lithium & solar power LiFePO4

FAQ: Mennekes type of EVCharge connectors - the resistor value

The proximity switch PP (resistor value between PP a PE) is available for the vehicle to describe its input charging capacity to the charging station asking to limit the current. This is done by setting a resistor between the PP and PE wires – adapter cables can use a resistor encoding to define the maximum current rating. 

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!

Overview of support information for the LiFePO4 cell charging
Overview of FAQs related to charginghttp://gwl-power.tumblr.com/post/20369751437/   
Questions on charging LFP cellshttp://gwl-power.tumblr.com/post/22582172319/    
I want to make the initial charge of all the LiFePO4 cells to the same maximal voltage …. How can I do that?http://gwl-power.tumblr.com/post/46595246130/  
The single cells charges: 3.6V 5 Amp and 3.6V 18 Amphttp://gwl-power.tumblr.com/post/90848216126/ 

Overview of support information for the LiFePO4 cell charging

Freewheels for EVBike - available from specialized companies

FAQ: I just bought 36v500w 26“ rear EVBike set. I tried to install Shimano freewheel on it, but it has a lock. In my bike repair shop, they told me that I need spacer for the freewheel. What dimension should be for 7 speed Shimano freewheel?

Answer: There are different combinations of the free-wheels,  we suggest to consult the professional bike components companies who have a wide range of accessories including the spacers.  Some companies offer freewheels designed for E-Bikes (EVBike) directly. See example of such promotion leaflet from a supplier called Sunrace.

FAQ: Is CE Mark needed for lithium cells and batteries?

No. It is not needed.  If you examine cells, battery packs and batteries from renowned producers your will not find any CE Mark. 

The CE mark in Europe is needed only for following groups of complete products:

  • Toys
  • Machinery
  • Electrical equipment
  • Electronic equipment
  • Personal protective equipment
  • Pressure equipment
  • Medical devices
  • Active implantable medical devices
  • In vitro diagnostic
  • Radio and Telecommunications terminal equipment
  • Simple pressure vessels
  • Gas appliances
  • Lifts
  • Recreational craft
  • Equipment and protective systems for use in explosive atmospheres
  • Non-automatic weighing instruments
  • Cableways
  • Construction products
  • Explosives for civil use
  • New hot water boilers
  • Measuring Equipment

Products that are not covered by the European CE marking directives may fall within the scope of other European or national legislation (for example special standards for mining industry, for automotive industry [E-Mark] and for air-craft related parts and products). If there is no specific legislation, the General Product Safety Directive (2001/95/EC) may apply. This European Directives requires that products are safe, but is does not require any marking.

Lithium cells, batteries and packs do not need any CE marking. Complete products or systems with electronics - for example a battery solution consisting of lithium cells and battery management electronics may need to obtain CE tests, if marketed as „Electrical equipment“ or as a part of „Measuring Equipment“. 

The person or company, who is assembling such complete products from individual parts, is the subject responsible to make sure of CE Mark needs to be applied. It is not possible to ask the supplier of just one part (e.g. the supplier of the cells) to give the CE mark documents for a complete product. Those, who are putting components together and sell the product under their (brand) name, need to bear the responsibility for the CE compliance by themselves.

Concerning the CE certification of electrical/electronic devices related to electromagnetic compatibility (EMC): These certifications and tests related to EMC are designed to ensure that electromagnetic radiation (physical radio waves) from components of the complete products do not interfere with other devices such as TV, radios, computers, medical equipment and mobile phones.

However passive components and products (like cells, batteries or battery packs) do not radiate any electromagnetic radiation, and that is why they are not required to undergo the tests.

Some Asian battery manufacturers have been persuaded by various testing organizations that they should be tested and this is why you will see the CE mark on many Chinese batteries.  Or such produces will provide the CE conformity document to you. However such CE marks are false in their placing and are misleading. It is like putting a CE Mark on a piece stone or a tree or onto your house-hold animal. 

If somebody is requesting the CE mark for the cells, batteries or battery packs, it shows his limited knowledge of the conformity procedures.

FAQ: Getting the “EU” socket for EU standard products for 220V/230V

Most products sold in EU have the EU type socket: either the French style with the central ground pin, or the German type - Schuco.

It is quite easy to get the EU type sockets to be able to plug the EU standard products. Simply buy the EU type extension power-strip, and change the “plug-in” head to fit your local socket system. 

