Refractometers to measure battery specific gravity?

WYsolarWYsolar Solar Expert Posts: 31
Is there a preference between using a temperature compensated hydrometer vs. a refractometer for measuring battery specific gravity?

I have a chance to purchase a used coolant/battery refractometer for $40 locally and was wondering if it was worth it. The item I am considering looks like this:

http://www.made-in-china.com/showroom/zhongjintech/product-detailUokEpveAItYr/China-Antifreeze-Battery-Refractometer-ATO-.html

Thanks for the advice.

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    WYsolar wrote: »
    Is there a preference between using a temperature compensated hydrometer vs. a refractometer for measuring battery specific gravity?

    I have a chance to purchase a used coolant/battery refractometer for $40 locally and was wondering if it was worth it. The item I am considering looks like this:

    http://www.made-in-china.com/showroom/zhongjintech/product-detailUokEpveAItYr/China-Antifreeze-Battery-Refractometer-ATO-.html

    Thanks for the advice.

    I don't have any information about the quality or ease-of-use of that particular product, but a refractometer needs temperature correction just as a hydrometer does.
    But by the time you read the refractometer, the sample of acid is going to be at whatever the room temperature is for the instrument itself, unlike a hydrometer where you may be measuring warm or hot electrolyte different from the room temperature.

    Some refractometers claim to have temperature compensation built in, just as some hydrometers do.

    See this somewhat related discussion from a home-brew forum.

    Six of one, half dozen of the other in terms of ease of use: Do you such a large amount of electrolyte out of the cell and try to read it in place to avoid dripping acid or do you actually take some electrolyte out and put it in the instrument, requiring rinsing, etc. (Not that you don't need to rinse a hydrometer between reading, but...)

    A refractometer does give a more precise (easier to read small differences) value, as well as arguably a more accurate (correct in absolute terms) reading.
    SMA SB 3000, old BP panels.
  • RybrenRybren Solar Expert Posts: 348
    Re: Refractometers to measure battery specific gravity?

    FWIW, I use a refractometer on a daily basis to measure the salinity of my salt-water aquariums. Some things to note:

    The refrac needs to be calibrated using a prepared calibration solution that closely matches the refractive index of the solution that you are measuring. Distilled water is not close enough.

    The refrac actually measures the refractive index of the solution and not the Specific Gravity. The scale on the unit may or may not show both (or more units of measurement) via a standardised conversion table.

    The automatic temperature compensation function generally works fairly well if the unit is stored at the same (or close to the same) temp as the fluid being measured. If there is a drastic temp change, the calibration often drifts rather significantly.
  • Ralph DayRalph Day Solar Expert Posts: 876 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?

    "The refrac needs to be calibrated using a prepared calibration solution that closely matches the refractive index of the solution that you are measuring. Distilled water is not close enough."

    Glad to hear that! I bought a refractometer and found using distilled water was no good, all the readings of acid were too low. My solution, use my bulb type hydrometer to put some 1.265 acid in a baby food jar and use that as my calibration medium. Works fine, but for the coarse resolution needed for battery acid, hardly worth the effort of using the refract. It's there in case I break the glass tube of the hydrometer.

    Ralph
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    Ralph Day wrote: »
    Works fine, but for the coarse resolution needed for battery acid, hardly worth the effort of using the refract. It's there in case I break the glass tube of the hydrometer.

    Huh? I don't understand. It seems that you need pretty good resolution (0.01) to pick up the small differences in SG that indicate a need for equalization.

    Also, is there much more effort involved in using the refractometer (vs hydrometer)? It seems to me that the refractometer is less effort. My hydrometer needs a lot of rinsing to prevent sticking, and after rinsing with water it reads too low until I rinse it out a couple of times with battery acid. Also, the hydrometer tends to dribble a couple of drops of acid every time I hold it up high enough to read it.
    inetdog wrote:
    A refractometer does give a more precise (easier to read small differences) value, as well as arguably a more accurate (correct in absolute terms) reading.
    That is my experience.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • VicVic Solar Expert Posts: 2,958 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?

