lithium & solar power LiFePO4

Lithium VS Lead-Acid

See the facts for yourself! Say now to lead acid soon.

(sourced from /metro-board.com)

FAQ: Cycle life of LiFePO4 versus Lead-Acid

Question: I talked to a supplier of Lead Acid battery. They told me that they have special stationery lead-acid battery for solar applications that can make 1500 cycles. For me it seems better to buy the cheaper lead-acid battery with 1500 cycles than to buy expensive LiFePO4 with only 2000 cycles

Answer: Recently some lead-acid battery suppliers have been promoting their products highlighting the number of cycles. However to compare the charge/discharge cycle in real performance additional parameters need to be taken into consideration:

1. The depth of the cycle (also called DOD – the depth of discharge). 

The DOD value gives the real energy received from the battery during one cycle. For example the DOD 80% means that 80% of the nominal capacity will be taken: with a battery of a  capacity 100h, it means 80AH will be taken from the battery during discharge (without any additional charging). 

The LiFePO4 cells support the deep charging. They allow taking 100% of the energy, even though for general application the DOD of 80% is recommended.

The Lead Acid batteries usually do not support deep discharge with many cycles. To reach long cycle life the DOD must be low: 20%, 30%.

2. The charge and discharge speed (also called the C-rating)

The C-rating value gives the time of the charge and discharge. The value of 1C means the battery is discharged (or charged) in 1 hour. The higher the C-rating the faster time of charge and discharge is supported. 

The LiFePO4 cells support the high speed charge and discharge. The typical value for LFP technology is 0.5C (or C2) this means the batteries are discharged (or charged) in two hours.

The Lead Acid batteries usually do not allow high speed charging or discharging. The typical discharge rating may be given at C6, C10, or C20 which means recommended discharge is 6 hours, 10 hours or 20 hours. With such type of batteries there is no way to store and release energy quickly. 

3. The remaining capacity (also called aging index)

The aging index means the decrease of the capacity during the cycle life. The new battery has 100% of capacity. With more and more cycles the capacity is reducing. The battery is getting weaker and weaker.

The  LiFePO4 cells have very low aging index. After 2000 cycles that batteries will stay keep 80% of the nominal capacity. This means the batteries can be used even after the nominal number of cycles was carried out.

The Lead Acid batteries often age gradually. The typical lifespan of 1500 cycles means that after these 1500 cycles the capacity of the battery will be 20% or perhaps less. 

4. The effectiveness of the charging cycle (ECC) - also called the effective energy yield

The ECC value means how much energy can be gained from the amount of energy stored. For example the effectiveness of 97% means that for a 100Ah battery you may need 100 Ah energy to charge and you will get 97Ah energy back (in case of 100% DOD).

The LiFePO4 cells have very high effectiveness. The new cells have some 97% of effective energy yield. The old cells (e.g. after 10 years of daily usage) still have some 90% effectiveness..

The Lead Acid batteries have a natural low effectiveness. Because this value is low, it is often never mentioned in the official data sheets. The effectiveness may be between 60 to 70% for high performance batteries. The old batteries may degrade to some 40% or less. 

Summary:

When comparing the LiFePO4 cells with other technology all of these factors need to be taken into consideration. After detailed consideration it is obvious that the LiFePO4 technology is far ahead of the other battery technologies. The other technology is lagging behind (see the animation).