The top photo shows the EU extension power-strip with the plug-in head exchanged for the UK style socket. 

The bottom photo shows the same power strip with “traveler sockets” that allow to get universal type of socket (US, UK, China, etc.)

If you need to get the EU type power strips, be sure to contact GWL for help. We are able to purchase locally and resell to you.

Question: Can the micro-inverter (in the GridFree installation) work in an island mode against some sine wave DC/AC generator? (e.g. in parallel with my own  independent 230V island system)?
Answer:  No, the microinverter in most cases will not work with in such mode. There are several reasons:
1) For legal and safety reasons the microinverter works only when connected to a real 230V AC grid. The inverter will start working only after detecting the presence of the real 230V AC grid power line. It will not start working with some simulated 230V AC power system.
2) The inverter must meet the exact requirements for the European 230V AC grid based on the strict settings given by the EN50438. The inverter must stop working if the specifications of the grid do not match the parameters given by this standard. For this reason the invertor will not work with some independent 230V island systems. Additionally the strict requirements of the EN50438 make the inverters non-functional in countries, where the quality of the grid is poor and unstable. 
3) For safety and legal reasons the micro-inverter works only in grid-tied mode. The island mode is not supported and trying to experiment with such operation is against the warranty conditions for this product.
4) Trying to connect to the input of DC/AC off grid inverter will most like result in burning the output of this equipment, since these products are designed to provide energy to the load and they are not designed to handle to receipt of energy from a parallel source. 
5) The impedance, voltage a power ratings of the real grid are far beyond the possibilities to emulate these in some small installations. Each microinverter contains high-tech protection and grid detection components. The inverter will not start when the real grid is not detected. 
Conclusion:
The MicroInverters work only with the 230V AC real grid that meets the limits of the specifications given by the EU standards. For technical, safety and other reasons the inverters cannot work against a simulated (local) power source. Additionally the MicroInverters are not allowed and cannot work in an island mode.

Question: Can the micro-inverter (in the GridFree installation) work in an island mode against some sine wave DC/AC generator? (e.g. in parallel with my own  independent 230V island system)?

Answer:  No, the microinverter in most cases will not work with in such mode. There are several reasons:

1) For legal and safety reasons the microinverter works only when connected to a real 230V AC grid. The inverter will start working only after detecting the presence of the real 230V AC grid power line. It will not start working with some simulated 230V AC power system.

2) The inverter must meet the exact requirements for the European 230V AC grid based on the strict settings given by the EN50438. The inverter must stop working if the specifications of the grid do not match the parameters given by this standard. For this reason the invertor will not work with some independent 230V island systems. Additionally the strict requirements of the EN50438 make the inverters non-functional in countries, where the quality of the grid is poor and unstable. 

3) For safety and legal reasons the micro-inverter works only in grid-tied mode. The island mode is not supported and trying to experiment with such operation is against the warranty conditions for this product.

4) Trying to connect to the input of DC/AC off grid inverter will most like result in burning the output of this equipment, since these products are designed to provide energy to the load and they are not designed to handle to receipt of energy from a parallel source. 

5) The impedance, voltage a power ratings of the real grid are far beyond the possibilities to emulate these in some small installations. Each microinverter contains high-tech protection and grid detection components. The inverter will not start when the real grid is not detected

Conclusion:

The MicroInverters work only with the 230V AC real grid that meets the limits of the specifications given by the EU standards. For technical, safety and other reasons the inverters cannot work against a simulated (local) power source. Additionally the MicroInverters are not allowed and cannot work in an island mode.

FAQ: Voltage adjustment for SBM
Question: I checked the datasheets for the SBM product. I think the over voltage and under-voltage does not fit my needs.  Can over and under-voltage levels be customized for lifepo4 cells? I think that 3.9 volt over and 2.0 volt under protection voltages are too high/low.
Answer:  The voltage settings of the SBM are designed by the manufacturer and cannot be changed.  The settings correspond to the lowest  (2.0V) and highest (3.9V) values for the LiFePO cells.  These are the emergency cut-off values. 
The SBM is designed for small capacity cells. When discharging with peak currents, the voltage on these cells may go as low as 2.0V.  In order to prevent random disconnection under big loads, the voltage of the SBM is set to 2.0V per cell.
Also, the charging should be managed by the charger and kept at 3.65 per cell. The setting of 3.9V for the SBM is the maximal charge level. In fact it may be possible to use the CBU to keep the voltage balanced down to 3.65V per cell.
The SBM is a simple low cost solution to allow simple monitoring of battery packs. The SBM should be viewed as a lowest level of the cell protection. We suggest monitoring the voltage of the whole pack as well and stopping discharging when the voltage gets low.  Please see the explanation here at this post.
For higher current applications and high capacity cells, we suggest to use BMS. Unlike the SBM, where the settings are fixed and cannot be changes,  the BMS allows to change the settings and is suitable  for systems that need complete battery monitoring and management.
We suggest to use the BMS123 solution for the battery systems. See also the blog posting.