    Hydrometers will dribble. That is why it is best to keep the tip in the vent well of the batt while reading it. This is where taller batteries are convenient. When a reading is complete in one cell, expel the fluid and then pump the bulb a few more times. Then one can gently gently knock the tip back and forth, in the upper part of the vent well to help dislodge any remaining drops.

    One needs to take three or four "pulls" of electrolyte to get the most accurate readings. If one is careful, it is possible to make measurements within about two points of repeatability.

    If there is worry about diluting the electrolyte by using the same Pilot Cell for an extended time, try taking the first reading in your measuring session in the highest SG cell/s.

    Using a Glass Tube/glass float type Hydrometer is far better than the plastic ones with colored balls, or the pointer with a colored "Good", Bad, Ugly or similar indications. Rinse, and rinse the hydro after each session. These are just my personal experience. YMMV. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Refractometers to measure battery specific gravity?
    inetdog wrote: »

    See this somewhat related discussion from a home-brew forum.

    Six of one, half dozen of the other in terms of ease of use: Do you such a large amount of electrolyte out of the cell and try to read it in place to avoid dripping acid or do you actually take some electrolyte out and put it in the instrument, requiring rinsing, etc. (Not that you don't need to rinse a hydrometer between reading, but...)
    Especially if you're going to use it to measure your beer... :D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Refractometers to measure battery specific gravity?

    Hydrometer: <$10, good enough to tell if there's something amiss, keep a spare on hand 'cause they can break (usually when you're using it).
    Don't obsess with 0.001 differences in specific gravity. No one's eyes are that good. :roll:
  • WYsolarWYsolar Solar Expert Posts: 31
    Re: Refractometers to measure battery specific gravity?

    Thanks for the input, guys.

    It turns out the refractometer was already sold by the time I contacted the owner. So...I went with this temp compensated bulb hydrometer : http://www.summitracing.com/parts/OTC-4619/ for <$15 shipped to me. It is built by OTC in Taiwan and looks to be of good construction. It just arrived and I will check it out tonight.
  • CDN_VTCDN_VT Solar Expert Posts: 492 ✭✭✭
    Re: Refractometers to measure battery specific gravity?
    WYsolar wrote: »
    So...I went with this temp compensated bulb hydrometer : http://www.summitracing.com/parts/OTC-4619/ for <$15 shipped to me. .
    Thanks for the link & post.
    I too just purchased a spare . My 1960's one has been great , but !! Best to have a spare.

    VT
  • Ralph DayRalph Day Solar Expert Posts: 876 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?

    From the 1960's??!! How have you ever made one last that long? You must be very careful with them. My spares usually get sold, loaned or given to some needy nooby so there's never a spare around;)

    Ralph
  • WYsolarWYsolar Solar Expert Posts: 31
    Re: Refractometers to measure battery specific gravity?

    I tried my new hydrometer and it seems to work ok. The floating vial tends to tip over all the time so that its top contacts the side of the main glass tube when taking a reading. I hope this is not causing serious inaccuracies. Is this a common problem? I suppose the more expensive hydrometers have some kind of bushing to keep the vial centered in the main tube.

    Oh well. This one appears to be built well and is better that the 4-ball type I had before....
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Refractometers to measure battery specific gravity?
    WYsolar wrote: »
    I tried my new hydrometer and it seems to work ok. The floating vial tends to tip over all the time so that its top contacts the side of the main glass tube when taking a reading. I hope this is not causing serious inaccuracies. Is this a common problem? I suppose the more expensive hydrometers have some kind of bushing to keep the vial centered in the main tube.

    Oh well. This one appears to be built well and is better that the 4-ball type I had before....