FAQ: What is the real cycle life for lithium LiFePO4 cells?
Question: I study the specifications of the LiFePO4 (LFP) cells and I see that the information about the cycle life of the cells is changing. For example in some older technical sheets the cycle life is only 2000 cycles. In the new ones there is 5000 cycles.  Some manufacturers give 2000 cycles, other give 3000, 5000 or even more. What is the real cycle life and how to compare the values given by various manufacturers?
Answer: GWL/Power has been doing the business with LFP cells since 2008. The 7 years have proved that the LFP technology is very stable, lasting and reliable. The manufacturers have the same results and feedback from their battery applications and customers. In addition to this, the technology, production methods and the purity of the raw materials keep improving over the years. Based on these real results the manufacturers are updating the estimated life span in the official datasheets. That is why the new datasheets publish higher cycle number data. 
Simply said: all of the manufacturers, GWL is working with, give the same basic specification of the cycle life: at 2000 cycles at standard discharge conditions. This kind of cycle life is defined as an irreversible drop of the capacity from 100% to 80%.
However, the real life of the cells in much higher. It means the cell can be used even after the 2000 cycles. This information is given not as guaranteed warranty information, but as an estimation reference of the future life expectancy. Some manufactures give 3000, 5000, 8000 or even more cycles.
This is the same as with a car: How many kilometers can a car drive until a serious breakdown? The manufacturer may give the basic warranty of 100 000 kilometers, but everybody knows the car will of cause drive much longer. Depending on the driving style, driving conditions, the maintenance and the behaviors towards the car, the car may drive 300 000, 500 000 or even 1 million kilometers without a serious defect. However this cannot be provided as official “guaranteed information”.  Everybody knows this, everybody understands it, but it is never given by the car manufacturer as some official data.
And the lithium battery life span is the same. The manufacturers give the basic warranty of usually 2000 cycles, but what is beyond this is only an approximate estimation.
Some manufacturers can be rather conservative, giving the “safeway” estimation, some may give the higher “nominal” estimation. Other manufacturers are very optimistic about their products and can give more far reaching results.  This is seen from the attached graph. 
Keep in mind that the life span of the LFP cells is really very long. Making the thousands of cycles means many years of continuous service.  It is again the same logic as with a car: the investment in purchase will return in some 5 to 7 years and beyond that the car (LFP cells) will keep serving many additional years, as if free of charge. 
The functional service life of the LFP cells is given as 10, 20, 30 or even more years. When the cells are stored in a stable environment and charged and discharged properly, they will keep serving years after years. 
Final note: the very long life- span for LFP cells is a completely different approach from other types of battery technology (like Ni-Cd, Lead-Acid, Sodium-sulfate, etc): all these types of cells need a complex maintenance and service cycles - this keep increasing the operational costs. There is nothing like this for LFP cells.
We encourage to start using the LFP technology for all new installations.  Get your DC power now!

FAQ: What is the real cycle life for lithium LiFePO4 cells?

Question: I study the specifications of the LiFePO4 (LFP) cells and I see that the information about the cycle life of the cells is changing. For example in some older technical sheets the cycle life is only 2000 cycles. In the new ones there is 5000 cycles.  Some manufacturers give 2000 cycles, other give 3000, 5000 or even more. What is the real cycle life and how to compare the values given by various manufacturers?

Answer: GWL/Power has been doing the business with LFP cells since 2008. The 7 years have proved that the LFP technology is very stable, lasting and reliable. The manufacturers have the same results and feedback from their battery applications and customers. In addition to this, the technology, production methods and the purity of the raw materials keep improving over the years. Based on these real results the manufacturers are updating the estimated life span in the official datasheets. That is why the new datasheets publish higher cycle number data. 

Simply said: all of the manufacturers, GWL is working with, give the same basic specification of the cycle life: at 2000 cycles at standard discharge conditions. This kind of cycle life is defined as an irreversible drop of the capacity from 100% to 80%.

However, the real life of the cells in much higher. It means the cell can be used even after the 2000 cycles. This information is given not as guaranteed warranty information, but as an estimation reference of the future life expectancy. Some manufactures give 3000, 5000, 8000 or even more cycles.

This is the same as with a car: How many kilometers can a car drive until a serious breakdown? The manufacturer may give the basic warranty of 100 000 kilometers, but everybody knows the car will of cause drive much longer. Depending on the driving style, driving conditions, the maintenance and the behaviors towards the car, the car may drive 300 000, 500 000 or even 1 million kilometers without a serious defect. However this cannot be provided as official “guaranteed information”.  Everybody knows this, everybody understands it, but it is never given by the car manufacturer as some official data.

And the lithium battery life span is the same. The manufacturers give the basic warranty of usually 2000 cycles, but what is beyond this is only an approximate estimation.

Some manufacturers can be rather conservative, giving the “safeway” estimation, some may give the higher “nominal” estimation. Other manufacturers are very optimistic about their products and can give more far reaching results.  This is seen from the attached graph. 

Keep in mind that the life span of the LFP cells is really very long. Making the thousands of cycles means many years of continuous service.  It is again the same logic as with a car: the investment in purchase will return in some 5 to 7 years and beyond that the car (LFP cells) will keep serving many additional years, as if free of charge. 

The functional service life of the LFP cells is given as 10, 20, 30 or even more years. When the cells are stored in a stable environment and charged and discharged properly, they will keep serving years after years. 

Final note: the very long life- span for LFP cells is a completely different approach from other types of battery technology (like Ni-Cd, Lead-Acid, Sodium-sulfate, etc): all these types of cells need a complex maintenance and service cycles - this keep increasing the operational costs. There is nothing like this for LFP cells.