FAQ: Voltage adjustment for SBM

Question: I checked the datasheets for the SBM product. I think the over voltage and under-voltage does not fit my needs.  Can over and under-voltage levels be customized for lifepo4 cells? I think that 3.9 volt over and 2.0 volt under protection voltages are too high/low.

Answer:  The voltage settings of the SBM are designed by the manufacturer and cannot be changed.  The settings correspond to the lowest  (2.0V) and highest (3.9V) values for the LiFePO cells.  These are the emergency cut-off values. 

The SBM is designed for small capacity cells. When discharging with peak currents, the voltage on these cells may go as low as 2.0V.  In order to prevent random disconnection under big loads, the voltage of the SBM is set to 2.0V per cell.

Also, the charging should be managed by the charger and kept at 3.65 per cell. The setting of 3.9V for the SBM is the maximal charge level. In fact it may be possible to use the CBU to keep the voltage balanced down to 3.65V per cell.

The SBM is a simple low cost solution to allow simple monitoring of battery packs. The SBM should be viewed as a lowest level of the cell protection. We suggest monitoring the voltage of the whole pack as well and stopping discharging when the voltage gets low.  Please see the explanation here at this post.

For higher current applications and high capacity cells, we suggest to use BMS. Unlike the SBM, where the settings are fixed and cannot be changes,  the BMS allows to change the settings and is suitable  for systems that need complete battery monitoring and management.

We suggest to use the BMS123 solution for the battery systems. See also the blog posting.

GWL and deliveries of goods at fair prices to remote locations
Question: I want to order 4 pieces of the solar panels from GWL. I like your pricing. But when I add the VAT and the shipment costs, your price becomes higher. Perhaps if you make a 15% discount for me, I can buy from you. I am from a small village in Dagestan. 
Answer: We welcome customers from all locations. However our customers need to be reasonable concerning the expectation of the final pricing for the delivery. The shipping costs need to by paid, and the applicable taxes must be added This may increase the price, especially for small orders.  
Check following suggestions:
* Making a bigger order volume: we suggest increasing your order volume, by adding additional components to your order. This will split the shipping costs between more products and the final price of the individual products will be lower. 
* Share your order with more people: we propose to get some of your local people around you to share the order together. Perhaps you may encourage your relatives, your colleagues, friends or neighbors to buy similar products. When you mane one order together, you may reach an additional volume discount and share the shipping costs together.
* Find a local partner for regular co-operation with GWL: you may contact your local hobby shop or some other specialized company and propose to them to make the purchase from GWL for you. Perhaps they decide to get involved and become GWL local partner. This way the company may order at volume order pricing and you can benefit from this kind of co-operation.
* Start your own small business: Another idea is that you decide simply to go ahead, and to start offering the GWL products and solutions to people at your vicinity. This way you can soon reach the volume discounts and benefit from lower pricing.
—> See some tips for co-operation here.
The most distant parts of the earth
We understand that sometimes our customers live in very distant parts of the earth where there is not any direct way to buy the DC power solution products. We will be very happy to serve you and to help you to supply these products. However we cannot substitute the costs for such deliveries. 
Each customer needs to be self-responsible and self-sufficient concerning the decision to make an order and to bear the costs for such an order.

GWL and deliveries of goods at fair prices to remote locations

Question: I want to order 4 pieces of the solar panels from GWL. I like your pricing. But when I add the VAT and the shipment costs, your price becomes higher. Perhaps if you make a 15% discount for me, I can buy from you. I am from a small village in Dagestan. 

Answer: We welcome customers from all locations. However our customers need to be reasonable concerning the expectation of the final pricing for the delivery. The shipping costs need to by paid, and the applicable taxes must be added This may increase the price, especially for small orders.  

