Accurate Hydrometer?

[scottsAI]

Anybody buy one of these?:

http://cgi.ebay.com/ebaymotors/Battery-Fluid-Tester-Hydrometer-Thermometer-Set-OTC_W0QQcmdZViewItemQ



Q_trksidZp1713Q2em153Q2el1262QQcategoryZ35625QQihZ020QQitemZ300261924058QQtcZphoto

Any good?

Thanks.

Have fun,

Scott.

[bob g]

no i have not bought one yet, but that will soon be rectified

thanks for the tip

bob g

[scottsAI]

Yes, it does look good.

I wrote a list of what I wanted in a Hydrometer... has it for $10.50!

Wanted to know if anybody used one, does it live up to the add?

If you get one let me know how it works!-)

Have fun,

Scott.

[wpowokal]

accurate and affordable do not fit well with me even in the current meltdown. I am constantly distressed by ppl wanting a Roals Royce for the cost of a "####". While you may get lucky, one has to pay for quality.

OK Allan steps down off his soap box.

Concidering, all sales garbage asside, specific gravity is the only real measure of how your wet cell batteries are coping, a quality hydromiter is a good investment for those living off grid. Voltage alone is not relevent enough.

allan down under

allan down under

[TheCasualTraveler]

     The hydrometer in that link looks like the same model I bought from NAPA, It is glass, well made with temp. compensation scale and works just fine. It is not one of the cheap plastic ones with floating balls or a crappy sidewinder needle. If there is something that works better than that I don't know what it is.

[bob g]

reportedly it is an "OTC" tool

as such it will be everybit as good as any you will find, and vastly better

than all the consumer grade junk.

OTC markets professional grade tooling to professional mechanics, manufacturing and industry.

you won't find one any more accurate, at least more accurate save for one needed by a highly skilled research scientist where precision to .000000005 is necessary. even then there is likely something other that would be used, and suffice it to say it probably would cost the government 1000's of dollars.

like i said, i would go for it if i were you,,, and i did,,its on its way.

bob g

[scottsAI]

Wpowokal,

accurate and affordable do not fit well with me even in the current meltdown.

I have learned price does not guarantee quality.

Frequently price is not indicative of quality.

If I needed a Roals then I would buy it assuming I could afford it.

SG is important, requires better than 5 floating balls, yes, yes.

Do I need 0.001 accuracy? NO.

Do I need better than 0.1 accuracy. Yes.

Do I need 0.01. maybe not, but sounds good.

I have learned to understand what I need and buy nothing better for the price.

Inexpensive harbor fright tools (HFT) DVM compared to my HP 5.5 digit lab DVM both have the same reading for the numbers displayed, compared 5 or so meters (I keep giving them to friends, keep a couple in my car). Looking at $2.09 post, some people have problems with them. I know the leads are cheap and fail after a few years... not a problem, the better DVM have cheap leads also. The accuracy has been fine for what I need. If better accuracy is required I use the HP meter. I turn it on quarterly to keep it working.

I like the HFT DVM, if I loose one I don't spend much time looking for it, just grab another from the bag of 10 from the last sale at $1.99!

I cant buy a set of test leads for that!

Have fun,

Scott.

[electrak]

Ok as a research tech, accuracy is having the absolote number, precession is having the same number over and over, some of the glass float hydrometers with the paper inside, the paper can shift, there goes accuracy, your precession remains, if you are comparing your batteries to your batteries "accuracy" does not mater as much.

[zeusmorg]

 This is the type of hydrometer that I would recommend for wet cell battery testing.

Having a thermometer attached makes temperature scaling easier.

 I'm actually quite surprised at the price usually a glass tubed hydrometer goes for around $50. USD.

 NEVER buy a ball floating type or the ones with the floating arrow. They are NOT accurate and just a waste of money. their readings can vary so dramatically you may as well lick two fingers and touch the terminals to determine your charge.(not recommended btw)

 Want to check the accuracy of your hydrometer? Distilled(pure) water has a SG reading of 1.000 @70 F 21.1C

[zeusmorg]

 CORRECTION that should read: 1.000 @ 60 F 15.55 C

Deg F      Adjustment to Reading

40.     Subtract .002
    
50.     Subtract .001
    
60.     CORRECT
    
70.     Add .001
    
80.     Add .002
    
90.     Add .004
    
100.     Add .005
     
110.     Add .007
     
120.     Add .008
     
130.     Add .010
     
140.     Add .013
     
150.     Add .015
     

[scottsAI]

Zeusmorg,

How to calibrate if the scale is 1.1 to 1.3?

Have fun,

Scott.

[wpowokal]

Scott each to their own.

Electrak makes a very relevent statment, if one was to take a SG reading after a 4-5 hour equalising charge and use that as the benchmark then the accuarcy of the reading may not matter, but then that assumes the batterie/s are in good order.

I log the SG of one of my batteries each morning, it's not the highest or lowest just my baromiter. After an equalising charge it will read 1.255, im happy if it reads 1.25 in the morning, if they have been under heavy load with little overnight recharge it could be 1.24.

I have learnt to interprit the SG of my batteries against what power has been taken out. That last 0.005 is expensive to put in due to charge efficiences at the top end, particually if being suplied by non Re. Sandia National Laborities posted a good artical on top end efficiency.

So is accuracy important, maybe not, but a reading to 3 decimal places is important to me. Fortunatly I live in a climate where temperature in my battery room does not vary much, so I ignore temperature correction.

When I started out I had a chart that said at 'x' SG my batteries would be a cetrain % charged, never had much relevence to my batteries. I have made a diary entry of one bank of my batteries under a C10 discharge if anyone wants to see how SG changes with discharge.

I paid $45 Australian for my hydrometer, is it highly accurate, I don't know but I do know it reads vastly different from the cheep one I had and gives me repeatable readings. Batteries are expensive so I try to look after mine, for 20 year old batteries they do me well.

allan down under

[scottsAI]

Wpowokal, I think its good we are talking about this, others can read and see different points and decide what works for them, not a one sided recommendation!

Congratulations on taking great care of a battery, 20 years is not easy.

Sandia National Laboratories, I think that is where I got my numbers.

I have 8 golf cart batteries, only 3 years old, not used a hydrometer, yet. Only used for back up, not daily cycled! So not a good example of battery care. (not the sealed LAB battery I just fired).

Not willing to pay 12% of the battery cost on a tool do not need. If I cycle the battery daily I would think differently! Yet If a tool comes along capable of doing the job cheaply then I am game. Wasted more time than its worth looking, but that is part of the fun.

In the Navy I took care of a 1Mw battery, took daily SG readings on two cells of a 120's battery.

For fun we would look at the logs and predict the SG reading. 3 digits.

After an equalizing charge took all cell data, added water etc. then compared all cells to our reference cells. Took forever! Had to lay on top of the battery to take readings.

As you mention the relative accuracy is what's important.

If I take a reading today, will I get the same tomorrow? (same conditions).

Your readings sound like they did not agree with manufactures... typical.

And, support my point. Un-necessary accuracy is wasting money if there is a cost to it. The cheap Hydrometer will give the same accuracy from the start.

Function of the float is fixed once manufactured, adjust your readings based on knowledge of your battery and work from there, much as you have been doing.

Why pay $60 when a temperature compensated one is only $10.50.

Just so you know I will wait to hear from Bob if its any good!-)

Have fun,

Scott.

[simonbrookes]

I have used one of these http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=150298061357  for many years and got very good results. If you look around you can get them for half this much, from good car shops. I don't know if the reading has to be adjusted due to temp.

[scottsAI]

Did it come in yet?

How is it?

Scott.