lithium & solar power LiFePO4
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.

FAQ: Battery Overcharged – What to do? 

In case of failure to charge properly, the overcharge will result in damage of the internal cell structure. In base of mild overcharge, there is some chance to recover the function of the cell.  

If overcharge happens, follow these guide lines:

1) Remove the charger and stop charging immediately.
2) Discharge the cell slowly with reasonable currents (bellow 0.1C, bellow 10A for 100Ah cell). The discharge should last until the voltage drops to normal level (e.g. 3.2V for LFP cells)
3) While discharging, open the safety valve to allow the internal pressure to release. (Not all cells have the safety valve designed to be opened. Please contact us for specific instructions.)
4) If the cells are swollen, we suggest to follow the instruction to press the cells back to their original size (see details here).

After the cells have been restored, we suggest to make some testing cycles to see the performance of the cell. (E.g. 5 to 10 cycles). For cells that were overcharged by mistake, we strongly suggest to avoid repeated charging them to full voltage. Charging to 80% ~ 90% level of nominal capacity is a good way to avoid further degradation of the cells that were already overcharged.

FAQ: Battery Overcharged – What to do?

In case of failure to charge properly, the overcharge will result in damage of the internal cell structure. In base of mild overcharge, there is some chance to recover the function of the cell.

If overcharge happens, follow these guide lines:

1) Remove the charger and stop charging immediately.
2) Discharge the cell slowly with reasonable currents (bellow 0.1C, bellow 10A for 100Ah cell). The discharge should last until the voltage drops to normal level (e.g. 3.2V for LFP cells)
3) While discharging, open the safety valve to allow the internal pressure to release. (Not all cells have the safety valve designed to be opened. Please contact us for specific instructions.)
4) If the cells are swollen, we suggest to follow the instruction to press the cells back to their original size (see details here).

After the cells have been restored, we suggest to make some testing cycles to see the performance of the cell. (E.g. 5 to 10 cycles). For cells that were overcharged by mistake, we strongly suggest to avoid repeated charging them to full voltage. Charging to 80% ~ 90% level of nominal capacity is a good way to avoid further degradation of the cells that were already overcharged.

FAQ: Low temperature operation: What is the capacity of the LiFePO4 battery at different temperatures? (at 25°C,  at 0°C,  at -20°C ?)

1) Battery capacity

For 10*C to 40*C the battery nominal capacity is 100%. For temperatures bellow 10*C the internal resistance of the battery increases and as a result the total capacity decreases. The information is published here at GWL/Blog.

at 0°C:  we estimate some 90% of available capacity.at -20°C: we estimate some 60% of available capacity.

2) Low voltage disconnect (under load)

he discharge voltage level changes (from suggested 2.8V) with the change of temperature.

The information is published here at GWL/Blog:

at 0°C: the low voltage level changes from 2.8V to 2.4Vat -20°C: the low voltage level changes from 2.8V to 2.0V

3) Battery operating temperature

We do not recommend to leave the battery unattended to become frozen to low temperatures. In cold climates, we suggest to make sure the temperature of the battery pack will stay at least at +5*C (or more).

We do not recommend operating the battery in bellow zero temperatures.4) Some tips to operate the battery in cold climate

a) Make proper insulation of the pack so that the pack does not lose temperature to outside cold environment

b) Arrange for the pack heating (during charge). Properly insulated pack may be preheated to quite high temperature (even to 30*C) to absorb the thermal energy. This way the properly insulated pack of large capacity may stay warm for several days.

c) Arrange for the pack “defrosting”. Properly insulated pack may use some part of its energy to warm itself before or at the beginning of the operation in cold climate. Usually about 5% to 8% od energy may be used to increase the temperature of the properly insulated battery pack.

FAQ: Low temperature operation: What is the capacity of the LiFePO4 battery at different temperatures? (at 25°C, at 0°C, at -20°C ?)

1) Battery capacity

For 10*C to 40*C the battery nominal capacity is 100%. For temperatures bellow 10*C the internal resistance of the battery increases and as a result the total capacity decreases. The information is published here at GWL/Blog.

at 0°C: we estimate some 90% of available capacity.
at -20°C: we estimate some 60% of available capacity.