Check following suggestions:

* Making a bigger order volume: we suggest increasing your order volume, by adding additional components to your order. This will split the shipping costs between more products and the final price of the individual products will be lower. 

* Share your order with more people: we propose to get some of your local people around you to share the order together. Perhaps you may encourage your relatives, your colleagues, friends or neighbors to buy similar products. When you mane one order together, you may reach an additional volume discount and share the shipping costs together.

* Find a local partner for regular co-operation with GWL: you may contact your local hobby shop or some other specialized company and propose to them to make the purchase from GWL for you. Perhaps they decide to get involved and become GWL local partner. This way the company may order at volume order pricing and you can benefit from this kind of co-operation.

* Start your own small business: Another idea is that you decide simply to go ahead, and to start offering the GWL products and solutions to people at your vicinity. This way you can soon reach the volume discounts and benefit from lower pricing.

—> See some tips for co-operation here.

The most distant parts of the earth

We understand that sometimes our customers live in very distant parts of the earth where there is not any direct way to buy the DC power solution products. We will be very happy to serve you and to help you to supply these products. However we cannot substitute the costs for such deliveries.

Each customer needs to be self-responsible and self-sufficient concerning the decision to make an order and to bear the costs for such an order.

EVBike battery voltage indicator – only voltage level
Question: When I press the button on the EVBike battery indicator, the battery shows to be 100% full or 80%, but when I drive just few hundred meters, the battery will be empty very soon. Where is the problem?
Answer: The EVBike battery indicator indicates the total voltage of the battery. With lithium cells, the battery has always the full voltage (with no load) even when the battery is nearly empty. It is important to understand that the indicator is only a voltage indicator – it is not a capacity indicator. For regular operation of the battery (with no load) this indicator should always be at 100% or 80%. If the indicator is bellow 80% (with no load) there may be some problem with the battery, or the battery is deeply discharged. 
In case your battery is empty, you should charge your battery as soon as possible. Never left empty batteries without charging!  Always charge the battery to full before storing your bike. 
If you stop using you EVBike with the empty battery, most likely you will find the battery damaged and not working properly several weeks or months later. This kind of damage is not covered by the warranty.
When driving your EVBike, the battery is under the load. You can try to press the EVBike battery voltage indicator while driving to see the voltage drop under load. If the voltage of the battery is low, the EVBike battery voltage indicator will show it. When the voltage of the battery is low, we suggest to charge as soon as possible.  The proper charging will extend the service life of the battery.
Please remember: First charge, then drive.

EVBike battery voltage indicator – only voltage level

Question: When I press the button on the EVBike battery indicator, the battery shows to be 100% full or 80%, but when I drive just few hundred meters, the battery will be empty very soon. Where is the problem?

Answer: The EVBike battery indicator indicates the total voltage of the battery. With lithium cells, the battery has always the full voltage (with no load) even when the battery is nearly empty. It is important to understand that the indicator is only a voltage indicator – it is not a capacity indicator. For regular operation of the battery (with no load) this indicator should always be at 100% or 80%. If the indicator is bellow 80% (with no load) there may be some problem with the battery, or the battery is deeply discharged. 

In case your battery is empty, you should charge your battery as soon as possible. Never left empty batteries without charging!  Always charge the battery to full before storing your bike. 

If you stop using you EVBike with the empty battery, most likely you will find the battery damaged and not working properly several weeks or months later. This kind of damage is not covered by the warranty.

When driving your EVBike, the battery is under the load. You can try to press the EVBike battery voltage indicator while driving to see the voltage drop under load. If the voltage of the battery is low, the EVBike battery voltage indicator will show it. When the voltage of the battery is low, we suggest to charge as soon as possible.  The proper charging will extend the service life of the battery.

Please remember: First charge, then drive.

FAQ: EVBike Kits - which to choose? How to install the rear one?

Question: I want to get the EVBike conversion kit. Which type of the kit do you suggest: the front or the rear wheel?

Answer: we sell both types of kits. We do not prefer any type of the kit. The customer must decide which EVBike kit to choose. 

See some guide lines for the rear wheel drive kit: Even though rear wheel drive conversion may seem more complex and not that easy to install as a front wheel drive, it has these advantages:

  • The rear fork is stronger (this is a must for high power projects)
  • The disc brake fits more probably
  • The “motorbike” design and feel

See above the picture with a nine speed freewheel.  (The motor is the same dimensions as the EVBike 500W motor). You may need to use a washer to make a bigger distance between freewheel and motor (in case the chain interferes with the motor). Another washer might be needed for the other side of the free-wheel (in case the chain interferes with rear fork). These washers may widen the standard dropout of 135mm a bit.  However it is not a problem in most cases.

