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

[rescue at sunhelp.org]

Ok, I think I'm now truly confused.  I know of three types of batteries
involved, Lead Acid, the old type that you have to add water to, Sealed
Lead Acid, what I see in cars and upses, and gell cells, which I've only
seen once in a Mazda Miata, which was expensive, and hard to charge.  Are
sealed lead acid batts gell cells?  If so why are SLA batteries cheapish
compared to gell cells?
	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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