If you change to Li-Ion, you give up the ability to ship by air or at least
carry it in any passenger aircraft.
You might look at the Li-Ion motorcycle batteries. They are designed to
charge from a normal Pb-Ac system. Down side is a pair of them will run
~$600. They are >20 AH at 12 volts nominal.
Regards,
Tom
----- Original Message -----
From: "Tom Knox" <[email protected]>
To: "Discussion of precise voltage measurement" <[email protected]>
Sent: Saturday, March 08, 2014 10:42 AM
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?
In my humble opinion your are best off first checking for a local Cal Lab
with a Josephson Junction Array Voltage Standard.
You can then drop it off and pick it up your 732A. I would imagine the day
of abuse during shipping has more effect on uncertainty then the rest of
the year combined sitting in a controlled lab environment. And Speaking of
Lab environments adding precise temp and humidity control will have a
substantial effect on 732A and 3458A stability. Hooking a number of small
electric heaters to PID controllers can provide even out room temperature.
Also I would almost always assume the 732A is more accurate then your
3458A even if you have the 002 or HFL option. Has anyone attempted
changing the battery technology to Li-Ion and redesigning the charger? I
am sure you could get greatly improved battery life.
Thomas Knox
From: [email protected]
To: [email protected]
Date: Sat, 8 Mar 2014 07:50:55 -0600
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?
Charles,
Thanks for the info on batteries. I agree, some are definitely better
than
others. However, I'm no 'connoisseur' of batteries yet. The 732A I got
was
'unknown working condition' and I wanted the cheapest batteries I could
find
to test the unit and see if I could get it up and running. So far, it
looks
good.
Do you wind up having to re-solder some of the battery wires in the
battery
module in order to use the 12 V 5 AH batteries or will they just swing to
the other side since it appears that the (+) and (-) terminals will wind
up
on the same side, instead of opposite sides with the 6 V 4.5 AH
batteries?
I have not faced the shipping question yet, but, as David pointed out,
there
is an issue with shipping batteries. I suspect it could be shipped but
would be ground and, therefore, need a huge battery in order to get it to
the other side of the country 'hot'. I recall reading some thoughts on
current drain for the unit when on batteries but I do not remember what
it
was. Clearly, it should be at a minimum, and therefore the battery
should
last the longest, when already 'hot' when removed from AC power. Has
anyone
done that experiment? I live in NW FL and I am not aware of Cal Labs in
my
neighborhood that could do the work. Atlanta, perhaps? Does anyone have
a
recommendation of a capable Cal facility 'close by' to NW FL?
Short of sending it to Fluke or another facility, I will be limited to
using
my Agilent Cal'd 3458A to 'adjust' the 732A, then 'tracking' the 732A
from
year to year as the 3458A comes back from Cal.
I paid less than Michael and more than you for my unit but it seems to
work.
I have seen these sell on theBay for $450 and up.
Joe
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