[HH] universal power tool battery

[Tom Metro]

Ever been annoyed that every cordless power tool you own requires a
different, incompatible battery? What's worse is that for each tool you
really need multiple batteries, and you have to replace them every few
years. This can be a big problem if the manufacturer discontinues the
product line and makes no more batteries, or decides not to update the
product line to use newer battery technologies.

Manufacturers apparently think this approach will maximize profits by
locking customers into their product line, but what actually happens is
that you "buy-in" to one or two tool families, and then ignore the
others, even if they happen to offer a unique tool. If a suitable choice
isn't available in one of the families I already own batteries for, I
just buy a corded tool, or nothing. The battery overhead cost is too
high, and too inconvenient if you need to pack and take your tools
somewhere (batteries and chargers take up a lot of space).

Several years back there was some company with a promotional video on
YouTube that had cobbled together a "universal" power tool battery. They
standardized on the Ryobi ONE 18 V battery. They then built adapters for
various other product families by taking a battery pack from the other
vendor, removing the cells, and fitting a socket for the Ryobi ONE to
the bottom of the hollow pack.

The end result looked ungainly, ugly, and by moving the real battery a
few more inches away from the tool body, probably threw off the balance
on many tools. I'm sure on some tools it wouldn't even have the space to
fit.

I was hoping they'd replace the makeshift adapters with some custom
built adapters that could be substantially smaller. Also, switching to a
"flat" rectangular pack instead of the Ryobi ONE, which has a stem,
would result in an adapter that would only need to separate the tool
from the battery by a fraction of an inch.

But they apparently couldn't commercialize the technology, as I never
saw it again.

I've rebuilt NiCd packs (usually replacing the cells with higher
capacity NiMh cells), but a while back I decided not to spend any more
money on NiCd/NiMh technology. I've pondered rebuilding the NiCd packs I
have with LiOn, but aside from mechanical differences in the cell size -
getting fewer, but bigger 3V cells to fit into a box made for a pile of
1.2V NiCds - you also need to find room for a protection circuit (under
and over voltage and current limiter), and add a multi conductor
connector so each LiOn cell can be individually charged and balanced.

I've since upgraded to vendor supplied LiOn batteries for the tool
families where they are available, but for some they aren't. I've
considered the adapter approach...for a while I even looked for a busted
as-is cordless drill on eBay with the thought of chopping off the
battery socket to make an adapter.

In the end I took the quick hack approach. I took one of my end-if-life
NiCd packs, hollowed it out, drilled a hole in the back and threaded
through some 16 AWG zip cord wired up to the battery pack contacts. On
the other end I put on alligator clips, which mate nicely with the not
quite 1/4" tabs on my 24V Ryobi LiOn pack.

This brought new life to a line of Tack Force (Lowes house brand) yard
tools that were abandoned by the vendor, and a Black & Decker chain saw
(which uses a 99% identical battery to Tack Force (clearly produced in
the same Chinese factory), with just enough difference to make them
mechanically incompatible; a prior hack to the saw's battery socket
allowed the Tack Force batteries to fit).

So the end result is a battery on a short cord. Makes the tool lighter,
but the battery needs a belt clip or something to get it out of the way.

Today I ran across a commercial version of this:

18V Nicad Battery Belt with Adapter and Charger
http://www.mcmelectronics.com/product/22-14562&cid=prodCrossSell

See the cheesy video for a demo.

Their solution to the dangling battery was to stick it in a "fanny
pack." (A backpack version is also available.) Nice that it comes with a
5 Ah battery (compared to the 1 to 2 Ah typical of most tools), but I
don't get why they'd use old NiCd technology, particularly seeing as
they are asking $200 for this battery plus adapter kit. (This kit
happens to come with a Ryobi ONE adapter, but Dewalt and Craftsman
adapters are also available.)

I think in the end my components are better. Aside from the electrical
performance advantages of LiOn, it is lighter, and even in a belt I'd
rather carry a smaller, lighter battery, and have a couple of them that
can be cycled through the charger. What my solution needs is a belt
holster of some sort, and a proper socket for the Ryobi pack.

 -Tom