The manufacturer's replacement battery pack was priced at around €100, and a replacement from a third-party supplier was available for around half that price, which is not that bad. From its specification, I was looking for an 18 V replacement pack with a capacity of 2.1 Ah. That meant five cells, probably in the standard. Figure 2a shows that two recesses in the battery lid encroach into the available battery space, ruling out the fitting of two rows of five cells to double capacity. There are, however, more. Building a battery pack from individual cells generally requires a degree of dexterity, electrical expertise, and a spot welder. As you can see. As already mentioned, the battery compartment cannot accommodate the five cells arranged in rows of two and three to form a W configuration, so I had to find a different pack construction. In Figure 5, you can see that. With no spot welder to hand, I decided to solder stranded wire directly to the battery terminals. As long as you are careful, this can be done without.