    Normal operation.
    If they put a bushing in it there would be even more friction and the reading would be less accurate.
    The most important aspect of using a hydrometer is to take readings on the batteries when new and fully charged and compared subsequent readings to that (as well as cell to cell). In the end the actual numbers don't matter as much as it's all relative. Getting hung up on differences between your readings as the standard specs or fretting over 0.005 variations will drive you crazy. SG readings, like all the other numbers in the system, need a certain amount of +/- tolerance.
  • CDN_VTCDN_VT Solar Expert Posts: 492 ✭✭✭
    Re: Refractometers to measure battery specific gravity?
    Ralph Day wrote: »
    From the 1960's??!! How have you ever made one last that long? You must be very careful with them. My spares usually get sold, loaned or given to some needy nooby so there's never a spare around;)

    Ralph

    Very Lucky

    The glass hydro was bought in 1969 from Motor Car Parts on 2nd ave Vancouver. Still have the warranty card 8) and still in the original box .
    ~~~~~~~~~~~~~~~~~~~
    Like everything , touch / understanding is SO important, Im old and still learning .

    VT
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    WYsolar wrote: »
    The floating vial tends to tip over all the time so that its top contacts the side of the main glass tube when taking a reading. I hope this is not causing serious inaccuracies. Is this a common problem?

    Yes. I think it is the main reason why some folks prefer refractometers.
    In the end the actual numbers don't matter as much as it's all relative. Getting hung up on differences between your readings as the standard specs or fretting over 0.005 variations will drive you crazy. SG readings, like all the other numbers in the system, need a certain amount of +/- tolerance.

    Good advice, but the problem with hydrometers is repeatability. The important thing is: can you measure a cell, walk away for a minute, then come back and measure the same cell and get the same reading? If you can do that, the hydrometer is a good thing.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Refractometers to measure battery specific gravity?
    vtmaps wrote: »
    Yes. I think it is the main reason why some folks prefer refractometers.



    Good advice, but the problem with hydrometers is repeatability. The important thing is: can you measure a cell, walk away for a minute, then come back and measure the same cell and get the same reading? If you can do that, the hydrometer is a good thing.

    --vtMaps

    I can get the same reading two days in a row, never mind two minutes. :D
    That's another thing; once the system works, it works. You'd be amazed at how little significant variation in SG there is on a good working system.
  • unicorniounicornio Solar Expert Posts: 217 ✭✭
    Re: Refractometers to measure battery specific gravity?

    I do not like the method of the refractometer, take a sample and put it on the refractometer is not reliable for me ... cleaning whenever the refractometer is also not a practical matter ...I bought one (very expensive) and do not use it because I do not feel comfortable taking a drop and coming out at the sun to read it, I can't see the density if it's nighttime and my suffering eyestrain for each check ...and not seem to have very good feng-sui having sulfuric acid near the eye, or look at a drop of sulfuric acid with your eye!...hehehehe

    I think it's more accurate to upload a couple of times the hydrometer (to remove the electrolyte), measure the density (*write it!!!) and empty well, and go to the next cell, and once finished put it in a glass of distilled water and rinse a couple of times ...

    There are many types of hydrometer ... the classics may be fine, but nevertheless there have been great advances in this field (thank goodness) and now there are some that measure consistently and with total repeatability ...

    8<

    Attachment not found.
    This is a Spanish (Catalan) award-winning invention, based on magnetic performance and temperature compensation ... has a good scale that can be read easily, but you need to give each measure tapped by the result may be masked by the presence of bubbles if you're not careful when loaded with electrolyte ...
    http://www.antoni-vilas.com/antoni-vilas/e_prod_frames1.htm

    8<

    Attachment not found.

    but I really like this density meter, has a very broad scale and therefore very good resolution and easy to read ... is swiss made and is supposed to have some temperature compensation, plus which is not affected too much by the bubbles...simply because there are no bubbles!...and is indestructible, made ​​of long-lasting plastic, compact and robust ... if dropped, the only problem may be that you splashing of acid! ...;-)

    I just had to change the plastic tube for one more long, since the two that come in the box are short for the size of our batteries...

