FAQ: How to connect the small cylindrical cells together?
Answer: First never try to solder the contact to these cells. You are sure to damage the cell by over heating. Any temperature above 70*C is damaging to the cells! Without professional soldering equipment it is not possible to make the connection.
We suggest using the round-cell battery holders. The holders for big „D“ size cells can fit some of the cell. The contacts for the holders for the lithium cells can be purchased form a local electronics shop (check the German Conrad as an example).
See the photos of some possible solutions.
GWL/Power Socket with swich 230V 16A
A simple solution to disconnect a 230V device from the AC power (off the grid). The built in light also gives an evident identification if the socket is on the power or not. Check the GWL/Power Socket with swich 230V 16A .
A safety hint: We always recommend a complete hardware disconnetion of any equipment from the power sources when the equipment will be left unsupervised.
Another cell strapping photo! Enjoy.
FAQ: What is the capacity of a SuperCap?
The calculation is showed in the picture. For a 6000 F capacitor working with 2.5V nominal voltage, the total energy is 5.2 Wh. Divided by the discharge voltage of 2V, the capacity is 2.6 Ah.
The Result: 6000 Farad SuperCap at 2.5V has about 2.6 Ah capacity. To make a 12V 40Ah SuperCap “battery” you need 112 pieces of 6000 F super capacitors (16P7S configuration). (Source)
Simple Battery Management Board (SBM)
The easiest way to protect a lithium battery pack. The SBM board manages a pack of cells and disconnects the load under any unfavourable circumstances: cell over voltage, cell undervoltage.
SBM16/60 - the management board for 16 LFP cells (48V) with power up to 60A. (photo) Check the PDF with technical specifications for SBM16/60. For higher loads you need to use a DC contactor to be managed by the SBM board. This drawing shows the DC contactor installation.
Mounting cells using the strapping belts
Check more details here….
Parametric selector of off-the-shelf BMSs for large Li-Ion battery packs
By now, dozens of Li-Ion BMSs are commercially available, making a choice somewhat daunting. This web page offers you to chose the right, commercially available BMS, for your large Li-Ion battery pack application based on your needs.
High speed balancing with high currents using Akumons
A simple solution using the automotive 12V relay and the 12V halogen bulbs.
Simple solution to make a 24V battery pack
Two 12V batteries (here 12V 60A) are packed together. A plastic handle is mounted too, to allow easy carrying of the pack.
A high power fuse (400A) and two Akumons are mounted inside a plastic box.
Replacing SLA in the UPS with LFP
Multiply the performance of any UPS (Uninterruptable Power Source) by replacing the SLA (Sealed Lead Acid) batteries with the LFP (Lithium Phosphate) technology.
The old battery pack on the photos is from APC 1000VA rack UPS model. The nominal capacity of the pack is 24V 14Ah (2S2P configuration). The real energy available from the pack is max 250Wh. This means that a 250W computer may run up to 60 minutes from the UPS with the original SLA battery.
The Charging 12 pcs of 20Ah cells
The initial charging of the number of cells. For charging we are using a laboratory power supply capable of 5V 100A. We set the nominal voltage for 3.8V and connect the cells.
These 12 cells in parallel make a big 3V 240AH cell together.
Warning: when charging in parallel, it is a MUST (!) to double check the correct polarity of the cells. Connecting a cell in reverse polarity will cause a dangerous short circuit that may result in a strong sparking. BE EXTREMELY CAREFULL (!).
Warning: we suggest to wear protective eye-glasses to avoid a possible damage to the eyes by sparks or melted metals in case an accident happens.
Charging 12V batteries in a parallel pack
Six 12V 60AH batteries chargered with 12V 100A charger. The batteries are in parallel and make 12V 360AH pack.
Hint 1: Note that the terminals of the charger are connected on the oposite sides of the pack. This is a small hint to make sure that all the batteries will be chargered equally during the high speed charging.
Hint 2: Additionally after the charge cycle is finished, it seems good to let the batteries rest and equalize over 1 or 2 hours and then make another charge to full. This may be repeated 2 to 3 times to make the batteries in the pack equally charged.
Cleaning all the battery terminals with a wire brush before you connect them up makes a remarkable difference to how the pack performs. ThunderSky cells use bare copper and aluminium for the terminals which quickly builds up an oxide layer (Al2O3 is particularly pernicious). In one extreme case (a couple of years back) the oxide layer caused so much resistive heating at some terminals that there was heat discoloration on the interconnector, melting of the plastic around the terminals, and fried BMS modules!
Hint: pressing the swelling cells using the carpenter’s holders or clamps
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