Calibrate your Hydrometer

Rngr275
Rngr275 Solar Expert Posts: 127 ✭✭
in Off Grid Solar & Battery Systems #1
I have been wanting to find a refernce source to calibrate/check my hydrometer. I did not want something hazardous. So I dug into my old Handbook of Chemistry and Physics to find a solution that would have an SG/density in the correct range. I think I found the perfect solution ( pun intended! :D). A 50/50% solution of sucrose (table sugar) and distilled water should yeild an SG of 1.2317. If you want you can bump up the wt% of the sugar to 56% and it will yeild an SG of 1.2654. A couple of points. This is by weight so you need to weigh both the water and sugar as closely as possible. You may also need to heat the solution to ensure that the sugar is completely disolved. I will be mixing a batch and test it with my Hydro and then test the solution here at work to double check. FYI a 1% change in WT% gives about a 0.01 change in SG in the range we are concerned with......
now back to your regulary scheduled program....
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #2
    Re: Calibrate your Hydrometer

    Hey, for the bargin basement price of $148.98, you could send you hydrometer off to be calibrated. :cool:

    http://www.coleparmer.com/Product/NIST_Traceable_Calibration_Hydrometer_with_test_data_one_point_midpoint_of_Hydrometer_s_range/YO-17107-00
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #3
    Re: Calibrate your Hydrometer

    I would worry about contaminating the battery cell...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #4
    Re: Calibrate your Hydrometer
    Rngr275 wrote: »
    I have been wanting to find a refernce source to calibrate/check my hydrometer. I did not want something hazardous. So I dug into my old Handbook of Chemistry and Physics to find a solution that would have an SG/density in the correct range. I think I found the perfect solution ( pun intended! :D). A 50/50% solution of sucrose (table sugar) and distilled water should yeild an SG of 1.2317. If you want you can bump up the wt% of the sugar to 56% and it will yeild an SG of 1.2654. A couple of points. This is by weight so you need to weigh both the water and sugar as closely as possible. You may also need to heat the solution to ensure that the sugar is completely disolved. I will be mixing a batch and test it with my Hydro and then test the solution here at work to double check. FYI a 1% change in WT% gives about a 0.01 change in SG in the range we are concerned with......
    now back to your regulary scheduled program....

    Sugar is not absolutely dry, so you would need to dry it first, for example keep it at 105C for few days (not more, or it'll burn). Even if you fo that, it'll suck in some moisture from the air fairly quickly. Then you would have to weight it very precisely. Most likely, you do not have scales that are capable of such measurement. Then you will have to warm it to make a solution. When you be cooling it, it's likely to become crystallized at the edges before it reaches 25C. And finally, the solution might have very high viscosity, and it will be impossible to use hydrometer.

    You should be able to buy a calibration acid solution with known SG.

    Or, you can use any acid solution, measure a fixed volume and weight it. This way you will know the exact SG of the solution and can calibrate your hydrometer against. However, this again will require precise scales.

    Or, you can buy a hydrometer which is already calibrated. Although that may not be easy. I tried to find a precise hydrometer, but I couldn't.
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  • Rngr275
    Rngr275 Solar Expert Posts: 127 ✭✭
    #5
    Re: Calibrate your Hydrometer

    As with all things there are limits:
    Sucrose will react with Sulfuric Acid so rinsing the hydrometer thoroughly would be required. A post rinse with Acetone wouldn't hurt.

    While sucrose does hold water on the surface of the molecule I doubt that a scale that reads to the hundereds of a gram (0.01g ) would be able to discern the difference between dry and "Wet" sugar. Of course if you have an analytical scale that can weigh to the submicrogram level then yes you would indeed see a difference. At 50 wt% I don't think that the sugar solution will be saturated enough to recrystalize ... but I don't know for sure. I will check it out.



    It is all about the precission you are looking for. I wanted a quick check to make sure that my hydrometer was in the right range... for me +-0.005 which I can read easily on mine.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #6
    Re: Calibrate your Hydrometer
    Rngr275 wrote: »
    At 50 wt% I don't think that the sugar solution will be saturated enough to recrystalize ... but I don't know for sure. I will check it out.

    depends very much on the temperature. If it gets too cool you will make rock candy inside your hydrometer. --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Calibrate your Hydrometer

    Glycerin has a specific gravity of 1.263 - pretty darn close to electrolyte solution, your don't have to mix it up, and it's available at most chemists/pharmacies/drug stores.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #8
    Re: Calibrate your Hydrometer

    Rngr275: perhaps you might be interested in this post I sent about a type of hydrometer that is my favorite, and I think that needs no calibration as this is very well built to be stable and accurate even suffering bumps and drops ...

    http://forum.solar-electric.com/showthread.php?17274-Refractometers-to-measure-battery-specific-gravity&p=132335#post132335

    Blackcherry04 and others have found it here :http://seekpart24.com/hella/tester-battery-8pd006541001?c=702970

    hope this help!...
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #9
    Re: Calibrate your Hydrometer

    I'm skeptical about this.