    There is an explanation of its operation, the electrolyte slowly enters the measuring chamber ...:
    http://www.technical-design.de/advantages.html

    in Spain sells it our outback official representative (who else? ...;-)
    here's a brochure with images:
    http://www.technical-design.de/hydro_prospekt_en.pdf

    after spend half a lifetime to be measuring densities, measuring something different each time, this surprised me for its accuracy, consistency and repeatability ...I found it thanks to my friend Stephen! ... he had one of these and I thought his performance was very curious ... finally a breakthrough has been there and know that you can work with ...

    I always recommend this to my clients, what happens is that maybe it is not getting easier to find someone to sell over there, so I recommend from here to Northern Arizona Wind & Sun attempts in their distribution in America, I think is a great product ...;-)

    *to measure densities is more important notebook and pencil that densimeter!...;-)
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Refractometers to measure battery specific gravity?
    unicornio wrote: »
    I do not like the method of the refractometer, take a sample and put it on the refractometer is not reliable for me ... cleaning whenever the refractometer is also not a practical matter ...I bought one (very expensive) and do not use it because I do not feel comfortable taking a drop and coming out at the sun to read it, I can't see the density if it's nighttime and my suffering eyestrain for each check ...and not seem to have very good feng-sui having sulfuric acid near the eye, or look at a drop of sulfuric acid with your eye!...hehehehe



    Attachment not found.

    but I really like this density meter, has a very broad scale and therefore very good resolution and easy to read ... is swiss made and is supposed to have some temperature compensation, plus which is not affected too much by the bubbles...simply because there are no bubbles!...and is indestructible, made ​​of long-lasting plastic, compact and robust ... if dropped, the only problem may be that you splashing of acid! ...;-)

    I just had to change the plastic tube for one more long, since the two that come in the box are short for the size of our batteries...

    There is an explanation of its operation, the electrolyte slowly enters the measuring chamber ...:
    http://www.technical-design.de/advantages.html

    in Spain sells it our outback official representative (who else? ...;-)
    here's a brochure with images:
    http://www.technical-design.de/hydro_prospekt_en.pdf

    after spend half a lifetime to be measuring densities, measuring something different each time, this surprised me for its accuracy, consistency and repeatability ...I found it thanks to my friend Stephen! ... he had one of these and I thought his performance was very curious ... finally a breakthrough has been there and know that you can work with ...

    I always recommend this to my clients, what happens is that maybe it is not getting easier to find someone to sell over there, so I recommend from here to Northern Arizona Wind & Sun attempts in their distribution in America, I think is a great product ...;-)

    *to measure densities is more important notebook and pencil that densimeter!...;-)
    I want to thank you guys for posting about this Hydrometer. I found them in Germany. After 40 years of checking SG's this the easiest to use and read. It's fool proof. Delivered to the USA it's a little pricey, but worth every penny even if the shipping is outrageous..

    http://seekpart24.com/hella/tester-battery-8pd006541001?c=702970

    From the Pictures it's hard to tell what your getting, The tester is about 4" x 5 " and the Dials are 2 " in Diameter. The Squeeze Bulb is EDM Rubber and won't give up over time, it's large and easy to use. One squeeze and the chamber is full. The graduations on the Dial are so easy to read, you just cannot go wrong. The way it is Temperature Compensated, is built into the rotation of the dials. This was invented for " Murphy " so even I can use it.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    I want to thank you guys for posting about this Hydrometer. I found them in Germany. After 40 years of checking SG's this the easiest to use and read. It's fool proof. Delivered to the USA it's a little pricey, but worth every penny even if the shipping is outrageous..
    http://seekpart24.com/hella/tester-battery-8pd006541001?c=702970

    Bc04, thanks for the link to seekpart24.com, I spent an hour trying to find one after Unicornio posted about it, but couldn't find anywhere to buy it (in a language I can read). How much is it delivered to US? Maybe I can get NAWS to import them...