2) Low voltage disconnect (under load)

he discharge voltage level changes (from suggested 2.8V) with the change of temperature.

The information is published here at GWL/Blog:

at 0°C: the low voltage level changes from 2.8V to 2.4V
at -20°C: the low voltage level changes from 2.8V to 2.0V


3) Battery operating temperature

We do not recommend to leave the battery unattended to become frozen to low temperatures. In cold climates, we suggest to make sure the temperature of the battery pack will stay at least at +5*C (or more).

We do not recommend operating the battery in bellow zero temperatures.

4) Some tips to operate the battery in cold climate

a) Make proper insulation of the pack so that the pack does not lose temperature to outside cold environment

b) Arrange for the pack heating (during charge). Properly insulated pack may be preheated to quite high temperature (even to 30*C) to absorb the thermal energy. This way the properly insulated pack of large capacity may stay warm for several days.

c) Arrange for the pack “defrosting”. Properly insulated pack may use some part of its energy to warm itself before or at the beginning of the operation in cold climate. Usually about 5% to 8% od energy may be used to increase the temperature of the properly insulated battery pack.

FAQ: The difference between the LiCoO2 and LiFePO4 battery technology

Learn about the differences of these two battery technologies: 1. General information, 2. Faster charging and safer performance, 3. Large overcharge tolerance and safer performance, 4.  Longer cycle life, 5.  High temperature performance.

Check and download the GWL Support document

FAQ: The difference between the LiCoO2 and LiFePO4 battery technology

Learn about the differences of these two battery technologies: 1. General information, 2. Faster charging and safer performance, 3. Large overcharge tolerance and safer performance, 4. Longer cycle life, 5. High temperature performance.

Check and download the GWL Support document

FAQ: The discharge level of the 12V batteries with PCM

** Question: I keep discharging the 12V battery with PCM. But when the voltage gets to some 11V, the voltage suddenly drops to 0V. Is the battery defective?

No, the battery is not defective. The PCM board in side this type of battery will disconnect the output when the voltage level of the cells inside the battery is getting too low. That is why the voltage will change to 0V – the battery protection will disconnect the battery.

Note: we strongly recommend not using the PCM protection as a last resort to stop the equipment from draining the battery. Follow the suggestions at this article.


** Question: When I discharge the 12V PCM battery, the voltage will drop to 0V. After that the voltage stays at 0V. I need to disconnect the battery from my equipment to get the battery to work again. This is annoying. What should I do?

The LiFePO4 battery has the protective circuit – called the PCM. The PCM will physically disconnect the battery from the load to prevent the discharging. In order to release the PCM back to ordinary function, the load must be disconnected completely. (Note: in some cases the release may take some time, until the voltage of the cells increases to safe level again.)

If you keep draining the battery, the voltage will stay at 0V (disconnected) until the equipment is turned off or disconnected. This is a proper function of the PCM battery. If you have some equipment that keep draining the battery, we suggest: A) install a mechanical switch to disconnect the battery from this equipment B) start charging the battery BEFORE the battery is fully depleted.

** Question: I discharge the 12V battery with PCM. Some of the batteries will discharge till 10.5V some to 11.2V. The label on the battery says 10V. What is wrong?

As long as the battery has the nominal capacity, nothing is wrong. The battery consists of 4 cells inside the package. Each of the cells is monitored by the PCM. The nominal voltage of the low voltage disconnect is at 2.5V per cell. This means: in case all of the cells will be discharged identically, the disconnect voltage will be at 4x 2.5V = 10V. However the cells are seldom discharged at the same level. One of the cells will always be discharged earlier. In such a situation the voltage level of the total pack will be higher. For example: 2.5V + 2.8V + 2.8V+ 2.9V = 11V. However the difference may be even bigger: 2.5V + 3.0V + 3.0V+ 3.1V = 11.6V. This is not a fault of the battery; this is the normal function of the PCM board.

In addition to the various voltage levels of the cell, the tolerance of the PCM board is about 5%. This means the low voltage-disconnect level may be around 2.5V to 2.62 V per cell. This again can cause some difference of the results from different units of the battery with PCM.