    In their docs they mention high precision, but do not really specify what the precision is. If the scale is 0.005, it doesn't mean it's precise to 0.005. I tried a hydrometer with similar construction. It was very easy to use and read, but also incredibly inconsisent.

    Their other product, with plastic floater, which is supposed to automatically adjust for temperature, has a scale of 0.02. If you're so imprecise, why would you ever care about temperature compensation?

    Their third product claims to accurately predict state of charge by measuring voltage immediately after the load has been removed. I don't think it's possible with any degree of accuracy.

    It doesn't seem like this company is making seriously precise instruments.

    Anyone did any tests with these hydrometers comparing them to conventional ones?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Calibrate your Hydrometer

    It's all relative anyway.
    Charge the batteries when new before use. Check the SG of every cell. EQ if they are not consistent. Write it down.
    From then on you are judging against the original numbers anyway.
    If you keep your batteries in a consistent environment (as you should) and check the readings under like conditions (as you should) the actual numbers that come up are not as important as how they compare to the baseline figures.

    Specific gravity will vary with temp, barometric pressure (altitude), state of charge, and age. Becoming obsessed with readings to the third decimal place is unhealthy for the mind. Not so much so for the batteries. Differences big enough to indicate problems will be evident even without temp compensation.

    Or so I have found over the past few decades and hundreds of batteries in different applications.
    (Your actual results may vary. Void where prohibited. Not an offer that can be made by formal prospectus only. Closed course/professional driver. Et cetera.)
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #11
    Re: Calibrate your Hydrometer
    Cariboocoot wrote: »
    Specific gravity will vary with temp, barometric pressure (altitude), state of charge, and age. Becoming obsessed with readings to the third decimal place is unhealthy for the mind.

    I absolutely agree. When you have a good experience and done this many times, you know what's important and know what to look at.

    However, when you have absolutely no prior experience and spend good amount of money on batteries you need to take care of, things are different. When tech support tells you that your new batteries are in a very bad condition because your SG is 1.248 (and 1.255, or even 1.253 would be good), you would think that precision of your hydrometer is a thing of the foremost importance.

    Anyway, the hydrometer of a similar construction (with a wheel) that I tried, was very inconsistent. You take one sample - 1.275, you take another one from the same cell - 1.230. May be it was broken. I decided to stay with the regular one.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #12
    Re: Calibrate your Hydrometer
    Rngr275 wrote: »
    I have been wanting to find a refernce source to calibrate/check my hydrometer. I did not want something hazardous. So I dug into my old Handbook of Chemistry and Physics to find a solution that would have an SG/density in the correct range. I think I found the perfect solution ( pun intended! :D). A 50/50% solution of sucrose (table sugar) and distilled water should yeild an SG of 1.2317. If you want you can bump up the wt% of the sugar to 56% and it will yeild an SG of 1.2654. A couple of points. This is by weight so you need to weigh both the water and sugar as closely as possible. You may also need to heat the solution to ensure that the sugar is completely disolved. I will be mixing a batch and test it with my Hydro and then test the solution here at work to double check. FYI a 1% change in WT% gives about a 0.01 change in SG in the range we are concerned with......
    now back to your regulary scheduled program....
    You cannot generate precision from imprecise measurements. Even discounting effects others have mentioned (water of hydration of the sugar crystals, temperature of the solution, etc.), you would have to weigh the water and sugar to the same number of known significant figures (in this case, five, which means six with the last SF estimated) as that of the SG you are trying to generate. 56% won't do, it has to be 56.0000 +/-0.0005%.

    You would have to do it with a very precise scale or with very large quantities of sugar and water. Either way it's not going to be cheap or easy.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #13
    Re: Calibrate your Hydrometer

    I have two of the Hydro's Volts that Unicornio was talking about. I have found them to be very accurate. The way it's made with two dials is different from most. The one dial has the scale on it, it's weighted on the bottom where it always stays level. The second wheel has the mark on it and rotates to line up on the scale. They are both fully submerged in the electrolyte. There are NO bubbles to give you faulty readings and there is nothing floating on the surface.