We encourage to start using the LFP technology for all new installations.  Get your DC power now!

The new profesional Battery for EV bikes 36V & 48V

The new series of batteries for electric bikes, contains smart BMS circuit that continuously monitors the quality of internal cells and in case of failure, provides actual information through an LED panel. Please see PDF specification of LED faults. This circuit also protects the battery against deep discharge. 

NOTE:

If the battery is discharged so that it turns off the internal BMS module, next charging turns up in a few hours. Therefore is necessary to keep connected charger on the battery until it does not start charging.

Winston Battery - new models 160AH 

Check the specifications of the two models of Winston 160AH cells. The cells have identical nominal capacity, but have different dimensions, to meet the needs of various customers. 

LFP160AHA - original model (TALL) - size: 278x182x71 mm, factory code:WB-LYP160AHA(A)

LFP160AHA-B - new model (WIDE) - size: 278x209x65 mm, factory code: WB-LYP160AHA(B)

Winston Battery - new models 100AH 

Check the specifications of the two models of Winston 100AH cells. The cells have identical nominal capacity, but have different dimensions, to meet the needs of various customers. 

LFP100AHA - original model (TALL) - size: 218x143x67 mm, factory code: WB-LYP100AHA(A)

LFP100AHA-B - new model (WIDE) - size: 218x179x62 mm, factory code: WB-LYP100AHA(B)

Winston Battery - the LP12V models - 40AH, 60AH, 90AH

Check the Winston Battery product specifications here:

http://www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/

Winston Battery - dimensions and drawings - cells 300AH to 1000AH

http://www.ev-power.eu/Winston-300Ah-1000Ah/

Winston Battery - dimensions and drawings - cells 40AH to 260AH

http://www.ev-power.eu/Winston-40Ah-200Ah/

Winston Battery Cell Specification
Check the specifications for the Winston Battery Cells. Download the file here.
See also the previous information about Winston Battery cell from 2011.

Winston Battery Cell Specification

Check the specifications for the Winston Battery Cells. Download the file here.

See also the previous information about Winston Battery cell from 2011.

The BMS2405 - basic information
General function
Battery management system for Li-Ion, LiFePo4 and LiPo chemistry cells
Protect and balance cells during charge and discharge
Measure SOC (remaining charge/energy in battery)
Fully balance cells in single charging cycle if charger is not disconnected
Integrated display which shows:
—->  Mode (Charge, Discharge, Full, Error)
—->  Current state of battery 0-9
Cell balancing
Passive balancer with resistor across each cell. Balancing algorithm is executed only in charge mode.
Integrated discharge resistors for each cell. Resistors cooled to back plate.
Adjustable balancing parameters:
—-> Minimum difference voltage between cells to turn on balancing resistor
—->  Minimum cell voltage for balancing (prevents balancing in early in charge cycle)
Smart overheating protection – balancing resistors on cells with biggest voltage difference will be disconnected later as on cells which have smaller voltage difference.
Charging mode
Monitoring of each cell voltage during charge
Integrated charger disconnect relay to prevent battery overcharging
Input for two temperature sensors (standard 10 kOhm NTC)
If charger is connected after battery is fully charged, cells are continuously balanced. No need to do more charging cycles to balance all cells to 100%.
Charger detect with separate input or detection of voltage on charger input connector.
Discharge mode
Monitoring of each cell voltage during discharge
Integrated ignition switch, which disconnect ignition line in case of empty battery – when first cell reaches minimum voltage
Adjustable low voltage cell limit
SOC monitoring
Requires external battery current sensor (standard current hall probe – recommended
Monitoring of charge and discharge current and calculation SOC
Automatic adjustment of SOC when battery is fully charged or totally discharged
Analogue voltage output for connection of external battery state display.
Battery monitoring
Measures next battery data:
—->  total battery voltage
—->  battery current
—->  up to 2 x battery temperature, internal circuit temperature. Requires inexpensive NTC resistors for temperature sensing
—->  Min and max cell voltage and cell ID
—->  SOC (in %, user adjustable total battery capacity)
Battery data is send over serial port to controller. Additional can be send to programming RS232 connector for external logging devices connection.
Records battery historical data for maintaining and supervision:
—->  number of charge cycles
—->  number of deep discharge cycles
—->  total accumulated charge out (in Ah)
—->  min and max temperature for all thermometers
—->  min cell voltage and cell ID
Specifications
Works with 16 or 24 cells Li chemistry batteries. User setting of number of cells (from 6 to 24)
Balancing current 0,5 A per cell
30 A charger relay
5 A ignition switch (for disconnecting motor controller when battery is empty)
<100 uA standby power consumption
Dimensions 188 x 106 x 35 mm , weight 0,55 kg
Operating temperature -20/+65 *C, heat sink temperature protection at 80 *C.

