[Chhanda Das]

DIY battery replacement of Philips HC 5450 model hair clipper

It has been more than a decade since I bought a Philips HC 5450 model hair clipper from their brand store here in Kolkata. I bought it for my son to help him save time for his studies instead of queuing up at the barber shops with questionable hygiene in our locality. The 5 year warranty expired around 6 years ago.

Recently, the hair clipper started getting quite hot (not just warm) to the touch and would take several hours to get fully charged. Sometimes it wouldn't even get fully charged after charging it for hours. And even if it did get fully charged it wouldn't last for more than 5 minutes. Those are some very clear signs that its nickel metal hydride (NiMH) battery setup was either worn out or out of balance. It is rated to be charged for one hour to deliver upto one and a half hours of usage. This hair clipper can be run from the wall outlet too but its heating was an issue and using such an electrical/electronic gadget on a hot sweaty head in summer makes us very uncomfortable. So the only reasonable option was to repair/replace the battery setup.

The first step was to disassemble the hair clipper to get access to the battery setup. For that the plastic silver trim needs to be removed first as can be seen in the image below to get access to the 4 screws which need a T9 screw driver bit for their removal.

Next the two longitudinal halves need to be carefully separated without damaging the plastic clips as shown below. A thin flathead screwdriver can be used for this.

Then we need that T9 screwdriver bit once more to remove the single screw for the spindle for comb length adjustment along with the motor from the housing assembly as can be seen in the image below.

A careful examination of the battery setup revealed that the 2 battery cells are in series (2S configuration) and there is no balancing feature as can be seen below. Additionally, these 1.2 volt cells have a rated capacity of 750 milli ampere hour (mAh) each. So this is a 2.4 volt 750 mAh battery pack. A quick Google search revealed that this battery pack costs approximately ₹2500 which is more than what I paid for the hair clipper itself more than a decade ago

After carefully prying open the spot welded nickel strips from the cells with a small flathead screw driver, my son was surprised to see that the cells were showing a voltage of around 1.35 volts and 0.9 volts which meant that the cells were not balanced. But since these cells were already more than a decade old my son decided to go ahead with their replacement instead of trying to balance them and use them again. We could always reuse these old rechargeable AAA cells in our remotes, clocks, cameras, etc.

From here it was just a simple matter of using the spot welder from our old DIY portable lithium power station project to connect two new Duracell AAA 1.2 volt 900 mAh NiMH rechargeable cells in the same 2S configuration to the printed circuit board (PCB) using nickel strips as earlier as you can see below. The new Duracell batteries cost us ₹ 300 from a local shop for a blister pack of two.

After reassembling the hair clipper and greasing the self-sharpening blades, we tested it with a few charge and discharge cycles. And we can confidently say that the hair clipper is not even getting warm to the touch and it is holding the charge very well. Great success

Disclaimer : This replacement/upgrade was done solely by my son. If you want to replicate this then please do so at your own risk. I hope that you found this informative

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!