Best type of hydrometer

[russ_drinkwater]

A stupid question, but I am after the most accurate tool for reading the SG in my batteries.
I have numerous analog hydrometers but would like a more accurate tool.
Suggestions please?

I am aware of the midnite refractometer!

[Westbranch]

You want a digital unit?  ie electronic , not the type you have to read a dial or float on?

sorry cant get to the MN site it now is locked down adn I can't get in???        

The requirement appears to be a spoof.....

ITEM:  MNHYDROMETER

http://www.midnitesolar.com/productPhoto.php?product_ID=505&productCatName=Battery%20Accessories&productCat_ID=39&sortOrder=1&act=p

[tecnodave]

@Russ_drinkwater,

First off , the MNHYDROMETER is not a refractometer! It is a float on arm specific gravity reader,
It compares the weight of the acid with water as the reference point (1.000)


Roninair, a U.S. based company is marketing a refractometer on Amazon for about $38 USD,
I have used these and they are probably more accurate than an average hydrometer but there is little difference with using either this unit or a high quality hydrometer.

The one shortcoming of most hydrometers is lack of temperature correction for the float readings.
This is dealt with in lab grade instruments that have a temp. float


I have an U.S. NAVY WWII submarine B battery (high voltage radio battery) hydrometer that has been the best I've seen yet,
Very accurate with 4 floats in the set, it is a precision lab grade unit, one float is a thermometer to accurately assess the acid temp. and the other three are for different acidity ranges......did you know that weaker acid is used in the tropics and conversely stronger acid is used in the artic.....we used 1.320 S.G. Acid at Alaska Husky Battery Co. in Fairbanks, Alaska!....used only in winter to start and run your car at 70 below!....we stored them in a cool place for the summer!.....it gets over 100 degrees F in Fairbanks in the summer!

I use a standard automotive grade hydrometer for bulk readings.....it is a fine line etched glass tube type with accurate graduations every .005 .....purchased at a more professional auto parts house for about $10.00......I break a few of them now and then,   If I see trouble I break out the better hydrometer, the Navy one

I am sure that lab supply houses carry these (lab grade units)

To get th most accurate readings I let the acid sit for at least an hour to settle before I take readings and discard the first few readings to get the hydrometer stabilized to the acid temp.

Thinking about it from your side...shipping,etc, the Robinair would be much less expensive than the lab hydrometer


I admit I am very old school....born in backwoods remote Alaska in the 40's. Tinkered electricity since I was little guy. We were way,way off grid......Budda putter fuel generator and paddle wheel in willow creek

Hope this helps.....td

[CDN-VT]

Dave post a link on the Roninair, a U.S. based company is marketing a refractometer on Amazon for about $38 USD,


I have 2 of the red MN ones , I CAN READ them
Old eyes HATE small print .
I do have a  real good one & on compare , there close 2% +

VT

[russ_drinkwater]

Thanks for the replies. Pity you did not get the sub batteries with the hydrometer! I will have a look on amazon.
I have 4 different configs of float hydrometers and was just trying to get the most accurate reading I could.
We were pretty backwoods here when I was kid. Petrol/kero lister single cylinder motor, 32 volt aircraft geny, 6 x 6 volt rubber cased batteries. Was like that until I was 11 years old. My dad was amazed at what we were doing with solar here when I started to get into it.
How could so much power be made just from sunlight/Uv.

[TomW]

Back when we had the farm and the lead acid batteries, I grabbed a Robinair refractomer type.

It seemed pretty good but I have since read that type can be inaccurate so who knows?

I liked that it needed no temperature compensation as the fluid acquired the testers' temp. It seemed easy to read for me. Only needs a drop of the electrolyte as well.

This is the one I got:

http://www.amazon.com/Robinair-75240-Coolant-Battery-Refractometer/dp/B000HTNODE?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage

[tecnodave]

Russ,

TomW and I bought the same one and I do like it but I am not convinced that it is more accurate than a good hydrometer.    That is my opinion , but realize, I am way old school, been doing FLA. batteries for over 50 years but I'm not such an old fart I won't tinker with the new stuff, I have LiPo's installed in my older NiCad powered Panasonic power tools. I use an iCharger i208B to charge all types of batteries ( not main solar system) as battery or as cell by cell. 

Maybe VT's old eyes and mine have gone the opposite ways...it's easier for me to see the float, but I have not had the MidNite hydrometer

I avoid the plastic hydrometer as too cheap and flimsy to be reliable for such a big investment but I look for a finely graduated glass float in tube type, my auto parts dealer does the many large farms around here so does stock and sell better quality units but the auto industry is throw away these days so people do the least maintaince possible.

td

[russ_drinkwater]

Got a couple of refractometers coming. Evil bay here was way cheaper than amazon. yeah life comes full circle at times.
From when I was born we had lead acid batteries for power. Then we had grid power, plus ever increasing costs. And now I have returned to
batteries after 50 years! Dad was pretty neglectful with the cleaning of the batteries and they must have gassed and bubbled out a lot with
the old aircraft geny. I can remember as a kid the white crud everywhere on the wood and asbestos battery bench. Not sure what losses the old lead joining straps had, but they looked mean. 1 1/2 inches wide and 1/2 inch thick.