Another new tool
Those of you that have been paying attention will know I do like a reason to buy a new toy tool.
A job came along recently which meant buying another welder sadly not another TIG as I already have one which is was more capable then I am able to exploit. This is a tiny spot welder which does one thing and one thing only. It welds nickel strips onto battery cells. Enter the SEQURE SQ-SW2
So why have I bought such a thing?
A customer brought in for service a set of Liveryman Whisper clippers and one of the faults i found was both batteries where showing very low voltages. This battery uses NiCad cells and if you drop the voltage too low it damages the cells. Opening up the battery showed a few cells had leaked as well as cells showing zero volts which basically means the cell is dead.
More info
Before we get into the bones of gutting a battery lets take a brief moment to consider what is actually going on.
These battery packs are made from a series of 6 smaller batteries linked together in series which means each small battery aka cell add’s it’s voltage to the entire voltage. For this type of cell Nickel cadmium this is typically about 1.2V which should give you 7.2V. When a battery measures below this value it is quite likely that some of the cells are damaged.
The reason that the battery is made this way is due to economy of scale as uses the same size and shape of battery cell internally saves a huge amount of money compared to making your own battery cells. All a company does is stacks battery cells in the right amount and right shape to fit your product.
Nickel cadmium are a very early type of rechargeable battery with the first ones going into production in 1946. They remained popular until the late 1990’s when other types of battery such as Nickel metal hydride and Lithium polymer started to take the market share because NiCad cells aren’t actually that good.
They are very sensitive to charging and discharging mistakes. They are only really happy if you store them fully charged, discharge them almost completely and fully recharge them.
No normal person does this which results in a rapid drop in battery performance which gets you to the point that these batteries are at with a total failure.
Now back to the job inhand
Internals of the battery
This should be reading something over 6V ideally over 7.2V
This reading basically means it is quite probably dead
A replacement new battery is about £100 which is kind of pricey. The cells inside are industry standard sub-c size which are an older tech but you can still buy them. There is a few packs floating around which use NiMh which share a very similar voltage per cell to NiCad but I don’t know how well they will play with the standard charger so i’d advise against using them.
A gutted battery
The internals of the battery opened out and laid bare.
You can see the nickel stripes joining the cells together. The staining on the end of the cell also shows leakage which means it’s dead
Of course I completely forgot to take pictures while concentrating on building up the new pack. In fact the picture below is after i closed everything up so i had to re-open the battery to show the internals
The finished internals
The new cells I purchased where plastic wrapped instead of paper. I also wrapped up the joins and then shrink wrapped the four cells at the end to neaten things up.
Finished product
A much more healthy 7.8V which is at the top end of the NiCad cells (1.3V with 6 cells in series)
Added bonus is these cells are 2400mAh instead of the old cells which where 2000mAh so it’s an upgrade in capacity
This refurbishment can also be done to Heiniger cordless clippers as well as the Liveryman sprinter and Liscop Equiclip.
The batteries haven’t gone back to the customer yet but once they do and they have given them a test run I will add them to the online store at £35
Finished batteries
Two cordless clipper batteries ready to return