These are 26650 cells by A123 put on a pcb with almost the equivalent of 10awg copper traces.
8mmx.2mm nickel strip.
Balance plug attached.
Full charge in just 15 minutes at 30a!
Battery Details:
- Configuration: 12s3p
- Nominal Voltage: 39.6v
- Max Voltage: 43.8v
- Min Voltage: 24v (not recommend as there’s little power left after 36v)
- Capacity: 7.5 ah
- Wh: 297 Wh
- Range: 15-25 miles, depending on rider conditions and setup
This is similar to a 10s li-ion battery in voltage.
Benefits of Lithium Iron:
- Longer Life Cycle (2000 to 80% instead of 400 cycles to 80% with Li-ion)
- Higher discharge rate (Mooch tested 30a continuous instead of 15a with 30q)
- Far less voltage sag (stays at 3.3v for most of discharge)
- Much higher charge (10a vs 4a with 30q)
- Far safer and difficult to catch on fire.
Downsides of Lithium Iron
- Less energy density (meaning less capacity and less range)
How these batteries are made
All of these cells are slightly used cells from the battery hookup a123 deal. We have tested these batteries to 95% capacity or higher so far, as advertised. This means they still have more than 3x the life cycle left of brand new li-ion batteries.
- Solder JST XHP-13 2.5mm port to pcb
- Sort cells using the same p groups as the original battery (which is a 12s4p), by taking 1 cell from each p.
- Fishpaper donuts are applied to the button side cells
- Weld nickle tabs to the cells first (no less than 3 good welds per tabs)
- Align cells and add silicon to each cell between pcb and cell (This ensures the cells are held in place)
- Weld the nickle to the PCB (These nickle strips are supported by the silicon)
- Kapton tape the entire bare side of the pcb
- Kapton tape each cell to the pcb
- Add foam to the center of the pcb to create a physical barrier so even worse case, the cells can’t short across
- Attach Velcro to battery with a slight flex
These batteries have especially 18 bend points where it can bend without stressing the nickle so they are ok to flex a bit. We want our boards to flex like a non-electric deck, not be stiff as a rock.
Dimensions
- Battery: 496mm x 143mm x 29mm
- Enclosure: 585mm x 145mm x 19mm
- Deck Pocket: 585mm x 145mm x 13mm
So combined, you have 585mm x 145mm x 32mm to work with.
After the battery, you are left with 89mm x 145mm x 32mm.
If you use this smart bms, you are left with 89mm x 145mm x 22mm.
Now velcro takes up about 2mm, so realistically, you need to fit your esc(s) in a 89mm x 145mm x 20mm footprint.
It’s a bit tight, but 2 Official VESC 6’s fit perfectly.
Smart BMS
We choose to use a charge only smart bms that 108mm x 65mm x 10mm thick. They are very thin and you can stack the esc’s on top of the bms.
The nice feature is you can see every cell’s voltage right on your smart phone. Also, with 2 temp sensors, you can see the temperature of the battery in 2 different places. You can see how many amps it’s charging at and which cells are being balanced, so you can see that your bms is actually doing what it should be doing, instead of operating your bms blindly.
Prices (shipping Included)
- Battery solo (w/ velcro): $250
- Battery (w/ velcro) and Smart BMS prewired: $310
- Hummie deck w/ frit (color of choice) and custom logos (if desired), 1/16" foam seal, custom Kydex enclosure w/ fender washers and screws, and Battery (w/ Velcro) and Smart BMS prewired (comes fully assembled): $500
Payment:
PayPal: humminashadeeba@gmail.com
(Friends and family or 10$ more due to PayPal Fees)
(Give your name and address to me through PayPal)
These are ideal for high power electric skateboards. Mooch rates cells to 30a each, so 90a discharge without impacting the life cycle ratings. a123 claims 50a per cell, so they can run up to 150a.
They are also ideal for people worried about battery fires. Our testing has shown that even if you puncture a cell in the middle of the battery pack, that cell will go up in flames and not cause thermal runaway event. Same with short circuits and over charging. Smoke, but no fire. Your house is not going to burn down.
they exist. Though it is still untested…