Roger Bisby: Loading Up with Dewalt Batteries

Roger Bisby: Loading Up with Dewalt Batteries

DeWalt’s Flexvolt 54 volt battery has now been out for nearly a year with no reported teething troubles. Roger Bisby thinks it is time to take a closer look.

I must admit that when I first came across DeWalt’s Flexvolt system early last year it took me a few minutes to work out what was going on.

You have what is basically a standard 18 volt battery which somehow transforms itself into a 54 volt battery when you plug it into a Flexvolt power tool.

On closer examination it turns out it is nothing more complicated than wiring up the cells in series or parallel. In fact they are wired in both and it is only when you plug into the correct pair of terminals that it transitions from the parallel-wired 18 volt to the series wired-54 Volt.

You don’t have to do anything to make this happen because the terminals in the power tool’s battery port will dock with the appropriate terminals on the battery. It is simple but very clever.

Now the geeks (and electricians) among you will already be thinking that there must be a lot fewer amp hours with the series-wired 54 volt pack than with having several bays of cells in parallel.

This is true but the fact that the voltage is increased means that the machine needs to draw less current from each cell.

In essence you have the same amount of stored energy in the battery and you are just drawing on it in a different way. At the moment there are 2 Flexvolt batteries available: 18v 6ah (54v 2ah) and 18v 9ah (54v 3ah)

I have not had an opportunity to test the runtime on the 54 volt but look forward to doing so in the near future. The obvious applications for this kind of voltage are the heavier drawing tools such as the mitre saw, circular saw and nine inch angle grinder.

The really good news is that you will not be restricted to battery use on tools such as the mitre saw because DeWalt is introducing a plug-in mains adaptor which is basically a transformer that sits where the battery sits. This means you can save your batteries for where you need them.

At the time of writing the AC adaptor is designed only for the two 54v tools (currently the only one is the DHS780 305mm double bevel compound sliding mitre saw which is launching in June, there will be more in due course).

There will be two adaptors available: a 230v version and a 115v version; these will be supplied separately so the user can choose which one they prefer after purchasing the saw. So, essentially, one tool can be used in 3 ways: cordless, 230v or 115v.

Another point that often worries people is the transportation or shipping restrictions on batteries. Only this week a train was evacuated in London when a tradesman’s battery caught fire in the carry box.

This was not a Flexvolt or even a DeWalt but it highlights a point that there is more than enough energy in a power tool battery to do damage if it malfunctions. Stray screws in the drill box can short out the terminals.

There are no restrictions to shipping the Flexvolt battery if the red transport cap is fitted (each battery comes with the transport cap) and DeWalt is the only manufacturer at the moment who has this.

The batteries as they stand on their own are 18v 6ah (108wh) and 18v 9ah (162wh) so both ordinarily would need to be sent by special transportation as they exceed the 100wh limit set by the transport regulations.

All manufacturers have to do this and all distributors should be doing this. However with the transport cap attached the battery is essentially divided into three: Three 18v 2ah (three 36wh batteries) or three 18v 3.ah (three 54wh batteries) and are thus declared so they can be sent normally.

The bottom line is hung on the cap and using it that way your battery is safer than any ordinary 18 volt battery without terminal protection. You might also want to take some documentation with you if you are flying to save any disputes at the security check in.

For more information on Dewalt’s battery range click here.

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