The BMS2405 - basic information

General function

  • Battery management system for Li-Ion, LiFePo4 and LiPo chemistry cells
  • Protect and balance cells during charge and discharge
  • Measure SOC (remaining charge/energy in battery)
  • Fully balance cells in single charging cycle if charger is not disconnected
  • Integrated display which shows:
  • —->  Mode (Charge, Discharge, Full, Error)
  • —->  Current state of battery 0-9

Cell balancing

  • Passive balancer with resistor across each cell. Balancing algorithm is executed only in charge mode.
  • Integrated discharge resistors for each cell. Resistors cooled to back plate.
  • Adjustable balancing parameters:
  • —-> Minimum difference voltage between cells to turn on balancing resistor
  • —->  Minimum cell voltage for balancing (prevents balancing in early in charge cycle)
  • Smart overheating protection – balancing resistors on cells with biggest voltage difference will be disconnected later as on cells which have smaller voltage difference.

Charging mode

  • Monitoring of each cell voltage during charge
  • Integrated charger disconnect relay to prevent battery overcharging
  • Input for two temperature sensors (standard 10 kOhm NTC)
  • If charger is connected after battery is fully charged, cells are continuously balanced. No need to do more charging cycles to balance all cells to 100%.
  • Charger detect with separate input or detection of voltage on charger input connector.

Discharge mode

  • Monitoring of each cell voltage during discharge
  • Integrated ignition switch, which disconnect ignition line in case of empty battery – when first cell reaches minimum voltage
  • Adjustable low voltage cell limit

SOC monitoring

  • Requires external battery current sensor (standard current hall probe – recommended
  • Monitoring of charge and discharge current and calculation SOC
  • Automatic adjustment of SOC when battery is fully charged or totally discharged
  • Analogue voltage output for connection of external battery state display.

Battery monitoring

  • Measures next battery data:
  • —->  total battery voltage
  • —->  battery current
  • —->  up to 2 x battery temperature, internal circuit temperature. Requires inexpensive NTC resistors for temperature sensing
  • —->  Min and max cell voltage and cell ID
  • —->  SOC (in %, user adjustable total battery capacity)
  • Battery data is send over serial port to controller. Additional can be send to programming RS232 connector for external logging devices connection.
  • Records battery historical data for maintaining and supervision:
  • —->  number of charge cycles
  • —->  number of deep discharge cycles
  • —->  total accumulated charge out (in Ah)
  • —->  min and max temperature for all thermometers
  • —->  min cell voltage and cell ID

Specifications

  • Works with 16 or 24 cells Li chemistry batteries. User setting of number of cells (from 6 to 24)
  • Balancing current 0,5 A per cell
  • 30 A charger relay
  • 5 A ignition switch (for disconnecting motor controller when battery is empty)
  • <100 uA standby power consumption
  • Dimensions 188 x 106 x 35 mm , weight 0,55 kg
  • Operating temperature -20/+65 *C, heat sink temperature protection at 80 *C.

Overview of the Cell Terminal Connectors and the Compatibility Guide

See the updated document with Overview of the Cell Terminal Connectors and the Compatibility Guide.

Check the PDF (and also XLS) with the dimensions of the terminals connectors for the battery cell models.

Please note that the manufacturer of the WINA cells does not supply terminal connectors. The connectors from other manufacturers do not fit exactly right, because the WINA cells WN10AH  and WN15AH are very narrow. The one of options is to modify the shortest available connector by bending  -  LFP020-CON-V2

CALB CA100 discharge diagram

This diagram shows the discharge rates for various temperatures. The discharge is done at 0.3C (about 32Amp).

The CALB CA series dimensions overview

Check the CALB products on-line here.

Specification of the 290Wp solar panels

The 290Wp solar panel can be used with the MicroInverters. During the low sunshine days, the 290Wp solar panel will produce 20% more energy than the 240Wp panels.

Solar panels - http://www.ev-power.eu/Solar-Panels/Solar-panel-SCHUTTEN-Poly-290Wp-72-cells-MPPT-35V-EUFREE.html

Microinverters - http://www.ev-power.eu/Micro-Inverters-1/