[rescue] [Slightly OT] Smart-UPS 1400 Battery replacement

[James Fogg]

On Thu, 02 Aug 2001, THOU SPAKE:
> Ok, What am I missing??  Gell cells (in general)  Suck Dried Donky
> turds.  They're picky, expensive, and easy to damage.  Most UPSs I have
> used (mostly various APCs) use lead acid, heavier per AH, don't understand
> the word "picky" and generally a good battery.  Why would someone use gell
> cells in a UPS?  IIRC APC uses solely Lead Acid.
> 	Nick

No, they didn't use "lead acid", and yes they did use lead acid.

explanation:
Gells are "gelled electrolyte lead acid" batteries. Same formula as "wet lead
acid", but the acid is gelled. If your ups used wet cells then someone did a
switcharoo on you.

Why gelled electrolyte?
1) they don't spill.
2) they don't gas (give off hydrogen while charging, a big boom potential).
3) they don't need water added every week (the gassing causes the electrolyte
to boil off water).
4) much less likely to have corrosion deposits around vents and terminals
(caused by gassing and condensing electrolyte).
5) they have a flatter discharge output (full charge to near discharge voltage
curve is flatter).

Now, I am sure someone will ask... Can I switch cheaper wet cells with the
gells? The answer is no. Gells have different charging rates than wet cells.
Gells charge by current, wet cells charge by voltage (and charge much more
quickly). If you swap in wet cells you will find that your batts are always
hot, never fully charged and all the steel in your box will begin to rust
furiously within a month (from acid fumes). Take it from someone who tried.

Gells don't suck. Nicads suck (another story).

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	 James D. Fogg, Network Engineer
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