    If a hydrometer only had one dial you could never get accurate readings, because you'd never get it level. The ones with the floating needles can't be trusted. Even with the way they are made, you have to draw up some electrolyte to get the temperature of the hydrometer to equalize, then draw the test sample.
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #14
    Re: Calibrate your Hydrometer

    The Hydrovolt is a very good piece of kit we use them and sell them at www,prismsolar.co.uk , I saw on the other thread relating to the Hydrovolt that some one imported one to the USA from Germany for 44 euros plus shipping........seeems a bit expensive, we sell them at 19,99 euros. They are accurate but the no bubbles thing is not quite correct even if you cant see them they are there. especially on charging or recenly charged banks, so a quick single flick of a finger wants the unit is full of acid gives a shock release, lust like soda in a glass and insures accurate readings time and time again, I sent some of these to Midnight Solar for evaluation a while back. You guys who tread there might see if they are intending to stock them.
    Ive had the same unit for 3 years and it sees more action on a weekly basis that most owners would do in a month or two, across many types of FLA batteries from many manufacturers hasnt given me a false call yet.They are extremly easy to use and even easier to read.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #15
    Re: Calibrate your Hydrometer

    Blackcherry04, I completely agree with you, I too have found that this type of densimeter is accurate, robust, reliable and convenient to use ... besides being cheap and durable ...
    the density measurement involves some difficulties, beyond the type of densimeter we are using, should be taken into account,but in the end the most important of the density measurement is to check that all vessels have the same density, beyond the number that we get ...

    for those seeking a more precise and advanced densimeter:
    Attachment not found.

    you can buy here, if you have so much money...;-)
    http://www.testequipmentdepot.com/sbs/sbs-3500.htm

    I've checked the HydroVolt, comparing it with one of these, (which costs more than a four thousand of bucks) and the result is very satisfactory, measuring almost the same ...
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #16
    Re: Calibrate your Hydrometer

    Hi Uni C I think Stephen introduced you to these, guess where he got them from, always a pleasure to supply you at installer prices,
    stictly this side of the pond as not to upset the host,:blush:
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #17
    Re: Calibrate your Hydrometer

    Don't worry--Our host just does not want to end up hosting free advertising for people that do not support the community here.

    Folks who participate here, and answer questions with links to our host's, or other sites (or even their own on occasion), is fine.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #18
    Re: Calibrate your Hydrometer
    nigtomdaw wrote: »
    Hi Uni C I think Stephen introduced you to these, guess where he got them from, always a pleasure to supply you at installer prices,
    stictly this side of the pond as not to upset the host,:blush:

    yeah!...Stephen (Stephendv) showed me this densimeter ... hehehe
    and i always be grateful with him...
    Stephen (and blackswan555, Tim) has been testing a arduino based optical densimeter, which was in the middle of their development, and does not seem to work very well yet ... maybe they can tell us how it goes now ...;-)

    here are:
    http://www.casanogaldelasbrujas.com/blog/2011/01/31/sg-data-logger-first-steps/

    Attachment not found.


    nigtomdaw, thanks so much for your offer!...:-)
    but here, in spain, the outback representative (Gimborntrading) sell it for 14€ + IVA
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #19
    Re: Calibrate your Hydrometer
    BB. wrote: »
    Don't worry--Our host just does not want to end up hosting free advertising for people that do not support the community here.

    Folks who participate here, and answer questions with links to our host's, or other sites (or even their own on occasion), is fine.

    yeah ... I know we are in good hands here!...;-)
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #20
    Re: Calibrate your Hydrometer

    19.99 is retail......:D
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #21
    Re: Calibrate your Hydrometer
    NorthGuy wrote: »
    Anyway, the hydrometer of a similar construction (with a wheel) that I tried, was very inconsistent. You take one sample - 1.275, you take another one from the same cell - 1.230. May be it was broken. I decided to stay with the regular one.

    This has been my experience with swing-arm type hydrometers for aquarium use. It doesn't take much of an air bubble to throw the reading significantly off.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #22
    Re: Calibrate your Hydrometer
    nigtomdaw wrote: »
    19.99 is retail......:D

    well, Nigel!...you are living in spain, our prices will be the same!... :-)
    I have been watching your web server and I think that we are in the same boat! ...hehehehe
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #23
    Re: Calibrate your Hydrometer
    unicornio wrote: »
    Stephen (and blackswan555, Tim) has been testing a arduino based optical densimeter, which was in the middle of their development, and does not seem to work very well yet ... maybe they can tell us how it goes now ...;-)

    Hehe, yes it has come full circle, I bought the hydrometer from Nigel.. and then recommended it to you :)
    Regarding the arduino project, it is dead in the water. The manufacturers of the digital SG sensor could not get it out of the prototype phase because of reliability problems. If you find a digital SG sensor with a voltage output, please let me know.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #24
    Re: Calibrate your Hydrometer
    stephendv wrote: »
    Hehe, yes it has come full circle, I bought the hydrometer from Nigel.. and then recommended it to you :)
    Regarding the arduino project, it is dead in the water. The manufacturers of the digital SG sensor could not get it out of the prototype phase because of reliability problems. If you find a digital SG sensor with a voltage output, please let me know.