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Refractometers to measure battery specific gravity?
    vtmaps wrote: »
    Bc04, thanks for the link to seekpart24.com, I spent an hour trying to find one after Unicornio posted about it, but couldn't find anywhere to buy it (in a language I can read). How much is it delivered to US? Maybe I can get NAWS to import them...

    --vtMaps
    It was 45,00 EUROS. Todays rate $58.00 or so. It was the shipping of $29,00 that is a killer.

    Here is something I added to my original post in case you missed it.

    "From the Pictures it's hard to tell what your getting, The tester is about 4" x 5 " and the Dials are 2 " in Diameter. The Squeeze Bulb is EDM Rubber and won't give up over time, it's large and easy to use. One squeeze and the chamber is full. The graduations on the Dial are so easy to read, you just cannot go wrong. The way it's made Temperature Compensation, is built into the rotation of the dials. This was invented for " Murphy " so even I can use it. "

    Here is a PDF. you can see a better picture of it. They come in two colors, Blue and Red, The Hella is Blue and private branded.

    http://www.technical-design.de/hydro_prospekt_en.pdf
    .
    .
  • larcallarcal Registered Users Posts: 43 ✭✭
    Re: Refractometers to measure battery specific gravity?

    So, I hate hydrometers, even the #11 freas model. Many years on batteries and never could get readings I really felt sure about, what with floats sticking etc, even when taking all that time to flush hydrometer several times. Mainly just relied on cell voltage differences.

    So got an Eichart refractometer awhile back for around $135.00 and it's a totally different world. Fast easy accurate. Check a cell 10 times and it's allways the same. Considering the cost of batteries, it's way worth it. Wish I'd known before. Don't know why all those early HP editions and other authors in 80's 90's didn't mention them.
  • BB.BB. Super Moderators, Administrators Posts: 28,613 admin
    Re: Refractometers to measure battery specific gravity?

    I think somebody here said their Refractometer needed a known SG electrolyte to calibrate the meter... (had to use electrolyte because distilled water was off scale as I recall).

    What has been your experiences with the Refactometer?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RybrenRybren Solar Expert Posts: 348
    Re: Refractometers to measure battery specific gravity?

    I use a refractometer to measure the salinity of my salt-water aquariums. Calibration to a known standard is critical to getting an accurate reading.

    Here's a link to a great article on calibration. It's geared toward measuring salinity, but the same principles apply.

    http://reefkeeping.com/issues/2006-12/rhf/

    The author, Randy Holmes-Farley, is a PhD in chemistry and a leading authority in reefkeeping and biochemistry.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    larcal wrote: »
    Many years on batteries and never could get readings I really felt sure about, what with floats sticking etc, even when taking all that time to flush hydrometer several times.
    <snip>
    So got an Eichart refractometer awhile back for around $135.00 and it's a totally different world. Fast easy accurate. Check a cell 10 times and it's allways the same.

    I feel the same as you about hydrometers... I worry about repeatability. I have used refractometers and prefer them to hydrometers, but I haven't yet purchased a refractometer. In my research the Misco unit looks promising. It has a lighted viewfinder and it claims readability to 0.005. Has anybody used a Misco refractometer? Do you like it?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Ralph DayRalph Day Solar Expert Posts: 876 ✭✭✭✭
    Re: Refractometers to measure battery specific gravity?
    I think somebody here said their Refractometer needed a known SG electrolyte to calibrate the meter... (had to use electrolyte because distilled water was off scale as I recall).

    Yep, that was me. Refractometer when zero-ed with distilled water reads SG low. I have a sample of 1.265sg electrolyte as my control. Test it, zero to it and all is well. How did I get my control you ask? Measured sample with good old float hydrometer.

    Ralph
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