Question: Do you sell the 7 gears free-wheel cassette?

Answer: We do not sell the free-wheel spare parts any more. Customers prefer various brand types and sizes of the free-wheels: 6, 7, 8, 9. It is easier you can buy such a free-wheel according to your wish in your local bicycle shops.  

Note: please note that you must use a freewheel with the thread, not the cassette type! (see details here)

Steca XPC 2200-24 integrated charger details – FAQ part 2

The XP-Compact (XPC) model offers integrated automatic battery charger.  See some more FAQs for Steca XPC 2200-24:

Question: What is the MIN voltage for Steca XPC charger?
Answer:
 The battery is disconnected when 2.9V per cell is reached and “Batt. Undervolt.” LED goes on.

Question: Can I control the charging current?
Answer:
 The Steca XPC allows user to adjust charging current with the turning the knob 22 – charger current adjustment. Please keep the maximum current within the declared continuous charging current limit of your LiFePO4 batteries.

Question: How do I find out how much charged my battery is?
Answer: SOC can be checked with Steca RCC-01 remote control, which is not supplied together with Steca XPC. With RCC-01 you can monitor state of charge of your batteries in four levels, you can change factory predefined voltage levels for MIN (low battery), MAX (absorption voltage) and FLOAT (maintained voltage at full charge). Without Steca RCC-01 remote controller only MAX and EMPTY levels can be observed at the Steca XPC itself. Additionally the Steca RCC-01 is designed for lead-acid batteries, it doe not support LiFePO4. When detailed monitoring for LiFePO4 pack is needed, we suggest using the BMS for this purpose

http://www.ev-power.eu/Inverters-DC-AC/

Steca XPC 2200-24 integrated charger details – FAQ part 1

The XP-Compact (XPC) model offers integrated automatic battery charger. It is designed to work with lead acid or gel batteries, but it can also work with LiFePo4 perfectly, when set up properly for the LFP voltage levels.  See some FAQs for Steca XPC 2200-24:

Question: How to turn on the integrated charger?
Answer:
The Charger is fully automatic. It switches on itself if minimum alternating voltage is detected at the AC input. During the charging phase the appliances at the outlet AC OUT are continually supplied with AC power.

Question: Can I leave LiFePo4 batteries connected to Steca XPC permanently?
Answer:
Yes, internal float charge system allows you to connect LiFePo4 batteries and keep them connected. Equalization charge option must be switched off! There is small switch at the bottom of Steca XPC called “equalize.” This must be switched OFF!

Question: What is the MAX voltage for Steca XPC charger:
Answer: Integrated automatic charger stops charging when 3.6V per cell absorption charge is reached and 3.37V is maintained (float charge). Green LED “Batt 100%” goes ON.

More details: http://www.ev-power.eu/Inverters-DC-AC/ 

The Steca Solarix PI 1100 with LiFePO4 - FAQ

Q: Can the Steca PI 1100 inverters with LiFePo4 batteries?
Yes, the Steca PI1100 inverters were tested with the LiFePo4. The 24V models are designed to be used with a pack of 8 cells (24V).

Q: If batteries are getting empty, when is the load disconnected?The “Safety Low voltage disconnect function” is will disconnect the load when the battery voltage drops down (usually because of discharge). The disconnect level depends on the amount of current. If a high current is being taken from the batteries, the safety disconnect is done later than if the low currents are taken.

Q: What is the disconnecting voltage?
Our tests show following:  with high currents the load is being disconnected at 20.8V per pack, with small currents the low voltages disconnect is between 21.6V to 23.2V,

Q: Should I use the BMS?
Yes. We strongly recommend using the BMS to monitor and protect the cells on the individual cell level. We suggest always to use the BMS as additional safety disconnect at low voltage. In case of failure of the Steca inverter, the BMS would disconnect the battery pack as a protection. See additional information here: why to install a BMS and understanding the BMS operation.

Q: Does the Steca PI 1100 need restarting manually after low voltage fail-safe was activated?
No, the PI1100 inverter does not need a manual restart after the low voltage disconnect. When the voltage at the batteries returns back to the normal level, the inverter will start working again automatically.