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leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

Batteries and hydrometers

With a hydrometer is it possible to measure the pH of the electrolyte in a gel or AGM battery?

Assuming you are prepared to drill battery case.

Brendan

23rd Mar 2011 8:18am

Paul_1978

Member Since: 08 Nov 2009
Location: South Yorkshire
Posts: 384

I thought a Hydrometer measured the alcohol content of a fluid, weather its water or home brew.

To measure pH you need some small strips of test paper which turn a different colour for differnet pH's.

23rd Mar 2011 8:28am

party monkey

Member Since: 31 Dec 2010
Location: Oxon.
Posts: 1311

2005 Defender 110 Td5 XS CSW Cairns Blue

Paul_1978 wrote:
I thought a Hydrometer measured the alcohol content of a fluid, weather its water or home brew.

To measure pH you need some small strips of test paper which turn a different colour for differnet pH's.

Yep, I've got a very simple Hydrometer to measure the specific gravity (density) of liquids...from this you can work out the alcohol content using a conversion table

Is it Litmus paper for measuring Ph??? .... Although i think you can also buy a PH meter too. Sure I read that somewhere when I was trying to make cider from the bumper crop of apples we had last year

Jon - 110 td5 [sold]. Currently Defenderless.

Last edited by party monkey on 23rd Mar 2011 8:46am. Edited 1 time in total

23rd Mar 2011 8:37am

Paul_1978

Member Since: 08 Nov 2009
Location: South Yorkshire
Posts: 384

Thats it, Litmus paper.

Goes red in acid, green for neutral and somet

for alkaline, but the colour is read off on a chart which tells you the pH.

23rd Mar 2011 8:41am

party monkey

Member Since: 31 Dec 2010
Location: Oxon.
Posts: 1311

Blue for Alkaline I think.....

Weyhey.... I knew that chemistry A level would come in handy.... Only taken 22 years to find an application for it Jon - 110 td5 [sold]. Currently Defenderless.

23rd Mar 2011 8:46am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

Doooh yes hydrometer measures specific gravity.

So back to basic question can you use a hydrometer to measure specific gravity of the electrolyte in a gel or AGM battery?

It is a long, long time since I did chemistry!

Brendan

23rd Mar 2011 8:57am

party monkey

Member Since: 31 Dec 2010
Location: Oxon.
Posts: 1311

I don't see any reason why not....

BUT based on my limited experience of them.... the one I've got is cheap and cheerful and not terribly accurate (fine for home brew where you just want to get the SG to stabilise but thats about it).

I'm guessing that you'd need something that would be able to monitor fairly small fluctuations in the SG during the battery charge/discharge cycle..... Sounds like a digital jobby to me.....but i've not got the first clue on them.

Would Optima be able to help you out with a meter ? Jon - 110 td5 [sold]. Currently Defenderless.

23rd Mar 2011 9:27am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

I am used to density columns Slightly more accurate then the standard hydrometer but is aimed at solids. Basically measure a range of about 0.1 over a metre column

Am having a discussion with someone who says use a hydrometer on a sealed battery. I argue that a hydrometer is not suitable in a gel battery or a good AGM battery as there is no free electrolyte in liquid form to be sucked up into a hydrometer. Or have I made a basic mistake in either use of a hydrometer or the 'physical state' of electrolyte in a gel/AGM battery

As for Optima batteries, there is a reason why we sell Odyssey batteries

However that is a different story

Brendan

23rd Mar 2011 9:48am

party monkey

Member Since: 31 Dec 2010
Location: Oxon.
Posts: 1311

Whoops

Optima / Odessey - sorry, knew it began with an 'O'

Have neither so can't comment

I see where you're coming from now with regard to the debate and must admit I didn't read your post properly so kinda skipped over gel/agm and just read electrolyte and the ability to measure the SG of the 'liquid'

I can see that could be a problem in a gel battery, where don't they add something to thicken the electrolyte to a 'gel' but I thought an agm battery's electrolyte was still liquid...

Sorry mate, I'm stumped - call Odessey

Jon - 110 td5 [sold]. Currently Defenderless.

23rd Mar 2011 10:11am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

Odyssey says

Quote:
Q. Are these a gel cell? What’s the difference?
A. No, the ODYSSEY battery is NOT a gel cell. It is an absorbed electrolyte type battery, meaning that there is no free acid inside the battery; all of the acid is kept absorbed in the glass mat separators. These separators serve to keep the positive and negative plates apart.

The key difference between the gel cell and the absorbed glass mat (AGM) cell lies in the fact that in the AGM cell all of the electrolyte is in the separator, whereas in the gel cell the acid is within the cells in a gel form. In fact, if the ODYSSEY battery were to split open, there would be no acid spillage!

Hence my argument in that you can not use a hydrometer to measure SG of the electrolyte in a AGM battery.

However someone disagrees with me. (Yes I do at times get things wrong and misunderstand things) Am trying to understand if it is possible or wether the other person has got hold of the wrong end of the hydrometer.

Me? I am old enough and daft enough to ask questions if I don't understand something

Brendan

PS Have used Optimas in the past, now all our Land Rovers have Odysseys fitted

23rd Mar 2011 10:21am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

Have spoken to a technical guy. When I explained the situation to him he just laughed and ask what drugs the guy was on!

Apparently if you split an Odyssey battery open, you will find all the lead plates in some 'wadding' which is virtually dry to the touch. i.e. no free acid and so hydrometer is of no use whatsoever in this case.

Brendan

23rd Mar 2011 8:54pm

party monkey

Member Since: 31 Dec 2010
Location: Oxon.
Posts: 1311

So.... armed with this info....

Ask the guy to buy an Odessey batttery from you and then demostrate how it would work with a hydrometer. If he can prove it works... give him a free battery.. If he can't.... well .... he's just fooked his £200+ battery trying to prove the point.

UNLESS of course he's a very GOOD customer, then I'd just tell him you spoke to technical.

Jon - 110 td5 [sold]. Currently Defenderless.

23rd Mar 2011 10:31pm

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