Battery charger question
 

I have a Uniross CX2000 battery charger for Ni-cads. Can this be used
to charge Ni-MH batteries?

Regards and thanks in advance

Syke

Battery charger question
 

On Oct 19, 10:46*pm, Syke wrote:
I have a Uniross CX2000 battery charger for Ni-cads. *Can this be used
to charge Ni-MH batteries?

Regards and thanks in advance

Syke

You've not given us the charging characteristics of the charger or the
specs of the ni-mh. Generally its possible to use nicd chargers on
nimh or nimh chargers on nicd /if/ the charge current matches what the
battery needs. In no way can one assume it will though, it frequently
wont. For fast charging there is partial swappability, IIRC nimh are
fussier about overcharging.


NT

Battery charger question
 

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Syke
saying something like:

I have a Uniross CX2000 battery charger for Ni-cads. Can this be used
to charge Ni-MH batteries?

It will put a partial charge into them, but without knowing what NiCads
and what NiMHs, it's anyone's guess how much and when /if it stops or
overcharges.

Battery charger question
 

On Tue, 19 Oct 2010 22:46:28 +0100, Syke
wrote:

I have a Uniross CX2000 battery charger for Ni-cads. Can this be used
to charge Ni-MH batteries?

The CX2000 is a low output charger (about 120mA max) which takes 14 to
16 hours to fully charge a battery. That charging regime is pretty
benign and should be fine for NiMH as well as NiCd as long as you
don't leave the battery on charge for several days.

A fairly simple, but reliable, test is the battery temperature. If
they are getting quite warm to hot when held in the hand they are
being overcharged and damaged.

Battery charger question
 

On 19 Oct, 22:46, Syke wrote:
I have a Uniross CX2000 battery charger for Ni-cads. *Can this be used
to charge Ni-MH batteries?

Why take the risk of damaging them when you can get a NiMH charger for
4 quid delivered, eg http://www.7dayshop.com/catalog/prod...ucts_id=109889

Battery charger question
 

On 19 Oct, 22:46, Syke wrote:
I have a Uniross CX2000 battery charger for Ni-cads. *Can this be used
to charge Ni-MH batteries?

Chargers do two things:

* They shove some current in to charge.

* They measure the terminal voltage and use this to determine when to
stop charging (better ones look at rate of change)

Crude NiCd chargers only do the first and rely on you switching them
off manually after a time. These chargers are now obsolete. Given the
high cost of many cells and the low cost of a single good charger
(Aldi, 13 quid, still the best deal around) it's worth switching to a
decent charger. Most rechargeable radio-control toys use this sort.
It's worth replacing those, as specialised battery packs aren't cheap.

Charge current is roughly the same for NiCd and NiMH of about the same
cell size and capacity, so the first part is no problem. Assume C/10
for starters, i.e. charge a 700mAh cell with 70mA for about 12-15
hours. Anything more precise than this needs knowledge of particular
cells (mostly because "C" should be the one-hour capacity, not the "C/
10 for 10 hours" that they're labelled with, because it's bigger).

Now for automatic chargers. If you have a crude auto NiCd charger that
measures terminal voltage (i.e. anything over 5 years old) then it
works adequately for NiCds, but poorly for NiMH. Not because it's
using the wrong target voltage (it is), but because simple voltage
measuring isn't such a good algorithm for NiMH. A simple fix for this
is a switchable NiCd / NiMH setting on the charger, and a selectable
target voltage (i.e. early NiMH chargers of 5 years ago). Avoid these
chargers for NiMH use! They use a crude algorithm that doesn't control
well.

Better automatic chargers support NiMH, and don't need to be switched
between battery technologies. This is because they use delta-V sensing
instead of just an absolute voltage and delta-V can work for both
technologies. Delta-T is also good, but only used on powertools with
dedicated battery packs with inbuilt temperature sensors. These are
the only sorts of charger really worth using these days.

If you have a non-automatic, non-NiMH, NiCd charger, then it _can_ be
used to charge NiMH cells. But treat it like a dumb manual charger -
only leave it on for 5 hours at a time, switch off when the cells
become warm, don't expect it to fully charge your cells, expect
reduced service life on your cells, and look at upgrading to a modern
charger.

Fast-charging NiMH is usually better and easier on the cells, because
it's done with better chargers than the older slow chargers.

Battery charger question
 

On 20 Oct, 10:36, Peter Parry wrote:

A fairly simple, but reliable, test is the battery temperature. *If
they are getting quite warm to hot when held in the hand they are
being overcharged and damaged.

Trouble with that is that by the time you can feel it outside the cell
(or even worse, outside the plastic battery case) it's too late.

Battery charger question (Update)
 

Thanks everybody for taking the time. My situation is that I have the
Uniross CX2000 charger which I use for charging four Uniross D type
batteries for a torch. Incidentally these are now about ten years old!
I'm getting a new radio which takes Ni-mh batteries and of course I
wondered if it would be necessary to buy another charger. In the light
of your contributions this looks like the way to go, and with luck, I'll
be able to keep my old Ni-cads going with it as well. I did contact
Uniross and they said that I could use the old charger safely, it would
just take longer to charge the Ni-MHs.

Regards

Syke

Battery charger question
 

On Oct 20, 11:52*am, pcb1962 wrote:
On 19 Oct, 22:46, Syke wrote:

I have a Uniross CX2000 battery charger for Ni-cads. *Can this be used
to charge Ni-MH batteries?

Why take the risk of damaging them when you can get a NiMH charger for
4 quid delivered, eghttp://www.7dayshop.com/catalog/product_info.php?products_id=109889

Hmmm "safe and smart" but no mention of what that actually means. If
it's "smart" it should be able to charge them faster than 6-10 hours.
I wouldn't risk my cells in what is probably cheap s***e that will
cook them if forgotten about.

MBQ