Specific Gravity considerations?

[William P. N. Smith]

I'm looking at Surette batteries, which seem to have dlightly
different ratings depending on SG. For instance, 'normal' is 1.280,
derate 5% for 1.265, derate 10% for 1.250.

What are the tradeoffs for different SG 'settings', and why?

Thanks!

 

[William P. N. Smith]

I'm looking at Surette batteries, which seem to have dlightly
different ratings depending on SG. For instance, 'normal' is 1.280,
derate 5% for 1.265, derate 10% for 1.250.

Speaking of measuring SG, has anyone used a refractometer instead of
the float-style devices? They are pretty expensive ($160 for the
temperature-compensated ones at
http://www.kerncoinstr.com/battcool.htm ) but if they help preserve
the lifetime (or warranty status) of $10K worth of batteries it might
be worthwhile...

 

[wmbjk]

Speaking of measuring SG, has anyone used a refractometer instead of
the float-style devices? They are pretty expensive ($160 for the
temperature-compensated ones at
http://www.kerncoinstr.com/battcool.htm ) but if they help preserve
the lifetime (or warranty status) of $10K worth of batteries it might
be worthwhile...

Have you seen this $40 version?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90716

http://www.harborfreight.com/manuals/90000-90999/90716.pdf


Wayne

 

[William P. N. Smith]

Have you seen this $40 version?
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90716

I hadn't, but now I have one on order! Thanks, Wayne!

 

[wmbjk]

Wayne,

Have you used these?

No, but William owes us either a full report, or the $120 he saved.
I'm looking forward to his comments, I've always wondered about
the utility of that device. Even if he isn't happy with it, at least
he'll be getting 5 pounds of free paper for life from Harbor Freight
now that he's on their mailing list. <G>

Wayne

 

[William P. N. Smith]

Ron Rosenfeld

No, but William owes us either a full report, or the $120 he saved.

It's got to be better than the float-style, which I have a lot of
trouble with. Between the meniscus, the float sticking to the side of
the tube, temperature compensation, and the basic inaccuracy of the
reading, the float type SG meters just aren't doing it for me.

I've seen the optical type, but never found a reasonable source for
them. If this one doesn't work, I'm not out very much money in the
grand scheme of things, and I'll hopefully know enough about them to
know if I should buy one of the {better,more expensive} models.

I'll definitely let you know!

 

[daestrom]

It's got to be better than the float-style, which I have a lot of
trouble with. Between the meniscus, the float sticking to the side of
the tube, temperature compensation, and the basic inaccuracy of the
reading, the float type SG meters just aren't doing it for me.

I've seen the optical type, but never found a reasonable source for
them. If this one doesn't work, I'm not out very much money in the
grand scheme of things, and I'll hopefully know enough about them to
know if I should buy one of the {better,more expensive} models.

I'll definitely let you know!

The one thing I'm hesitant about is how much electrolyte you remove from a
cell each time you test it. If you take readings on pilot cells everyday,
this could end up a sizeable amount. And replenishing with water would
dilute the cell. The old 'float' type, you can take a reading and return
electrolyte to the cell each time.

But hey, let us know...

daestrom

 

[John]

The Navy used to use 1.220 SG when I was an EM back in the 50s batterys
used to last forever but would discharge faster

 

[[email protected]]

Newsgroups: alt.energy.homepower
It's got to be better than the float-style, which I have a lot of
trouble with. Between the meniscus, the float sticking to the side
of the tube,

Standard practice is to read at the bottom (flat) of the maniscus.

A good float has small nubs on the side to prevent this sticking to the
syringe barrel.

See www.freasglass.com


Tom Willmon
near Mountainair, (mid) New Mexico, USA

Net-Tamer V 1.12.0 - Registered

 

[William P. N. Smith]

The one thing I'm hesitant about is how much electrolyte you remove from a
cell each time you test it.

According to
http://www.harborfreight.com/manuals/90000-90999/90716.pdf it's "one
or two drops", which is probably the amount you lose with each use of
the float type.

 

[Bruce in Alaska]

Wayne,

Have you used these?

My initial impression, looking only at the manual, is that while it might
be useful for one or two readings; to perform 48 consecutive readings would
be more difficult than using the "old-fashioned" float-style device. It
seems like it would take longer to clean between checking each cell.

Also, I wonder how accurately one can read that scale.


-- ron (off the grid in Downeast Maine)

Most of the Telco Guys have gone to Internal Resitance Testing for
Battery System Certifacation. they now have portable IRT's that have
little builtin printers that give the Internal resitance for each cell
in the bank, as it is tested. When these are compared to the Original
Installation Printouts, it really gives you a very good idea of the
condition of the Battery System, as a whole and at the cell level.

When our LongLines Guy comes out every six months to do routines on the
Microwave Gear, and battery system, I usually get to run my Inverter
Banks and Radioroom batteries. I have records going back 4 or 5 years
now, on both my Absolyte II, and L16 Banks.


Bruce in alaska

 

[daestrom]

The Navy used to use 1.220 SG when I was an EM back in the 50s batterys
used to last forever but would discharge faster

You must have been on a diesel boat or are talking small engine-starting
batteries. Nuc boat batteries ran 1.280 at 80F. As the purity goes up, one
can use a higher SG without too much self-discharge. The more impurities in
the battery, the more self-discharge. But at 1.220,sulfphation and shedding
probably wasn't much of a problem.

daestrom

 

[William P. N. Smith]

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90716

It's here, but it's been #defined Fathers Day Present, so I'll report
back in a bit over a week. I _did_ have to check it out and make sure
it's functional, by testing the calibration with a couple of drops of
tap water, and I'd have to say it's incredibly easy to read. More
news as it happens, bug me again if you haven't heard anything in a
couple of weeks. I've got 6 golf carts, four boats, and a set of golf
cart batteries on my weather station that are calling out to me for
testing! 8*)

 

[William P. N. Smith]

William owes us either a full report, or the $120 he saved.

See the thread titled: Measuring Specific Gravity with a Refractometer

Thanks Wayne!