[CentOS] OT: UPS battery vendor, cont'd

Warren Young warren at etr-usa.com
Thu Feb 14 17:09:00 UTC 2013


On 2/13/2013 06:12, mark wrote:
> Huh. No, I want to pay on the order of $12/individual battery,

Please don't misuse "order."  It's a corruption of the scientific term 
"order of magnitude"[1][2] which, used correctly, means that the values 
you're comparing use the same factor of 10 in scientific notation.  If 
we take your claim literally, you'd be satisfied with any complete 
battery that cost less than $120 * 8 = $960.

(I will also come after you if you misuse "literally". :) )

> $100 or so for the set of 8;

You've got one low-ball quote, and now you're demanding that everyone 
else meet it?  Sigh...

The way I see it is, you've also got a whole bunch of people offering 
the same thing for $20-30 per VRLA[3] unit.  That means either:

a) $20-30/VRLA is a good price and consequently you should be worrying 
about how others are managing to low-ball that; or

b) there's widespread price-fixing.

Given how many news stories you can find about misbehaving cheap 
batteries, I'd bet on option a).  Just because the label has the same 
voltage and amp-hour rating as what came out of the APC UPS, doesn't 
mean it's exactly the same thing.  Batteries are tricky.  Boeing and 
Tesla Motors are both in the news now because too few people really 
understand batteries.

If you're willing to open up the APC sled and replace the individual 
VRLAs directly, the cheapest *reputable* vendor I've found is Mouser. 
Their part # 632-GP1245 looks close, but don't take my word on that. 
I'm just eyeballing photos and springboarding off the McMaster 
dimensions; I have no direct experience on that particular swap.

Mouser wants $16.30 each of these in qty 10.  Just for reference, one of 
Mouser's direct competitors, DigiKey, wants about $25 for the same 
thing.  That put's the $22-26 McMaster quote you've tried to reject 
right in the same range.

I also don't see that you're accounting for return shipping and the cost 
of the sled.  If you buy the pack from APC, they ship you a complete, 
assembled battery pack, along with a reusable box and return shipping 
label.  You put the old one back in the box you got the new one in, and 
send it back for recycling.  That's worth something.

When you buy individual VRLAs, you have to account for your time opening 
up the sled, swapping VRLAs, and reassembling it all.  Then you add in 
your time to dispose of the spent VRLAs.  I'm sure you can find plenty 
of places locally that will take them, but I'll bet your salary and gas 
costs will wipe out your DIY savings.

You're probably not counting opportunity costs[4], either.

---------
[1] https://en.wikipedia.org/wiki/On_the_order_of
[2] http://mathworld.wolfram.com/OrderofMagnitude.html
[3] https://en.wikipedia.org/wiki/VRLA
[4] https://en.wikipedia.org/wiki/Opportunity_cost



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