Lithium batteries have a history of catching fire, indeed they brought down a 747 in Dubai recently when a cargo container of them caught fire.
It's mainly due to charging the battery faster than it should be, causing minute lithium dendrites to form on carbon anodes which in turn cause short circuits which heating the battery up beyond it's safe level. So make sure it's the right charger for the unit when you use it.

I've never heard of lead acid batteries catching fire, as such, exploding due to blocked vents happens occasionally though or melting when someone drops a spanner across the terminals.

RG wrote in newsp.wopoawg3gkcl5l@home1:

On Sun, 02 Dec 2012 18:44:42 -0000, Baz wrote:

RG wrote in newsp.woo4cn1cgkcl5l@home1:

On Sun, 02 Dec 2012 14:14:02 -0000, Baz wrote:

RG wrote in newsp.wom4wac0gkcl5l@home1:

On Fri, 30 Nov 2012 21:26:01 -0000, jim dixon
wrote:


I bought a hedge trimmer and a cutter both battery operated.
Didnt use (medical reason) for 2 years. Now cant get batteries
to take a charge. Have checked charger and engines, all okay. Is
this normal? Any solution?

As others have said, after two years it's likely that they will
have failed, particularly if they are lead acid.

However it would do no harm to leave them on charge for a day or
two and see if they can at least partly recover, before laying
out your money on a new set. Just check the charger from time to
time to check that it's not getting too hot, which it might
possibly do if the battery has gone short-circuit. That's
unlikely though - they are more likely to have gone
high-resistance and not accept a charge.


That is some very, very bad advice.
Don't do that.


smiles
Please explain why it's very bad to attempt charging a sulphated
lead acid battery, Baz.
I'm interested to learn.
Don't hesitate to use specific technical terms - I am qualified to
understand.

Nah. Anyone can say that about being qualified. Genuine or not. Don't get
on your high horse. Your qualifications, or lack of them mean Zero.

Only because I have seen, and been to board up homes who's occupants
have bought fake items and fires have resulted.
A big % of these have come from scam batteries and chargers.
No smiles here RG.


Err yes. I understand your concern about fake items.
But how does that apply to the OP, whose problem is due to putting his
equipment into store for two years.
I don't see any suggestion that those are 'scam' items.


Read or re read your previous post. Starts with "Please explain why"
I have heard ducks farting in water before. Gas and hot air.

Baz

On Mon, 3 Dec 2012 11:34:17 +0000, Granity wrote:

Lithium batteries have a history of catching fire, indeed they brought
down a 747 in Dubai recently when a cargo container of them caught
fire.

Hadn't heard about that.

http://gigaom.com/cleantech/lithium-...for-jet-crash/

Oh nasty... The big snag with a lithium battery fire is that there is
enough oxygen available within the battery for them to burn even when
totaly isolated from the atmosphere. Ergo they are damn difficult to put
out...

I've never heard of lead acid batteries catching fire, as such,
exploding due to blocked vents happens occasionally though or melting
when someone drops a spanner across the terminals.

They can explode but only when there is a source of ignition for the
hydrogen released if over charged. Which is why one should always switch
off the charger before disconnecting it from the battery.

--
Cheers
Dave.

On Mon, 03 Dec 2012 11:34:17 -0000, Granity
wrote:

Lithium batteries have a history of catching fire, indeed they brought
down a 747 in Dubai recently when a cargo container of them caught fire.

It's mainly due to charging the battery faster than it should be,
causing minute lithium dendrites to form on carbon anodes which in turn
cause short circuits which heating the battery up beyond it's safe
level. So make sure it's the right charger for the unit when you use
it.

Lithium batteries (and nicad and niMH) are all more critical with their
charging requirements.
Many devices such as mobile phones containing lithium batteries now have
the charge control circuitry built into the device rather than the
charger, so they can be run from relatively simple PSU's without risk of
damage.

The OP shouldn't have any of these problems since his gardening equipment
will have been bought complete with batteries and chargers.

I've never heard of lead acid batteries catching fire, as such,
exploding due to blocked vents happens occasionally though or melting
when someone drops a spanner across the terminals.

Or charging in a confined space where the liberated hydrogen can build up
to dangerous levels.