    hi, stephen!...hehehehe
    very good story!... only need to know where Nigel find this very good instrument!...and if Gunter from gimbortrading find if thanks to Nigel too?...;-)
    meanwhile, thanks so much, Nigel!...;-)))))

    remember how i was following with illusion your perseverance to make work this realtime densimeter? ... que tiempos aquellos!!! ...jejejeje

    Attachment not found.
    Attachment not found.
    Attachment not found.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #25
    Re: Calibrate your Hydrometer

    Oh my, sounds like we all have the Hydro Flu and caught it from each other, but I think it started in Spain. For the record, I heard about it here and found that distributor in Germany. I paid $12,00 & $14,00 euros for them ( The Blue one marked " Hella " cost more ). The problem in the pricing came from the fact they have a shipping deal with DHL Transportation and that is they only ship through them and they charge a brokerage fee. The shipping to the USA is $29,00 euros. ( rip off )

    Even though they were pricey, they work and are easy to use. Most of the batteries I have to work on are on a Boat and stuffed into a compartment and the Hydro Volt makes it easy to do.

    A big Thank You to who ever found them ........ lol
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #26
    Re: Calibrate your Hydrometer

    While we are all coming clean, I want to say I am the one who assembled the first " BAT TEMP " tm. It was created to solve a problem I had when Equalizing Batteries in my Cooling Tank. I am posting it here so anyone can knock it off, if they feel the need for one.

    I cannot take total credit for this idea, I saw one on a RV site that was a copper lug with a thermometer attached to it, for $20.00. What can I say, he's making $14.00 for everyone he sells.

    Mine's a cheap Chinese Digital Thermometer , a spare battery cap and a glass tube. In choosing the cap one must be careful to find one that glass tube will not interfere with the venting of the cell. The glass tube must be long enough to be immersed into the electrolyte, but not long enough to damage the plates. I made mine so the glass tube is adjustable and can be slid up or down for the depth in the cap, just touching the plates. This IMPORTANT you will damage your battery and short it out if you allow it to be jammed into the plates.

    A picture is worth a 1,000 words, enjoy if you need one. I also think a RTS / BTS could be adapted to fit a cap or maybe a new thermistor installed.

    Attachment not found.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #27
    Re: Calibrate your Hydrometer
    Blackcherry04 wrote: »
    Oh my, sounds like we all have the Hydro Flu and caught it from each other, but I think it started in Spain. For the record, I heard about it here and found that distributor in Germany. I paid $12,00 & $14,00 euros for them ( The Blue one marked " Hella " cost more ). The problem in the pricing came from the fact they have a shipping deal with DHL Transportation and that is they only ship through them and they charge a brokerage fee. The shipping to the USA is $29,00 euros. ( rip off )

    Even though they were pricey, they work and are easy to use. Most of the batteries I have to work on are on a Boat and stuffed into a compartment and the Hydro Volt makes it easy to do.

    A big Thank You to who ever found them ........ lol

    yeah ... this is one of the good things that you find in your life ... after years using all kinds of hydrometers, more expensive and cheaper, suffering finally to determine which is the true density, the first time that use this I was pleasantly surprised ...

    I have (well, i have five densimeters) another developed in Spain (Catalonia) who also put in the post, which is also pretty good, and pricely (60euros) but it has nothing to do, this is brilliant! ... ;-)

    I am radically fanatic of the people who do things right, like I say, "proudly made ​​with love", and can not stand mediocrity ... ( I'm too old for now! ...;-)
    and in fact I wish that the manufacturer knew all we're talking about your meter, the engineers who designed it ... etc, but unfortunately we often we die without realizing the good things that other people think of us ... hehehehe
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #28
    Re: Calibrate your Hydrometer

    http://www.youtube.com/watch?v=BkUBffSv2O0

    Enjoy Nigel...No regrets:p
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #29
    Re: Calibrate your Hydrometer
    nigtomdaw wrote: »
    http://www.youtube.com/watch?v=BkUBffSv2O0
    Enjoy Nigel...No regrets:p

    very good the videos of Tom Carpenter, who looks good, of course...he living in hawaii!!!.... hehehehe
    So at Midnite also liked the hydrovolt, and they know very well the matter! ... lol
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #30
    Re: Calibrate your Hydrometer

    Id buy a case of 12 , but trying to find them on the posted website as Tom Carpenter say's , is hidden well.
    The Midnight address also posted is just around the corner from the WA house in Arlington.

    VT
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #31
    Re: Calibrate your Hydrometer

    Try sending a PM to image.php?u=517&dateline=1218042272 nigtomdaw...

    And Nigel, you are welcome to put a link to your website in your signature.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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