EXTREME POWER NMC
Lithium Ion 48v 16Ah battery pack
Please note, our LiIon packs are now in production in limited
quantity. I am expecting the first batch in August!
Our new LiIon
battery packs are being built from 32mm cylindrical cells. We are using 32700
cells; these are Lithium NMC 3.7v 8Ah capacity and 5c discharge rate. I have
been told Mercedes is using the same cells in their EV packs! (difficult to discover if this is true of course!) These
cells are rated at 40A discharge, two in parallel gets us 80A discharge
rating. Perfect for the 40-45A load from our 2000w mid drive kit as you never
want to load your cells up more than around 50% of their rating if possible.
am using 32mm cells is they are much easier to build into packs, with only 2
cells in parallel it is easier to find a bad one and easier to replace it if
needed. 18650 cells have come a long way in the last 5-10 years and you can
get some amazing high power versions (not cheap though) but you still need
5-6 cells in parallel to get the capacity high enough for a bike. 10c
discharge means 2500mah per cell maximum, larger capacity cells don’t have
the same discharge ratings so a 4000mah 18650 cell might only be 2c, this
means 8A max, 5 of them in parallel gets you a 20Ah pack with a max rating of
40A discharge, its just not enough for high power bikes like ours.
building the packs with a quality BMS board that features balancing circuit,
over charge and over discharge protection, a 40A constant output stage and
has a 100A short circuit protection built in.
shipment was a semi triangle, approx 200mm across the top and 200mm down the
back, it easily fits our LUNA triangle bag. Testing was very positive and the
48v LiIon pack performed as well as the old hi power 45v LiPO packs we always
We use AMASS
XT90s anti-spark plugs for main connection, you charge through the same plug
as the BMS is shared port design. Pack weight is 4.4kg.
Production packs will be a rectangular pack that will be approx 240mm long,
130mm high, 70mm thick.
ABOUT OUR BATTERIES
LiIon PACKS (Lithium Nickel
Manganese Cobalt Oxide)
One of the most successful Li-ion systems is a cathode combination of
nickel-manganese-cobalt (NMC). Similar to Li-manganese, these systems can be
tailored to serve as Energy Cells or Power Cells. For example, NMC in an
18650 cell for moderate load condition has a capacity of about 2,800mAh and
can deliver 4A to 5A; NMC in the same cell optimized for specific power has a
capacity of only about 2,000mAh but delivers a continuous discharge current
of 20A. A silicon-based anode will go to 4,000mAh and higher but at reduced
loading capability and shorter cycle life. Silicon added to graphite has the
drawback that the anode grows and shrinks with charge and discharge, making
the cell mechanically unstable.
The secret of NMC lies in combining nickel and manganese. An analogy
of this is table salt in which the main ingredients, sodium and chloride, are
toxic on their own but mixing them serves as seasoning salt and food
preserver. Nickel is known for its high specific energy but poor stability;
manganese has the benefit of forming a spinal structure to achieve low
internal resistance but offers a low specific energy. Combining the metals
enhances each other strengths.
NMC is the battery of choice for power tools, e-bikes and other
electric power trains. The cathode combination is typically one-third nickel,
one-third manganese and one-third cobalt, also known as 1-1-1. This offers a unique blend that also
lowers the raw material cost due to reduced cobalt content. Another
successful combination is NCM with 5 parts nickel, 3 parts cobalt and 2 parts
manganese (5-3-2). Other
combinations using various amounts of cathode materials are possible.
Battery manufacturers move away from cobalt
systems toward nickel cathodes because of the high cost of cobalt.
Nickel-based systems have higher energy density, lower cost, and longer cycle
life than the cobalt-based cells but they have a slightly lower voltage.
NOTE: Using a quality charger and storing batteries
safely in a steel tool box are necessary habits to get in to with Lithium batteries and
something we expect our customers to do. We do not warranty
overcharged batteries that are charged with 3rd party chargers.
batteries inside your house! We say this to every customer, it’s in our battery
instruction notes, and it NEEDS TO BE FOLLOWED. We will not be held responsible for you damaging your property by
charging or storing these batteries inside the house! Charge outside under
cover, or in the garage on a non flammable surface away from everything!
Lithium cells start to degrade as soon as they are manufactured, they have a
finite shelf life, storing LiIon correctly at 70-80%
capacity increases their lifespan a lot. It is this reason that claims from
sellers of thousands of cycles is completely pointless, as most of these
batteries will fail due to age and not cycles!!
strict guidelines will get the most life from your batteries, being careless
with how you use and store them will result in shorter lifespan. Storing them
for weeks on end fully charged can degrade the cells over time, we suggest
charging the battery back to 48-50v before storing it, 54.6v is fully
charged, 48v is nominal. Get yourself a cheap $15 multi meter from Jaycar so
that you can measure the voltage of your battery pack via the XT90 plug, its
cheap and easy to do.