Re-Building Hoover Lithium-Ion Battery ?

[(PeteCresswell)]

One of these Bad Boyz: http://tinyurl.com/ydbb7jj7

Has anybody rebuilt one?

Would I be naive thinking that all I need to do is

- Obtain replacement cells

- Gracefully crack the case

- Figure out how to connect the new
cells

- Replace the old cells with new cells

- Close up the case
--
Pete Cresswell

[mike]

On 1/30/2018 6:55 AM, (PeteCresswell) wrote:
> One of these Bad Boyz: http://tinyurl.com/ydbb7jj7
>
> Has anybody rebuilt one?
>
> Would I be naive thinking that all I need to do is
>
> - Obtain replacement cells

Assumes you can find QUALITY replacement cells.
You want HIGH CURRENT cells like used in power tool batteries.
High CAPACITY cells rarely have HIGH CURRENT capability.
Anything you buy on EBAY with "fire" in the name probably won't
be satisfactory.
Purchased in low quantity, QUALITY cells probably cost as much
as a new battery.
If they're 18650 cells, Lowe's sells a Kobalt tool battery for
$10. Contains six QUALITY HIGH CURRENT cells.

>
> - Gracefully crack the case

Can't tell from the picture whether those are screws holding it together.
If it's glued...
My favorite trick is to whack the seam with a sharp wood chisel
and a hammer. Slow wont' do it. You need a high impulse
whack with a low mass hammer wielded at high speed to crack the seal.
It's very easy once you get the hang of it.

>
> - Figure out how to connect the new
> cells

The circuit is trivial. Your problem is the spot welder you need to
hook 'em up. DO NOT under any circumstances solder to the cells.
If you start with tabbed cells, or remove tabbed cells from something like
the Kobalt pack, you can often salvage enough of the old tab that you
can solder the tabs quickly without hurting the cell.

>
> - Replace the old cells with new cells

Sometimes, this works. Other times, the battery protection circuit
notices that you removed power and commits suicide. Without special
equipment and the secret sauce, you can't recover the pack.
Some have claimed that they hook up another set of cells to keep it
alive while they remove and replace the cells. Never tried that.

>
> - Close up the case
>

I spent more than a decade trying to rebuild laptop batteries.
I can point to exactly ONE success.
And I have a spot welder.
Vendors try very hard to prevent you rebuilding the pack.
It's a big liability issue for them.
It can be a big issue for you if you damage something and it
sets your house on fire.

Bottom line...go buy a new battery.

[N_Cook]

Check the charger as well.
A nimh version I looked at recently, intermittent shorted wires on the
the charger had drained the battery to internal dendriting or such.

[(PeteCresswell)]

Per mike:

>Bottom line...go buy a new battery.

I think it's finally starting to soak in....

Thanks for the detailed account.
--
Pete Cresswell