Note: in earlier deliveries of the cells the low voltage was set at 2.0V per cell, making the disconnection level as low as 8V. Based on our long term tests the setting was changed to 2.5V per cell, making the level at 10V (with tolerance between 10V to 11.6V)

Proper position of the LiFePO4 cells

The LiFePO4 should be always mounted with the terminals facing upwards. Installations with the terminals on the side is not supported. The cell operation in such a possition may result into a hazardous situation, such as the internal short circuit, buring or fire.

Avoid storing and using the cells in this kind of possition. Always store and use the cells in the regular position.

FAQ: The shipping costs of the delivery of repaired products

Question: I have a product that needs a repair. I want to send the product for repair. However I see that the customer needs to pay for the delivery on both ways. I think this is a quite bad service to pay for delivery on both ways.

Answer: First we are sorry to hear that your product needs a repair (RMA). We will do our best to provide a repair or replacement (based on the instruction from the manufacturer). For the shipping of the defective products to get the repair, the customer needs to care for both delivery (to our company) and for the return way (from our company). This is a standard situation in any business.  

See an example:  you buy a nice watch in a watch shop that is across your city. But for some reason the watch is not working fine and needs a repair from the watchmaker specialist. What do you need to do? First you need to travel to the watch shop to place the watch for repair. When the watch is repaired after some time, you need to travel to the watch shop again to take the watch from the repair.  You need to travel both ways. You always need to do this – to travel two ways – and it is a normal situation. We have never heard that a watchmaker specialist would make the delivery of the watch back to you home – you always need to go to the watch shop again.

In the same way, as a standard situation, the customer needs to take care (to pay) of the costs for the delivery to and return from our company. 

As a special benefit to returning customers, we offer FREE shipping in this way:

The customer can make a new order (after the RMA is processed and solved) and the RMA product will be shipped together with the goods form this new order without any additional shipping fee. 

Be sure to check with our team of technicians if you wish to make a new order to cover the costs of the return of the repaired (RMA) products.

FAQ: The shipping costs of the delivery of repaired products

Question: I have a product that needs a repair. I want to send the product for repair. However I see that the customer needs to pay for the delivery on both ways. I think this is a quite bad service to pay for delivery on both ways.

Answer: First we are sorry to hear that your product needs a repair (RMA). We will do our best to provide a repair or replacement (based on the instruction from the manufacturer). For the shipping of the defective products to get the repair, the customer needs to care for both delivery (to our company) and for the return way (from our company). This is a standard situation in any business.

See an example: you buy a nice watch in a watch shop that is across your city. But for some reason the watch is not working fine and needs a repair from the watchmaker specialist. What do you need to do? First you need to travel to the watch shop to place the watch for repair. When the watch is repaired after some time, you need to travel to the watch shop again to take the watch from the repair. You need to travel both ways. You always need to do this – to travel two ways – and it is a normal situation. We have never heard that a watchmaker specialist would make the delivery of the watch back to you home – you always need to go to the watch shop again.

In the same way, as a standard situation, the customer needs to take care (to pay) of the costs for the delivery to and return from our company.

As a special benefit to returning customers, we offer FREE shipping in this way:

The customer can make a new order (after the RMA is processed and solved) and the RMA product will be shipped together with the goods form this new order without any additional shipping fee.

Be sure to check with our team of technicians if you wish to make a new order to cover the costs of the return of the repaired (RMA) products.

The operation of the battery pack and its capacity
The battery should never be discharged too low. It should also never bee overcharged. You should always stay within the safe limit of the operation. See the suggestion of the capacity indication by the BMS123 software settings.

The operation of the battery pack and its capacity

The battery should never be discharged too low. It should also never bee overcharged. You should always stay within the safe limit of the operation. See the suggestion of the capacity indication by the BMS123 software settings.

