odd number of batteries, where the "center tap" is off by one.
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  #19  
Old 12-13-2017, 07:58 AM
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Quote:
Originally Posted by Kartorbust View Post
We need a more up to date thread on electric motors next. Reading all this on electric karts and how some are coming back http://actevmotors.com it's sparked (pun intended) a slight interest in me for the future. I mean let's face it, small gas engines mighy be going the way of the dodo within 40 years if not sooner. Might as well stay ahead of the curve. But more info would be nice on what size electric motor as a replacement for gas engines in the 3-10hp range. How many watts and so on as replacements, and some examples of said motors.

Looking at some battery packs and kits are running about $1200-12,000 for 24v to 144 volt systems. I've seen your videos and your system looks great, I can't imagine what 72+ volts would be like. I know this is more or less on Chevy Volt battery packs, but what are some examples given that we can look at in those given cells and voltage range to look for?

Sent from my SAMSUNG-SM-G935A using Tapatalk
It seems that the best "bang" for the buck

in electric motors is

For under $1,000

...MY 1020 48V 1,000W brushed DC motor ~$100.00 w/speed controller
https://www.ebay.com/itm/48V-1000W-M...-/132117018597

or

...Boma 48V 1,800W brushless DC motor ~$200.00 w/ speed controller
https://www.ebay.com/itm/1800W-48V-B...-/132097846668

I have used them both, their spunky & have lots of power

IMHO their comparable to 3 - 5 hp gas engines

Converting a small kart from gas to electric (depending on batteries) can be done for under ~500.00


For over $1,000

Their are many options, the one I am kinda familiar with is

...Motenergy ME-0708 48 V ~5,000 brushed DC motor ~$500.00
http://www.thunderstruck-ev.com/motenergy-me0708.html
...plus a Kelly speed controller ~$300.00
...plus contactor ~$70.00
...plus fuses, cables etc. etc.

IMHO its comparable to a 10+ hp gas engine

I have used a motor like this it's BAD AZZ!!
Pure Power
You just Goooooooooooooooooooooooooooooo
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  #20  
Old 12-13-2017, 10:08 AM
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Quote:
Originally Posted by Functional Artist View Post
Check out this simple little devise

Lee Hart's Batt-Bridge Battery Balance Alarm


The Batt-Bridge is about as simple as you can get; that's why it is so inexpensive. If all you want is an 'idiot' light to say, "Stop driving, your batteries are dead," I can't imagine anything any simpler. You really don't need dozens of ICs and hundreds of components just to light a light.
The Batt-Bridge divides the pack in half, and compares the voltage of each half. It lights an LED when one of them is 1v less than the other.

If a cell dies somewhere in the pack, it typically causes a 2 volt *change. So the Batt-Bridge warns you that a cell went dead. There are two LEDs, so they indicate which half-pack contains the bad cell.

R1 and R2 are chosen to draw about 10-20ma from the pack. For example, if you have a 120v pack, R1 and R2 each have about 60v across them. At 15ma, they would be R = 60v / 0.015a = 4k ohms. They need to be identical values (1% or hand picked or trimmed). And they must be power resistors; 60v x 0.015a = 0.9 watts, so use at least a 2 watt resistor.

Use an ordinary low brightness green LED. Its purpose is just to indicate that power is on, and to act as a low-voltage 2.4v "zener" diode. However, the red LEDs should be high brightness types -- the brighter the better, so you can see them even in daylight.

Here's how it works. All voltages are relative to the pack center tap. If +pack == -(-pack), then the green LED lights. The green LED's anode is at +1.2v, and its cathode is at -1.4v. The red LEDs don't light because they only have 1.2 volts across them (they need over 1.5v to light).

Now, suppose you have a dead cell in the upper half of the pack. Then +pack is 2v less than -pack. R1 and R2 form a voltage divider, so both ends of the green LED are 1v more negative; its anode is at +0.2v, and its cathode is at -2.4v. This means there is now 2.4v across the lower red LED; so it lights! Likewise, if the dead cell is in the lower half, then the upper red LED lights.

The total resistance of R1 and R2 sets the sensitivity, and the ratio of these resistors sets the desired center-tap voltage of the pack. If both LEDs light, then the resistors are too low a value; increase the resistance of both of them proportionately. Ten milliamps through the resistors is low sensitivity (over 2v difference to light an LED); 20ma is normal sensitivity; 40ma gives you high sensitivity (less than 1v difference to light an LED).

If one LED lights when the half-pack voltages are correct, then adjust the value of one of the resistors. This is also how you deal with packs with an odd number of batteries, where the "center tap" is off by one.
I think ima gonna make one of these

I drew it out a few different ways (repetition helps with understanding)

...& how it would be layed out in a box

...even adding a switch so it can de turned off when not in use


I am going to start off small to help me fully understand & test the concept

It may come in handy for the 24V battery packs that are on the kids karts
(balance is not as important on SLA's as lithium but, still important for safety & longevity)


So, according to Lee Hart's diagram/description

If the battery pack is 24V, (we need resistors for each half of the pack)

that's

24V / 2 = 12V
12V / .015 = 800 ohms
12V x .015 = .18 watts (then they roughly doubled it)

So, it looks like we need

...(2) power resistors that are 800 ohms, 1/2 watt with a 1% tolerance


* For the 2kWh section of a Chevy Volt battery (44.4V)

that's

44.4V / 2 = 22.2V
22.2V / .015 = 1,480 ohms
22.2V x .015 = .33 watts

So, it looks like

1.5k ohm 1 watt resistors with a 1% tolerance would be the proper choice?
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