Re: NiMH battery compatibility with NiCd chargers

From: Wild Bill (kwag98_at_usachoice.net)
Date: 06/29/04 

Date: Tue, 29 Jun 2004 03:19:44 -0400

Thanks for the additional info Andy. While the phone example you mentioned
isn't a highly scientific analysis, it's just the sort of example I was
hoping to see. I'm confident from reading your posts for years, that you're
prone to practical solutions, and don't think too much of half-assed
fixes/solutions.

I've got some handheld test gear that use sub-C cells and they have too
little space to install full-sized C cells (even alkaline would be fine for
them, though). These instruments use the simple rectifier, filter, resistor
components for charging from a wall wart.

I haven't bought much rechargeable stuff like most consumers do because of
the poor characteristic experiences I've had with NiCd cells. I'm sure I
never got enough use out of any NiCds to say that they were worn out..
instead, they just failed before any useful life was gotten from them.

I'm drawn to the extra capacity of NiMh, and hope they can provide a much
better service life for some equipment that will primarily be used in remote
locations.

Cheers
WB
............

"Andy Cuffe" <baltimora@psu.edu> wrote in message
news:h1u1e05bpgcaem9ho65mqn191orcul5pfm@4ax.com...
> On Mon, 28 Jun 2004 19:45:00 -0400, "Wild Bill" <kwag98@usachoice.net>
> wrote:
>
> >Hi.. I don't have any experience with NiMH batteries, and I never much
cared
> >for the problems associated with NiCd cells, so I'd like to know if using
> >NiMH will be less problematic than NiCd.
> >
> >Will NiMH cells charge and last perfectly well in NiCd chargers, or will
> >NiMH chargers be required for best results?
> >When I use the term NiCd charger, I mean the more sophisticated
commercial
> >chargers, not just the transformer & diode types.
> >
> >Ideally, I'd like to find a trouble-free, rechargeable battery (if
possible)
> >for a few applications.
> >I'd like to avoid any type of battery that will short if it's not being
> >charged or used.. which always seems to happen with any of the NiCd types
> >I've had.
> >
> >Thanks
> >Cheers
> >WB
> >
>
>
> For best results, you need a charger designed for Ni-MH, but they seem
> to be more tolerant than many people would have you believe. I
> rebuilt the Ni-Cd battery pack in my cordless phone using some Ni-MH
> cells I had on hand and it still works well after 3 or 4 years of
> almost constant charging. I would think you would have more trouble
> with a 'smart' Ni-Cd charger than a simple charger because it's hard
> to say how the smart charger will handle the wrong type of battery. I
> have no seen any shorted Ni-HM cells yet. What I have seen is a very
> high self discharge rate in old Ni-MH laptop batteries. It's not
> unusual to see a laptop battery that will run for 2 hours when freshly
> charged, but if it's left sitting for even a few hours it becomes
> mostly discharged.
> Andy Cuffe
> baltimora@psu.edu

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