BMS123 - Frequently Asked Questions
What cells can be used? Most block-type LiFeYPO4 cells, say from 60 Ah and up. As the boards are mounted on the positive pole, different lenghts of thick copper-wire  to the negative pole adjusts for different cell-dimensions. Can I use other cells then LiFeYPO4? As all voltage-levels are user programmable (between 2 and 5 Volts) other battery types can be used too. Off course, battery technology is changing rapidly, and we are always prepared to help you solve particular problems.   What charger should I specify? As the BMS-controller forms a happy marriage with any TC-charger…specify a model with the required voltage- and current- level….no need to order the CAN-bus-option, the standard three-wire interface will do!
Do the BMS-boards increase self-discharge? Yes, off course, although the BMS-boards use « 100 uA, which is roughly 1 / 50-th (!) of the self-discharge-current for a 90 Ah LiFeYPO4-cell.  The controller is also using very little current: less then 15 mA from a 12 Volt battery. Low enough to stay alive for months (!) on an average car-battery. Can I split my battery-pack? Yes, we thought about that too! Off course, we see people hide one pack in the back, and another pack in the front of the car, for instance. It is important to treat each pack separately…each pack will have to be fitted with its own “IN”- and an “OUT”-board. What if a cell gets too empty? If the cell-voltage gets way too low, that particular board would block communication, and THUS the charging. By selecting ‘Emergency charge’ the charging process can be started, even if there is no BMS-communication.
How does the balancing work? Each BMS-board is equipped with a so-called ‘programmable current-source’. Bypass-current is set to 1 Amp, irrespective of the bypass-voltage chosen.  Depending on the TC-charger used, the “minimum charging-current” should be set to ~ 1 Ampere. (For a 20 Amp. charger this would be 5 %) When balanced-charging is selected, the controller will slowly reduce the charging-current, until all cells have reached the bypass-voltage set. In quick-charging mode however, the entire charging process is carried out with maximum charging current, until one of the cells reaches the maximum-voltage set. How many cells can I use? A maximum of 255 cells can be used, albeit that the time needed to get a message through that many cells slows down the response-time of the electronic PC-dashboard notably.

BMS123 - Frequently Asked Questions

What cells can be used?
 
Most block-type LiFeYPO4 cells, say from 60 Ah and up. As the boards are mounted on the positive pole, different lenghts of thick copper-wire  to the negative pole adjusts for different cell-dimensions.
 
Can I use other cells then LiFeYPO4?
 
As all voltage-levels are user programmable (between 2 and 5 Volts) other battery types can be used too. Off course, battery technology is changing rapidly, and we are always prepared to help you solve particular problems. 
 
What charger should I specify?
 
As the BMS-controller forms a happy marriage with any TC-charger…specify a model with the required voltage- and current- level….no need to order the CAN-bus-option, the standard three-wire interface will do!

Do the BMS-boards increase self-discharge?
 
Yes, off course, although the BMS-boards use « 100 uA, which is roughly 1 / 50-th (!) of the self-discharge-current for a 90 Ah LiFeYPO4-cell.
 
The controller is also using very little current: less then 15 mA from a 12 Volt battery. Low enough to stay alive for months (!) on an average car-battery.
 
Can I split my battery-pack?
 
Yes, we thought about that too! Off course, we see people hide one pack in the back, and another pack in the front of the car, for instance. It is important to treat each pack separately…each pack will have to be fitted with its own “IN”- and an “OUT”-board.
 
What if a cell gets too empty?
 
If the cell-voltage gets way too low, that particular board would block communication, and THUS the charging. By selecting ‘Emergency charge’ the charging process can be started, even if there is no BMS-communication.

How does the balancing work?
 
Each BMS-board is equipped with a so-called ‘programmable current-source’. Bypass-current is set to 1 Amp, irrespective of the bypass-voltage chosen.
 
Depending on the TC-charger used, the “minimum charging-current” should be set to ~ 1 Ampere. (For a 20 Amp. charger this would be 5 %)
 
When balanced-charging is selected, the controller will slowly reduce the charging-current, until all cells have reached the bypass-voltage set.
 
In quick-charging mode however, the entire charging process is carried out with maximum charging current, until one of the cells reaches the maximum-voltage set.
 
How many cells can I use?
 
A maximum of 255 cells can be used, albeit that the time needed to get a message through that many cells slows down the response-time of the electronic PC-dashboard notably.